A Pholidota chinensis-derived dihydrophenanthrene acts as a bioactive constituent to trigger GPx4-mediated ferroptosis in colorectal cancer.

Pholidota chinensis Lindl. has been used as a traditional medicinal plant for heat-clearing and detoxifying purposes, as well as for inflammatory and gastrointestinal conditions.

However, the bioactive constituents and pharmacological mechanisms underlying the potential effects of P. chinensis in gastrointestinal disorders and colorectal carcinogenesis remain unclear.

This study aimed to identify anticancer constituents from the pseudobulbs of P. chinensis and to investigate the pharmacological mechanisms of P. chinensis-derived natural products against colorectal cancer (CRC). Through bioactivity-directed fractionation, the chromatographic fingerprint of P. chinensis pseudobulbs was analyzed, and phenanthrene-type phytochemicals were isolated and identified. The anticancer potential and pharmacological mechanisms were evaluated using human CRC cells, in silico simulations, and a zebrafish xenograft model. The ethyl acetate (EtOAc) fraction of P. chinensis pseudobulbs exhibited stronger anticancer activity than those of the ethanol and water fractions.

A rare dihydrophenanthrene derivative, 1-(4'-hydroxybenzyl)imbricatin (3), was identified from the EtOAc fraction as a potent ferroptosis inducer. Compound 3 showed selective cytotoxicity against human CRC cells while exhibiting lower cytotoxicity toward non-tumor intestinal cells. Compound 3 triggered hallmark features of ferroptosis, including intracellular Fe2+ accumulation, lipid peroxidation, and disruption of the GPx4-related antioxidant defense system. Cellular thermal shift assays and molecular docking further supported the interaction of compound 3 with the catalytic pocket of GPx4.

Importantly, compound 3 significantly reduced tumor burden in a zebrafish CRC xenograft model.

These findings highlight the EtOAc fraction of P. chinensis pseudobulbs as a valuable source of anticancer lead compounds and identify 1-(4'-hydroxybenzyl)imbricatin (3) as a promising dihydrophenanthrene scaffold for inducing GPx4-associated ferroptosis in CRC.