Six new steroidal saponins (1-6), angudracanosides A-F, were isolated from fresh stems of Dracaena angustifolia (Agavaceae), together with eight known compounds. The structures of compounds 1-6 were determined by detailed spectroscopic analyses and chemical methods. Antifungal testing of all compounds showed that 6 and 7 were active against Cryptococcus neoformans with IC 50 s of 9.5 and 20.0 μg/mL, respectively.The genus Dracaena (Agavaceae) contains more than 60 species that are distributed from the Old World tropic region to the Canary Islands. Some species contain C27 steroidal saponins 1 , as evidenced in our previous phytochemical study of D. cochinchinensis. 2 The C27 steroidal saponins have demonstrated antitumor 1 , anti-inflammatory 3 , and hypoglycemic 4 activities as well as therapeutic potential for cardiovascular diseases. 5 Some C27 steroidal saponins have antifungal activity, which varies with the aglycone structure and with the number and structure of monosaccharide units in their sugar chains. 6 Dried roots and rhizomes of D. angustifolia Roxb (Agavaceae) collected in Vietnam have been studied, revealing the presence of several steroidal saponins with antiproliferative activity. 7 Our interest in antifungal steroidal saponins prompted us to investigate fresh stems of this species that were collected in Southwest China. As a result, six new steroidal saponins (1-6), which were named angudracanosides A-F, and eight known compounds were isolated. The antifungal activity of these compounds against several human fungal pathogens was evaluated, and the results are presented in paper.
Results and DiscussionThe fresh stems of D. angustifolia were extracted with methanol under reflux. A n-butanolsoluble portion of the methanol extract was chromatographed on the highly porous absorption resin Diaion HP-20, normal phase silica gel, Sephadex LH-20, and reversedphase silica gel RP-18 to afford six new compounds (1-6). In addition, eight known compounds were identified as (25S)-spirost-5-en-1β,3β-diol-1-sulphate 8 , (25R)-* Author to whom correspondence should be addressed. Tel.: +86-871-522-3235. Fax: +86-871-515-0124. zhangyj@mail.kib.ac.cn. .
Supporting Information Available:The NMR spectra for angudracanoside A-F (1-6), structures of the known compounds (8-14) isolated from Dracaena angustifolia, important HMBC correlations for 1, and selected ROESY correlations of 3. This material is available free of charge via the Internet at http://pubs.acs.org.
NIH Public AccessThe differences between 1 and the known compound were the molecular weight and the 13 Thus, the aglycone of 1 was determined to be as shown. The sequence of the sugar chain in 1 was determined to be the same as that of (25R)arabinopyranoside, by the HMBC and HSQC experiments. HMBC correlations from the anomeric signal at δ 6.29 (Rha H-1) to δ 76.0 (Ara C-2) and from δ 4.64 (Ara H-1) to δ 82.3 (Agly C-1) were observed. Moreover, the deshielded chemical shifts observed in the HSQC spectrum for the arabinosyl C-4 and H-4 at δ 76.1 and...