Pregnane steroidal glycosides and their cytostatic activities

Author： Garca Vctor P Bermejo Jaime Rubio Sara Quintana Jos Estvez Francisco

ISSN： 1460-2423

Source： Glycobiology, Vol.21, Iss.5, 2011-05, pp. : 619-624

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Abstract

Four new steroidal glycosides such as 3-O-6-deoxy-3-O-methyl--d-allopyranosyl-(14)--d-oleandropyranosyl-(14)--d-cymaropyranosyl-(14)--d-cymaropyranoside-12--tigloyl-14--hydroxy-17--pregnane (1), 3-O-6-deoxy-3-O-methyl--d-allopyranosyl-(14)--d-oleandropyranosyl-(14)--d-cymaropyranosyl-(14)--d-cymaropyranoside-12--(2'-amino)-benzoyl-14--hydroxy-17--pregnane (2), 3-O-6-deoxy-3-O-methyl--d-allopyranosyl-(14)--d-oleandropyranosyl-(14)--d-cymaropyranosyl-(14)--d-cymaropyranoside-12--14--dihydroxy-17--pregnane (3) and 3-O-6-deoxy-3-O-methyl--d-allopyranosyl-(14)--d-oleandropyranosyl-(14)--d-cymaropyranosyl-(14)--d-cymaropyranoside-12--14--dihydroxy-17--pregnane (4) were isolated from the aerial parts of Ceropegia fusca Bolle (Asclepiadaceae), a crassulacean acid metabolism plant, an endemic species to the Canary Islands that has been used in traditional medicine as a cicatrizant, vulnerary and disinfectant. The dichloromethane extract exhibited significant cytostatic activity against HL-60, A-431 and SK-MEL-1 cells, human leukemic, epidermoid carcinoma and melanoma cells, respectively. As shown in TableI, compounds 1 and 2 showed very similar IC₅₀ values. The acetylation of 1 to give the diacetate 5 increases 5-fold the cytotoxicity against HL-60 cells. Compounds 3 and 4 did not show cytotoxicity at the assayed concentrations. With respect to the compounds containing only the steroid ring (68), the presence of a charged O-amino-benzoyl but not a tigloyl group improved the cytotoxicity.