Browsing by Author "Samanthi, K.A.U."
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Item A new bioactive curvularin macrolide from an endolichenic fungus, Curvularia trifolii, isolated from Usnea sp., in Sri Lanka(Book of Abstracts, Annual Research Symposium 2014, 2014) Samanthi, K.A.U.; Wickramaarachchi, S.; Wijeratne, E.M.; Paranagama, P.A.The search for new bioactive natural products is still the main way of discovering new drug leads. Although fungi are well-known producers of secondary metabolites with new structurally diverse bioactive compounds, isolation of bioactive compounds from endolichenic fungi still remain underexplored as potential source of natural products. Endolichenic fungi are microorganisms living in the thalli of lichens that are analogous to the plant endophytic fungi inhabiting the intercellular spaces of the host. Curvularia trifolii was isolated from the lichen, Usnea sp., available in Hakgala botanical garden, Sri Lanka. Identification of the fungus was confirmed using morphological characters followed by the molecular identification (DNA sequencing). Invitro large scale cultures of C.trifolii were prepared in 60 large Petri dishes containing potato dextrose agar medium and after 10 days secondary metabolites were extracted into ethyl acetate. The crude extract was tested using two types of bio assays, for the investigation of antioxidant and anti-inflammatory activities. Antioxidant activity of the crude ethyl acetate extract was explored by carrying out DPPH free radical scavenging assay and Anti-inflammatory activity was evaluated using Human Red Blood Cell Membrane Stability (HRBC) assay. Since the crude extract showed high activity in both the assays, it was partitioned into hexane, chloroform (CHCl3) and 60% aq.MeOH and identified the bioactive fractions. The activity of CHCl3 fraction was confirmed and it was further fractionated using bioassay guided column chromatography (silica, sephadex) and preparative TLC to isolate pure compounds. One florescent active pure bioactive compound (C23H30O6) was isolated from the CHCl3 fraction and identified as using 1D, 2D NMR, MS, IR and UV spectral data. The structure of new compound was thus established as 5-methoxy-4,8,15-trimethyl-3,7-dioxo-1,3,7,8,9,10,11,12,13,14,15,15?-dodecahydrocyclododeca[de]isochromene-15-carboxylic acid and the bioassay results revealed that it is a new curvularin macrolide with IC50 values, 68.6�4.3 ?g/mL and 310�48.2 ?g/mL for DPPH antioxidant assay and anti-inflammatory assay respectively. Hence it is revealed that derivative isolated from C. trifolii can be developed as an important antioxidant and anti-inflammatory drug.Item Antioxidant active novel secondary metabolite from endolichenic fungus, Penicillium citrinum, inhabiting the lichen, Pamotrema sp. available in Sri Lanka(Faculty of Graduate Studies, University of Kelaniya, 2015) Samanthi, K.A.U.; Wickramarachchi, S.; Wijerathne, E.M.K.; Paranagama, P.A.Item In Vitro Anti-Inflammatory Activity of Organic Extracts of Endolichenic Fungus,Daldinia eschscholzii, Occurring in Lichen,Parmotrema sp. in Sri Lanka(Preceedings of International Conference on Chemical Education and Research,Institute of Chemistry Ceylon, Adamantane House, Rajagiriya, Sri Lanka, 2014) Samanthi, K.A.U.; Wickramaarachchi, P.A.S.R.; Paranagama, P.A.K.A.U., , P.A.S.R, P.A.Item Investigating the bioactive compounds of endolichenic fungus Hypoxylon anthochroum isolated from the lichen, Pseudocyphellaria sp.(Faculty of Graduate Studies, University of Kelaniya, 2015) Antony, K.N.L.; Samanthi, K.A.U.; Paranagama, P.A.It has been reported that 11 endolichenic fungal strains were isolated from lichen, Pseudocyphellaria sp. Endolichenic fungi live asymptomatically within the lichen thallus and known as a new source useful of bioactive secondary metabolites. Secondary metabolites in endolichenic fungi show distinct bioactivities including antimicrobial, anti-inflammatory, analgesic, antioxidant and cytotoxic activities. These bioactive compounds have potential importance in development of pharmaceutical drugs, nutraceuticals and agrochemicals. The present study was carried out to investigate antioxidant activities of secondary metabolites produced from Hypoxylon anthochroum inhabiting the lichen, Pseudocyphellaria sp. In this research, H. anthochroum was cultured in 50 large petridishes containing potato dextrose agar (PDA) medium and incubated at room temperature for seven days. After the incubation period, secondary metabolites were extracted into ethyl acetate in order to obtain crude extract. The crude extract was partitioned using solvents hexane, chloroform and 60% aqueous methanol. Antioxidant activities of three fractions were evaluated using micro plate DPPH assay. Since chloroform fraction showed the highest antioxidant activity (81.96 % Inhibition at 800 μg/mL) it was further subjected to silica gel column chromatography and preparative thin layer chromatography to isolate bioactive compounds. One UV active pure compound which has antioxidant activity (43.21 % Inhibition at 800 μg/mL) was isolated from chloroform fraction and its structure elucidation will be carried out using 1H NMR, 13C NMR, and 2D NMR spectral data.Item New Bioactive poliketide from endolichenic fungus, Curvularia trifolii, inhabiting the lichen, Usnea sp. collected from Haggala Botanical Garden(Faculty of Graduate Studies, University of Kelaniya, 2015) Samanthi, K.A.U.; Wickramaarachchi, S.; Wijerathne, E.M.K.; Paranagama, P.A.Endolichenic fungi (ELF), which live in healthy tissues of lichens, are one of the promising producers of structurally diverse novel bioactive secondary metabolites. It has been reported that endolichenic fungi are rich sources for the discovery of new compounds with significant medicinal values and this was demonstrated by isolation and identification of new anticancer, antifungal, antibacterial and antioxidant agents from endolichenic fungal extracts. In Sri Lanka, research group of University of Kelaniya initiated a research program on ELF and have isolated few interesting bioactive poliketides from ELF of three lichen species available in Sri Lanka. They have shown great potential to be a source for novel bioactive natural products. The objectives of this study were isolation and identification of bioactive compounds of the endolichenic fungus, Curvularia trifolii isolated from the lichen Usnea species. In a continuation of our chemical investigations in search of secondary metabolites of endolichenic fungi with medicinal value led to the isolation of few bioactive compounds. In this present study, C. trifolii was grown in large scale and incubated at room temperature for 10 days. The metabolites were extracted into ethyl acetate (EtOAc). Antibacterial, anticancer and insecticidal activities of the EtOAc extract were evaluated using in-vitro bioassays. The EtOAc extract was subjected to a silica gel column chromatography resulting, one major compound with high bioactivities. The isolated pure white crystalline compound was identified as 1,14-dihydroxy-6-methyl-6,7,8,9,10,10,14,14 -octahydro-1H-benzo[f][1] oxacyclododecin-4(13H)-one using 1H, 13C NMR, 2D NMR and MS data. The compound was found to possess antibacterial activity against three test pathogens, anticancer activity at (NCIH-460), (MCF-7), (SF-268), (PC3M), and (MDA-MB-231) cell lines and insecticidal activity.Item Two new antioxidant active polyketides from Penicillium citrinum, an endolichenic fungus isolated from Parmotrema species in Sri Lanka(National Science Foundation of Sri Lanka, 2015) Samanthi, K.A.U.; Wickramaarachchi, S.; Wijeratne, E.M.K.; Paranagama, P.A.Bioassay guided fractionation of the ethyl acetate extract of a laboratory culture of Penicillium citrinum, an endolichenic fungal strain isolated from a Parmotrema species in Sri Lanka, led to the isolation of two new fungal polyketides (1 and 2). The structures of these compounds were determined on the basis of their 1D NMR, 2D NMR and FABMS spectroscopic data. The two compounds (1 and 2) showed radical scavenging activity with IC50 values of 159.7 ± 22.3 μg/mL and 68.6 ± 4.3 μg/mL, respectively in DPPH antioxidant assay. The antioxidant activity of compound 2 was comparable to the standard antioxidant compound butylated hydroxytoluene (BHT).Item Two new bioactive poliketides from Culvularia trifolii, an endolichenic fungus isolated from Usnea sp., in Sri Lanka(2015) Samanthi, K.A.U.; Wickramarachchi, S.; Wijeratne, E.M.K.; Paranagama, P.A.