Browsing by Author "Gumula, Ivan"

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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.
Antimicrobial activity of crude methanolic extract fractions from balanites aegyptiaca (L.) delile
(African Journal of Education Science and Technology (AJEST), 2025-12-15) Asio, Santa Maria; Gumula, Ivan; Lulago, Zedde Muwanguzi; Kigozi, Stephen; Ekakoro, Newton; Eboyu, Thomas
Microbial infections remain a major global health concern, with mortality rates continuing to rise each decade. Projections estimate that by 2050, antimicrobial resistance could account for up to 10 million deaths annually. This study investigated the antimicrobial potential of phytochemical groups present in crude extracts of B.aegyptiacaas a possible alternative for managing microbial infections. Plant materials (leaves, stem bark, and root bark) were collected from two local varieties of B. aegyptica which are tentatively referred to as the “sweet” and “sour” varieties growing in Ajeluk village, Katakwi District, North-Eastern Uganda. The dried and pulverized samples (100 g each) were subjected to successive extraction with n-hexane, dichloromethane, and methanol. The resulting crude extracts were concentrated using a rotary evaporator, followed by fractionation through silica gel column chromatography. Fractions were further purified using preparative thin-layer chromatography, with separated bands visualized under Ultra Violet(UV)light, eluted, and tested for antimicrobial activity. Test organisms included multidrug-resistant AmericanType Culture Collection (ATCC) Escherichia coli ATCC 25922, Candida albicans ATCC 10231, and Aspergillus flavus ATCC 6275. The methanolic fractions demonstrated notable antimicrobial activity, with inhibition zones greater than 8 mm. Among the phytochemical groups, phenolics exhibited the strongest activity(23.67 ± 1.15 mm), while coumarin-containing fractions displayed the lowest activity (7.00 ± 0.00 mm). Statistical analysis revealed significant differences between inhibition zones of the phytochemical groups and the positive control (p < 0.05). Phytochemical screening confirmed the presence of phenolics, flavonoids, alkaloids, cardiac glycosides,and coumarins in the extracts. Overall, the findings suggest that B. aegypticacontains diverse bioactive compounds with antimicrobial potential, particularly against fungal pathogens. C. albicansand A. flavuswere more susceptible to these extracts than E. coli, highlighting the plant’s promise as a source of antifungal agents.
Fruits and vegetables used in treating respiratory and other troubles in Africa: ethnopharmacology and phytochemistry
(Springer Nature Link, 2025-08-01) Gumula, Ivan; Buyinza Daniel; Onen Patrick; Kyarimpa Christine
This book provides a comprehensive overview of bioactive compounds derived from African traditional medicinal plants, shedding light on their potential applications in modern medicine. It compiles crucial information on compounds with proven in vitro and in vivo activity against various diseases, providing a foundation for further research in drug discovery. The book also introduces the use of these bioactive secondary metabolites in cosmetics, nutrition, and pest control, with detailed description of medicinal plant species, including their botanical names, ethnomedicinal uses, and pharmacological activities, making it an invaluable resource for researchers and pharmaceutical companies. Key concepts include the exploration of secondary metabolites from plants in Ethiopia, Egypt, Kenya, Uganda, Zimbabwe, Cameroon, Tanzania, Madagascar, and Nigeria, and their industrial applications. The chapters cover ethnobotanical knowledge, bioactivities, and chemical profiling of these plants, including the ethnobotanical and phytochemical studies of Ethiopian flora, the role of rose-scented geranium in the perfume industry, and the use of fruits and vegetables in treating respiratory ailments. Readers will also discover insights into the use of secondary metabolites for pest control, the conservation strategies for endangered African plants, and the synthesis of bio-nanoparticles for therapeutic applications. The book presents a detailed analysis of medicinal plants with anti-malarial, antileishmanial, improve sexual desire and antimicrobial properties, highlighting their significance in traditional and modern medicine. This volume is an essential resource for researchers, graduate students, and professionals in the fields of natural products, phytochemistry, and pharmaceuticals. It provides a unique perspective on the integration of traditional African medicine with contemporary scientific research, offering valuable insights into the potential of these bioactive compounds in drug development.