Isolation, identification, and inhibitory enzyme activity of phenolic substances present in Spirulina.

Spirulina species are edible with high nutritional as well as potential therapeutic values. In this work, we show that phenolic extracts from Spirulina (p-Coumaric acid) possessed inhibitory potential on alpha-glucosidase (IC50 = 1.67 +/- 0.02 mM) and tyrosinase (IC50 = 52.71 +/- 3.01 mM). Moreover, p-Coumaric acid inhibited alpha-glucosidase and tyrosinase in a reversible mixed-type manner. Interestingly, molecular docking demonstrated that p-Coumaric acid penetrated in depth of the active-site of tyrosinase and alpha-glucosidase by the noncovalent force or interaction. Among them, making polar interactions with Cu2+ ions and the amino acid residue capable of forming cation-pi significantly contribute to the strong binding of p-Coumaric acid on tyrosinase. p-Coumaric acid was isolated and identified from Spirulina for the first time, which can be used as a lead compound for the design of functional food additives and skin-lightening active ingredient in cosmetics, and pharmaceuticals against type 2 diabetes.