Isolation Of Active Ingredients From The Sericin Layer Of Silkworm Bombyx Mori Cocoon And Their Bioactivities

In the present paper, as the experimental material, We prepared five crude extracts of five different kind of cocoons and their purified sericin with ethanol by extraction processing repeatly. The results in vitro showed that all these ethanolic extracts from the silkworm cocoons had much stronger inhibitory activities of DPPH free radical and tyrosinase in comparison with their purified sericin proteins. In addition, the former had strong inhibitory activity ofα-glucosidase while the latter had no such activity in the determination in vitro. Of all bioactivities, the inhibiting ability of the ethanolic extract in Daizo Bombyx mori cocoon was the strongest of all cocoon shells and its IC50 values for the inhibition of DPPH free radical, tyrosinase andα-glucosidase were 170μg/mL, 27μg/mL and 110μg/mL, respectively.And then, the measurement ofα-glucosidase inhibition of ethanol extract and its sericin of Daizo cocoon in vivo tests showed that the former could significantly reduce the blood glucose of the STZ-induced diabetic mice, while the latter had a weak effect. In addition, the active ingredient analysis of ethanolic extract showed that they were mainly flavonoids and free amino acids and so on. The analysis of amino acid composition and total flavonoids revealed that these bioactivities of ethanol extracts were related positively to the level of total flavonoids but not related to that of total amino acids in the ethanolic extract from silkworm cocoon.