Browsing by Author "Kahwa, Ivan"

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Integrative LC-HR-QTOF-MS and computational metabolomics approaches for compound annotation, chemometric profiling and in silico antibacterial evaluation of Ugandan propolis
(Metabolites, 2026-02-03) Kahwa, Ivan; Seel, Christina; Tumwesigye, Ronnie; Onen, Patrick; Oehme, Ramona; Billig, Susan; Wangalwa, Rapheal; Tusiimire, Jonans; Wiesner, Claudia; Kaysser,Leonard
Background/Objectives: Propolis is a complex bee product with a composition that varies according to local vegetation, environmental conditions, and bee foraging behaviours. Recently, gas chromatography–mass spectrometry (GC–MS) has been employed in Uganda to analyse its volatile components. This study examined Ugandan propolis non-volatile metabolites to determine chemotypes and identify antibacterial compounds. Methods: Ethanolic extracts were analysed using liquid chromatography–high-resolution quadrupole time-of-flight mass spectrometry (LC-HR-QTOF-MS) in an untargeted MS/MS mode. Data processing was carried out using MZmine, then annotated with Global Natural Products Social Molecular Networking (GNPS) and SIRIUS. Chemometric methods assisted in identifying regional chemical signatures. Metabolites highlighted by the heatmap were evaluated for antibacterial activity using molecular docking against bacterial targets, followed by ADMET (absorption, distribution, metabolism, excretion, and toxicity) assessments. Results: Out of 3252 features, 234 and 52 putative compounds were annotated in GNPS and SIRIUS, respectively, as indicated by molecular networking, suggesting high chemical complexity. The chemical space mainly comprises flavonoids (including glycosides, aglycones, methylated, and prenylated derivatives), phenolic acids, amides, hydroxycinnamate derivatives, lignans, megastigmanes, and various diterpenoid skeletons. Multivariate analyses clearly distinguish geographical chemotypes, separating flavonoid-rich regions from diterpenoid-rich regions. Docking studies revealed flavonoids, diterpenoids, and lignans with strong predicted antibacterial activities and favourable ADMET profiles. Conclusions: This study provides the first LC–MS characterisation of the non-volatile metabolome of Ugandan propolis, thereby expanding its chemical diversity. Metabolomics and computational approaches lay a foundation for future ecological, chemotaxonomic, and pharmacological research.
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.
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.