Bioactive selaginellins from Selaginella tamariscina (Beauv.) Spring

A new selaginellin named selaginellin O (1), along with three other known selaginellins (2-4) were isolated from Selaginella tamariscina (Beauv.) Spring. On the basis of spectroscopic analysis, the structure of selaginellin O was demonstrated to be 4-[(4'-hydroxy- 4-formyl-3-((4-hydroxyphenyl)ethynyl)biphenyl-2-yl)(4-hydroxyphenyl)methylene]cyclohexa-2,5-dien-1-one. Compound 1, 2 and 3 exhibited appreciable cytotoxic activity against cultured HeLa cells (human cervical carcinoma cells), as well as significant antioxidant activity.