A new bischromanone from the stems of Semecarpus caudata
From an CHCl3-soluble fraction of the stems of Semecarpus caudata, one new bischromanone named semecarpanone (1), together with 5 known flavonoids (2–6) were isolated. Their structures were elucidated based on interpretation of spectroscopic data. The stereo-configuration of 1 was identified based on the calculated and experimental coupling constants. Compounds 4–6 showed potent tyrosinase inhibitory activity with the IC50 values ranging from 15.0 to 76.3 μM.