Abstract:
The antioxidant activities of four extracts (alkali extracts,ethyl acetate extract,60% ethanol extract and crude polysaccharide) from Cryptoporus volvatus(Peck) Hubbard were evaluated by methods of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical,2,2'-azino-di-(3-ethyl-2,3-dihydrobenzthiazoline-6-sulfonate)(ABTS),Salicylic acid,and Fenton reaction.The results indicated that ethyl acetate extract showed the strongest free radical scavenging ability with IC50=(67.43±1.41) mg/L by the ABTS method.Further study by bioassay-guided fractionation of the ethyl acetate extract led to the isolation and identification of nine cryptoporic compounds including cryptoporic acid A trimethyl ester ( 1 ),cryptoporic acid A ( 2 ),cryptoporic acid D tetra-methyl ester ( 3 ),cryptoporic acid D ( 4 ),cryptoporic acid C ( 5 ),cryptoporic acid C pentamethyl ester ( 6 ),cryptoporic acid E pentamethyl ester ( 7 ),cryptoporic acid B trimethyl ester ( 8 ) and crytoporic acid B ( 9 ).Among them,compounds 1,3,6,8 were isolated for the first time from this fungus.The results of the ABTS scavenging ability showed that compound 8 (cryptoporic acid B trimethyl ester) has a higher antioxidant activity with IC50=(5.29±0.25) mg/L than the positive control VC with IC50=(5.76±0.58) mg/L.In addition,the structure-relationship of sesquiterpenes as antioxidant agents was analyzed.