Renoprotective Effects of Hypoxylonol C and F Isolated from Hypoxylon truncatum against Cisplatin-Induced Cytotoxicity in LLC-PK1 Cells

Although cisplatin is the standard platinum-based anticancer drug used to treat various solid tumors, it can cause damage in normal kidney cells. Protective strategies against cisplatin-induced nephrotoxicity are, therefore, clinically important and urgently required. To address this challenge, we investigated the renoprotective effects of Hypoxylon truncatum, a ball-shaped wood-rotting fungus. Chemical investigation of the active fraction from the methanol extract of H. truncatum resulted in the isolation and identification of the renoprotective compounds, hypoxylonol C and F, which ameliorated cisplatin-induced nephrotoxicity to approximately 80% of the control value at 5 μM. The mechanism of this effect was further investigated using hypoxylonol F, which showed a protective effect at the lowest concentration. Upregulated phosphorylation of p38, extracellular signal-regulated kinases, and c-Jun N-terminal kinases following cisplatin treatment were markedly decreased after pre-treatment with hypoxylonol F. In addition, the protein expression level of cleaved caspase-3 was significantly reduced after co-treatment with hypoxylonol F. These results show that blocking the mitogen-activated protein kinase signaling cascade plays a critical role in mediating the renoprotective effect of hypoxylonol F isolated from H. truncatum fruiting bodies.