@boku.ac.at
Institute of Chemistry of Renewable Resources, Department of Natural Sciences and Sustainable Resources
BOKU University
Analytical Chemistry, Food Science, Environmental Science
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Christine Betty Nagawa, Isaac Sebuyiira Kitiibwa, Simon Savio Kizito, Agatha Syofuna, Christine Mugumya Kyarimpa, and Timothy Omara
Elsevier BV
Gerald Kwikiriza, Ivan Abaho, Papius Dias Tibihika, Andrew A. Izaara, Faith Atukwatse, Timothy Omara, Juliet K. Nattabi, Nasser Kasozi, Manuel Curto, Andreas Melcher,et al.
MDPI AG
Despite the importance of Nile tilapia as a main aquaculture species in Uganda, limited research has been conducted concerning its genetic diversity, particularly in farmed populations. This gap has hindered the development of a systematic breeding program for this species. Successful aquaculture development, especially for genetic improvement, relies on the diversity and purity of wild and farmed populations as germplasm sources for selective breeding. Using microsatellite markers, the current study evaluated the genetic diversity of 480 samples collected from 20 populations of Nile tilapia (Oreochromis niloticus) in Uganda. All the populations exhibited a higher expected heterozygosity (0.50 ± 0.01) than observed heterozygosity (0.42 ± 0.01), although this was not significantly different. Populations from ponds showed lower FST values (<0.001), an indication of lower genetic differentiation. The populations formed four main clusters; the first comprising of mainly cages (Pal and Busana), the second with cages: Katosi and SON in addition to Rocks hatchery, the third comprised of Bawe cage fish farm and Tendo hatchery, and the fourth were populations from ponds and beaches on Lake Victoria. Given the higher genetic diversity and genetic differentiation of Tendo and Rocks populations, these farms would provide potential candidates for the development of local strains in Uganda. These results provide more insights into the management of local Nile tilapia strains towards reduction of inbreeding levels.
Calton Nantinda, Esther Lynnet Kisakye, David Musana, Isaac Ssessanga, Ukashar Ssenabulya, Timothy Omara, Ivan Kahwa, and Florence Nalimu
Elsevier BV
Hannington Gumisiriza, Eunice Apio Olet, Lydia Mwikali, Racheal Akatuhebwa, Owen Kembabazi, Timothy Omara, and Julius Bunny Lejju
Elsevier BV
Andrew Kaggwa, Denis Byamugisha, Timothy Omara, and Emmanuel Ntambi
MDPI AG
Artisanal and small-scale gold mining (ASCGM) provides a livelihood for many communities worldwide, but it has profound environmental impacts, especially on the quality of nearby water resources. This study assessed the impacts of ASCGM on the physicochemical quality of water and sediments from Kitengure stream, Buhweju Plateau, Western Uganda. Surface water (n = 94) and superficial sediments (n = 36) were sampled between October 2021 and January 2022 from three different sections of Kitengure stream (upstream, midstream around the ASCGM area, and downstream). The samples were analyzed for various physicochemical parameters and selected potentially toxic elements (PTXEs), namely: zinc (Zn), cadmium (Cd), lead (Pb), copper (Cu), and arsenic (As). A health risk assessment was performed using the hazard index and incremental life cancer risk methods. Pearson’s bivariate correlation, geoaccumulation, and pollution indices were used to establish the sources and potential risks that PTXEs in sediments could pose to aquatic organisms. The results indicated that water in Kitengure stream draining the ASCGM site was highly colored (1230.00 ± 134.09 Pt-co units; range = 924.00–1576.00 Pt-co units) and turbid (194.75 ± 23.51 NTU; range = 148–257 NTU). Among the five analyzed PTXEs, only Cd (0.082 ± 0.200–0.092 ± 0.001 mg/L) and Cu (0.022 ± 0.004–0.058 ± 0.005 mg/L) were detected in water, and Cd was above the permissible limit of 0.003 mg/L for potable water. Upon calculating the water quality index (WQI), the water samples were categorized as very poor for upstream samples (WQI = 227) and unfit for use (WQI = 965 and 432) for midstream and downstream samples, respectively. In sediments, the mean concentration ranges of Zn, Cd, Pb, Cu, and As were 0.991 ± 0.038–1.161 ± 0.051, 0.121 ± 0.014–0.145 ± 0.025, 0.260 ± 0.027–0.770 ± 0.037, 0.107 ± 0.017–0.422 ± 0.056, and 0.022 ± 0.002–0.073 ± 0.003 mg/kg, respectively, and they were all below their average shale, toxicity reference, and consensus-based sediment quality guidelines. Geoaccumulation indices suggested that there was no enrichment of the elements in the sedimentary phase and the associated ecological risks were low. However, there were potential non-carcinogenic health risks that maybe experienced by children who drink water from Kitengure stream. No discernable health risks were likely due to dermal contact with water and sediments during dredging or panning activities. It is recommended that further studies should determine the total mercury content of water, sediments, and crops grown along the stream as well as the associated ecological and human health risks.
Hannington Gumisiriza, Eunice Apio Olet, Lydia Mwikali, Racheal Akatuhebwa, Timothy Omara, Julius Bunny Lejju, and Duncan Crispin Sesaazi
MDPI AG
The leaves of Gouania longispicata Engl. (GLE) have been traditionally used to treat more than forty ailments in Uganda, including stomachache, lung and skin cancers, syphilis, toothache, and allergies. In this study, pure compounds were isolated from the methanolic extract of GLE leaves and their structures elucidated using ultraviolet visible spectroscopy, liquid chromatography–tandem mass spectrometry, high performance liquid chromatography, and 1D and 2D NMR techniques. The antibacterial and antioxidant activities of the compounds were assessed using the broth dilution and DPPH assays, respectively. Two known flavonoid glycosides (kaempferol-3-O-α-rhamnopyranoside and rutin), a phenolic glycoside (4,6-dihydroxy-3-methylacetophenone-2-O-β-D-glucopyranoside), and flavonoids (kaempferol and quercetin) were characterized. This is the first time that the kaempferol derivative, the acetophenone as well as free forms of quercetin, kaempferol, and rutin, are being reported in GLE and the Gouania genus. The compounds exhibited antibacterial activity against Streptococcus pneumoniae and Escherichia coli with minimum inhibitory concentrations between 16 µg/mL and 125 µg/mL. The radical scavenging activities recorded half-minimum inhibitory concentrations (IC50) ranging from 18.6 ± 1.30 µg/mL to 28.1 ± 0.09 µg/mL. The IC50 of kaempferol and quercetin were not significantly different from that of ascorbic acid (p > 0.05), highlighting their potential as natural antioxidant agents. These results lend credence to the use of GLE leaves in herbal treatment of microbial infections and oxidative stress-mediated ailments.
Stephen Super Barasa, Fidele Ntie-Kang, , Enos W. Wambu, Jonathan Metuge, Philippe Belle Ebanda Kedi, Richard Amewu, Daniel M. Shadrack, Daniel Tevin Barasa, Timothy Omara,et al.
Springer Science and Business Media LLC
Ronald Tenywa, Timothy Omara, Gerald Kwikiriza, Christopher Angiro, and Emmanuel Ntambi
MDPI AG
For millennia, springs have provided water for drinking, domestic use, balneological treatment, liminality rites as well as tourist attractions. Amidst these uses, anthropogenic activities, especially urbanization and agriculture, continue to impair the functionality of springs. With the looming decadal climate change, freshwater springs could be a sustainable source of clean water for the realisation of Sustainable Development Goal 6. This paper presents the results of the sanitary inspection and assessment of limnochemical characteristics and quality of water samples (n = 64) from four freshwater springs (coded SPR1, SPR2, SPR3, and SPR4) in Kansanga, a flash flood-prone area in the African Great Lakes region of Uganda. Each sample was analysed for 17 parameters (temperature, pH, electrical conductivity, turbidity, fluorides, sulphates, chlorides, nitrates, orthophosphates, total dissolved solids, dissolved oxygen, total alkalinity, potassium, sodium, total, magnesium and calcium hardness) following the standard methods. Water quality index (WQI) was calculated to establish the quality of the water samples based on the physicochemical parameters measured. Based on the sanitary risk assessment results, the springs had medium- to high-risk scores, but most water parameters were within the WHO guidelines for potable water, except for nitrates (in SPR1 and SPR2), hardness levels (in SPR2), and dissolved oxygen (in all the samples). Sampling season and location had significant effects on the limnochemistry of the freshwater springs (p < 0.05). The water quality indices calculated indicated that the water from the springs was of good quality (WQI = 50–57), but there was a reduction in water quality during the wet season. The best water quality was recorded in samples from SPR4, followed by those for SPR3, SPR1, and SPR2. These results provide insights into the contribution of floods and poor sanitation facilities to the deterioration of spring water quality in Kansanga, and the need to leverage additional conservation strategies to support vulnerable communities in the area. Further studies are required to establish the risk posed by trace metals and microbes that may contaminate freshwater in the studied springs, especially following flood events.
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.
Innocent Ayesiga, Shabnoor Iqbal, Yusuf Kyejjusa, Joash Okoboi, Timothy Omara, Thomas Adelina, Delafrique Deogratias, Arthur Amule Anyole, Braize Ben Kagimu, Denis Odongo,et al.
CRC Press
Shabnoor Iqbal, Timothy Omara, Ivan Kahwa, and Usman Mir Khan
Springer Science and Business Media LLC
AbstractBisphenol S (BPS) is one of the monomers preferred in the manufacturing of polycarbonate plastics. Unfortunately, its estrogenic and genotoxic effects are similar to those of bisphenol A. The protective effects of Sphaeranthus indicus floral extract (SFE) against reprotoxic effects of BPS (50 µg/kg per body weight) in rats exposed to it via drinking water was investigated. Different SFE doses (25, 50, and 100 mg/kg) were administered via oral gavage for 10 weeks. High-performance liquid chromatography (HPLC) results indicated that SFE was rich in polyphenols, with rutin and quercetin being important bioactive molecules modulating BPS-induced necroptosis and apoptosis. Biochemical analyses unveiled that rats administered BPS only exhibited considerable elevation of biomarkers of nitro-oxidative stress, necroptotic (RIPK1/RIPK3 and MLKL), and apoptotic mediators (Fas/FasL and caspase 3/caspase-8). These events caused changes in sperm characteristics (sperm motility, sperm head, and sperm viability), sperm count, and hormonal profile (thyroid stimulating hormone, luteinizing hormone, and follicle-stimulating hormone) of the rats. Histological analysis suggested that there was pronounced sloughing of Sertoli cells, reduced spermatogenic cell density, increased levels of seminiferous tubules, and disorganized morphometric parameters related to seminiferous tubules. The SFE supplementation in rats with BPS-containing water restored nitro-oxidative stress biomarkers, which led to the reduction of necroptosis and apoptosis. Reinstatement of all the biomarkers of oxidative stress, inflammation, necroptosis, and apoptosis after SFE supplementations restored the hormonal profile and normal histoarchitecture of the testes. Virtual screening elucidated that the key regulators of the necroptosis are RIPK3-rutin and RIPK1-quercetin complexes. Further studies are needed to assess its pharmacodynamics, kinetics, and effective concentration for daily use in humans.
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.