Department of Chemistry and Physics

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A HPLC-MS/MS method for screening of selected antibiotic adulterants in herbal drugs
(The Royal Society of Chemistry, 2022) Mwankuna Christopher Johnson; Uwamaliya Grâce Ange; Mariki Eliapenda Elisante; Mabiki Faith; Malebo Hamisi M.; Mdegela Robinson; Styrishaveb Bjarne
The use of herbal products adulterated with conventional drugs increases the risk of developing microbial resistance and causes herb-to-drug interaction, leading to severe clinical consequences. The complex nature of herbal products has been a challenge for the unambiguous identification of adulterants. The improved analytical selectivity and sensitivity of hyphenated techniques such as high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) enable the confirmatory screening of adulterants in herbal products. Simultaneous screening of adulterants is necessary and efficient because it has been established that more than one chemical adulterant may be present in one herbal product. An HPLC-MS/MS method for the simultaneous detection and quantification of amoxicillin, ampicillin, metronidazole, ciprofloxacin, sulfamethoxazole, and trimethoprim in powdered herbal drugs was developed. Deuterated metronidazole-d3, trimethoprim-d3, ciprofloxacin-d8, and sulfamethoxazole-d4 were used as internal standards (ISs). For each analyte, two transitions were monitored using protonated molecules as precursor ions. The extraction of analytes from herbal products was performed using a simple methanol : water : formic acid (90 : 10 : 0.05, v/v) extraction solvent. Chromatographic separation was done in a gradient of 0.01% formic acid in methanol and 0.01% formic acid in MilliQ water. The calibration curves were linear (r2 $ 0.996) over the range of 0.005–2.5 mg mL 1 for all compounds except metronidazole, whose range was 0.005–1 mg mL 1. The limit of detection (LOD) ranged from 0.012 to 0.046 mg mL 1, while the limit of quantification (LOQ) ranged from 0.066 to 0.153 mg mL 1. The accuracy, expressed as the recovery of spiked herbal products, ranged from 45% to 114%. The precision, expressed as relative standard deviation (RSD) at two concentration levels, ranged from 1.6% to 15.9%. The matrix effect expressed as the matrix factor (MF) ranged from 0.79 to 0.92. The developed method was applied to powder herbal products purchased in Tanzania. Amoxicillin, ampicillin, trimethoprim, sulfamethoxazole, and ciprofloxacin were not detected in all samples. Metronidazole was detected in eight samples with the highest concentration of 1.38 mg g 1. The developed method is suitable for the detection of all the studied antibiotic adulterants in herbal products. Quantification can be performed for all the compounds except ciprofloxacin due to its lower recovery.
A new ellagic acid rhamnoside and other biologically active compounds from roots and stems of Synadenium Glaucescens pax
(Sokoine University of Agriculture, 2023-05) Rwegoshora Frank
Medicinal plants have been used as a source of drugs and drug templates. The extracts of Synadenium glaucescens Pax (SG) from roots and stems contain bioactive secondary metabolites against bacterial and viral infections. However, majority of its pure compounds were uncharacterized and their phytochemical profiles in different phytogeographical regions were unknown. Therefore, this study aimed at characterization of more compounds which are promising drug leads. Furthermore, the study investigated the phytochemical profiles of SG from three regions of Tanzania. Samples of SG were collected from Njombe, Morogoro and Tanga regions as representatives of three phytogeographical zones of Tanzania. All sample were dried in a cold and dark room between 15 to 18 oC at the Tanzania Tree Seed Agency-Morogoro. Samples were pulverized using a laboratory milling machine (Christy Hunt Engineering Ltd, England) to afford approximately 1 mm particles’ size. The isolation of pure compounds involved root barks and stem barks of SG from Njombe. Phytochemical profiling involved five parts (root barks, root wood, stem barks, stem wood and leaves). Sample extraction was done by total maceration using either methanol or ethanol. Fractionation of the crude extracts was done through vacuum Liquid chromatography in solvent gradient systems from Hexane, ethyl acetate/ dichloromethane and finally methanol/ ethanol. Concentration of extracts was done using rotary evaporator at <60 oC. Isolation of pure compounds was done by column chromatography in a solvent gradient system. A single spot on the thin layer chromatography plate in both treatments was an indicator for a pure compound. Structures of compounds were elucidated through (1D and 2D) of a 600 MHz Bruker Avance III HD nuclear magnetic resonance (NMR) machine. Confirmation of structures involved LC/GCMS, FTMS-ESI, NIST library and in comparison, to the literature. The SciFinder database was used for reference of a new compound. The processing NMR spectral data was performed using Bruker TopSpin 3.6.2 while compound structures were drawn in ChemDraw Professional 16.0. Biological activities involved cytotoxicity and antibacterial tests of pure compounds. Cytotoxicity studies were done using Brine shrimp assay involving Artemia salina cysts which were hatched and used within 24 hours of incubation. The varying concentrations (2400- ȝJ PO LQ P/ RI % v/v DMSO were employed in duplicate. 7KH FRPSRXQGV¶ concentration killing 50 % of the nauplii larvae was determined. An In vitro antibacterial efficacy of pure compounds was done by using microtitre plate assay. Four standard strains of bacteria were used (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC51559, Escherichia coli ATCC25922 and Pseudomonas aeruginosa ATCC 27853. The activities of the compounds were evaluated using the observed MIC values. Determination of the phytochemical profiles on the thin layer FKURPDWRJUDSK\ SODWHV XVHG DQ RSWLPDO ȝ/ YROXPH RI mg/mL. The number of compounds were recorded at 254nm, 365nm of an ultraviolet lamp and after colour reaction. Data from the thin layer chromatography were analysed in JMP statistical software. A total of fifteen (15) compounds were isolated and elucidated. A new ellagic acid rhamnoside 3',4'-di-O- methylellagic acid-4-Į-L-rhamnopyranoside, 28 mg (32) was isolated as greyish powder. it showed high res. FTMS-ESI- of 476.0921 and melting point of 251.0~ 252.7 oC. Other known phenolics 3,4,3'-tri-O-methylellagic acid, 14 mg (33), hemicosanylferulate,65 mg (34) and octacosylferulate, 19 mg (35) were also isolated. The study also led to isolation of two hydrocarbons from the root barks: 1-nonacosene, 11 mg (38), and hexacosane,173 mg (39) and one fatty acid from the stem barks; hexacosanoic acid, 26 mg (40). The isolated triterpenoids include Lupeol, 65 mg (18) from the stem barks, euphol, 1855.5 mg (28) from both roots and stem barks, epifriedelanol, 167 mg (36) from both roots and stem barks and a steroid ȕ-sitosterol 64 mg (30) from the root barks. Cytotoxicity tests indicated that all the tested compounds were non-toxic (LC50 ! ȝJ P/) up to a maximum tested FRQFHQWUDWLRQ RI ȝJ P/ Octacosylferulate demonstrated strong activity against S. aureus (MIC= 0.125 mg/mL) Phytochemical screening by TLC indicated a significant variation in concentration and distribution of compounds in SG among the three regions (p< 0.0001). Njombe registered the highest number of compounds (mean= 12.4000) while Morogoro had the least of all (mean= 9.7000). Euphol, a triterpenoid in root barks was detected to be at the highest concentration in Tanga and the lowest in Morogoro. Derivatives of ellagic acid were detected in root barks at all ages and locations. The results also indicated continuous disappearance of red fluorescing compounds in stems barks and leaves as the plant age increased. The number of compounds increased with age while the optimal age for a maximum number of phytochemicals was 3 to 4.5 years. Furthermore, the stem barks registered the highest number of phytochemicals (>15). A new compound: 3',4'-di-O-methylellagic acid-4-Į-L- rhamnopyranoside along with 14 other known compounds were isolated from root and stem barks of SG. The isolated compounds during this study represent six major groups of secondary metabolites of pharmacological importance which are Phenolics, triterpenoids, steroids, long chain hydrocarbons, long chain amine and Fatty acids. This new compound is suggested to serve as a marker for standardization and quality control of any formulation from the root barks of S. glaucescens Pax.
Activity of sterols isolated from the leaves of commiphora swynnertonii (Burtt) against some nosocomial infectious bacteria
(The Journal of Phytopharmacology, 2022-09-04) Credo, David; Mabiki, Faith P.; Machumi, Francis; Chacha, Musa; Cornett, Claus
Commiphora swynnertonii (Burtt) is traditionally used for medicinal purposes both in humans and animals in Tanzania. Previously, its leaves extract has been demonstrated antibacterial activity. However, there is limited information on identification of pure compounds responsible for its observed antibacterial activity. Therefore, this study was conducted to isolate and evaluate antibacterial activity of pure compounds isolated from its leaves extract. Colum chromatographic separation of its dichloromethane leaves extract afforded the isolation of two sterols namely, Cholest-7-en-3β-ol (1) and β-sitosterol (2). Their structures were deduced by using NMR data experimentally obtained and comparison with spectral data available in literatures. The sterols were evaluated for activity against four nosocomial infectious bacteria namely; Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa to determine Minimum Inhibitory Concentrations (MIC) by broth microdilution method. Cholest-7-en-3β-ol (1) demonstrated strong activity against S. aureus (MIC= 0.5 mg/ml) and weak activities (MIC >2mg/ml) against other bacteria. β-sitosterol (2) exhibited weak activities (MIC >2mg/ml) against all tested bacteria. Therefore, presence of antibacterial active compound(s) such as Cholest-7-en-3β-ol (1) among others in the leaves of C. swynnertonii can justify its earlier reported antibacterial activity and further confirms the claimed traditional uses of this plant in the treatment of bacterial infections.
Analytical methods for screening and determination of conventional drugs adulterated in herbal products
(Sokoine University of Agriculture, 2023) Mwankuna Christopher Johnson
Herbal products are popular worldwide. Their popularity is threatened by untrustworthy manufacturers who add conventional drugs. The addition of conventional drugs increases the risk of developing antimicrobial resistance and herb-drug interactions. To safeguard the users and enhance the safety of herbal products, analytical methods for screening and determining conventional drugs adulterated in herbal products are required. Therefore, this study was carried out to develop analytical methods and apply them in screening and determination of antibiotic, antimalarial, pain killer and erectile dysfunction adulterants in herbal products. Thin layer chromatography methods for screening twelve conventional drugs in herbal products were developed and applied. The analytes were extracted from herbal products using a solvent mixture of acetonitrile:methanol:acetic acid:water (4:4:1:1, v/v). The mobile phase consisting of dichloromethane:ethyl acetate:methanol (75:15:10, v/v) separated well trimethoprim, sildenafil, paracetamol and sulfamethoxazole. Pyrimethamine, metronidazole and sulfadoxine were well separated by dichloromethane:ethyl acetate:methanol (77.5:12.5:10, v/v). In addition, acetyl salicylic acid, ibuprofen, diclofenac, quinine and lumefantrine were well separated by ethyl acetate:methanol:30% ammonia (75:22.5:2.5, v/v). Chromatographic separations were highly reproducible and more than 10 samples were analysed in one run. The developed methods were used to screen 229 herbal products. Consequently, 24.0% of the samples contained one adulterant while 21.4% contained at least two adulterants. A high performance liquid chromatography–tandem mass spectrometry method was developed and used for screening and determining six conventional antibiotics (amoxicillin, ampicillin, metronidazole, trimethoprim, sulfamethoxazole, v and ciprofloxacin) in herbal products. The developed method had linear (r2 ≥ 0.996) calibration curves over the range of 0.005–2.5 µg mL–1 for all compounds except metronidazole, whose range was 0.005–1 µg mL–1 . The limit of detection ranged from 0.012 to 0.046 µg mL–1 while the limit of quantification ranged from 0.066 to 0.153 µg mL–1 . Accuracy, expressed as recovery of spiked herbal products ranged from 45% to 114%. The precision expressed as relative standard deviation at two concentration levels ranged from 1.6% to 15.9%. The matrix effect, expressed as matrix factor ranged from 0.79 to 0.92. The developed method was used to analyse 78 herbal products purchased from Njombe, Morogoro, Manyara, Arusha, Mwanza and Dar es Salaam in Tanzania. Metronidazole was detected in eight samples with the highest concentration of 1.38 µg g–1 . Another high performance liquid chromatography–tandem mass spectrometry method was developed and used to screen and determine eleven conventional antimalarials (chloroquine, quinine, sulfadoxine, pyrimethamine, mefloquine, lumefantrine, amodiaquine, artemisinin, dihydroartemisinin, artesunate and artemether) in herbal products. The developed method had linear (r2 ≥ 0.991) calibration curves over the range of 0.001–0.3 µg mL–1 for all compounds. The limit of detection ranged from 0.002 to 0.02 g mL–1 while the limit of quantification ranged from 0.006 to 0.08 g mL–1 . Accuracy, expressed as recovery of spiked herbal products ranged from 52% to 128%. The precision, expressed as percent relative standard deviation at two concentration levels, ranged from 1.0% to 13.8%. The matrix effect, expressed as the matrix factor ranged from 0.77 to 0.97. The developed method was used to analyse 50 herbal product samples from Njombe, Morogoro, Manyara, Arusha, Mwanza and Dar es Salaam in Tanzania. Ten of the herbal products were found to contain amodiaquine, sulfadoxine, pyrimethamine, mefloquine, dihydroartemisinin, artemether and lumefantrine. Herbal products are popular worldwide. Their popularity is threatened by untrustworthy manufacturers who add conventional drugs. The addition of conventional drugs increases the risk of developing antimicrobial resistance and herb-drug interactions. To safeguard the users and enhance the safety of herbal products, analytical methods for screening and determining conventional drugs adulterated in herbal products are required. Therefore, this study was carried out to develop analytical methods and apply them in screening and determination of antibiotic, antimalarial, pain killer and erectile dysfunction adulterants in herbal products. Thin layer chromatography methods for screening twelve conventional drugs in herbal products were developed and applied. The analytes were extracted from herbal products using a solvent mixture of acetonitrile:methanol:acetic acid:water (4:4:1:1, v/v). The mobile phase consisting of dichloromethane:ethyl acetate:methanol (75:15:10, v/v) separated well trimethoprim, sildenafil, paracetamol and sulfamethoxazole. Pyrimethamine, metronidazole and sulfadoxine were well separated by dichloromethane:ethyl acetate:methanol (77.5:12.5:10, v/v). In addition, acetyl salicylic acid, ibuprofen, diclofenac, quinine and lumefantrine were well separated by ethyl acetate:methanol:30% ammonia (75:22.5:2.5, v/v). Chromatographic separations were highly reproducible and more than 10 samples were analysed in one run. The developed methods were used to screen 229 herbal products. Consequently, 24.0% of the samples contained one adulterant while 21.4% contained at least two adulterants. A high performance liquid chromatography–tandem mass spectrometry method was developed and used for screening and determining six conventional antibiotics (amoxicillin, ampicillin, metronidazole, trimethoprim, sulfamethoxazole, v and ciprofloxacin) in herbal products. The developed method had linear (r2 ≥ 0.996) calibration curves over the range of 0.005–2.5 µg mL–1 for all compounds except metronidazole, whose range was 0.005–1 µg mL–1 . The limit of detection ranged from 0.012 to 0.046 µg mL–1 while the limit of quantification ranged from 0.066 to 0.153 µg mL–1 . Accuracy, expressed as recovery of spiked herbal products ranged from 45% to 114%. The precision expressed as relative standard deviation at two concentration levels ranged from 1.6% to 15.9%. The matrix effect, expressed as matrix factor ranged from 0.79 to 0.92. The developed method was used to analyse 78 herbal products purchased from Njombe, Morogoro, Manyara, Arusha, Mwanza and Dar es Salaam in Tanzania. Metronidazole was detected in eight samples with the highest concentration of 1.38 µg g–1 . Another high performance liquid chromatography–tandem mass spectrometry method was developed and used to screen and determine eleven conventional antimalarials (chloroquine, quinine, sulfadoxine, pyrimethamine, mefloquine, lumefantrine, amodiaquine, artemisinin, dihydroartemisinin, artesunate and artemether) in herbal products. The developed method had linear (r2 ≥ 0.991) calibration curves over the range of 0.001–0.3 µg mL–1 for all compounds. The limit of detection ranged from 0.002 to 0.02 g mL–1 while the limit of quantification ranged from 0.006 to 0.08 g mL–1 . Accuracy, expressed as recovery of spiked herbal products ranged from 52% to 128%. The precision, expressed as percent relative standard deviation at two concentration levels, ranged from 1.0% to 13.8%. The matrix effect, expressed as the matrix factor ranged from 0.77 to 0.97. The developed method was used to analyse 50 herbal product samples from Njombe, Morogoro, Manyara, Arusha, Mwanza and Dar es Salaam in Tanzania. Ten of the herbal products were found to contain amodiaquine, sulfadoxine, pyrimethamine, mefloquine, dihydroartemisinin, artemether and lumefantrine.
Analytical methods for screening and determination of conventional drugs adulterated in herbal products
(Sokoine University of Agriculture, 2023-05) Mwankuna Christopher Johnson
Herbal products are popular worldwide. Their popularity is threatened by untrustworthy manufacturers who add conventional drugs. The addition of conventional drugs increases the risk of developing antimicrobial resistance and herb-drug interactions. To safeguard the users and enhance the safety of herbal products, analytical methods for screening and determining conventional drugs adulterated in herbal products are required. Therefore, this study was carried out to develop analytical methods and apply them in screening and determination of antibiotic, antimalarial, pain killer and erectile dysfunction adulterants in herbal products. Thin layer chromatography methods for screening twelve conventional drugs in herbal products were developed and applied. The analytes were extracted from herbal products using a solvent mixture of acetonitrile:methanol:acetic acid:water (4:4:1:1, v/v). The mobile phase consisting of dichloromethane:ethyl acetate:methanol (75:15:10, v/v) separated well trimethoprim, sildenafil, paracetamol and sulfamethoxazole. Pyrimethamine, metronidazole and sulfadoxine were well separated by dichloromethane:ethyl acetate:methanol (77.5:12.5:10, v/v). In addition, acetyl salicylic acid, ibuprofen, diclofenac, quinine and lumefantrine were well separated by ethyl acetate:methanol:30% ammonia (75:22.5:2.5, v/v). Chromatographic separations were highly reproducible and more than 10 samples were analysed in one run. The developed methods were used to screen 229 herbal products. Consequently, 24.0% of the samples contained one adulterant while 21.4% contained at least two adulterants. A high performance liquid chromatography–tandem mass spectrometry method was developed and used for screening and determining six conventional antibiotics (amoxicillin, ampicillin, metronidazole, trimethoprim, sulfamethoxazole, and ciprofloxacin) in herbal products. The developed method had linear (r2 ≥ 0.996) calibration curves over the range of 0.005–2.5 μg mL–1 for all compounds except metronidazole, whose range was 0.005–1 μg mL–1. The limit of detection ranged from 0.012 to 0.046 μg mL–1 while the limit of quantification ranged from 0.066 to 0.153 μg mL–1. Accuracy, expressed as recovery of spiked herbal products ranged from 45% to 114%. The precision expressed as relative standard deviation at two concentration levels ranged from 1.6% to 15.9%. The matrix effect, expressed as matrix factor ranged from 0.79 to 0.92. The developed method was used to analyse 78 herbal products purchased from Njombe, Morogoro, Manyara, Arusha, Mwanza and Dar es Salaam in Tanzania. Metronidazole was detected in eight samples with the highest concentration of 1.38 μg g–1. Another high performance liquid chromatography–tandem mass spectrometry method was developed and used to screen and determine eleven conventional antimalarials (chloroquine, quinine, sulfadoxine, pyrimethamine, mefloquine, lumefantrine, amodiaquine, artemisinin, dihydroartemisinin, artesunate and artemether) in herbal products. The developed method had linear (r2 ≥ 0.991) calibration curves over the range of 0.001–0.3 μg mL–1 for all compounds. The limit of detection ranged from 0.002 to 0.02 g mL–1 while the limit of quantification ranged from 0.006 to 0.08 g mL–1. Accuracy, expressed as recovery of spiked herbal products ranged from 52% to 128%. The precision, expressed as percent relative standard deviation at two concentration levels, ranged from 1.0% to 13.8%. The matrix effect, expressed as the matrix factor ranged from 0.77 to 0.97. The developed method was used to analyse 50 herbal product samples from Njombe, Morogoro, Manyara, Arusha, Mwanza and Dar es Salaam in Tanzania. Ten of the herbal products were found to contain amodiaquine, sulfadoxine, pyrimethamine, mefloquine, dihydroartemisinin, artemether and lumefantrine. The developed thin layer chromatography and high performance liquid chromatography–tandem mass spectrometry methods are considered valuable tools for a better understanding of the adulteration of herbal products by addition of conventional drugs. The thin layer chromatography methods can be used for preliminary screening of herbal products prior to confirmation by other techniques such as high performance liquid chromatography–tandem mass spectrometry. On the other hand, confirmation and quantification of the selected antibiotic and antimalarial adulterants in herbal products can be achieved using the developed high performance liquid chromatography–tandem mass spectrometry methods.
Analytical methods for screening and determination of conventional drugs adulterated in herbal products
(Sokoine University of Agriculture (SUA), 2023-05) Mwankuna Christopher Johnson
Herbal products are popular worldwide. Their popularity is by untrustworthy manufacturers who add conventional drugs. The addition of conventional drugs increases the risk of developing antimicrobial resistance and herb-drug interactions. To safeguard the users and enhance the safety of herbal products, analytical methods for screening and determining conventional drugs adulterated in herbal products are required. Therefore, this study was carried out to develop analytical methods and apply them in screening and determination of antibiotic, antimalarial, pain killer and erectile dysfunction adulterants in herbal products
Antibacterial effects of single and combined crude extracts of synadenium glaucescens and commiphora swynnertonii
(2022) Ochollah, G, Mary; Olsen, E, John; Mdegela, H, Robinson; Kusiluka, J.M, Lughano; Mabiki, P, Faith; Msengwa, S, Zaituni
Background: Synadenium glaucescens and Commiphora swynnertonii are among the reported plants used traditionally for treatment of bacterial infections. This study reports antibacterial effects of single and combined extracts from leaves, stem and root barks of Commiphora swynnertonii and Synadenium glaucescens. Materials and Methods: Plants were collected from Manyara and Njombe regions in Tanzania. Extraction was done using dichloromethane and methanol. The extracts were assessed for antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa). Minimum Inhibitory Concentrations (MIC) was determined by broth microdilution, while Fractional Inhibitory Concentration (FIC) indices were calculated from MIC values of combined extracts to determine combination effects. Results: Strong antibacterial activities were demonstrated by all extracts of S. glaucescens (MIC 0.011-0.375mg/mL) against Gram-positive bacteria and methanol extracts of C. swynnertonii (MIC 0.047-0.375mg/mL). Synergistic effect was observed when combining methanol extracts of C. swynnertonii stem bark with S. glaucescens leaves against S. aureus (∑FIC 0.5), Other synergistic effects were observed against E. faecalis with dichloromethane extracts of C. swynnertonii stem bark and S. glaucescens stem bark (∑FIC 0.5), and C. swynnertonii root bark and S. glaucescens root bark (FIC index 0.3). For the remaining combinations, mainly additive effects were observed. Conclusion: Synergistic effects on bacteria were observed by combining different plant parts of S. glaucescens and C. swynnertonii suggesting that it could be beneficial to combine such extracts when used for antibacterial purposes.
Assessing significance of community documented climate impacts and adaptation preferences and options in the lake victoria region, Tanzania
(Ethiopian Journal of Environmental Studies & Management, 2017-02-13) Elisante, E.; Tungaraza, C.
The study was conducted in Ukerewe Island in the Lake Victoria, Tanzania in order to ascertain the communities’ awareness on climate change impacts and adaptation/coping strategies. The methodology involved randomly selected 420 people mostly farmers and fishermen who were interviewed and involved in focus groups. It was observed that communities were aware of the changes in climatic parameters consequently impacting their livelihood. The most significant impacts were scarcity of water and poor crop production which received 100% support of the respondents. Other impacts included the change of water quality of the Lake Victoria (94.5%) and loss of biodiversity (35.7%). On the non-climatic factors, the major concern was on population growth (98.3%), loss of soil fertility (96%) and deforestation (84.8%). Of the suggested adaption options, provision of alternative food crops and fertility improvement to increase production were highly supported with highest total score of 48 on an arbitrary total assessment scale of maximum of 50. This was also observed on fish farming activities. The observations highlighted gender-based labour division imbalance where women and children were shown to shoulder the burden. It can be concluded that communities in the Lake Victoria region are affected by multiple impacts related to climate and also those not related to climate. Under various impacts communities set their own coping and adaptation strategies based on importance to livelihood. However, there is a need for proper guidance on how adaptation strategies are being executed.
Assessment of sources and transformation of nitrate in groundwater on the slopes of Mount Meru, Tanzania
(Springer, 2015-09-21) Elisante, Eliapenda; Muzuka, Alfred N. N.
The stable isotope compositions of nitrogen-nitrate ( 15 N-NO 3 ) and oxygen-nitrate ( 18 O-NO 3 ), and concentration of nutrients (NO 3 - , NH 4 ? , NO 2 - , PO 43- ) for water samples collected from springs, shallow wells and boreholes during dry and wet seasons were used to inves- tigate sources and biogeochemical transformation of NO 3 - in groundwater along the slopes of Mount Meru. About 80 % of all water sources had nitrate concentration higher than background concentration of 10 mg/l during both seasons, while NH 4 ? and NO 2 - concentrations were very low probably due to nitrification. Concentrations of NO 3 - above 50 mg/l were observed in some water sources. Concentrations of PO 43- in all groundwater sources were very low during the two seasons owing to dilution and adsorption. The d 15 N-NO 3 - for boreholes waters averaged ?11.6 ± 2.1 and ?10.7 ± 2.1 % during dry and wet seasons, respectively. Similarly, the d 18 O-NO 3 - of bore- hole waters for the wet and dry seasons averaged ?5.2 ± 1.3 and ?4.6 ± 1.9 %, respectively. With regard to dug wells, the d 15 N-NO 3 - of well water averaged ?13.3 ± 2.5 and ?12.5 ± 2.3 % during dry and wet seasons, respectively, while the d 18 O-NO 3 - for the wet and dry seasons averaged ?7 ± 2.3 and ?6.4 ± 2.1 %, respectively. The d 15 N-NO 3 - , for springs averaged ?11.2 ± 2.2 % during dry season and ?11.7 ± 3.5 % during wet season whereas the d 18 O-NO 3 - for the wet and dry seasons averaged ?7.3 ± 3.6 and ?5.9 ± 2.6 %, respectively. The isotopic data suggested that the source of NO 3 - in the water sources are dominated by sewage and/or animal manure and to less extent, soil organic N. Few samples collected in close proximity of manure heaps and sanitary facilities had d 15 N values between 16 and 20 %suggesting occurrence of denitrification.
Bacteriostatic and haemolytic activities of extracts and compounds of commiphora swynnertonii
(Research Journal of Pharmacognosy, 2023) Msengwa, Zaituni; Credo, David; Mafuru, Magesa; Mwesongo, James; Mabiki, Faith Philemon; Mwang’onde, Beda John; Mtambo, Madundo Mkumbukwa; Kusiluka, Lughano Jeremy; Mdegela, Robinson Hammerthon; Olsen, John Elmerdahl
Background and objective: Commiphora swynnertonii (Pax) is used in traditional medicine to treat infectious diseases. Previous studies have reported antimicrobial activity of this plant; however, the activity of compounds that are present in extracts of this plant has not been thoroughly documented. Likewise, the primary mode of action (bactericidal or bacteriostatic) and the possible toxicity on red blood cells have not been reported. Methods: Extracts of leaves, whole root, root bark, root wood, whole stem, stem bark and stem wood, were produced using hexane, dichloromethane, methanol and water. Cold and hot extraction methods were employed. Antibacterial activity of extracts was tested against selected medically important Gram-positive and Gram-negative bacteria by growth inhibition, minimum inhibitory concentrations and time kill assays. Moreover, haemolytic activity against sheep red blood cells was determined in vitro. Results: The hexane extracts of whole root and root bark, methanol extracts of root wood, and dichloromethane extracts from the leaves of C. swynnertonii inhibited the growth of S. aureus. MIC values for the extracts and compounds, indicated moderate activity against Gram-positive bacteria (Staphylococcus aureus, Streptococci species and Enterococci species) while the activity against Gram-negative bacteria (Escherichia coli, Klebsiella species, Pseudomonas aeruginosa, Salmonella species, Shigella sonnei and Yersinia enterocolitica) was weak. Time kill profiles showed the extracts have bacteriostatic activity against S. aureus, and low haemolytic effect, except for extracts of whole root and leaves at the concentration of 1000 μg/mL. Conclusion: Extracts of C. swynnertonii showed bacteriostatic activity against Gram-positive bacteria with low toxicity on red blood cells.
Comparison of two models in the estimation of nitrogen uptake rates using data from 15-N incubation experiments
(nstitute of Oceanology PAS, 2005-08-16) Tungaraza, Clavery; Brion, Natacha; Baeyens, Willy
This paper compares two uptake rate models, Dugdale & Goering’s (D&G) model and Elskens’ model. The aim is to provide an insight into how estimates of uptake processes, i.e. regeneration and loss rates from both dissolved and particulate nitrogen pools, influence the total uptake rates when the two models are compared. The uptake rates of three nitrogenous nutrients (nitrate, ammonium and urea) from 15-N incubation experimental data were compared. The comparison indicated that the D&G model underestimated nitrate uptake rates by about 34%, implying a significant regeneration and loss rates of the nutrient. Elskens’ model further showed that the loss rates from the dissolved phase were about 40% and 25% for the ammonium and urea pools, respectively, indicating that the D&G model underestimated the experimental uptake rates of the nutrients. On average, nitrification made up about 30% of the total ammonium uptake flux, whereas the sinks from particulate nitrogen and dissolved nitrogen were estimated at 36% and 56%, respectively. The D&G model sometimes overestimated the f -ratio values to about 60% and higher as a result of ammonium and urea uptake rates underestimation. This paper also shows that detritus adsorption, bacterial uptake and cell lysis are equally important processes.
Contamination and health risk assessment of heavy metals in selected highly edible fish species from lake Nyasa, Tanzania
(Springer, 2023-04) Mwambene, Bupoki; Mwakalesi, Alinanuswe J.; Nehemia, Alex Nahnson
Heavy metal contamination emanating from increased industrial and anthropogenic activities poses considerable environmen- tal risks to water resources, aquatic biodiversity, and human health. These metals are major sources of various unfavorable environmental changes and human health hazards. This research investigated the potential contamination level and health risk assessment of heavy metals (Fe, Zn, Ni, Cu and Cr) in five highly edible fishes (O. microlepis, C. gariepinus, O.niloticus, R. moorii,B. meridionalis) from Lake Nyasa. The results indicated that gills contained higher amounts of heavy metals compared to muscles. The levels of Fe and Zn were higher in the gills of C. gariepinus and O.niloticus than O. microlepis, R. moorii, and B. meridionalis. Similarly, amounts of Cu and Cr were higher in the gills of C. gariepinus and O. microlepis. The general trend of heavy metal concentrations accumulated in selected fish species was Fe > Zn > Ni > Cu > Cr. The amounts of heavy metals found in the fish samples were within acceptable limits set by FAO and WHO. Furthermore, the risk assessments indicated that the current exposure levels are unlikely to cause serious health risks. However, the progressive monitoring of levels of heavy metals in various aquatic organisms from Lake Nyasa is important for the continued protection of human health against hazardous health effects.
Corrosion inhibition of Amino Pentadecylphenols (APPs) derived from Cashew Nut shell liquid on mild steel in Acidic medium
(Scientific Research Publishing Inc., 2016-08) Philip, Joseph Yoeza Naimani; Buchweshaija, Joseph; Mwakalesi, Alinanuswe J.
In this study, corrosion inhibiting properties of amino pentadecylphenols (APPs) derived from Cashew Nut Shell Liquid (CNSL) on mild steel in aerated 0.10 M HCl at 303 K were studied using Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization measurements. Both methods indicated the potential of a mixture of amino pentadecyphenols to serve as a corro- sion inhibitor in mild steel in 0.10 M HCl. Corrosion inhibition efficiencies were observed to in- crease with increase in the inhibitor concentration, with maximum corrosion inhibition of about 98% at inhibitor concentration of 600 ppm. The adsorption of the inhibitor on mild steel surface was found to obey Temkin adsorption isotherm, signifying physical adsorption of the inhibitor molecules on mild steel surface.
Corrosion inhibition of mild steel in sulphuric acid solution with tetradenia riparia leaves aqueous extract: kinetics and thermodynamics
(ResearchGate, 2022-01-23) Mwakalesi, Alinanuswe J.
One of the most successful ways for maximizing profit and lowering costs is to use mild steel over other corrosion-resistant alloys. As a result, mild steel is the most commonly used metallic material in many industries, and its corrosion resistance has received a lot of attention. The mild steel corrosion inhibition using compounds derived from plants is the most practicable and preferable technique because of their linked low cost and green chemistry credentials. This study reports on the kinetics and thermodynamics of mild steel corrosion inhibition in sulphuric acid media utilizing Tetradenia riparia leaves aqueous extract as a potential green inhibitor. The investigations were carried out using the gasometric technique. The findings indicated that the corrosion inhibition efficiency (IE) increased with increasing inhibitor concentration with an optimal value of 90.6% at 500-ppm. The increase in temperature 298 to 338 K lowered the corrosion inhibition efficiency by only 4%. The adsorption kinetics of the extract on the mild steel fit into Langmuir, Temkin, EL-awady, and Freundlich models, but the Langmuir was the best. The results of this investigation show that adsorption of the extracted chemicals on mild steel in a sulphuric acid solution is feasible and most likely involves a combination of physical and chemical adsorption.
Dependence of air quality on meteorological parameters in Dar es Salaam, Tanzania
(Tanzania Journal of Natural and Applied Sciences, 2010) Mkoma, Stelyus L.; Kimambo, Offoro N.; Mabiki, Faith P.; Tungaraza, Clavery T.
The influence of meteorology on air quality in Dar es Salaam was investigated. Precipitation, temperature, relative humidity and wind speed were measured during wet and dry seasons of 2005 and 2006 period and their relationship with reported mass of particles of aerodynamic diameter smaller than 10 μm (PM10) for the site was assessed. Results indicate that the highest median concentrations for the PM10 mass (58 μg/m 3 ) was observed during the 2005 dry season and the lowest median (40 μg/m 3 ) during the 2006 wet season. It is interpreted that reasons for the higher levels of the PM10 mass in the dry season are due to temperature inversions, soil dust dispersal and absence of rain wash-down. The observed PM10 levels are also affected by the variations in sources strengths and in meteorological conditions such as mixing height, precipitation, relative humidity, wind speed and direction as supported by air mass trajectories.
Development and validation of lc-ms/ms method for determination of non-opioid analgesics in adulterated herbal medicines
(Sokoine university of agriculture, 2022) Mpanyakavili, Anna Lucas
Background: Herbal medicines are increasingly used worldwide despite the increased concern of their adulteration with conventional drugs. Non-opioid analgesics are among of the conventional drugs reported to be used in adulteration of anti-pain herbal medicines. This rise a need for developing reliable analytical method for determination of adulterated conventional drugs in herbal medicines for quality control. This study aimed at developing a high throughput Liquid Chromatography coupled with Tandem Mass Spectrometry for determination of non-opioid analgesics (acetaminophen, caffeine, acetylsalicylic acid, diclofenac, and ibuprofen) in herbal medicines in one run. The study also aimed at optimizing a sample preparation technique to enhance detection of the adulterants in herbal medicine obtained from the Tanzania market. Methodology: Solid Phase Extraction (SPE) and Ultrasonic Assisted Extraction (UAE) methods were compared in respect of recoveries, extraction time, complexity, matrix effects, and expenses for sample preparation. Waters OASIS Hydrophilic-lipophilic balance (HLB) 200 mg 6 mL, a C 18 sorbent was used in Solid Phase Extraction method optimization. The optimized parameters were effects of filters on sample filtration, sample loading pH, selection of suitable solvents for conditioning, washing, and elution. Ultrasonic bath and centrifuge were used for optimization of ultrasonic assisted extraction method parameters including effectives of organic solvent in extraction, extraction solvent content, and sample to extraction solvent volume ratio. Both methods were evaluated by calculating their matrix effects, absolute recoveries, and percentage recovery for sub- steps. The effective sample preparation method was used in development and validation of an advanced hyphenated method using an Agilent Technologies 1100 series Liquid Chromatography coupled with Waters Tandem Mass spectrometry (LC-MS/MS) with electrospray ionization. The LC-MS/MS method was validated for its selectivity, sensitivity, linearity, accuracy, precision, recovery, matrix effects, and stability. It was then used to analyse 132 samples collected from the markets of four regions in Tanzania. Results and Discussion: The Ultrasonic Assisted Extraction method showed to be efficient to Solid Phase Extraction method for extraction of selected non-opioid analgesics. This was clearly evidenced by high recoveries, minimum extraction time, good peak shape, its simplicity in procedures, and use of less expensive consumables. The absolute recoveries for Ultrasonic Assisted Extraction were at acceptable range (> 60%) ranging from 60 % to 107 % while for Solid Phase Extraction method showed poor recovery except for diclofenac and ibuprofen having 83% and 67%, respectively. The matrix effect expressed as signal suppression/enhancement ranged from 70% - 122% for Ultrasonic Assisted Extraction method and 3% to 124% for Solid Phase Extraction method. From the results the Ultrasonic Assisted Extraction method was chosen for sample extraction for analysis of Herbal Samples. The developed LC-MS/MS method was linear with coefficient of determination of R 2 ≥ 0.9931. The Limit of Detection (LOD) and Limit of Quantification (LOQ) for selected non-opioid analgesics were within the range of 0 – 3.7 μg/mL. The intra-precision of the LC-MS/MS method was expressed as Relative Standard deviation and was less than 9.5% with varying matrix effect among analytes. Twenty one percent (21%) of 132 collected herbal medicines were adulterated with caffeine and acetylsalicylic acid. 1,029.22 μg/mL was one of the highest concentration of caffeine detected in one of the analysed herbal medicines. Conclusion and recommendation: This is the first study in Tanzania to report an analytical method for analysis of five (5) non opioid analgesics in herbal medicines in Tanzania. The developed LC-MS/MS method is suitable for the identification and quantification of 5 non opioid analgesics explored adulterants. The method can be adopted by the regulatory authorities for routine analysis of herbal medicines for monitoring its quality and safety. Further studies are recommended for Ultrasonic Assisted Extraction method using additional internal standards. Key words: Herbal medicines, Adulteration, Analgesics, Solid Phase extraction, Ultrasonic assisted extraction, LC-MS/MS. Usuli wa tatizo: Ongezeko la matumizi ya dawa zitokanazo na mimea-dawa linazidi kukua ulimwenguni licha ya wasiwasi uliopo wa kuathiriwa kwa dawa hizo kwa kuchanganywa na dawa za kisasa. Dawa za kutuliza maumivu za kisasa ni miongoni mwa dawa zinazoripotiwa kuongezwa katika dawa zitokanazo na mimea dawa za kupunguza maumivu na hivyo kushusha ubora wake. Hivyo, kuna uhitaji mkubwa wa kuunda njia ya kisayansi yenye kuaminika kwa ajili ya uchambuzi na utambuzi wa dawa zitokanazo na mimea dawa zilizochanganywa na dawa za kisasa ili kudhibiti ubora na kuongeza usalama kwa watumiaji. Utafiti huu ulilenga kutengeneza njia ya kisayansi ya uchambuzi inayotumia teknolojia ya LC-MS/MS ili kubaini aina na kiasi cha dawa za kisasa za kutuliza maumivu (asetaminopheni, kafeini, aspirini, diclofenaki, na ibuprofeni) zilizomo ndani ya dawa zitokanazo na mimea dawa. Utafiti huu pia ulilenga kuboresha mbinu ya utayarishaji wa sampuli ili kuboresha ugunduzi wa dawa za kisasa ndani ya dawa zitokanazo na mimea dawa zinazopatikana katika soko la Tanzania. Methodolojia: Utafiti ulilinganisha njia mbili, Solid Phase Extraction (SPE ) na Ultrasonic Assisted Extraction (UAE), kwa kuzingatia uhuishaji, muda ambao ulitumika kuchukua kiziduo, athari za dutu za ziada, na gharama za uandaaji wa sampuli. Teknolojia ya Waters OASIS Hydrophilic-lipophilic balance (HLB) 200 mg 6 mL, sobanti C18 ilitumika katika mchakato wa kuchambua dutu lengwa. Vigezo stahiki vilipatikana kutokana na athari zilizojitokeza katika uandaaji wa sampuli. Pia teknolojia ya ultrasonic assisted extraction ilitumika kuweka sawa mchakato wa kikemikali wa kuchambua dutu lengwa kutoka kwenye sampuli. Njia zote mbili zilitathiminiwa kwa kukokotoa athari zilizojitokeza, kiasi cha dutu zilizopatikana katika mchakato, na kiasi cha dutu kilichopatikana katika hatua zilizofuata. Njia bora ya kuandaa sampuli stahiki ilitumika katika kutengeneza na kuthibitisha njia yenye ufanisi wa kuchambua dutu lengwa. Kukamilisha zoezi hili, teknolojia ya Agilent Technologies 1100 series Liquid Chromatography na ile ya Waters Tandem Mass spectrometry (LC-MS/MS) yenye electrospray ionization vilitumika. Njia ya LC-MS/MS ilihakikiwa uwezo wake katika kubaini dutu husika, usahihi, utoshelevu, na umadhubuti. Aidha, njia hii ilitumika kuchambua sampuli 132 zilizokusanywa kutoka kwenye masoko ya mikoa minne nchini Tanzania. Matokeo na mjadala: Njia ya UAE ilionyesha kuwa na ufanisi katika kuandaa sampuli ya dawa za kupunguza maumivu zilizochaguliwa kwa ajili ya utafiti. Hii ilithibitishwa na uwezo mkubwa katika kuhuisha, kutumia muda mchache, kutoa taswira nyoofu, urahisi katika kutumia pamoja na utumiaji wa malighafi za gharama ndogo. Uhuishaji halisi wa UAE ulikuwa katika kiwango kinachokubalika, yani, kuanzia 60 % hadi 107 %, wakati njia ya SPE ilionesha uhuishaji dhaifu isipokuwa kwa diclofenac (83%) na ibuprofen (67%). Athari za ziada zilizooneshwa kama alama zilizodhibitiwa (fiche) zilianzia 70% - 122% kwa njia ya UAE na 3% hadi 124% kwa njia ya SPE. Kutokana na matokeo, UAE ilichaguliwa kwa ajili ya kuandaa sampuli zitokanazo na mimea dawa kwa ajili ya uchambuzi. Njia ya LC-MS/MS ililandana na kizigeu-tambuzi, R 2 ≥ 0.9931, upeo wa kubaini pamoja na upeo wa kiasi kwa dawa za kuzuia maumivu zilizotafitiwa zilikuwa kati ya 0 – 3.7 μg/mL. Utashelevu wa ndani wa njia ya LC-MS/MS ilijidhihirisha kama achano sanifu-wiano ambalo lilikuwa 9.5% iliyokuwa na athari za ziada mbalimbali katika dutu zilizochambuliwa. Asilimia ishirini na moja (21%) ya dawa 132 za asili zilikuwa zimechanganywa na kafeini na aspirini. Kiasi cha juu cha kafeini kilichogunduliwa katika dawa zilizochunguzwa ni 1,029.22 μg/mL. Hitimisho na mapendekezo: Huu ni utafiti wa kwanza nchini Tanzania uliotumia njia changanuzi kuchunguza uwepo wa dawa tano za kisasa ndani ya dawa zitokanazo na mimea dawa za kutuliza maumivu. Njia iliyobuniwa ya LC-MS/MS ilifaa katika kutambua na kupima dawa tano za kupunguza maumivu zilizotumika kama viharibifu. Hivyo, njia hii inaweza kutumiwa na mamlaka za udhibiti wa ubora na usalama wa dawa za asili. Inapendekezwa kuwa tafiti zaidi zifanyike kutengeneza njia zingine za LC-MS/MS kwa dawa zingine ili kudhibiti ubora wake. Maneno muhimu: Dawa za mimea-dawa, kuchanganywa, dawa za kutuliza maumivu, uziduzi, LC-MS/MS.
Development and validation of LC-MS/MS method for determination of non-opioid analgesics in adulterated herbal medicines
(Sokoine University of Agriculture, 2022-11) Mpanyakavili, Anna Lucas
Background: Herbal medicines are increasingly used worldwide despite the increased concern of their adulteration with conventional drugs. Non-opioid analgesics are among of the conventional drugs reported to be used in adulteration of anti-pain herbal medicines. This rise a need for developing reliable analytical method for determination of adulterated conventional drugs in herbal medicines for quality control. This study aimed at developing a high throughput Liquid Chromatography coupled with Tandem Mass Spectrometry for determination of non-opioid analgesics (acetaminophen, caffeine, acetylsalicylic acid, diclofenac, and ibuprofen) in herbal medicines in one run. The study also aimed at optimizing a sample preparation technique to enhance detection of the adulterants in herbal medicine obtained from the Tanzania market. Methodology: Solid Phase Extraction (SPE) and Ultrasonic Assisted Extraction (UAE) methods were compared in respect of recoveries, extraction time, complexity, matrix effects, and expenses for sample preparation. Waters OASIS Hydrophilic-lipophilic balance (HLB) 200 mg 6 mL, a C 18 sorbent was used in Solid Phase Extraction method optimization. The optimized parameters were effects of filters on sample filtration, sample loading pH, selection of suitable solvents for conditioning, washing, and elution. Ultrasonic bath and centrifuge were used for optimization of ultrasonic assisted extraction method parameters including effectives of organic solvent in extraction, extraction solvent content, and sample to extraction solvent volume ratio. Both methods were evaluated by calculating their matrix effects, absolute recoveries, and percentage recovery for sub- steps. The effective sample preparation method was used in development and validation of an advanced hyphenated method using an Agilent Technologies 1100 series Liquid Chromatography coupled with Waters Tandem Mass spectrometry (LC-MS/MS) with electrospray ionization. The LC-MS/MS method was validated for its selectivity, sensitivity, linearity, accuracy, precision, recovery, matrix effects, and stability. It was then used to analyse 132 samples collected from the markets of four regions in Tanzania. Results and Discussion: The Ultrasonic Assisted Extraction method showed to be efficient to Solid Phase Extraction method for extraction of selected non-opioid analgesics. This was clearly evidenced by high recoveries, minimum extraction time, good peak shape, its simplicity in procedures, and use of less expensive consumables. The absolute recoveries for Ultrasonic Assisted Extraction were at acceptable range (> 60%) ranging from 60 % to 107 % while for Solid Phase Extraction method showed poor recovery except for diclofenac and ibuprofen having 83% and 67%, respectively. The matrix effect expressed as signal suppression/enhancement ranged from 70% - 122% for Ultrasonic Assisted Extraction method and 3% to 124% for Solid Phase Extraction method. From the results the Ultrasonic Assisted Extraction method was chosen for sample extraction for analysis of Herbal Samples. The developed LC-MS/MS method was linear with coefficient of determination of R 2 ≥ 0.9931. The Limit of Detection (LOD) and Limit of Quantification (LOQ) for selected non-opioid analgesics were within the range of 0 – 3.7 μg/mL. The intra-precision of the LC-MS/MS method was expressed as Relative Standard deviation and was less than 9.5% with varying matrix effect among analytes. Twenty one percent (21%) of 132 collected herbal medicines were adulterated with caffeine and acetylsalicylic acid. 1,029.22 μg/mL was one of the highest concentration of caffeine detected in one of the analysed herbal medicines. Conclusion and recommendation: This is the first study in Tanzania to report an analytical method for analysis of five (5) non opioid analgesics in herbal medicines in Tanzania. The developed LC-MS/MS method is suitable for the identification and quantification of 5 non opioid analgesics explored adulterants. The method can be adopted by the regulatory authorities for routine analysis of herbal medicines for monitoring its quality and safety. Further studies are recommended for Ultrasonic Assisted Extraction method using additional internal standards.
Ecotoxicity of mercury contaminated sediment collected from Mabubi river (Geita district, Tanzania) to the early life stages Of African catfish (clarias gariepinus)
(Elsevier, 2009) Chibunda, R.T; Pereka, A. E; Phiri, E.C.J; Tungaraza, C.
The quality of Hg contaminated sediments in artisanal gold mining areas of Tanzania have to date only been assessed through bulk chemical analysis. However, measurement of contaminant levels alone has a limited ability to predict adverse effects on living resources. In this study we investigated the possible effects of Hg contaminated sediments from the river Mabubi which drains the artisanal gold mine on the hatching success, larval survival and growth of the African catfish (Clarias gariepinus). The tested species is a resident fish whose demersal behaviour keeps it in frequent contact with the sediment. Sediments collected downstream of the mine decreased survival and impaired growth of Clarias gariepinus but did not affect its hatching success. These effects were observed up to six kilometres downstream of the mining activity. The calculated 5 d- LC 50 value (larval survival) was 1.75 μg/g Hg dw (95% CL of 0.72 – 2.53), the 5d-NOEC for hatching was >2.3 μg/g Hg dw and that for larval survival and growth was 0.23 μg/g Hg dw. In conclusion, chemistry and ecotoxicity results from this study suggest that sediments collected downstream of the mine adversely affect catfish and probably other fauna and as such present a considerable local environmental risk.
Effect of changes in business environments on traded medicinal plants products in Tanzania: an explorative study
(Heliyon, 2022) Mpelangwa, Eziacka Mathew; Makindara, Jeremia Ramos; Sorensen, Olav Jull; Bengesi, Kenneth Michael Kitundu; Mabiki, Faith Philemon
In Tanzania, a complex rural to urban supply network for the medicinal plants' products trade has developed over time driven by changes in business environments at the macro level notably in the policy and regulatory frameworks and the micro level resulting from traders’ reactions and responses to those changes and pandemics. These changes in business environments and responses of traders have shaped the current trade practices. However, the response of traders to changes in business environments and the evolutionary paths over time are not well documented. Therefore, this paper aimed to synchronize changes in business environment over time and empirically determine how the trade has evolved concerning the responses of the medicinal plants' traders in Tanzania. The study applied economic evolution theory to describe the interactions of changes in business en- vironments and responses of traders to demarcate the evolutionary stages. Primary data were collected from traders, regulators, and researchers through ten focus group discussions and sixteen in-depth interviews from five regions of Tanzania. The results indicated that the traders of medicinal plant products responded by improving product appearance and modernizing both practices and business premises. The study findings have identified four evolutionary stages of trade in medicinal plant products in Tanzania: The first stage was the colonial era (1882–1961), the second is the government supremacy era (1961–1984), the third is the emergence of the private sector era (1985–2004), and the fourth is the market and regulation integration era (started in 2005). Moreover, because of the partial implementation of the regulatory framework, the fifth stage of trade evolution is also ex- pected. This stage is expected to be demarcated when the regulatory framework and market forces work together. Therefore, the study recommends that proper enforcement measures be put in place to ensure desired results whenever there are changes in business environments in traditional medicines practice. This is due to the expectation of the fifth stage whereby one of its characteristics is stiff competition among traders and which will require robust business models to survive in business.
Effective corrosion inhibition of mild steel in an acidic environment using an aqueous extract of Macadamia Nut Green Peel biowaste
(MDPI, 2022-12) Mwakalesi, Alinanuswe J.; Nyangi, Magori
Improving the corrosion resistance of mild steel in an acidic aqueous environment is an important industrial consideration due to the use of acids for descaling and cleaning. The application of corrosion inhibitors is one of the most effective and economical means of protecting metals against corrosion. Plant-derived compounds have recently gained attention due to their low cost, non-toxic, and environmentally friendly properties. Biowastes are recognized as a potential cheap source of green corrosion inhibitors, and their use can help to lower the costs associated with corrosion inhibitors. Green peel biowaste (GPBW) generated from macadamia nut processing is typically dumped into the environment, posing a disposal concern. The use of the waste as a potential source of organic compounds with green chemistry attributes for mild steel corrosion inhibition in an acidic solution was proposed in this study. The gasometric and optical methods were used to carry out the investigations. Results showed that mild steel corrosion rates decreased as extract concentrations increased. As a result, mild steel corrosion inhibition increased with increasing inhibitor concentration and reached a peak value of 81% at 0.5 g/L extract concentration. The optical images showed that the inhibitor molecules adsorbed on the metal surface to form a protective film that isolated the mild steel from the corrosive solution. The adsorption of inhibitor molecules on the mild steel surface followed the Langmuir adsorption isotherm, indicating the formation of a monolayer film with a homogeneous distribution of adsorbed molecules. A Gibbs free energy (G◦ ads) of 24 kJ/mol indicated the inhibition process was mainly characterized by physical adsorption. The results of this study suggest that aqueous GPBW extract could serve as an inexpensive, non-toxic, and renewable corrosion inhibitor of mild steel in acidic solutions.

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