Three Undescribed Iridoid Derivatives Isolated from the Fruits of Vitex trifolia with Their Cytotoxic and Antimicrobial Activities

Abstract

Vitex trifolia L. is a medicinal plant and widely distributed in the northern mountainous areas of Vietnam. Phytochemical study on the fruits of this plant led to the isolation of nine iridoid derivatives (1–9) including three undescribed compounds (1–3). Their structures were elucidated to be 3′′-hydroxyscrophuloside A1 (1), 3′′-hydroxycallicoside D (2), 2′-p-hydroxybenzoylaucubin (3), 6′-p-hydroxybenzoylmussaenosidic acid (4), nishindaside (5), agnuside (6), 10-O-vanilloylaucubin (7), 6′-O-p-hydroxybenzoyl-gardoside (8), and buddlejoside B (9) based on extensive analyses of HR-ESI-MS, 1D and 2D NMR spectra. Compounds 1, 2, 4, and 8 significantly posessed anti-barterial activity against Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa strains with MIC values in range of 16–64 μg/mL. At concentration of 20 μM, compounds 1–9 did not show cytotoxic effects against human lung cancer cells (PC9).