Browsing by Author "Rajapaksha, R.S.C.G."
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Item Antifungal and Insecticidal Secondary Metabolites Isolated from Endolichenic Fungi Inhabited to Lichen Usnea sp.(Int. Symposium, NaturalProducts, IPS, Kandy, Sri Lanka, 2011) Paranagama, P.A.; Kannangara, B.T.S.D.P.; Rajapaksha, R.S.C.G.Item Antifungal, antibacterial and insecticidal activities of the endolichenic fungi of the lichen Usnea sp. at Hakgala montane forest(Research Symposium 2010 - Faculty of Graduate Studies, University of Kelaniya, 2010) Paranagama, P.A.; Kannangara, B.T.S.D.P.; Rajapaksha, R.S.C.G.In a search for new bioactive natural products from endolichenic fungal species isolated from the lichens, bioactivity studies of fungi living with lichens were recently initiated and from this study, the potential of ethyl acetate extracts of endolichenic fungi inhabiting the lichen, Usnea sp. from Hakgala montane forest was investigated using antifungal, antibacterial and insecticidal properties. Selected four endolichenic fungal species, Chrysosporium sp.1, Fusarium sp., Curvularia sp. and dark sterile sp.1 were extracted with ethyl acetate (EtOAc) to obtain the secondary metabolites. Antifungal effects of theses extracts were tested against Colletotrichum musae, which cause anthracnose disease in banana, and the antibacterial activity was investigated against Bacillus subtilus and Staphyloccus aureus using filter paper disk method and well diffusion method respectively. Residual film bioassay (RFB) and Treated seed bioassay (TSB) were carried out to evaluate the insecticidal activity of the fungal extracts contained secondary metabolites against cowpea bruchid, Callosobruchus maculatus. The highest yield of the secondary metabolites was obtained from the dark sterile sp.1. (1.0610g). Results of the antifungal activity and antibacterial activity revealed an increase of the diameter of inhibition zone with increasing dose of extracts. EtOAc extracts of Curvularia sp. on PDA and PDB showed higher antifungal effects against C. musae. Highest inhibition of C. musae was observed at the dose of 400 μg of the EtOAc extracts. EtOAc extracts of Curvularia sp. on PDA and PDB showed higher inhibitory effects (diameter ~2.0cm) and both Curvularia sp. on PDA and PDB extracts showed similar effect with a MIC of 50 μg and Curvularia sp. on PDB indicated the lowest MLC of 100 μg against C. musae. Chrysosporium sp. 1 showed higher antibacterial effects against Staphylococcus aureus and Bacillus subtilis. Insecticidal assays revealed that percentage mortalities of C. maculatus shown in two bioassay methods were not significantly different from each other. Highest mortality (100%) of C. maculatus was observed in the EtOAc extracts of Curvularia sp. obtained from both PDB and PDA separately. Also the LC50 values for both Residual film bioassay and Treated seed bioassay confirmed that the lowest values were obtained for EtOAc extracts of Curvularia sp.on PDA and PDB.Item Bioactivities of ethyl acetate extracts isolated from endolichenic fungi Daldinia eschscholzii and Nigrospora sphaerica(University of Kelaniya, 2011) Rajapaksha, R.S.C.G.; Paranagama, P.A.; Kannangara, B.T.S.D.P.Although numerous bioactive natural products occur in endolichenic fungi, only a limited number of secondary metabolites with a variety of bio-activities have been isolated during the past few years. The objective of this study was to evaluate the potential of ethyl acetate extracts of endolichenic fungi Daldinia eschscholzii and Nigrospora sphaerica inhabiting the lichen, Usnea sp. from Hakgala montane forest using antifungal and insecticidal properties. Endolichenic fungi D. eschscholzii and N. sphaerica were extracted with ethyl acetate (EtOAc) to obtain the secondary metabolites. Antifungal effects of these extracts were tested against Colletotrichum musae, which cause anthracnose disease in banana. Residual Film Bioassay (RFB), and Treated Seed Bioassay (TSB) were carried out to evaluate the insecticidal activity of the fungal extracts containing secondary metabolites against cowpea bruchid, Callosobruchus maculatus. Since the EtOAc extracts of D. eschscholzii (671 mg) and N. sphaerica (503 mg) were bioactive against Colletotrichum musae and Callosobruchus maculatus, bioassay guided fractionations of hexane, chloroform and aqueous were conducted for the EtOAc extracts of these fungal species. The results revealed that chloroform fractions of both extracts showed higher insecticidal and antifungal activities. Therefore they were further purified using silica gel column chromatography. Three pure compounds CR/01/99/02, CR/01/100/01 and CR/01/100/06 were isolated from N. sphaerica and yielded 13 mg, 9 mg and 19 mg respectively. CR/01/94/06 (8 mg, 16%), CR/01/95/03 (11 mg, 16.4%) and CR/01/96/02 (21 mg, 48.8%) were the purified bioactive compounds isolated from D. eschscholzii. Antifungal activity against C. musae revealed that CR/01/100/06 showed higher inhibitory effects and the lowest MLC (80 μg) and MIC (50 μg) values. 100% mortality of C. maculatus was observed at the dose of 100 μg for the compound of CR/01/96/02. LD50 values for RFB and TSB for this compound were 37.4 μg and 41 μg respectively. These purified compounds will be identified using IR, NMR, mass spectroscopy, etc.Item Endolichenic fungal diversity in different ecosystems of Sri Lanka(National Mini Symposium on Bio-indicators of Environment Health and Biodiversity Indices, 2011) Kannangara, B.T.S.D.P.; Paranagama, P.A.; Rajapaksha, R.S.C.G.Item Endolichenic fungi in Usnia sp. From Hakgala Montane Forest in Sri Lanka as a Novel Source of Bioactive Natural Products(Proceedings of the international symposium on Natural Products Chemistry and its contribution to the economy, environment and the social well being, University of Peradeniya, Sri Lanka, 2010) Paranagama, P.A.; Kannangara, B.T.S.D.P.; Rajapaksha, R.S.C.G.Item Nature and bioactivities of endolichenic fungi in Pseudocyphellaria sp., Parmotrema sp. and Usnea sp. at Hakgala montane forest in Sri Lanka(Letters in Applied Microbiology, 2009) Kannangara, B.T.S.D.P.; Rajapaksha, R.S.C.G.; Paranagama, P.A.B.T.S.D.P. 1, R.S.C.G. 1 and P.A.Item A review on medicinal formulate for Rakta Pradara (Abnormal Uterine Bleeding) in indigenous medicine in Sri Lanka(Gampaha Wickramarachchi Ayurveda Institute, University of Kelaniya, 2014) Deepthika, S.H.K.; Wakkumbura, H.P.; Rajapaksha, R.S.C.G.