Phenylethanoids, iridoids and a spirostanol saponin from Veronica turrilliana

From the aerial parts of Veronica turrilliana two phenylethanoid glycosides, turrilliosides A and B and a steroidal saponin, turrillianoside were isolated and their structures elucidated as β-(3,4-dihydroxyphenyl)ethyl-4-O-E-caffeoyl-O-[β-glucopyranosyl-(1 → 4)-α-rhamnopyranosyl-(1 → 6)]-β-glucopyranoside, β-(3,4-dihydroxyphenyl)ethyl-4-O-E-caffeoyl-[6-O-E-feruloyl-β-glucopyranosyl-(1 → 4)-α-rhamnopyranosyl-(1 → 6)]-β-glucopyranoside and (23S,25S)-12β,23-dihydroxyspirost-5-en-3β-yl O-α-rhamnopyranosyl-(1 → 4)-β-glucopyranoside, respectively. Furthermore, eight known glucosides are reported namely, catalpol, catalposide, verproside, amphicoside, isovanilloylcatalpol, aucubin, arbutin, and 6-O-E-caffeoylarbutin, the latter two for the first time in the genus Veronica. The two phenylethanoid glycosides were found to be potent DPPH radical scavengers. All of the tested compounds were inactive against the representative species of fungi and bacteria. Two phenylethanoid glycosides, turrilliosides A and B, and a steroidal saponin, turrillianoside, together with eight known glucosides were isolated from Veronica turrilliana, Plantaginaceae. Radical scavenging potential, antifungal and antibacterial activities of selected compounds were tested.