Meroterpenoids with a large conjugated system from Ganoderma lucidum and their inhibitory activities against renal fibrosis

Baoslingzhines A–E (1–5), five new meroterpenoids were isolated from the fruiting bodies of Ganoderma lucidum. The structures including their absolute configurations were characterized by using spectroscopic and computational methods. Compound 1 is a novel trinormeroterpenoid featuring the presence of an unusual dihydronaphthalene representing an unprecedented meroterpenoid skeleton. Compounds 2–4 are mononormeroterpenoids characteristic of a large conjugated system. Among them, racemic 3 and 4 were separated by HPLC on chiral phase. Biological evaluation toward kidney fibrosis found that compounds 2 and (+)-3 could inhibit the expression of fibronectin and collagen I dose dependently in TGF-β1-induced rat kidney proximal tubular cells (NRK-52e). Additionally, (+)-3 could also down regulate ɑ-SMA in a concentration dependent manner. Further investigation showed that 2 could inhibit Smad2 phosphorylation.