Browsing by Author "Omara, Timothy"

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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.
Ethnomedicinal uses and nutritional composition of yams (Dioscorea hispida Dennst.) In Kitholhu, Kasese District, Uganda
(Springer, 2024-05) Makeo, Onani; Okot, Amito Patricia; Isabirye, Isaac; Omara, Timothy; Walugembe, Joel
Yams (Dioscorea species) are traditionally valued as famine foods and medicinal lianas in countries such as Uganda, Indonesia, Ethiopia, Sudan, Thailand and Singapore. However, little information exists on the traditional medicinal uses and nutritional composition of yams in Uganda, despite them being cultivated and considered to have medicinal benefits in Eastern and Western Uganda. This study was sought to document the ethnobotanical knowledge and assess the nutritional composition of Dioscorea hispida Dennst. (D. hispida) in Kasese District of Western Uganda. An ethnobotanical survey was carried out from November 2022 to May 2023 in Kitholhu subcounty, a flood-prone area in Kasese District to assess the indigenous knowledge on the medicinal uses of D. hispida. Using semi-structured questionnaires, a total of 47 respondents selected using snow ball technique were interviewed. The proximate composition (moisture, ash, crude fat, protein, crude fiber and total carbohydrate contents) of sampled D. hispida tubers were analyzed. The ethnobotanical data obtained was analyzed using descriptive statistics while nutritional data was subjected to a one-way analysis of variance at P < 0.05. Up to 83% of the respondents cultivate D. hispida, with 94% of these indicating that the tuber is used in traditional management of typhoid, diabetes mellitus, malaria, yellow fever, intestinal inflammation, cancer, peptic ulcers and hypertension, among other ailments. Proximate analysis indicated that D. hispida samples from Kitholhu had 72.29 ± 0.38% moisture, 6.08 ± 0.15% crude fiber, 1.24 ± 0.05% crude fat, 3.05 ± 0.03% ash, 5.65 ± 0.29% proteins and 11.67 ± 0.52% carbohydrates. Our results suggest that there is rich ethnobotanical knowledge on the use of D. hispida for the treatment of ailments among the local communities of Kitholhu. Thus, D. hispida is a famine and medicinal plant that needs to be considered for conservation to enhance food security in Kitholhu and Uganda as a whole. Further studies are required to assess D. hispida for its claimed bioactivities against the reported diseases and conditions.
Safety, toxicological and allergenic aspects of using algae for food
(Springer Link, 2024-07-14) Kyarimpa, Christine; Omute, Tom; Nakiguli, Caroline K.; Khanakwa, Alice V.; Angiro, Christopher; Kahwa, Ivan; Ahumuza, Fortunate; Omara, Timothy
Consumption of algae has been historically practiced, especially in East Asia and the Pacific region cultures. However, sporadic events and empirical studies have suggested that some compounds could be triggering intoxications, allergic reactions and mortalities in humans who consumed algae. This chapter is an effort to explore with in-depth attention the safety, toxicological and allergic reactions following human consumption of algae. Based on retrieved literature, it is clear that toxicities and allergies from ingestion of algae are not a rarity, and to date, at least seventy (70) illnesses, six (6) allergic reactions and fourteen (14) mortalities have been reported globally. Toxicities and mortalities from intake of edible algae has been reported in species of Gracilaria, Caulerpa and Acanthophora genus, and are associated with their bioaccumulation of contaminants such as excess iodine, heavy metals, cyanotoxins or toxic inherent compounds such as caulerpenyne, manauealides A and C, prostaglandin E2, polycavernosides, aplysiatoxins and their derivatives. Allergenicity has been reported in Arthrospira, Chlorella, Chondrus, Eucheuma, Gigartina and Palmaria species, with the sulfated polysaccharide (carrageenan) and the photosynthetic pigment (C-phycocyanin) being the implicated allergens. These allergic reactions are mediated through activation of innate immune pathways of inflammation that trigger NF-kB activation, modification of gut microbiota and thickness of mucus barrier. We contend that appropriate labelling of algae-derived food products, public education, proper cleaning of fresh algae before consumption and profiling of toxic and allergenic algal species and compounds could aid in reducing intoxications and allergic reactions from algae used in food and food products. Future studies should consider examining edible algae for contaminants of emerging concern such as microplastics, cyanotoxins, emerging per- and polyfluoroalkyl substances, pharmaceutical residues and personal care products.