Eight New Triterpenoids with Inhibitory Activity Against HMG-CoA Reductase from the Medical Mushroom Ganoderma Leucocontextum Collected in Tibetan Plateau

Eight new triterpenoids, ganoleucoins T-Z(1-3, 5-8), and AA (9), together with eleven known triterpenes were isolated and identified from the wild fruiting bodies of the medicinal mushroom Ganoderma leucocontextum. The structures of new compounds were determined on the basis of NMR and MS spectral analysis. The inhibitory effects of 1-9 on HMG-CoA reductase were tested in vitro. Compounds 1, 7 and 8 showed significant HMG-CoA reductase inhibition with IC values of 10.2, 9.72 and 8.68 μM, respectively. The other isolated compounds presented relatively weak inhibitory activity with IC values >100 μM. Preliminary structure-activity relationship analysis showed that the HMG moiety in 7 and 8 contributed greatly to their inhibitory activity against HMG-CoA reductase. This work further demonstrates the mushroom G. leucocontextum to be valuable herbal medicine that deserves deep investigation.