Oyster mushrooms form an integral part of many diets owing to their characteristic aroma, delicious taste and nutraceutical value. In this study, we examined oyster mushrooms by direct arc optical emission spectroscopy for the presence of various biologically important elements. Furthermore, we screened phytochemicals present in Pleurotus ostreatus by applying GC-MS. Additionally, the antioxidant, antibacterial and anticancer activities of the ethanolic extract of Pleurotus ostreatus were studied. Moreover, we docked the phytochemicals and examined their binding affinities with EGFR, PR and NF-κB proteins, which are overexpressed in breast cancer. The elemental analysis showed the presence of Fe, K, Na, Ca, Mg, Cr and Sr in the spectrum. Moreover, GC-MS data revealed the presence of 32 biologically active compounds in oyster mushrooms. The ethanolic extract displayed remarkable free radical scavenging activity (~50%) against DPPH. The mushroom has shown promising antibacterial activity against both Gram-positive (S. aureus) and Gram-negative bacteria (Pseudomonasaeruginosa, Proteus vulgaris and Proteus mirabilis). The present study also revealed that oyster mushrooms possess significant anticancer activity. The ethanolic extract inhibited the growth and proliferation of MCF-7 cells. It also induced cell shrinkage, membrane blebbing and nuclear fragmentation, resulting in apoptosis of malignant cells. The molecular docking analysis showed that ligand 15 (Linoleic acid ethyl ester), ligand 27 (Ergosta-5,7,9(11),22-tetraen-3-ol, (3. beta.,22E), ligand 28 (Stigmasta-5,22-dien-3-ol, acetate, (3. beta.,22Z), ligand 30 (Ergosta-5,7,22-Trien-3-Ol, (3. Beta.,22E) and ligand 32 (gamma. Sitosterol) exhibited better binding affinities with EGFR, PR and NF-κB proteins. This result provides a strong ground for confirmation of the in vitro anticancer effect of Pleurotus ostreatus. From the present in vitro and in silico studies, it can be concluded that Pleurotus ostreatus is a useful source of essential elements and reservoir of bioactive compounds which confer its significant antioxidant, antibacterial and anticancer properties.
Keywords: antibacterial; anticancer; antioxidant; bioactive compounds; molecular docking; oyster mushroom; spectroscopy.