Browsing by Author "Credo, David"

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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.
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.
Structural elucidation and toxicity evaluation of bioactive compounds from the leaves and stem woods of synadenium glaucescens pax.
(Pharmaceutical Sciences and Research, 2022-07) Credo, David; Mabiki, Faith Philemon; Machumi, Francis; Cornett, Claus
The leaves and stem woods of Synadenium glaucescens Pax. are traditionally used for treatment of various human diseases in Tanzania. However, there is limited information on the structural elucidation and toxicity properties of bioactive compounds responsible for their pharmacological properties. Thus, this study was aimed to elucidate and evaluate toxicity properties of bioactive compounds from these parts. Separation of bioactive compounds was achieved by using column chromatographic method, whereas their structures were determined by GC-MS and NMR data and by comparing with literature spectroscopic data. Toxicity properties of isolated compounds was done by brine shrimp lethality test (BSLT) method. In this study, column chromatographic separation led to isolation of tetracosane (1), hexadecyl palmitate (2), octacosane (3), tetracosanol (4) and β-sitosterol (5) from the leaves and 1-hexacosene (6), campesterol (7), octadecanoic acid (8) and tetracosanoic acid (9) from the stem woods. BSLT of compounds isolated in sufficient amount (1, 2, 3, 4, 5 and 7) were revealed to be non-toxic to brine shrimp larvae (LC 50 >100 μg/ml). Except compound 5, this study reports the isolation of other eight (8) compounds for the first time from this plant. Therefore, it can be reasonably concluded that S. glaucescens is a good source of bioactive compounds which justify its traditional uses in treatment of various ailments. Additionally, observed non-toxic effect of the tested compounds indicates safety and it is expected that its traditional use has no toxicity effect.