Biological Activities and Chemical Contents of Edible Hohenbuehelia petaloides (Bull.) Schulzer

Abstract

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. Hohenbuehelia petaloides, a member of the Pleuroteceae 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 H. petaloides 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 H. petaloides 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 Bacillus cereus, Staphylococcus aureus, Bacillus subtilis, and Micrococcus luteus with different inhibition zones. The major lipid components of H. petaloides 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 p-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 H. petaloides 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.

Figure 1

Macroscopic (a) and microscopic (b) views of H. petaloides.

Figure 2

Microscopic views of the lung (A549), breast (MCF-7), prostate (PC-3), and colon (HT-29) cancer cell lines, and healthy human (CCD18Co) cell lines (magnified at x20).

Figure 3

Flow cytometric analysis of A549 cells exposed to different concentrations of the hexane extract from H. petaloides: (a) control, (b) 2× IC₅₀, (c) IC₅₀, and (d) IC₅₀ 1/2.

Figure 4

Flow cytometric analysis of A549 cells exposed to different concentrations of the H. petaloides water extract: (a) control, (b) IC₅₀, and (c) 2× IC₅₀.

Figure 5

Flow cytometric analysis of A549 cells exposed to different concentrations of H. petaloides methanol extract for 24 h: (a) control, (b) IC₅₀, and (c) IC₅₀1/2.

Figure 6

Apoptotic gene caspase-3 expression in the A549 cancer cell line treated with different extracts of H. petaloides.

Figure 7

Cytokine (TNF-α) concentration of mushroom extracts in the A549 cell line. Statistical analysis of the data was performed using two-way ANOVA; mean ± standard deviation with three replicates is indicated by **** (p < 0.0001).

Figure 8

VEGF release from mushroom extracts in the A549 cell line. Statistical analysis of the data was performed using two-way ANOVA; mean ± standard deviation in three replicates is indicated by **** (p < 0.0001).