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.
Phytochemical screening and in-vitro antifungal activity of balanites aegyptiaca extracts against candida albicans and aspergillus flavus
(African Journal of Education Science and Technology (AJEST), 2025-12-15) Asio, Santa Maria; Gumula, Ivan; Lulago, Muwanguzi Zedde; Kigozi, Stephen; Ekakoro, Newton; Eboyu, Thomas
Fungal infections caused by Candida albicans and Aspergillus flavus pose major public health challenges, particularly in regions with limited access to effective antifungal drugs and increasing resistance to existing therapies. Although Balanites aegyptiaca is widely used in traditional medicine, its antifungal potential remains insufficiently studied. The study evaluated extracts against C. albicans, a causative agent of candidiasis, and A. flavus, a mycotoxin-producing fungus, to determine their therapeutic potential and relevance in managing fungal infections. Leaves stem bark, and root bark of B. aegyptiaca were collected from disease-free trees in Katakwi District, Uganda, washed, air-dried, pulverized, and stored under sterile conditions. Crude extracts were prepared via successive maceration using methanol, dichloromethane, and n-hexane. Qualitative phytochemical screening detected saponins, tannins, flavonoids, alkaloids, anthraquinones, coumarins, cardiac glycosides, terpenoids, and starch. Antifungal activity against C. albicans and A. flavus was evaluated using the agar-well diffusion method. Experiments were conducted in triplicate, and zones of inhibition were measured. Data were analysed using one-way ANOVA and Tukey’s post hoc test in STATA 14.0, with P < 0.05 considered statistically significant. Methanol proved the most effective solvent for extracting phytochemicals from B. aegyptiaca, yielding higher crude extract quantities than dichloromethane and n-hexane. Phytochemical screening identified alkaloids, flavonoids, phenolics, tannins, coumarins, cardiac glycosides, and phytosterols in leaves, stem bark, and root bark, with methanolic extracts containing the broadest range of compounds. Sour varieties generally had higher phenolic content than sweet ones. Antifungal assays showed methanolic extracts had the strongest activity, producing inhibition zones up to 23.67 mm against C. albicans and 23.00 mm against A. flavus, particularly in stem and root bark. Dichloromethane (DCM) extracts exhibited moderate antifungal activity, while n-hexane was least effective, except for some moderate inhibition of A. flavus by non-polar compounds. Polar solvents, particularly methanol, efficiently extracted bioactive compounds from B. aegyptiaca, with the sweet variety yielding more than the sour. Crude extracts inhibited C. albicans and A. flavus, suggesting combined plant parts may enhance antifungal efficacy.
Tetracycline residues in milk and beef from the Ugandan cattle corridor
(Journal of Environmental Science and Health, Part B, 2026-02-05) Mwesigye, Justus; Kwetegyeka, Justus; Gumula, Ivan; Omara, Timothy; Kiganda, Ivan
Veterinary antibiotic residues in foods of animal origin (FOAO) are of public health concern because they can contribute to antimicrobial resistance, disruption of gut microbiota, hypersensitivity reactions and developmental effects following chronic exposure. This study investigated the occurrence of six veterinary tetracyclines (oxytetracycline, tetracycline, doxycycline, chlortetracycline, demeclocycline and methacycline) in FOAO from the Ugandan Cattle Corridor districts of Nakaseke and Nakasongola. Raw milk, muscle tissue, liver and kidneys were analyzed for tetracyclines using high performance liquid chromatography and liquid chromatography-tandem mass spectrometry. District-wise analysis revealed a moderate prevalence of tetracycline residues in milk (5.3–42.1%) and beef (7.7–69.2%), with oxytetracycline being the most detected. Of these, 5.3–69.2% of the samples had oxytetracycline, methacycline and tetracycline concentrations exceeding their maximum residue limits established by the European Union Commission Regulation No. 37/2010. These results provide baseline data on the presence of tetracycline residues in marketed FOAO from the Ugandan Cattle Corridor. It emphasizes the need for strengthened antimicrobial stewardship, enforcement of veterinary drug withdrawal periods, and routine national antimicrobial residues monitoring in FOAO.