Calycosin-7-O-β-D-glucoside, a melanin biosynthesis inhibitor, is isolated from the methanol extract of astragalus. IC50 value: 68 μM in inhibition of Tyrosinase Target: In vitro: Calycosin-7-O-β-d-glucoside showed a melanin biosynthesis inhibition zone in a culture plate of Streptomyces bikiniensis. Furthermore, 75.78 μM of calycosin-7-O-β-d-glucoside dramatically decreased 50% of the melanin content on Melan-a cells without any apparent cytotoxicity [1]. Calycosin-7-O-β-D-glucoside was revealed to scavenge NO, inhibit the activities of MMP-2 and MMP-9, and attenuate cell death in the in vitro cultured brain microvascular endothelial cells under OGD condition. In vivo: Calycosin-7-O-β-D-glucoside treatment significantly reduced infarct volume, histological damage and blood–brain barrier permeability in the in vivo MCAO ischemia–reperfusion rat model [2]. To reveal its physiological functions under stress, seedlings with different isoflavonoid levels were established using a phenylalanine ammonia lyase (PAL) enzyme inhibitor, l-α-aminooxy-β-phenylpropionic acid (AOPP). The results showed that the significant promotion of antioxidant capacity in this species might be associated with the remarkable accumulation of Calycosin-7-O-β-D-glucoside after cold pretreatment. The results provided the first evidence that a type of isoflavonoid, Calycosin-7-O-β-D-glucoside, might play a very important role against freezing stress in vivo [3].