Background: Inonotus obliquus is a medicinal mushroom that has been used as an effective agent to treat various diseases such as diabetes, tuberculosis and cancer. In order to elucidate the active fraction and its constituents, the effects of ethyl acetate fraction from I. obliquus (EAFI) on hyperglycaemia were investigated and the main constituents of EAFI were isolated and identified.
Results: EAFI treatment led to a significant decrease in blood glucose level (P < 0.05) in alloxan-induced diabetic mice. It significantly decreased the total cholesterol level in serum, increased glutathione peroxidase activity and improved the growth physiological characteristics. In addition, EAFI treatment decreased the levels of triglyceride and malondialdehyde and increased the high-density lipoprotein cholesterol level in serum and the hepatic glycogen level in liver of diabetic mice. Five compounds were isolated from EAFI and identified as lanosterol (1), 3beta-hydroxy-lanosta-8,24-diene-21-al (2), inotodiol (3), ergosterol peroxide (4) and trametenolic acid (5) by spectral methods. Inotodiol and trametenolic acid were found to have an inhibitory effect on alpha-amylase activity and a scavenging effect on 1,1-diphenyl-2-picrylhydrazyl radicals.
Conclusion: EAFI showed significant antihyperglycaemic and antilipidperoxidative effects in alloxan-induced diabetic mice. Terpenoid and sterol compounds appeared to be the major active constituents of I. obliquus.
(c) 2009 Society of Chemical Industry.