Browsing by Author "Masalu, Rose"

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    Anticancer and antiviral activities from some Tanzania fungal metabolites
    (University of Dar es Salaam, 2012) Masalu, Rose
    This thesis describes anticancer and antiviral activities from some Tanzanian fungal metabolites. Nineteen fungal extracts including basidiomycetes, ascomycetes and zygomycetes were screened for the production of bioactive compounds using brine shrimp lethality test (BST) and free radical scavenging activity using 1,1-diphenyl-2-picrylhydrazyl α,α-diphenyl-β-picrylhydrazyl (DPPH) assay. Anticancer activities were tested for production of apoptotic compounds using flow cytometry in a panel of cancer cell lines while antiviral activities were tested through in ovo activities against infectious bursal disease virus and Pox virus. Unknown but potential fungi were identified through analysis of ribosomal DNA (rDNA) sequence. The BST assay revealed the Cantharellus symoensii being the most toxic with lethal dose that kill 50 % of the brine shrimp (LC50) 0.28 µg/ml while zygomycetes strain Z5 was the least toxic with LC50 32.9 µg/ml. The DPPH assay showed that a basidiomycetes Termitomyces microcarpus had the highest scavenging ability with effective concentration that decrease the initial DPPH radical by 50% (EC50) at 19µg/ml while the ascomycete Candida tropicalis showed the least EC50 at 60.4µg/ml. In the apopercentage apoptosis assay a basidomycete Cantharellus miomboensis extract at 2.5 mg/ml was able to induce apoptosis in ~80 % of HeLa cell lines and not in H157. The resistance of H157 cells to apoptosis induced by C. miomboensis extract was found to be associated with upregulation of glucose regulated protein 78 (GRP78) which validated by 40 % protection of grp78 transfected HeLa cells. The antiviral activities revealed that extracts from zygomycetes fungi were the most active, followed by basidiomycetes and ascomycetes. This study results infer that C. miomboensis have anticancer activity against HeLa cell line while some fungi have antiviral activity potentials for drug discovery research. This work has drawn attention to indigenous fungi from Tanzania as a potential source for anticancer and antiviral activities.
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    Lignin degrading enzymes from mycelial cultures of wild Tanzanian mushrooms.
    (University of Dar es Salaam, 2004) Masalu, Rose
    Twenty-four mushroom isolates collected from both woody and non-woody habitats were screened and investigated with respect to their lignin degrading capacity. Fifteen wood and nine non-wood inhabiting isolates were screened by testing for decolourization of an aromatic dye (Rhemazol Brilliant Blue-R, RBBR) and also for the production of extracellular polyphenol oxidase, laccase and peroxidases using guaicol, a-naphthol and pyrogallol oxidation, respectively 88 % of the isolates decolorized RBBR, 80 % oxidized guaicol and 33.3 % and 80 % were positive for laccase and peroxidases, respectively. Isolates were further investigated for lignin peroxidase (LiP), Manganese peroxidase (MnP) and laccase (Lac) activities using veratryl alcohol, guaicol and 2,2'-azino-bis(3-ethylbenzothiazole-6-sulphonic acid) as substrates for LiP, MnP and,Lac, respectively. MnP activity was found in 90.4 % of the isolates tested, while 57% and 52.5 % of the isolates exhibited LiP and Lac activities, respectively. The relative activities of LiP, MnP and Lac ranged between 25-65, 10-42 and 10-35 U/ml, respectively. The mushroom isolates tested reduced total fibres by 78 %, hemicellulose by 46.3 %, cellulose by 10 %, lignin by 30% and increase total nitrogen by 100 % in the rice straw. It was concluded that wild Tanzanian mushrooms have a potential for use in the bioremediation of sites polluted with recalcitrant compounds and for upgrading lignocellulosic materials for ruminant feed.