Browsing by Author "Shevkar, C. D."

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    Bioactive properties and metabolite profile of an endolichenic fungus, Hypoxylon lividipigmentum
    (Faculty of Science, University of Kelaniya, Sri Lanka., 2021) Weerasinghe, W. R. H.; Shevkar, C. D.; Silva, R. S. De; Attanayake, R. N.; Weerakoon, G.; Kate, A. S.; Kalia, K.; Paranagama, P. A.
    Endolichenic fungi (ELF) serve as a novel source of secondary metabolites. Hypoxylon lividipigmentum is an ELF isolated from the lichen Opegrapha medusulina, collected from mangrove plant Xylocarpus granatum from Negombo lagoon, Sri Lanka. The fungus was identified to the species level using morphological and DNA barcoding techniques. Ethyl acetate extract of the fungus was subjected to in vitro assays to determine antioxidant, anti-inflammatory, tyrosinase inhibitory and antibacterial potency. Liquid Chromatography-Mass Spectrometry (LCMS) dereplication was conducted on the crude extract in order to detect the secondary metabolites present. The extract reported a IC50 value of 18.34±1.37 µg/ml on par with the positive control BHT, in DPPH radical scavenging assay. It also exhibited moderate anti-inflammatory activity with an IC50 value of 81.08±1.05 μg/ml. Tyrosinase inhibitory activity was fairly comparable with an IC50 value of 121.20±2.55 μg/ml. Agar well diffusion assay was conducted to determine antibacterial activity against aerobic bacterial species Escherichia coli, Bacillus subtilis, Staphylococcus aureus and the anaerobic bacterial species Streptococcus mutans. Suppression of growth was shown only against B. subtilis. Five major mass peaks were observed during the study of LCMS profile of the extract. After a thorough dereplication process, two masses could be presumed to be from novel scaffolds. Since none of the mass peaks could be dereplicated within the species or genus level, it could be speculated that the chemical profile of Hypoxylon lividipigmentum was previously poorly explored in literature thus making it an interesting organism to study further for novel metabolites.
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    Bioprospecting of an Endolichenic Fungus Phanerochaete sordida Isolated from Mangrove-Associated Lichen Bactrospora myriadea
    (Journal of Chemistry,, 2022) Weerasinghe, R. H.; Shevkar, C. D.; Maduranga, K.; Pandey, K. H.; Attanayake, R. N.; Kate, A. S.; Weerakoon, G.; Behera, S. K.; Kalia, K. S.; Paranagama, P. A.
    Bioassay-guided fractionation of the ethyl acetate extract of Phanerochaete sordida, an endolichenic fungus (ELF) isolated from the host lichen Bactrospora myriadea, collected from Negombo lagoon, Sri Lanka, led to the isolation of a bioactive compound. Following the identification of the fungus using morphological and DNA barcoding techniques, the pure compound was isolated using column chromatography, preparative TLC, and semipreparative HPLC. The structure elucidation was carried out using IR, HR-ESI-MS and 1H, 13C & 2D NMR spectroscopic methods. The in vitro bioassays conducted revealed that compound 1 has a high antioxidant activity with ABTS•+ (IC5058:91 ± 1:35 μM), moderate anti-inflammatory activity (IC50254:79 ± 1:41 μM), comparable antibacterial activity against the oral-bacterial strain Streptococcus mutans (MIC 898.79 μM and MLC 1797.58μM), moderate tyrosinase inhibition (IC501713:69 ± 8:65 μM), and moderate cytotoxicity against oral cancer (IC5013:65 ± 0:02 μM), in comparison with respective positive controls. The in silico experiments conducted for tyrosinase inhibition and cytotoxicity using Schrödinger revealed results in line with the in vitro results, thus confirming the bioactivities. The molecule also satisfies the key features of drug likeliness according to pharmacokinetic studies.