Chemometric-Based Analysis of Metabolomics Studies of Bioactive Fractions of Pleurotus osteratus and Their Correlation with In Vitro Anti-Cancer Activity

Abstract

Richness in nutrients with an ample of the myco-bioactive molecules makes Pleurotus osteratus preferential mushroom. In this paper, we conducted a preliminary study on bio-assay-guided fractionation of dichloromethane:ethanol crude extract (1:1, v/v) of P. osteratus (CD) against human breast cancer cell line (MDA-MB-231). Later, CD and its potent hexane (H) and ethyl acetate (EA) fraction were screened against a panel of a human cancer cell lines. H fraction possesses higher cytotoxicity followed by EA and CD. Literature review revealed that polyphenol and ergosterol are the biomarkers found in P. osteratus and could responsible for its cytotoxic potential. Accordingly, hyphenated liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based polyphenol and ergosterol-targeted myco-metabolite profiling of CD, H, and EA fractions were carried out. Despite being significantly rich in polyphenol and ergosterol content, EA fraction showed moderate cytotoxicity. Considering this, liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF/MS)-based untargeted myco-metabolite profiling of CD, H and EA fractions was further conducted to identify a new biomarker. Tentatively, 20 myco-metabolites were identified, belonging to the class of steroids, alkaloid, terpenoid, fatty alcohol, and polyketide. The myco-metabolite variabilities among potent samples in correlation to their in vitro anti-cancer activity was explored using the different chemometric tools: principal component analysis (PCA), hierarchical clustering analysis (HCA), and partial least square (PLS). A probable synergistic action among identified myco-metabolites (betulin, solanocapsine, ophiobolin F, linoleoyl ethanolamide, (13R,14R)-7-labdene-13,14,15-triol, asterosterol, cholest-5-ene, (3b,6b,8a,12a)-8,12-epoxy-7(11)-eremophilene-6,8,12-trimethoxy-3-ol, beta-obscurine, myxalamid B, momordol, and avocadyne 4-acetate) may be responsible for the observed cytotoxicity potential of H fraction of P. osteratus.

Keywords: Anti-cancer; Chemometric; Cytotoxicity; Hierarchical clustering analysis; LC–MS/MS; Partial least square; Pleurotus osteratus; Principal component analysis.