Browsing by Author "Wijeratne, K."

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A NEW ANTIOXIDANT ACTIVE COMPOUND FROM THE ENDOLICHENIC FUNGUS, PENICILLIUM CITRINUM INHABITING THE LICHEN, PARMOTREMA SP
(International Journal of Pharmaceutical Sciences and Research, 2019) Wickramarachchi, S.A.; Samanthi, U.; Wijeratne, K.; Paranagama, P.A.
Context: Endolichenic fungi are the microorganisms living inside the thalli of the lichen and found to be a new source of bioactive secondary metabolites. This is an underutilized source of bioactive compounds and has not been studied extensively. Genus, Parmotrema is one of the foliose lichens with largely rounded lobes and occurs on rocks of rain forests, sub-montane and montane forests in Sri Lanka. Aims: The endolichenic fungi available in Sri Lanka and the chemistry of their secondary metabolites have not been explored thoroughly. This study aims at exploring novel bioactive compounds available in Penicillium citrinum inhabiting Parmotrema sp. Methods and Material: The lichen, Parmotrema sp., was collected from Hakgala Botanical Garden in Sri Lanka and its fungal strains were isolated and identified by Genomic DNA sequencing. Compounds were first extracted to ethyl acetate and subsequently subjected to bioassay-guided fractionation to isolate the bioactive compounds. The DPPH assay was used to determine the antioxidant activity. The active compound/s was separated by column chromatography, and its structure was elucidated by IR, 1D and 2D-NMR, 13C-NMR and MS. Statistical Analysis Used: The IC50 of the crude extract was calculated using Probit analysis (MINITAB® Release 14.1. Minitab Inc. 2003 Statistical Software). Results: A bioactive compound, named PP-PC-03 together with PP-PC-01 and PP-PC-02 was isolated from P. citrinum. All three compounds showed antioxidant activity in the DPPH assay with IC50 values 159.6 ± 22.3, 120.1 ± 11.7 and 68.6 ± 4.3 μg/mL respectively. Conclusion: Based on spectral analysis the structure of PP-PC-03was determined as 10-Ethylidene-2,4,9-trimethoxy-10,10a-dihydro-7,11-dioxa-benzo[b] heptalene-6,12-dione and identified as a new compound. Comparatively PP-PC-02 and PP-PC-03 had moderate antioxidant activities while PP-PC-01 showed strong radical scavenging activity.
A Novel Cytotoxic Compound From the Endolichenic Fungus, Xylaria psidii Inhabiting the Lichen, Amandinea medusulina
(Natural Product Communications, 2020) Santhirasegaram, S.; Wickramarachchi, S. R.; Attanayake, R. N.; Weerakoon, G.; Samarakoon, S.; Wijeratne, K.; Paranagama, P. A.
The lichen host, Amandinea medusulina, collected from mangrove habitats in Sri Lanka, and its associated endolichenic fungi were isolated and identified by rDNA-ITS sequence analysis and morphological features. One of the fungal strains frequently isolated from the lichen thalli was identified as Xylaria psidii. This study aimed at the isolation and identification of the cytotoxic compounds present in this fungus. Secondary metabolites of X. psidii were first extracted into ethyl acetate and subsequently subjected to bioassay-guided fractionation to isolate the bioactive compounds. Sulforhodamine B assay against a lung cancer (NCI-H292) cell line was used to determine the differential cytotoxic activity. Bioassay-guided fractionation led to the isolation of an active compound, SS/02/29/08, showing moderate cytotoxicity (IC50 = 27.2 μg/mL). Its structure was elucidated by IR, 1D- and 2D-NMR, and 13C-NMR spectrophotometry and MS, in combination with HRMS, 13C NMR, HSQC, HMBC, and DQF-COSY. The structure of SS/02/29/08 was determined as (Z)-3-{(3-acetyl- 2-hydroxyphenyl) diazenyl}-2,4-dihydroxybenzaldehyde and identified as a new compound. This novel compound has promising differential cytotoxic activity against human lung cancer cell line (NCI-H292).
A Novel Cytotoxic Compound From the Endolichenic Fungus, Xylaria psidii Inhabiting the Lichen, Amandinea medusulina
(Natural Product Communication, 2020) Santhirasegaram, S.; Wickramarachchi, P.A.S.R.; Attanayake, R.N.; Weerakoon, G.; Samarakoon, S.; Wijeratne, K.; Paranagama, P.A.
The lichen host, Amandinea medusulina, collected from mangrove habitats in Sri Lanka, and its associated endolichenic fungi were isolated and identified by rDNA-ITS sequence analysis and morphological features. One of the fungal strains frequently isolated from the lichen thalli was identified as Xylaria psidii. This study aimed at the isolation and identification of the cytotoxic compounds present in this fungus. Secondary metabolites of X. psidii were first extracted into ethyl acetate and subsequently subjected to bioassay-guided fractionation to isolate the bioactive compounds. Sulforhodamine B assay against a lung cancer (NCI-H292) cell line was used to determine the differential cytotoxic activity. Bioassay-guided fractionation led to the isolation of an active compound, SS/02/29/08, showing moderate cytotoxicity (IC50 = 27.2 µg/mL). Its structure was elucidated by IR, 1D- and 2D-NMR, and 13C-NMR spectrophotometry and MS, in combination with HRMS, 13C NMR, HSQC, HMBC, and DQF-COSY. The structure of SS/02/29/08 was determined as (Z)-3-{(3-acetyl-2-hydroxyphenyl)diazenyl}-2,4-dihydroxybenzaldehyde and identified as a new compound. This novel compound has promising differential cytotoxic activity against human lung cancer cell line (NCI-H292).