Browsing by Author "Eiman, H."

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    Antimicrobial and antiplasmodial activity displayed by actinomycetes isolated from soils from Kavango and Hardap regions in Namibia
    (2018) Iikasha, Albertina M.; Dushimemaria, Florence; Mbewe, Maria; Eiman, H.; Mumbengegwi, Davis R.
    Plasmodium falciparum and multidrug resistant bacteria such as Mycobacterium avium, Staphylococcus aureus and Escherichia coli are among the top causes of morbidity and mortality especially in developing countries. These pathogens are responsible for the reported antibiotic resistance incidents globally. Due to the increase in antibiotic resistance worldwide, there is an urgent need for new bioactive compounds. This study aimed at determining the antiplasmodial and antimicrobial activity of secondary metabolites produced by soil actinomycetes. Soil samples were collected from Kavango and Hardap regions and cultured on various media to isolate and identify actinomycetes. Secondary metabolites produced were extracted using different solvents. The antimicrobial activity of different isolated secondary metabolites was determined against M. avium, S. aureus and E. coli. Antiplasmodial activity of four bioactive fractions with potent antibacterial activity was further determined against a chloroquine resistant (D10) P. falciparum strain at various concentrations. Bioactive compounds from two isolates displayed activity against M. avium, whilst another two showed activity against E. coli. None of the secondary metabolites displayed activity against S. aureus. A concentration dependent reduction in parasitaemia for P. falciparum was observed across all four fractions both after 24 and 48 h. These results display a vast potential antibacterial and antiplasmodial activity and should be considered for future drug development.
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    An investigation into the antibacterial activity of pigmented secondary metabolites isolated from streptomyces from Windhoek soil
    (University of Namibia, 2017) Iikasha, Albertina M.; Eiman, H.; Mumbengegwi, Davis R.
    There is an increase in mortality from infectious diseases due to an increase in antibiotic resistance worldwide. Hence, his study aimed at investigating the antibacterial activity of Streptomyces that produces pigmented secondary metabolites .The soil samples were collected from 3 different sites in Windhoek. Streptomyces were isolated on starch case in agar. Biochemical and physiological tests were used to identify Streptomyces species. Case in slantagar method was used for preliminary anti-bacterial test. Chloroform and n-Hexane were used to extract secondary metabolites by solvent-liquid extraction method.Thin layer chromatography plates were used for antibacterial activity of the isolated secondary tabolites.Minimum inhibitory concentration of isolated secondary metabolites was determined by the broth dilution method at concentrations ranging from 50to1.5 μg/ml. Six out of nine Streptomyces isolates showed antibacterial activity against at least one of three test bacteria. Streptomyces isolate 1exhibited potentactivityof19.5mm ± 0.056 against M. avium. Different pigmented secondary metabolites were produced and showed antibacterial activity against at least against one of three test organism. Streptomyces isolate 4 and 6 showed the lowest minimum inhibitory concentration of 6.25 μg/ml against M. avium and E. faecialis. The results showed that Windhoek soil contain antibiotic producing Streptomyces.