Browsing by Author "Cornett, Claus"

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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.
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.