Browsing by Author "Odeleye, Olukayode Michael"

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    Investigation of chemical constituents, antimicrobial and antioxidant activities; and pharmacognostic characters of the leaves of momordica foetida and berkheya bergiana
    (University of Zululand, 2010) Odeleye, Olukayode Michael; Opoku, A.R.; Oyedeji, O.A.
    This research work was aimed at the isolation, structural elucidation and pharmacological evaluation of the chemical constituents of M. foetida (Cucurbitaceae) and B. bergiana (Asteraceae) and to determine the pharmacognotic profile of the plants. Phytochemical screening of the crude ethanol extract of Momordica foetida revealed the presence of alkaloids, flavonoids, terpenoids, steroids, saponins and tannins while that of B. bergiana had flavonoids, terpenoids, saponins and tannins as their major secondary metabolites. Six compounds were isolated from the various solvent extracts of the two plants, various chromatographic techniques were employed for the fractionation and purification of the isolates. Spectroscopic methods NMR, IR, MS were employed for the structural elucidation of the compounds. The NMR spectral pattern of four of the isolates suggests a triterpenoid based compound with the characteristics C30 carbon content. With the aid of the 1D and 2D NMR, MS and IR, these four compounds were identified as 3β,7β,25-trihydroxycucurbita-5,(23E)-dien-19-al; 3β,7β-dihydroxy-cucurbita-5(23E),23,25-triene-19-al; 3β-hydroxylup-20(29)-ene and lup-20(29)-en-3β-ol-1α-yl-acetate. The remaining 2 isolates were also identified with the help of full house NMR and Mass spectroscopy to be Kaempferol-3-O-β-D-glucopyranoside and 4-hydroxy-3-methoxy-benzaldehyde.Although Kaempferol-3-O-β-D-glucopyranoside has been reported isolated from Tephrosia calophylla and Clitoria ternatea, this is the first time that it is being reported and isolated from any Momordica species. Furthermore, the isolation of 3β,7β,25-trihydroxycucurbita-5,(23E)-dien-19-al and 3β,7β-dihydroxy-cucurbita-5(23E),23,25-triene-19-al is noteworthy because of the unique position of hydroxyl group at position 25 and the chromophore conjugation at position 23-25. These two compounds have not been reported isolate from M. foetida before. In-vitro antimicrobial activities of the crude extract and five solvent fractions were screened against 32 bacterial strains using disc diffusion and microplate dilution methods. Ethyl aceate fractions of M. foetida exhibited the highest broad spectrum antibacterial activity against the tested bacteria. The antibacterial activity followed the order: of ethyl acetate > butanol > chloroform > aqueous > hexane fraction at a 5.0 mg mL-1. The minimum inhibitory concentration (MIC) of M. foetida exhibited by the five fractions against the bacterial strains ranged between 0.156 and 5.0 mg mL-1. Chloroform extract of B. bergiana, exhibited the highest broad spectrum antibacterial activity against the tested bacteria and decreased in the order chloroform > ethyl acetate > butanol > hexane > aqueous extract at a concentration of 5.0 mg mL-1 while the minimum inhibitory concentration (MIC) of B. bergiana exhibited by successive extracts range between 0.078 mg mL-1 and 5.0 mg mL-1. Antioxidant activity of the extracts and fractions were investigated using four antioxidant assays namely DPPH, ABTS radical scavenging effect, reducing power and metal chelating effect on iron(II) ion. Total phenol, flavonoid and proanthocyanidin contents were also estimated. This study showed that M. foetida and B. bergiana possess substantial antibacterial and antioxidant potentials. They may be good potential drugs in the treatment of infection-related diseases because of their antibacterial activity. The antioxidant activity exhibited by the plants also provides a rationale for the ethnomedical use of the plants for the treatment of inflammation, neurodegenerative and cardiovascular disease conditions in traditional medicine.