Extraction optimisation and isolation of triterpenoids fromGanoderma lucidumand their effect on human carcinoma cell growth

The response surface methodology was used to optimise the extraction conditions of Ganoderma lucidum based on a Box–Behnken design. A quadratic model sufficiently simulated the response of ganoderic acid H with a determination coefficient (R2) of 0.98. The optimal condition for extracting triterpenoids was determined to be 100.00% ethanol at 60.22°C for 6.00 h, under which the yield of the reference triterpenoid ganoderic acid H increased from 0.88 to 2.09 mg/g powder. Following extraction, triterpenoid-enriched fraction was further isolated into 23 fractions, and 7 fractions were identified as ganoderic acids A, B, D, G, H and I and ganoderenic acid D. Of the seven triterpenoids, ganoderenic acid D was most cytotoxic with IC50 values of 0.14 ± 0.01, 0.18 ± 0.02 and 0.26 ± 0.03 mg/mL in Hep G2, Hela and Caco-2 cells, respectively. While ganoderic acids A, G and H were relatively non-cytotoxic. The variation of inhibitory effects for these triterpenoids was likely related to their chemical structures.