Browsing by Author "Kyarimpa, Christine"

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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.
Not one size fits all: µ FTIR and pyrolysis GC MS for complementary analysis of microplastics in eutrophic surface water
(Analytical and Bioanalytical Chemistry, 2026-03-22) Omara, Timothy; Benetková, Barbora; Sumerskii, Ivan; Ssebugere, Patrick; Kyarimpa, Christine; Omwoma, Lugasi Solomon; Rosenau, Thomas; Nagawa, Christine Betty; Böhmdorfer, Stefan
This study reports large microplastics found in Lake Victoria through an analytical workflow that combines the complementary methods stereomicroscopy, micro-Fourier transform infrared (µ-FTIR) spectroscopy and pyrolysis gas chromatography-mass spectrometry (Pyr-GC-MS) for the quantification of 11 environmentally relevant microplastic polymers. Algae-rich surface water samples (n = 18) were trawled using a 0.3 mm manta net from Lake Victoria, the world’s largest tropical lake. Stereomicroscopy as a determinant analytical technique detected 191 particles, which were primarily blue fragments and fibres. Polyethylene and polypropylene were the dominant polymers identified by µ-FTIR. Pyr-GC-MS allowed the detection and quantification of microplastics (MPs) with LOD and LOQ of 0.01–14.7 µg and 0.03–49.1 µg. Polyethylene (0.058–0.34 µg/L), polypropylene (0.024 µg/L and 0.043 µg/L), nylon 6 (0.0051–0.064 µg/L), nylon 66 (0.0022–0.084 µg/L), poly(ethylene terephthalate) (0.0029–0.027 µg/L) and poly(methyl methacrylate) (0.0036 µg/L) were quantified. µ-FTIR was found to be suitable for the identification of the most abundant polymers in the 0.3–4.9 mm size range whereas Pyr-GC-MS afforded the quantification of seven polymers, most of which were not detected by µ-FTIR. This complementary workflow gave a wider perspective on MP loading, providing both polymer concentrations and physical characteristics (sizes, colours, forms and count) of the MPs.
Nutraceutical benefits of seaweeds and their phytocompounds: a functional approach to disease prevention and management
(Journal of Science of Food and Agriculture, 2025-04-30) Kahwa, Ivan; Omara, Timothy; Ayesiga, Innocent; Shah, Kamal; Neh Neba Ambe,Gael Noel; Javidbhai Panwala, Zehbanaz; Mbabazi, Rachel; Iqbal, Shabnoor; Kyarimpa, Christine; Nagawa, Christine Betty; Singh Chauhan, Nagendra
Seaweeds (SWD), macroalgae or sea vegetables are a diverse group of over 9000 macroscopic and multicellular marine algae taxonomically classified (based on morphology and pigmentation) as green, brown and red algae. With microalgae, SWD represents one of the most researched oceanic resources turned to as treasure troves of bioactive compounds with ethnomedicinal, pharmaceutical, cosmeceutical and dietetic end-uses for millennia. This review compiles the nutraceutical uses of SWD and their bioactive compounds in nutrition and traditional management of diseases, offering future perspectives on using this group of organisms to improve human life. The review reveals that the nutraceutical application of SWD as nutrient-dense marine foods for treating diseases may be correlated with their inherent biosynthesis and possession of minerals, vitamins, dietary fibres and bioactive compounds. Compounds of algal origin have been validated and found to elicit antimicrobial, anti-inflammatory, free radical scavenging (antioxidant), antiproliferative and antidiabetic activities, among others. © 2025 Society of Chemical Industry.
Occurrence of microplastics in surface water, superficial sediments and Nile tilapia (Oreochromis niloticus) from fish breeding areas of Lake Victoria
(Discover Applied Sciences, 2026-03-27) Atukwatse, Faith; Nagawa, Christine Betty; Omara, Timothy; Kyarimpa, Christine; Omwoma, Solomon Lugasi; Basooma, Rose; Kwikiriza, Gerald; Ssebugere, Patrick; Bwanika, Gladys Namuswe
Lake Victoria, the largest African Great Lake and the world’s second largest freshwater lake by surface area has several bays and inlets along its shoreline, which serve as breeding grounds for fish. The ecological and economic importance of these bays are now under threat due to rapid urbanization and agricultural expansion that have introduced pollutants into them. Using stereomicroscopy and micro-Fourier transform infrared (µ-FTIR) imaging, we investigated the occurrence of microplastics (MPs) in surface water (n = 12), superficial sediments (n = 12) and Nile tilapia (Oreochromis niloticus, n = 66) from four fish breeding areas (Port Bell, Masese, Kigaya and Nabulugo) on the northern shores of Lake Victoria. The frequency of MPs detection was 100%, 83.3% and 56.1% in surface water, sediments and fish samples, respectively. The corresponding microplastic counts were 22–60 particles/L, 2–10 items/kg and 1–16 items/fish. Port Bell and Masese that are in close proximity to urban areas had higher microplastic contamination than Kigaya and Nabulugo, which are in less disturbed sites (P > 0.05). Across all the samples, filaments were the most dominant form of MPs (43.1–100%), followed by fragments (7.8–55.6%), fibers (2.2–21.4%), foams (5.3–31.1%) and pellets (1.7–6.7%). The particles were confirmed by µ-FTIR to contain mainly polyethylene, polypropylene and polystyrene. Total length of fish from Nabulugo showed a strong and significant negative correlation (ρ = – 0.753, P = 0.01) with the number of MPs ingested, indicating that larger fish are associated with lower microplastic loads. Branchial intrusion of MPs in Oreochromis niloticus provide evidence of potential direct human exposure to MPs through consumption of this fish species. These results indicate that there is a growing threat of MPs to fishery sustainability and food safety in Lake Victoria, emphasizing the need for targeted policy interventions to mitigate plastic pollution in catchments of fish breeding habitats.
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.