Lehmanniaside, a new cycloartane triterpene glycoside from Astragalus lehmannianus.

Chemical investigation of the aerial parts of Astragalus lehmannianus Bunge (Leguminosae) led to the isolation and identification of a new cycloartane triterpene glycoside - lehmanniaside (2'-O-acetyl-3-ß-O-D-xylopyranosyl-3ß,6α,16ß,24α-tetrahydroxy-20,25-epoxycycloartane). Its structure was elucidated by means of spectroscopic analysis (HR-MS, 1D and 2D NMR). Bioassays showed that lehmanniaside exhibits weak anthelmintic, antifungal, and cytotoxic activities.

Tyrosinase inhibition studies of cycloartane and cucurbitane glycosides and their structure-activity relationships.

In the present paper, tyrosinase inhibition studies and structure-activity relationship of eight cycloartane glycosides and one cucurbitane glycoside and its genin, which were isolated from Astragalus (Leguminoseae) and Bryonia (Cucurbitaceae) plants, have been discussed. The activities are compared with two reference tyrosinase inhibitors, kojic acid and l-mimosine. These studies and the SAR showed that the askendoside B which exhibited highly potent (IC50 =13.95 microM) tyrosinase inhibition could be a possible lead molecule for the development of new medications of several skin diseases related with the over-expression of the enzyme tyrosinase, like hyperpigmentation. The molecule also may be interesting for the cosmetic industries as a skin whitening agent.