Browsing by Author "Opio, Boniface"

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    Antibacterial properties of phytochemicals isolated from leaves of alstonia boonei and aerial parts of ipomoea cairica
    (Natural Product Communications, 2024-09-26) Gumula, Ivan; Kyarimpa, Christine; Nanyonga, Sarah Kiwanuka; Kwesiga, George; Busulwa, George; Opio, Boniface; Heydenreich, Mathias; Omara, Timothy
    Objective: The leaves of Alstonia boonei and aerial parts of Ipomoea cairica are used for treatment of microbial infections among other ailments in African traditional medicine. The aim of this study was to investigate the antimicrobial phytochemicals in A. boonei leaves and Ipomoea cairica aerial parts to validate their traditional use in Ugandan herbal medicine. Methods: The plant materials were separately extracted using a dichloromethane/methanol (1:1) solvent system and subjected to repeated chromatographic separation to isolate pure compounds. The chemical structures of the isolated compounds were determined through 1H NMR, 13C NMR and 2D NMR(COSY, HSQC and HMBC). The antibacterial activity of the extracts and pure compounds were assessed using the agar well diffusion method. Results: Chromatographic fractionation of the extracts yielded trans-fagaramide and a pentacyclic lupane-type triterpenoid, lupeol, from A. boonei, and friedelin from I. cairica. Trans-fagaramide was identified for the first time in the Alstonia genus while friedelin was identified for the first time in I. cairica. The isolated compounds demonstrated antibacterial activity, with trans-fagaramide showing a minimum inhibitory concentration (MIC) of 125 μg/mL against Pseudomonas aeruginosa and 250 μg/mL against Staphylococcus aureus, Salmonella typhi and Escherichia coli. Friedelin exhibited a MIC of 125 μg/mL against Escherichia coli and 250 μg/mL against Pseudomonas aeruginosa, Staphylococcus aureus and Salmonella typhi. Conclusion: The antibacterial activities observed in this study support the traditional use of A. boonei and I. cairica by indigenous communities in Uganda for treating microbial infections.
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    Phytochemical investigation of ipomoea cairica for antimicrobial agents
    (Kyambogo University [unpublished work], 2023-04) Opio, Boniface
    The emergence of new infectious diseases and the resurgence of several infections has put the people in Saharan and sub-Saharan Africa to an assiduous risk. This has created the necessity for studies directed towards the development of new alternatives for antimicrobial agents. In this study a portion of the dichloromethane/methanol (1:1, v/v) crude extract from the air dried and pulverized aerial parts of Ipomoea cairica was subjected to preliminary phytochemical screening which revealed the presence of alkaloids, sterols, flavonoids, tannins, saponins, terpenoids and phenols. Another portion of the crude extract was subjected to repeated column chromatography over silica gel leading to the identification of two compounds; Diisobutyl phthalate (53) and Friedelin (54) which were characterized and elucidated using various spectroscopic and spectrometric techniques. The crude extract and the isolated compounds were evaluated for antimicrobial activities against four bacterial strains; Escherichia coli, Salmonella typhi, Pseudomonas and Staphylococcuss aureus, and three fungal strains; Aspergillus niger, Penicillum chrysogenum and Candida albicans using well agar diffusion assay and their minimal inhibitory concentration (MIC) values determined using a 2-fold dilution technique. The crude extract exhibited good antimicrobial activities with zones of inhibitions; 20± 0.25, 26 ± 0.10, 24 ± 0.12 and 14 ± 0.05 mm for E. coli, S. typhi, P. aeruginosa and S. aureus, respectively, and the zones of inhibitions for fungal strains were as follows; 16± 0.5, 24± 0.00 and 20± 0.41 mm for A. niger, P. chrysogenum and C. albicans, respectively. The two isolated pure compounds were only tested against the four strains of bacteria and exhibited relatively weak activities: Compound (53); 8.0 ± 0.22, 4.0 ± 0.32, 6.0 ± 0.00 and 6.0 ± 0.55 mm, and Compound (54); 8.0± 0.05, 5.0± 0.50, 8.0± 0.12, 10± 0.50 mm for E. coli, S. typhi, P. aeruginosa and S. aureus, respectively. The two isolated pure compounds showed minimum inhibitory concentration (MIC) ranging from 125 to 1000 𝜇g/ml respectively.