Biological Activities and Chemical Contents of Edible <i>Hohenbuehelia petaloides</i> (Bull.) Schulzer

Mushrooms are a good diet with high protein and polyunsaturated fatty acid contents in health, food, and industry from past to present. Mushrooms have attracted a lot of attention in terms of the bioavailability of natural products. <i>Hohenbuehelia petaloides</i>, a member of the <i>Pleuroteceae</i> family, is an edible wood fungus that grows naturally on the trunks of old and decayed trees. In this study, the cytotoxic activities of hexane, methanol, and water extracts of <i>H. petaloides</i> against various cancer cell lines A549, MCF-7, PC-3, and HT-29 were investigated with the 3-(4,5-dimethylthiazol-2-yl)-2,5-dipenyltetrazolium bromide (MTT) assay. In addition, the apoptotic, inflammatory, angiogenic, and antimicrobial effects of the extracts were examined by flow cytometry, real-time quantitative polymerase chain reaction (RT-qPCR), enzyme-linked immunosorbent assay (ELISA), and well diffusion assays, respectively. Moreover, the antioxidant activity and phenolic and lipid components of <i>H. petaloides</i> were determined. The hexane extract showed the highest cytotoxic activity (IC₅₀ = 26.48 ± 0.02 μg/mL) against A549 cells, while water and methanol extracts exhibited the highest cytotoxicity (IC₅₀ = 83.18 ± 0.05 μg/mL and IC₅₀ = 90.95 ± 0.05 μg/mL, respectively) against PC-3 cells. The hexane extract killed A549 cells via apoptosis. The methanol extract, at the IC₅₀ level, was the most effective in decreasing both tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF) release. In antioxidant activity tests performed with 5 different methods, the methanol extract had higher antioxidant activity than the others, followed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical (IC₅₀ = 82.61 ± 0.90 μg/mL) and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) cation radical removal (IC₅₀ = 55.20 ± 0.65 μg/mL) and CUPRAC-reducing power (IC₅₀ = 76.41 ± 0.73 μg/mL). Among the extracts studied, the hexane extract showed antimicrobial activity against <i>Bacillus cereus</i>, <i>Staphylococcus aureus</i>, <i>Bacillus subtilis</i>, and <i>Micrococcus luteus</i> with different inhibition zones. The major lipid components of <i>H. petaloides</i> analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC/MS) were elaidic acid (38.22%), palmitic acid (30.59%), stearic acid (13.21%), linoleic acid (4.35%), and azelaic acid (4.29%). The phenolic compounds determined by the high-performance liquid chromatography with photodiode-array detection (HPLC-DAD) system were <i>p</i>-hydroxybenzoic acid (7.42 μg/g extract), cinnamic acid (6.83 μg/g extract), gallic acid (5.36 μg/g extract), and protocatechuic acid (1.83 μg/g extract). The results showed that <i>H. petaloides</i> has the potential to be a natural source for the development of novel anticancer and antimicrobial agents as well as a beneficial food supplement for the prevention of cancer.