Biological properties of different protein extracts from selenium-enriched Ganoderma lucidum

Our previous studies showed that Ganoderma lucidum bio-transformed 20-30% of inorganic selenium from substrate to organic forms by preferentially incorporating selenium into proteins. In the present study, four kinds of protein extracts from selenium-enriched G. lucidum were prepared with different extracting solvents, which contain water-soluble, alkaline-soluble, salt-soluble and alcohol-soluble protein extracts, and the effects on antioxidant activity of characterizations of protein extracts were studied. Results showed that water-soluble extract showed strongest antioxidant properties among all extracts as suggested by spin trapping experiment due to its characterizations, followed by the alkaline-soluble > the salt-soluble > the alcohol-soluble protein extracts, a result demonstrating that selenium content and amino acids composition of the protein extracts play important and direct roles in enhancing their antioxidant activities, and the protein distribution and sugar content have an indirect effect by influencing the characters and structures. The activity of water-soluble crude protein was verified by CuSO4-Phen-Vc-H2O2-DNA chemiluminescent analysis, and it should be selected as the subject to be studied and purified further.