Browsing by Author "Oloya, Benson"
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Item An ethnobotanical survey of plant species used for medicinal purposes in Amuru district, northern Uganda(Ilia State University, 2024-09-12) Gum, Bornfree; Opoke, Robert; Akwongo, Betty; Oloya, Benson; Omony, John Bosco; Opiro, Robert; Andama, Morgan; Anywar, Godwin; Malinga, Geoffrey MaxwellBackground: Medicinal plants provide health care to rural communities that have limited access to modern medicine in Uganda. Thus, documenting medicinal plants is important for their sustainable utilisation and conservation of medicinal plants and associated indigenous knowledge. Methods: A cross-sectional ethnobotanical survey was conducted in August 2021 to assess the knowledge and use of medicinal plants in Lamogi Sub-County, Amuru district. We randomly sampled and interviewed 334 household heads using semi-structured questionnaires. Data was analysed using descriptive statistics, familiarity index (FI), fidelity level (FL) and informant consensus factor (ICF). Results: Most of the respondents (90%) had knowledge of medicinal plants used for treating ailments in their community (high ICF values above 0.9). Plant with the highest FI value was Gymnanthemum amygdalinum (Delile) Sch.Bip. indicating its wide use in the community. Chi-square tests showed significant associations between the knowledge of medicinal plants and education level, occupation, age, marital status and monthly income of respondents (p < 0.05). Forty-nine medicinal plants from 30 families were documented, with Fabaceae and Asteraceae having the most species. Leaves were the most frequently used plant parts (65.4%), followed by roots (13.6%). Herbal remedies were mostly prepared by crushing and smearing on the body, infusion, decoction and administered orally. Conclusion: The people of Amuru district have rich indigenous knowledge of diverse medicinal plants used for treating ailments. Most medicinal plants are harvested from the wild, threatening their survival and this requires putting in place practical conservation measures.Item Antimycobacterial Activity of the Extract and Isolated Compounds From the Stem Bark of Zanthoxylum leprieurii Guill. and Perr.(SAGE Publications, 2021-08-24) Oloya, Benson; Namukobe, Jane; Heydenreich, Matthias; Ssengooba, Willy; Schmidt, Bernd; Byamukama, RobertZanthoxylum leprieurii Guill. and Perr. (Rutaceae) stem bark is used locally in Uganda for treating tuberculosis (TB) and cough-related infections. Lupeol (1), sesamin (2), trans-fagaramide (3), arnottianamide (4), (S)-marmesinin (5), and hesperidin (6) were isolated from the chloroform/methanol (1:1) extract of Z. leprieurii stem bark. Their structures were elucidated using spectroscopic techniques and by comparison with literature data. Furthermore, the extract and isolated compounds were subjected to antimycobacterial activity. The extract exhibited moderate activity against the susceptible (H37Rv) TB strain, but weak activity against the multidrug resistant (MDR)-TB strain with minimum inhibitory concentrations (MICs) of 586.0 and 1172.0 μg/mL, respectively. Compound 3 (trans-fagaramide) showed significant antimycobacterial activity against the susceptible (H37Rv) TB strain (MIC 6 μg/mL), but moderate activity against the MDR-TB strain (MIC 12.2 μg/mL). Compounds 2, 5, 6, and 1 showed moderate activities against the susceptible (H37Rv) strain (MIC 12.2-98.0 μg/mL) and moderate to weak activities against theMDR-TB strain (MIC 24.4-195.0 μg/mL). This study reports for the first time the isolation of compounds 1 to 6 from the stem bark of Z leprieurii. trans-Fagaramide (3) may present a vital template in pursuit of novel and highly effective TB drugs.Item Antimycobacterial activity, acute toxicity, and characterisation of compounds from selected medicinal plants used in the treatment of Tuberculosis in Uganda(Natural Product Research Network for East and Central Africa (NAPRECA), 2021-11-25) Oloya, Benson; Namukobe, Jane; Heydenreich, Matthias; Ssengooba, Willy; Afayoa, Mathias; Schmidt, Bernd; Byamukama, RobertTuberculosis (TB) is one of the leading causes of death globally, and the rise in drug-resistant forms of TB has become a significant threat (WHO, 2020). Subsequently, it is crucial to explore new, effective and safe anti-TB agents. Several plant species are used in traditional medicine for the treatment of TB in Africa. In Uganda, Acacia hockii, Albizia coriaria, Combretum molle, Warburgia ugandensis, and Zanthoxylum leprieurii are among the plant species used locally to treat tuberculosis, and they could have antimycobacterial compounds that may justify their traditional use but without scientific validation of their bioactivity and toxicity (Anywar et al., 2020; Bunalema et al., 2014; Muthee et al., 2011; Tabuti et al., 2010). This study aimed to conduct antimycobacterial activity and acute toxicity of the selected plant species’ crude extracts and isolate compounds from the stem bark of Z. leprieurii. The aqueous and methanol/dichloromethane (DCM) (1:1) extracts of each of the selected plant species and the isolated compounds were tested for antimycobacterial activity using microplate alamar blue assay (Lawal et al., 2011). For acute toxicity, a single dose (2000 mg/kg) of the aqueous extracts was orally administered to each adult female Winstar albino rat and then observed for 14 days (Lipnick et al., 1995; OECD, 2008). At the end of the experiment, blood samples were collected for haematological and biochemical analyses, while tissue samples from vital organs were collected for histopathological analysis. Isolation and purification of the compounds from the Z. leprieurii stem bark extract were performed using repeated column chromatography. Structure elucidation of the compounds was carried out using spectroscopic methods and by comparison with literature data. Aqueous extracts showed moderate-weak activity against the susceptible (H37Rv) TB strain and weak activity against the multidrug-resistant (MDR) TB strain. Methanol/DCM extracts showed significant-moderate activity against the susceptible (H37Rv) TB strain and moderate-weak activity against the MDR TB strain. After the acute toxicity tests, one mortality and significant lesions in the examined organs following histopathological analyses were recorded from the A. coriaria treated group. Still, the LD50 of all the extracts was estimated to be above 2000 mg/kg. Lupeol, sesamin, trans-fagaramide, arnottianamide, (S)-marmesinin, and hesperidin were isolated from the chloroform/methanol (1:1) extract of Z. leprieurii stem bark, and trans-Fagaramide showed significant antimycobacterial activity against the susceptible (H37Rv) TB strain (Oloya et al., 2021). A. hockii methanol/DCM extract had significant antimycobacterial activity against the susceptible (H37Rv) TB strain, and the methanol/DCM extracts of all the other selected plants had good antimycobacterial activity. The selected plant extracts except A. coriaria exhibited low acute toxicity levels and could be safe for formulations into herbal products. trans-Fagaramide may present a vital template in pursuit of novel and highly effective TB drugs.Item The cyanogenic potential of certain cassava varieties in Uganda and their fermentation-based detoxification(IntechOpen, 2023-04-04) Oloya, Benson; Adaku, Christopher; Andama, MorganCassava is the leading staple food in the developing world, providing an essential diet for about half a billion individuals. However, cassava contains significantly toxic compounds, the cyanogenic glycosides. Ingestion of such toxins in large quantities can lead to acute cyanide poisoning and may cause death in both humans and animals. Therefore, cassava may present a potential health risk to consumers. Information regarding the cyanogenic glycoside content is vital in averting health risks associated with cassava consumption. Accordingly, the seven most common local cultivars in Zombo district and six improved cultivars were grown and later characterized based on their cyanogenic potential. Additionally, the root tubers of Nyar-udota and Nyar-papoga were fermented to detoxify them from the cyanogens. The cyanogenic glycoside levels in the selected cultivars surpassed the critical value of 10 ppm established by the World Health Organization. The improved cassava had lower and moderately identical concentrations of HCN, unlike the local varieties. Cyanogenic contents were highest at 8-10 months. Fermentation led to substantial detoxification of the cyanogens, and the decrease varied with the fermentation period. In making choices for the cultivation and consumption of cassava, it is crucial to consider the cultivar, period of harvesting, and detoxification by fermentation.Item Cyanogenic potential of selected cassava varieties in Zombo District, Uganda(International Journal of Nutrition and Food Sciences, 2017) Oloya, Benson; Adaku, Christopher; Ntambi, Emmanuel; Andama, MorganBoth improved and local cassava varieties are widely grown and also, consumed in Zombo district as well as West Nile Sub region and Uganda as a whole. However, all cassava varieties contain cyanogenic glycosides which are toxic, although the amounts in each cultivar may vary considerably. Consumption of such toxins in sufficient quantities poses a health risk since they can cause acute cyanide poisoning and death in humans and animals. As such, information concerning the cyanogenic glycosides content in cassava cultivars is indispensable in averting health risks linked with cassava consumption. In this study, the cyanogenic content of the most common local cassava varieties (Bisimwenge, Nyar-anderiano, Nya-matia, Nya-pamitu, Nya-papoga and Nyar-udota) grown in Zombo district and six improved cassava varieties (NASE 3, NASE 9, NASE 14, NASE 19, TME 14 and TME 204) were investigated. Generally, the improved cassava varieties revealed lower levels (mean value was 108.75 mg/kg) of cyanogens than the local varieties (mean value was 201.65 mg/kg). The concentrations of the cyanogen in all the cultivars investigated were far above the FAO/WHO recommended value (<10mg/kg). Hence, adequate detoxification and reduced frequency of consumption of these cassava cultivars are necessary in order to limit the ingestion of toxic levels of cyanide.Item Detoxification of Nyar-Udota cassava variety in Zombo district by fermentation(2017) Oloya, Benson; Adaku, Christopher; Ntambi, Emmanuel; Andama, MorganFermentation is capable of detoxifying cassava cultivars. Cassava is one of the most important food crops in the world and in Uganda it is the second most consumed food crop after bananas. However, cassava has some toxic compounds, the cyanogenic glycosides such as linamarin and lotaustralin. Ingestion of the toxins in abundant quantities can be harmful to the health of both humans and animals. Cassava may hence, present a potential health risk to the consumers. Information regarding better detoxifying methods and processing conditions of cyanogenic glycosides content in cassava is vital for avoidance of health risks associated with cassava consumption. Accordingly, one local cultivar, Nyar-udota, was subjected to fermentation for detoxification of their cyanogenic content. Fermentation achieved significant detoxification of the cyanogenic glycosides in the cassava cultivar up to 64.7% and the decrease varied with period of fermentation.Item Effectiveness of traditional processing techniques in reducing cyanide levels in selected cassava varieties in Zombo District, Uganda.(International Journal of Food Science and Biotechnology, 2017) Andama, Morgan; Oloya, BensonThe root tubers of cassava (Manihot esculenta Crantz) contain varying amounts of cyanogenic glucosides which liberate toxic hydrogen cyanide with the resultant effect of poisoning especially the highly cyanogenic cultivars. These include some of the local and improved cassava varieties grown in Zombo district, Uganda among others. Therefore, this study explored the effectiveness of some traditional processing techniques used singly and in combination to reduce cyanide levels in highly toxic root tubers of selected local (Nyar-anderiano, Nyar-papoga, Nyar-udota, Nyar-pamitu, Bisimwenge, Nyar-matia) and improved (NASE 3, NASE 9, NASE 14, NASE 19, TME 14 and TME 204) cassava varieties grown in Zombo District, Uganda. The processed and the fresh cassava tubers were analysed for Hydrogen cyanide (HCN) by the standard titration method. The results indicated that heap fermentation followed by sun-drying reduced the cyanide levels in all the selected improved varieties to WHO safe levels for consumption (below 10mg/kg) in the dried chips. Mixed processing methods combining soaking, fermentation and sun-drying reduced the cyanide concentrations in the local varieties (Nyar-udota, Nyaranderiano) and improved variety (NASE 19) to World Health Organisation (WHO) safe levels. None of the processing techniques used singly reduced the HCN levels in the root tubers of the selected cassava varieties to safe levels. Hence mixed strategies combining several traditional cassava processing techniques should be adopted to detoxify the selected cassava varieties of cyanogens. The local cassava varieties (Bisimwenge, Nya-matia, Nya-pamitu, Nya-papoga) would require modifications of the combined traditional processing techniques or other more complex processes to detoxify them of HCN before human consumption.Item Phytochemical screening, antimycobacterial activity and acute toxicity of crude extracts of selected medicinal plant species used locally in the treatment of tuberculosis in Uganda(Springer Nature, 2022-02-17) Oloya, Benson; Namukobe, Jane; Ssengooba, Willy; Afayoa, Mathias; Byamukama, RobertBackground Tuberculosis (TB) is one of the leading causes of death globally, and the rise in drug-resistant forms of TB has become a significant threat. Subsequently, it is crucial to explore new, effective and safe anti-TB agents. This study aimed at conducting phytochemical screening, antimycobacterial activity, and acute toxicity of the selected plant species’ crude extracts to assess their toxicological potentials and efficacies against TB. Methods The aqueous and methanol/dichloromethane (DCM) (1:1) extracts of each selected plant species were subjected to phytochemical screening and antimycobacterial activity using microplate alamar blue assay. For acute toxicity, a single dose (2000 mg/kg) of the aqueous extracts was orally administered to each animal following the Organization for Economic Cooperation and Development (OECD) guidelines No. 425 and then observed for 14 days. The animals were closely observed on the general behavior and clinical signs of toxicity, and body weights were recorded. After the termination of the experiment, hematological, biochemical, and histopathological analyses were performed. Results The extracts contained alkaloids, flavonoids, tannins, saponins, steroids, terpenoids, resins, cardiac glycosides, phenolic compounds, and coumarins. Aqueous extracts showed moderate to weak activity against the susceptible (H37Rv) M. tuberculosis strain and weak activity against the MDR-TB strain with Minimum Inhibitory Concentrations (MIC μg/mL) ranging from 293.0–2344.0 and 1172.0–4688.0, respectively. Methanol/DCM extracts showed significant to moderate activity against the susceptible TB strain and moderate to weak activity against the MDR-TB strain with MIC (μg/mL) ranging from 98.0–586.0 and 293.0–781.0, respectively. One mortality was recorded from the A. coriaria treated group following the acute toxicity tests, but the LD50 of all the extracts was estimated to be above 2000 mg/kg. Histopathological analyses did not show any significant lesions in the examined organs except those from the A. coriaria treated group. Conclusion Phytochemical screening of the extracts revealed the presence of alkaloids, tannins, saponins, flavonoids, steroids, terpenoids, resins, cardiac glycosides, phenolic compounds, and coumarins. All the methanol/DCM extracts of the plant species studied have promising antimycobacterial activity. The selected plant extracts studied exhibited low acute toxicity levels except for A. coriaria and could be safe for formulations into herbal products.Item Potential of soaking and sun-drying in detoxifying toxic cassava root tubers(International Journal of Food Science and Biotechnology, 2017) Andama, Morgan; Lejju, Bunny Julius; Oloya, BensonRoot tubers of cassava (Manihot esculenta Crantz) have cyanogenic glucosides which liberate hydrogen cyanide (HCN) on hydrolysis in quantities that can be toxic to humans. As a result, several techniques have been used to detoxify the tubers including among others, soaking, sun-drying and fermentation which has been found to be the most effective. However, fermentation is associated with the growth of potentially mycotoxigenic moulds (fungi) which compromise the quality of the processed product hence suggesting the use of alternative mould free processing techniques like soaking and sun-drying. Therefore, this study investigated the potential of soaking and sun-drying in detoxifying root tubers of a toxic cassava variety, “Rutuga”, (interpreted as “strangler”) of cyanogens (total HCN, free HCN and bound HCN) in South Western Uganda. The cyanogens were determined by a standard titration method. The results indicated that soaking peeled cassava root tubers in cold distilled water for 4 days removed about 78% of bound HCN while sun-drying of peeled cassava chips for 5 days removed about 74% of free HCN. However, both methods are less effective in removing total HCN (soaking, 47%; sun-drying, 43%) due to the ineffectiveness of soaking and sun-drying in removing free HCN (21%) and bound HCN (3%) respectively. Hence a mixed approach employing both methods would be more appropriate in detoxifying cassava of total HCN.Item Two new compounds and the anti-mycobacterial activity of the constituents from Zanthoxylum leprieurii root bark(Elsevier Ltd., 2023-02-08) Oloya, Benson; Namukobe, Jane; Heydenreich, Matthias; Ssengooba, Willy; Martin, Johannes; M¨oller, Heiko Michael; Schmidt, Bernd; Byamukama, RobertThe emergence of resistance to the existing TB drugs necessitated a search for new anti-mycobacterial compounds from Z. leprieurii root bark, which is used locally for the treatment of tuberculosis (TB) in Uganda. Two new compounds: (E)-N-isobutyl-3-(4-((3-methylbut-2-en-1-yl)oxy)phenyl)acrylamide (1) and 4-(5,5a,6,8,8a,9-hexahydrofuro[3′,4′:6,7]-naphtha[2,3-d][1,3]dioxol-5-yl)-2-methoxyphenol (2), were isolated from the dichloromethane (DCM) extract. In addition, sixteen known compounds were isolated from the DCM and methanol extracts, with two of them, N-isobutylcinnamamide (9) and (E)-3-(4-hydroxy-3-methoxyphenyl)-N-isobutylacrylamide (14), being reported from a natural source for the first time. The structures of the isolates were elucidated by a combination of spectroscopic techniques. The isolated compounds were subjected to anti-mycobacterial activity testing using the microplate Alamar blue assay (MABA). Five compounds, 10 (MIC, 0.98 μg/mL), 11 (MIC, 7.82 μg/mL), 12 (MIC, 1.95 μg/mL), 13 (MIC, 3.91 μg/mL), and 14 (MIC, 3.91 μg/mL) exhibited significant anti-mycobacterial activities against the susceptible (H37Rv) strain and could provide vital templates for developing new and highly effective TB drugs. Also, compounds 4 (MIC, 62.50 μg/mL), 7 (MIC, 62.50 μg/mL) and 16 (MIC, 62.50 μg/mL) exhibited moderate activity against H37Rv.Item Variation of cyanogenic potential of selected cassava varieties with age in Zombo district, Uganda(Scholars World-International Refereed Journal of Arts, Science & Commerce,, 2018) Oloya, Benson; Adaku, Christopher; Andama, MorganCassava is a major staple food in the developing world, providing a basic diet for around 500 million people. In Uganda, it is currently one of the most important food crops and ranks second to bananas in terms of area occupied, total production and per capita consumption. However, cassava contains cyanogenic glycosides such as linamarin and Lotaustralin, which are toxic. Consumption of such toxins in sufficient quantities can cause acute cyanide poisoning and death in humans and animals. Thus, cassava is a possible health risk to the consumers. Awareness about the trend of cyanogenic glycosides content in cassava as it matures is paramount in minimizing the health risks associated with cassava consumption. As such, the most common local cultivars; Bisimwenge, Nyar-anderiano, Nyar-udota, in Zombo district and two improved cultivars: NASE 9 and TME 14, were investigated for variation in their cyanogenic content with age. The concentrations of cyanogens were determined using standard titration method. The results showed that cyanogeniccontent was highest at the ages of 8-10 months and generally decreased after the tenth month. It is therefore safer to harvest cassava after at least ten months when the levels of the hydrogen cyanide have reduced and stabilized.