Cryptoporic acid D

Cryptoporic acids D and E, isolated from the fungus Cryptoporus volvatus, are inhibitors of superoxide anion radical release. Cryptoporic acid E inhibited tumor promotion of okadaic acid in two-stage carcinogenesis experiments on mouse skin, initiated with 7,12-dimethylbenz[a]anthracene. Treatment with cryptoporic acid E using two different doses per application, 1 (1.2 mumol) and 5 mg (5.9 mumol), reduced the percentage of tumor-bearing mice from 73.3 to 53.3% and 20.0%, and the average number of tumors per mouse from 4.2 to 2.3 and 0.5 respectively in week 20 of tumor promotion. However, cryptoporic acid D slightly enhanced tumor promotion rather than inhibition of okadaic acid. Cryptoporic acid D was expected to have additional biochemical activities, such as activation of protein kinases. Cryptoporic acid D at concentrations of up to 100 microM activated protein kinase C and stimulated other protein kinase activity in vitro, whereas cryptoporic acid E did not. These two compounds provided differential effects on tumor promotion of okadaic acid on mouse skin.

A new drimane-type sesquiterpene with an isocitric acid moiety, cryptoporic acid S (1), together with six known compounds, cryptoporic acid D (2), β-sitosterol (3), β-daucosterol (4), stigmast-4-en-3-one (5), ergosterol (6), and (22E,24R)-ergosta-7,22-diene-3β,5α,6β-triol (7), was isolated from the fruiting bodies of Cryptoporus volvatus. The structures of these compounds were established on the basis of UV, IR, MS, 1D and 2D NMR analysis. In the meanwhile, compounds 1 and 2 were evaluated for antioxidant activity using the methods of 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity (DPPH-RSA) and ferric reducing antioxidant power (FRAP) assay, and they exhibited moderate antioxidant activities.