Bioactive steroidal saponins from Agave offoyana flowers

Bioguided studies of flowers of Agave offoyana allowed the isolation of five steroidal saponins never described previously, Magueyosides A-E (1-5), along with six known steroidal saponins (6-11). The structures of compounds were determined as (25R)-spirost-5-en-2 alpha,3 beta-diol-12-one 3-O-{beta-D-xylopyranosyl-(1 -> 3)-O-beta-D-glucopyranosyl-(1 -> 2)-O-[beta-D-xylopyranosyl-(1 -> 3)]-O-beta-D-glucopyranosyl-(1 -> 4)-O-beta-D-galactopyranoside} (1), (25R)-spirost-5-en-2 alpha,3 beta-diol-12-one 3-O-{beta-D-glucopyranosyl-(1 -> 2)-O-[beta-D-xylopyranosyl-(1 -> 3)]-O-beta-D-glucopyranosyl-(1 -> 4)-O-beta-D-galactopyranoside) (2), (25R)-spirost-5-en-2 alpha,3 beta,12 beta-triol 3-O-{beta-D-glucopyranosyl-(1 -> 2)-O-[beta-D-xylopyranosyl-(1 -> 3)]-O-beta-D-glucopyranosyl-(1 -> 4)-O-beta-D-galactopyranoside} (3), (25R)-5 alpha-spirostan-2 alpha,3 beta-diol-12-one 3-O-{beta-D-xylopyranosyl-(1 -> 3)-O-beta-D-glucopyranosyl-(1 -> 2)-O-[beta-D-xylopyranosyl-(1 -> 3)]-O-beta-D-glucopyranosyl-(1 -> 4)-O-beta-D-galactopyranoside} (4), and (25R)-5 alpha-spirostan-2 alpha,3 beta-diol-9(11)-en-12-one 3-O-{beta-D-xylopyranosyl-(1 -> 3)-O-beta-D-glucopyranosyl-(1 -> 2)-O-[beta-D-xylopyranosyl-(1 -> 3)]-O-beta-D-glucopyranosyl-(1 -> 4)-O-beta-D-galactopyranoside} (5), by comprehensive spectroscopic analysis, including one- and two-dimensional NMR techniques, mass spectrometry and chemical methods. The bioactivities of the isolated compounds on the standard target species Lactuca sativa were evaluated. A dose-dependent phytotoxicity and low dose stimulation were observed. (C) 2013 Elsevier Ltd. All rights reserved.