Cytotoxic Bioxanthracene and Macrocyclic Polyester from Endolichenic Fungus Talaromyces pinophilus: In-Vitro and...

Lichens are used in folklore medicines across the globe for wound healing and to treat skin disorders and respiratory diseases. They are an intricate symbiosis between fungi and algae with the domination of fungal counterparts. Recent research studies pointed out that yeast is a third major partner in lichens. Endolichenic fungi (ELF) are also a part of this complex miniature ecosystem. The highly competitive environment of lichens compels ELF to produce toxic metabolites which are comparatively less explored for their chemical diversity and use. Here, we investigated 31 ELF isolated from 32 lichens found on mangrove plants at Puttalam Lagoon of Sri Lanka to find cytotoxic molecules by applying LC-UV-HRMS analysis and in vitro bioassays. The studies resulted in the identification of three potent cytotoxic molecules from endolichenic fungi Talaromyces pinophilus isolated from host lichen Porina tetracerae. The ethyl acetate extract of this fungus showed moderate cytotoxicity against the breast cancer cell line. Chemical characterization of ethyl acetate extract of T. pinophilus produced peniazaphilin B, 152G256α-1, and ES-242-3. The structures of these molecules were confirmed by NMR and MS data. We are reporting ES-242-3 for the first time from the genus Talaromyces and peniazaphilin B and 152G256α-1 from T. pinophilus. The isolated compounds were evaluated for their anticancer potential against breast, oral and cervical cancer cell lines. Compound 152G256α-1 showed potent cytotoxicity against oral cancer (CAL-27 cell line) with an IC₅₀ value of 2.96 ± 0.17 µM while ES-242-3 showed the best activity against breast cancer (MCF-7 cell line) and cervical cancer (HeLa cell line) with IC₅₀ value 14.08 ± 0.2 µM and 4.46 ± 0.05 µM respectively. An in-silico analysis was carried out to predict the mechanism of in-vitro activity, drug likeliness, and pharmacokinetic profile of the isolated compounds. The study confirms the potential of ELF T. pinophilus to produce diverse bioactive scaffolds and encourages the researchers to further explore the fungus and its metabolites with newer technologies to produce potent anticancer leads.

The online version contains supplementary material available at 10.1007/s12088-021-00994-8.