Preparation of low molecular weight Enteromorpha prolifera polysaccharide and its antioxidant and tyrosinase inhibitory activities

Abstract

Enteromorpha prolifera polysaccharide (EP) is a water-soluble sulfated polysaccharide with many types of biological activities. In this study, the crude polysaccharide was extracted from Enteromorpha prolifera and degraded by different physical, chemical, and biological methods. The results showed that the enzymatic degradation products displayed the best tyrosinase inhibitory activity. The optimal enzymatic degradation conditions were as follows: 30 °C, pH 5.5, 750 U/mL enzyme dosage for 2 h. The enzymatic hydrolysates were then divided into six EP fractions (EPFs) by an ultrafiltration membrane. The in vitro tyrosinase inhibitory activity of these fractions showed that the smaller the molecular weight of EPF, the better the inhibitory effect on tyrosinase. The antioxidant and tyrosinase inhibitory effect of the most effective EPF, a molecular weight below 5 kDa, (EPF5), was further confirmed on B16 cells. A kinetic study of tyrosinase inhibitory activity revealed that EPF5 is a competitive-uncompetitive mixed-type inhibitor of tyrosinase. These findings suggested that EPF5 has significant potential as a skin-whitening agent in cosmetics as well as an antibrowning agent in the food and agriculture industries.

Keywords:
Enteromorpha prolifera polysaccharide; enzymatic degradation; low molecular weight; tyrosinase inhibitory activity; antioxidant activity