@boku.ac.at
Institute of Chemistry of Renewable Resources, Department of Chemistry
University of Natural Resources and Life Sciences Vienna (BOKU)
Timothy is with University of Natural Resources and Life Sciences, Vienna (BOKU), Austria and an Assistant Lecturer of Chemistry at Makerere University, Uganda
He was previously with the Department of Chemistry and Biochemistry, Moi University, Kenya and the Center of Excellence II in Phytochemicals, Textile and Renewable Energy (PTRE) hosted at the same University. He has proven research assiduity and track record of publications and refereeing across international peer-reviewed journals, with research interests including-but not limited to-food toxicology, analytical, natural products and environmental chemistry employing modern analytical techniques.
As of November 2023, he has over 70 publications and a book chapter to his name, and is serving as an Academic Editor in PLoS ONE, Journal of Food Quality, PeerJ Analytical Chemistry, Evidence-Based Complementary and Alternative Medicine and VEGETOS (Springer)
Analytical Chemistry, Food Science, Environmental Science
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Shabnoor Iqbal, Timothy Omara, Ivan Kahwa, and Usman Mir Khan
Springer Science and Business Media LLC
AbstractAnthocyanins are water-soluble naturally occurring flavonoids present in fruits, flowers, leaves, and roots of fruit plants and vegetables. One of the important anthocyanidin components of red wine and berries is delphinidin (DP). This review provides an update on the potential of DP in cancer therapy, with a further understanding of the mechanisms involved. Delphinidin has been shown to elicit inhibitory effects on catabolizing enzymes of human granulocytes and parasites, TNF-induced COX-2 expression in mouse epidermal cells, and reduce oxidative stress. It also inhibited anchorage-independent growth and caused cell death in breast cancer cell lines. Delphinidin increased Nrf2 expression, increased HO-1 production, and promoted mRNA expression of mitochondrial biogenesis-related factors. Further, DP has anti-proliferative and pro-apoptotic effects in various cancer cell lines such as lung, breast, and ovarian cancer cells. The mTOR-related pathway is the most important signaling pathway in the activation of autophagy, and DP has been shown to exert its cytotoxic effects on cancer cell lines via activating protein kinases. Among DP derivatives, delphinidin-3-O-glucoside has the best anticancer activity because it is easily absorbed. However, the metabolism of DP and its bioavailability in biological systems need to be explored to fully understand its benefits.
Onani Makeo, Amito Patricia Okot, Isaac Isabirye, Timothy Omara, and Joel Walugembe
Springer Science and Business Media LLC
Ivan Gumula, Christine Kyarimpa, Sarah Kiwanuka Nanyonga, George Kwesiga, George Busulwa, Boniface Opio, Mathias Heydenreich, and Timothy Omara
SAGE Publications
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.
Shabnoor Iqbal and Timothy Omara
Springer Science and Business Media LLC
AbstractCarbamazepine is a first-choice anticonvulsant, and its medication is typically well tolerated when compared to lithium and valproic acid. Patients of Alzheimer’s Disease who are administered carbamazepine tend to develop acute tubulointerstitial nephritis. In this study, we established an Alzheimer’s model using scopolamine in Sprague Dawley rats to find out the nephroprotective effect of matricin (a bioactive sesquiterpene isolated from chamomile flowers) against carbamazepine-induced acute tubulointerstitial nephritis and its underlying mechanism of action. Scopolamine (16 mg/kg) was intraperitoneally injected for induction of Alzheimer’s disease on the 28th day whereas carbamazepine (25 mg/kg) was given daily to induce acute tubulointerstitial nephritis. Treatment with matricin inhibited carbamazepine-induced mRNA expressions of RAS-ERK-MEK-JAK2-STAT3, cytokines (IL-1β, TNF-α, and IL-6), and restored the optimal levels of biomarkers of oxidative stress (MDA, SOD and CAT). Further, matricin treatments reinstated biomarkers of kidney function (creatinine, uric acid, and blood urea nitrogen), and refurbished the levels of MDA, SOD, and CAT. Histopathological analyses indicated that there was systemic dilation, tubular necrosis, interstitial edema, and glomerulus nephritis in the medulla region of the kidneys in rats with Alzheimer’s disease that received carbamazepine only. Treatment with matricin reconsolidated histopathology, and only mild glomerulus nephritis were observed in rats with Alzheimer’s disease. These results suggest that matricin could be utilized as a co-supplement with carbamazepine for the treatment of patients with Alzheimer’s disease to minimize the risk of kidney damage.
Samuel Baker Obakiro, Timothy Omara, Ambrose Kiprop, Lydia Bunalema, Isaac Kowino, and Elizabeth Kigondu
Springer Science and Business Media LLC
Sumel Ashique, Sourav Mohanto, Mohammed Gulzar Ahmed, Neeraj Mishra, Ashish Garg, Dinesh Kumar Chellappan, Timothy Omara, Shabnoor Iqbal, and Ivan Kahwa
Elsevier BV
Eunice Nuwamanya, Denis Byamugisha, Caroline K. Nakiguli, Christopher Angiro, Alice V. Khanakwa, Timothy Omara, Simon Ocakacon, Patrick Onen, Daniel Omoding, Boniface Opio,et al.
MDPI AG
Metal fabrication workshops (MFWs) are common businesses in Ugandan cities, and especially those producing metallic security gates, window and door frames (burglar-proof), and balcony and staircase rails. The objective of this study was to comparatively assess the pollution levels and potential health risks of manganese (Mn), chromium (Cr), cadmium (Cd), lead (Pd) and nickel (Ni) in pooled surface soil samples from four 5-, 7-, 8-, and 10-year-old MFWs (n = 28) and a control site (n = 8) in Mbarara City, Uganda. The concentration of the potentially toxic elements (PTEs) was determined using inductively coupled plasma–optical emission spectrometry. Contamination, ecological, and human health risk assessment indices and models were used to identify any risks that the PTEs could pose to the pristine environment and humans. Our results showed that PTE pollution of soils is occuring in the MFWs than at the control site. The mean concentrations of the PTEs (mg kg−1) in the samples were: Mn (2012.75 ± 0.23–3377.14 ± 0.31), Cr (237.55 ± 0.29–424.93 ± 0.31), Cd (0.73 ± 0.13–1.29 ± 0.02), Pb (107.80 ± 0.23–262.01 ± 0.19), and Ni (74.85 ± 0.25–211.37 ± 0.14). These results indicate that the PTEs could plausibly derive from the fabrication activities in these workshops, which is supported by the high values of contamination factors, index of geoaccumulation, and the overall increase in pollution load indices with the number of years of operation of the MFWs. Human health risk assessment showed that there are non-carcinogenic health risks that could be experienced by children who ingest PTEs in the soils from the 7-, 8- and 10-year-old MFWs. The incremental life cancer risk assessment suggested that there are potential cancerous health effects of Cd and Ni that could be experienced in children (who ingest soils from all the four MFWs) and adults (ingesting soils from the 8- and 10-year-old MFWs). This study underscores the need to implement regulatory guidelines on the operation and location of MFWs in Uganda. Further research should be undertaken to investigate the emission of the PTEs during welding operations in the MFWs.
Christine Kyarimpa, Tom Omute, Caroline K. Nakiguli, Alice V. Khanakwa, Christopher Angiro, Ivan Kahwa, Fortunate Ahumuza, and Timothy Omara
Springer Nature Singapore
Selamawit Shiferaw Deffar, Anil Kumar, Anthony Muliwa, Njira Njira Pili, and Timothy Omara
Cellule MathDoc/Centre Mersenne
Ayékotchami Jacques Dossou, Adandé Belarmain Fandohan, Timothy Omara, and Jean-Philippe Chippaux
Hindawi Limited
Snakebite envenomation (SBE) constitutes a public health, social, and economic problem affecting poor communities in intertropical and subtropical regions. This review sought to synthesize literature on snakebite envenomation in Benin to highlight research perspectives and strategies for better management of the menace. A literature search performed in multidisciplinary electronic databases showed that the prevalence of SBE is high in Benin, but the incidences, associated morbidities, and mortalities are greatly underestimated. Most snake envenomations are by Echis ocellatus in Northern Benin during the rainy season. Adults involved in agricultural activities are the most affected. The absence of antivenin serum in the most affected areas explains the preference for alternative and traditional medicine as the first-line treatment for SBE in Benin. In conclusion, it would be imperative to revitalize the snakebite reporting system in order to have better epidemiological data and to develop a sustainable national strategy for the control and management of snakebite envenomation.
Daniel Nimusiima, Denis Byamugisha, Timothy Omara, and Emmanuel Ntambi
MDPI AG
Increasing global pollution of water resources undermines the efforts invested in the realisation of Sustainable Development Goals. In developing countries, for example, water pollution is exacerbated by poor regulatory structures and improper waste disposal. This study, for the first time, investigated the physicochemical and microbial parameters of surface water from the Ugandan stretch of the Kagera transboundary river. Surface water (n = 135) from downstream, midstream and upstream of the river was sampled between February 2021 and June 2021, and analysed following standard methods for the examination of water and wastewater. Further, the samples were analysed using flame atomic absorption spectroscopy for the presence of heavy metals: nickel, lead, chromium, cadmium and copper. The obtained results showed that turbidity (24.77 ± 5.5–43.99 ± 6.87 mg/L), colour (118 ± 8.90–145.2 ± 30.58 Pt-co units), Escherichia coli (4.96 ± 7.01 CFU/100 mL), lead (23.0 ± 11.0–43.0 ± 12.0 µg/L) and cadmium (3.3 ± 1.0–10.1 ± 10.0 µg/L) were at levels that surpassed their permissible limits as per World Health Organization guidelines for potable water. These results are lower than previously reported for the Rwandese stretch of this river, but still present potential health risks to the population whose livelihoods depend on the river. Measures should therefore be instituted by the East African Community member states to mitigate riverine pollution and ensure sustainable use of the Kagera transboundary river.
Patrick Onen, Robin Akemkwene, Caroline K. Nakiguli, Daniel Nimusiima, Daniel Hendry Ruma, Alice V. Khanakwa, Christopher Angiro, Gadson Bamanya, Boniface Opio, Allan Gonzaga,et al.
MDPI AG
Pollution of water resources is one of the major impediments to the realization of Sustainable Development Goals, especially in developing countries. The aim of this study was to investigate the physicochemical quality and potentially toxic element (lead and cadmium) concentrations in surface water sampled from Pager River, a tributary of the Nile River in Northern Uganda. Water samples (n = 18) were taken from six different points upstream (A, B, and C) and downstream (D, E, and F) of the river and analyzed following standard methods for their physiochemical properties. Atomic absorption spectroscopy was used to quantify lead and cadmium concentrations. Human health risks from ingestion and dermal contact with potentially toxic metal-contaminated water were calculated. The results obtained indicated that the mean temperature (27.7 ± 0.5–29.5 ± 0.8 °C), turbidity (40.7 ± 2.1–50.1 ± 1.1 NTU), lead (0.296 ± 0.030–0.576 ± 0.163 mg/L) and cadmium (0.278 ± 0.040–0.524 ± 0.040 mg/L) occurred at levels that surpassed their permissible limits as per World Health Organization guidelines for drinking water. Human health risk assessment showed that there are potential non-cancer risks from the ingestion of water from Pager River by adults, as the total hazard quotients were greater than one. These results emphasize the urgency to restrict the dumping of wastes into the river to minimize chances of impacting the Nile River, which flows northwards to the Mediterranean Sea. Further studies should perform routine monitoring of the river during both dry and wet seasons to establish the spatiotemporal variations of physicochemical, microbial, and trace metal profiles of the river and the associated health risks.
Hannington Gumisiriza, Eunice Apio Olet, Paul Mukasa, Julius B. Lejju, and Timothy Omara
Springer Science and Business Media LLC
Abstract Background Malaria remains a major global health challenge and a serious cause of morbidity and mortality in sub-Saharan Africa. In Uganda, limited access to medical facilities has perpetuated the reliance of indigenous communities on herbal medicine for the prevention and management of malaria. This study was undertaken to document ethnobotanical knowledge on medicinal plants prescribed for managing malaria in Rukungiri District, a meso-endemic malaria region of Western Uganda. Methods An ethnobotanical survey was carried out between May 2022 and December 2022 in Bwambara Sub-County, Rukungiri District, Western Uganda using semi-structured questionnaire. A total of 125 respondents (81 females and 44 males) were randomly selected and seven (7) key informants were engaged in open interviews. In all cases, awareness of herbalists on malaria, treatment-seeking behaviour and herbal treatment practices were obtained. The ethnobotanical data were analyzed using descriptive statistics, informant consensus factor and preference ranking. Results The study identified 48 medicinal plants belonging to 47 genera and 23 families used in the treatment of malaria and its symptoms in the study area. The most frequently cited species were Vernoniaamygdalina, Aloevera and Azadirachtaindica. Leaves (74%) was the most used plant organ, mostly for preparation of decoctions (41.8%) and infusions (23.6%) which are administered orally (89.6%) or used for bathing (10.4%). Conclusions Indigenous knowledge of medicinal plants used as prophylaxis and for treatment of malaria still exist among the local communities of Bwambara Sub-County. However, there is a need to investigate the antimalarial efficacy, phytochemical composition and safety of species (such as Digitariaabyssinica and Berkheyabarbata) with high percentage use values to validate their use.
John R. S. Tabuti, Samuel Baker Obakiro, Alice Nabatanzi, Godwin Anywar, Cissy Nambejja, Michael R. Mutyaba, Timothy Omara, and Paul Waako
Springer Science and Business Media LLC
Abstract Background Malaria remains the leading cause of death in sub-Saharan Africa. Although recent developments such as malaria vaccine trials inspire optimism, the search for novel antimalarial drugs is urgently needed to control the mounting resistance of Plasmodium species to the available therapies. The present study was conducted to document ethnobotanical knowledge on the plants used to treat symptoms of malaria in Tororo district, a malaria-endemic region of Eastern Uganda. Methods An ethnobotanical study was carried out between February 2020 and September 2020 in 12 randomly selected villages of Tororo district. In total, 151 respondents (21 herbalists and 130 non-herbalists) were selected using multistage random sampling method. Their awareness of malaria, treatment-seeking behaviour and herbal treatment practices were obtained using semi-structured questionnaires and focus group discussions. Data were analysed using descriptive statistics, paired comparison, preference ranking and informant consensus factor. Results A total of 45 plant species belonging to 26 families and 44 genera were used in the preparation of herbal medicines for management of malaria and its symptoms. The most frequently mentioned plant species were Vernonia amygdalina, Chamaecrista nigricans, Aloe nobilis, Warburgia ugandensis, Abrus precatorius, Kedrostis foetidissima, Senna occidentalis, Azadirachta indica and Mangifera indica. Leaves (67.3%) were the most used plant part while maceration (56%) was the major method of herbal remedy preparation. Oral route was the predominant mode of administration with inconsistencies in the posology prescribed. Conclusion This study showed that the identified medicinal plants in Tororo district, Uganda, are potential sources of new antimalarial drugs. This provides a basis for investigating the antimalarial efficacy, phytochemistry and toxicity of the unstudied species with high percentage use values to validate their use in the management of malaria.
Shabnoor Iqbal, Farhat Jabeen, Ivan Kahwa, and Timothy Omara
Springer Science and Business Media LLC
Herbert Kariitu Mugume, Denis Byamugisha, Timothy Omara, and Emmanuel Ntambi
MDPI AG
Consumption of maize and maize-based products contributes a significant percentage to the total food energy intake in Uganda. However, the production of maize-derived foodstuffs is performed traditionally or by small- and medium-scale processors using different processing techniques. This can lead to differences in the quality of these products from processors, raising food safety concerns. In this study, the effects of mechanical processing (milling) methods on deposition of heavy metals into milled maize flour and the associated consumption health risks were assessed. Atomic absorption spectrophotometry was used to quantitatively establish the concentration of iron (Fe), manganese (Mn), zinc (Zn), cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu), cobalt (Co) and nickel (Ni) in 100 samples of maize milled using a wooden mortar (n = 2), a metallic mortar (n = 2), diesel engine−powered mills (n = 48) and electric motor−powered mills (n = 48). Results showed that the mean concentrations of heavy metals in mg/kg were Fe (11.60–34.45), Cu (0.50–8.10), Ni (0.50–1.60), Mn (0.70–25.40), Zn (4.40–15.90), Pb (0.53–10.20), Cd (0.51–0.85), Cr (0.50–1.53) and Co (0.50–1.51). The highest concentrations were found in flour milled using a traditional metallic mortar while the lowest levels were in those samples milled using a wooden mortar. The Fe, Pb and Cd contents of flours produced using the metallic mortar and some commercial mills was found to be higher than the permissible limits set by WHO/FAO. Human health risk assessment showed that there are potential carcinogenic health risks from adults’ intake of heavy metals in maize flour milled using a metallic mortar. Therefore, processing of maize flour needs to be monitored by the relevant statutory bodies in Uganda to minimize the possibility of heavy metal contamination of food products and animal feeds.
Timothy Omara, Ambrose K. Kiprop, and Viola J. Kosgei
Springer Science and Business Media LLC
Timothy Omara, Christine Betty Nagawa, Christine Kyarimpa, Stefan Böhmdorfer, Thomas Rosenau, Solomon Omwoma Lugasi, Henry Matovu, Silver Odongo, and Patrick Ssebugere
MDPI AG
Advected cyanobacteria, algal blooms and cyanotoxins have been increasingly detected in freshwater ecosystems. This review gives an insight into the present state of knowledge on the taxonomy, dynamics, toxic effects, human and ecological health implications of cyanobacteria, algal blooms and cyanotoxins in the East African Community lakes. The major toxigenic microalgae in East African lakes include Microcystis, Arthrospira, Dolichospermum, Planktolyngbya and Anabaenopsis species. Anatoxin-a, homoanatoxin-a, microcystins (MCs), cylindrospermopsin and nodularin have been quantified in water from below method detection limits to 81 µg L−1, with peak concentrations characteristically reported for the wet season. In whole fish, gut, liver and muscles, MCs have been found at concentrations of 2.4 to 1479.24 μg kg−1, which can pose human health risks to a daily consumer. While there have been no reported cases of cyanotoxin-related poisoning in humans, MCs and anatoxin-a (up to 0.0514 μg kg−1) have been identified as the proximal cause of indiscriminate fish kills and epornitic mortality of algivorous Phoeniconaias minor (lesser flamingos). With the unequivocal increase in climate change and variability, algal blooms and cyanotoxins will increase in frequency and severity, and this will necessitate swift action towards the mitigation of nutrient-rich pollutants loading into lakes in the region.
Timothy Omara, Ambrose K., and Viola J.
TMR Publishing Group
Timothy OMARA, Benard Otieno SADİA, Immaculate MBABAZİ, and Augastine OKWİR
The Turkish Chemical Society
Euclea divinorum Hiern (Ebenaceae) is a medicinal plant widely used in Yemen, Eastern and Southern Africa in traditional phytotherapy. This review was an attempt to compile a comprehensive report on its ethnomedicinal uses, phytochemicals, pharmacological activities, and toxicity, lending credence to the use of its various parts in herbal medicine. The literature encountered indicated that herbal formularies from different parts of Euclea divinorum (E. divinorum) are majorly used for traditional treatment of odontological, dermatological, respiratory, reproductive, and gastrointestinal ailments. At least 18 compounds have been isolated and characterized in extracts of E. divinorum, while 31 others have been identified in the crude extracts analyzed by GC-MS. Extracts, as well as isolated compounds from E. divinorum stem, stem barks, leaves, and roots, showed renoprotective, antiproliferative, antinociceptive, contractile, proteolytic, diuretic, antiprotozoal, anti-giardial, antioxidant, anti-inflammatory, antimicrobial, molluscicidal, and insecticidal activities. Further research is warranted to explore other pharmacological properties such as antisnake venom, aphrodisiac, antidiabetic, analgesic, and antimycobacterial activities and the responsible bioactive compounds in the different parts of E. divinorum claimed in herbal medicine. The composition and bioactivities of essential oils from this species also warrant further studies.
Timothy Omara, Ambrose K., Viola J., and Sarah Kagoya
TMR Publishing Group
Diana Rita Nanyanzi, Gilbert Gilibrays Ocen, Timothy Omara, Felix Bwire, Davis Matovu, and Twaibu Semwogerere
Springer Science and Business Media LLC
Abstract Objective The aim of this study was to design a domestic water temperature, pH and turbidity monitoring system that could constantly log temperature, pH and turbidity of water and give alerts in case the parameters are outside the acceptable limits for potable water. Results The system was designed, assembled and performed as expected. The study indicates that the proposed and designed system outperforms the existing manual monitoring system as it can constantly track and store changes in water quality. This could be used to prepare better treatment processes as well as identify problems in the water distribution system early enough.
Timothy Omara, Caroline Kiwanuka, Rania Awad Naiyl, Florence Atieno Opondo, Sadia Benard Otieno, M. L. Ndiege, Immaculate Mbabazi, Winfred Nassazi and Edmond Etimu
International Society of Communication and Development Between Universities (ISCDBU)
Poisonous snake envenomation is a complex neglected health problem implicated in mortality, disability, psychological morbidity, and socio-economic losses recorded worldwide. An antivenin serum, the only medically recommended treatment for snakebites, has several drawbacks including, hypersensitivity, inability to prevent local tissue damage, are scarce and unaffordable in most snakebite endemic areas. In many rural communities all over the world, plants have been utilized for managing snakebites. This review seeks to identify plants reported as antivenom remedies in the East Africa and the scientific studies thereof which could support their use in the treatment of snake envenomation. A review of scientific articles was undertaken to identify information on traditional knowledge of medicinal plants used to treat snake envenomation in East Africa and their antivenom efficacy. A total of 361 plant species were retrieved to have been reported as traditional therapies for snakebites in East Africa. The review identified distinct cases of doctrine of signatures and zoopharmacognosy in snakes using Opilia amentacea, Hugonia castaneifolia and Microglossa pyrifolia respectively. Evaluations of the antivenom efficacy of 44 species (12.2%) have been done globally, and most species found to be effective in neutralizing the lethal activities of snake venoms. Ethnomedicinal plants play a revered holistic role in East African antisnake venom therapy. Conyza sumatrensis, Hyptis pectinata, Justicia betonica, and Maesa lanceolata used to treat specific snakebites merit further studies.