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|Title: ||Antimicrobial and cytotoxicity activities of selected marine fungi in Malaysia and bioassay-guided fractionation and isolation of antimicrobial metabolites from Fasciatispora nypae|
|Authors: ||Nazura Zainuddin|
|Keywords: ||Marine fungi|
|Issue Date: ||Dec-2008 |
|Publisher: ||University Malaya|
|Abstract: ||The first part of this study on biodiversity involved four locations in Peninsular Malaysia namely, i) Langkawi Island; ii) Jarak and Sembilan Islands; iii) Morib and iv) Port Dickson. A total of 123 marine fungi were recorded, that included 111 ascomycetes, 10 anamorphic fungi and two basidiomycetes. The most common fungi in Langkawi Island are Dactylospora haliotrepha and Leptosphaeria australiensis. In Jarak and Sembilan Island, the most common fungi recorded were L. australiensis and Verruculina enalia. However, in Morib, Neolinocarpon globosporum, Halorosellinia oceanica and Rhizophora marina were the most common fungus encountered, while in Port Dickson, the most common fungi identified were D. heliotrepha, Massarina velatospora, H. oceanica and Kallichorma Tethys. Isolated fungal cultures were evaluated for their antimicrobial activity using two methods: i) plug assay, ii) disc diffusion assay. The plug assay was used as a preliminary screening method for antimicrobial activity and revealed 82 strains (43.4%) out of 152 marine fungi possessed antimicrobial activity against yeasts and bacteria. From the number of active marine fungi, 7 species (10.6%) showed a broad spectrum antimicrobial activity against yeast and bacteria. Most of the strains of marine fungi exhibited antibacterial activity against the Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus. In this study antibacterial activity was greater than antifungal activity.
In the disc diffusion assay, crude ethyl acetate extracts of five marine fungi namely, Caryosporella rhizophorae, Fasciatispora nypae, Melaspilea mangrovei, Leptosphaeria sp. and Ascomycete sp.19 (NF) were selected for antimicrobial testing. Results showed that incubation time and culture conditions affected the production of
secondary metabolites of marine fungi and varied between species. Fasciatispora nypa produced good activity after 35 days from static culture against Candida albicans and Saccharomyces cerevisiae, whereas C. rhizophorae produced active metabolites from shake culture with good activity achieved after 35 days incubation period against Escherichia coli and B. subtilis. Leptosphaeria sp. and M. mangrovei produced good active metabolites after 15 days cultivation against B. subtilis, S. aureus and 30 days against B. subtilis, respectively from static culture. Ascomycete sp.19 (NF) produced active metabolite at stationary phase with high activity achieved at 15 days incubation period against B. subtilis. Cytotoxic activity was screened by an in vitro assay system of growth inhibition against breast cancer cell line (MCF-7) using crude extract of C. rhizophorae, F. nypae, M. mangrovei, Leptosphaeria sp. and Ascomycete sp.19 (NF). Study showed that only two marine fungi, F. nypae and C. rhizophorae exhibited cytotoxic effect against MCF-7 tested at 100 μg ml-1, where the ED50 value of C. rhizophorae was 14.5 μg ml-1, and, ED50 value of F. nypae was 24 μg ml-1.
Bioassay-guided fractionation was performed on the crude extract of Fasciatispora nypae and yielded three active fractions; fraction 2, fraction 5 and fraction 6. One pure compound was successfully isolated from fraction 5 and determined as 2,2,7-trimethyl-2H-1-benzopyran-5-ol. This compound displayed antimicrobial activity against yeasts and bacteria, with weak activity against S. aureus, C. albicans and S. cerevisiae and moderately active against B. subtilis and against and active against Schizosaccharomyces pombe in disc diffusion assay. However, the MIC value of this compound showed that it exhibited weak activity against all bacteria and yeasts with MIC value of >12.5 mg ml-1 against S. aureus, C. albicans, S. cerevisiae and B. subtilis and 10.4 mg ml-1 against S. pombe.|
|Description: ||Dissertation -- Faculty of Science, University of Malaya, 2008.|
|Appears in Collections:||Masters Dissertations : Science|