Cytotoxic compounds from endemic Arnebia purpurea.

Phytochemical studies of the roots and aerial parts of endemic Arnebia purpurea S. Erik & H. Sumbul resulted in the isolation and characterization of four naphthoquinones [isovalerylalkannin (1), α-methyl-n-butanoyl alkannin (2), acetylalkannin (3), and alkannin (4)], a triterpene derivative [3-O-acetyl-oleanolic acid (5)], a steroid [β-sitosterol (6)], three flavonoid glycosides [isorhamnetin-3-O-rutinoside (7), kaempferol-3-O-rutinoside (8), kaempferol 3-O-(5"-acetyl) apiofuranoside 7-O-rhamnopyranoside (9)] and a phenolic acid [rosmarinic acid (10)]. 3-O-Acetyl-oleanolic acid, isorhamnetin-3-O-rutinoside, kaempferol-3-O-mrutinoside, and kaempferol 3-O-(5"-acetyl) apiofuranoside 7-O-rhamnopyranoside are reported from an Arnebia species for the first time. Cytotoxic activities on L929 murine fibrosarcoma cell line of the isolated compounds were investigated using MTT assay. Naphthoquinones (1-4) showed intermediate cytotoxic activity in comparison with the standard, doxorubicin.