Constituents of the Vietnamese Medicinal Plant Streptocaulon juventas and Their Antiproliferative Activity against the Human HT-1080 Fibrosarcoma Cell Line

Abstract

The methanolic extract of roots of Streptocaulon juventas, having shown strong antiproliferative activity against the highly metastatic human HT-1080 fibrosarcoma cell line, was subjected to activity-guided isolation to yield 16 cardenolides including five new ones, acovenosigenin A 3-O-β -digitoxopyranoside (1), digitoxigenin gentiobioside (2), digitoxigenin 3-O-[O-βglucopyranosyl-(1→6)-O-β-glucopyranosyl-(1→4) -3-O-acetyl-β-digitoxopyranoside] (3), digitoxigenin 3-O-[O-β -glucopyranosyl-(1→6)-O-β-glucopyranosyl-(1→4) -O-β-digitalopyranosyl-(1→4)-β-cymaropyranoside] (4), and periplogenin 3-O-(4-O-β-glucopyranosyl-β-digitalopyranoside) (5), and two new hemiterpenoids, (4R)-4-hydroxy-3-isopropylpentyl β-rutinoside (6) and (R)-2-ethyl-3-methylbutyl β-rutinoside (7), together with two known phenylpropanoids and a known phenylethanoid. The isolated cardenolides strongly inhibited the proliferation of the HT-1080 cell line (IC50 values, 54-1600 nM).