Triterpenoid saponins from corms of Crocus sativus: Localization, extraction and characterization

Abstract

A mixture of highly glycosilated triterpenoid saponins 114217139 isolated from the corm of Crocus sativus or saffron showed cytotoxic activity against HeLa tumoral cells. The main reverse phase HPLC fraction of this mixture (CS5-1) contains two new oleanane-type saponins, denominated Azafrine 1 (1) and Azafrine 2 (2). The bidesmosidic saponins were respectively characterized as (1) 3- O-β- d-glucopyranosiduronic acid echinocystic acid 28- O-β-D-galactopyranosyl-(1 → 2)-α- l-arabinopyranosyl-(1 → 2)-[β- d-xylopyranosyl-(1 → 4)]-α- d-rhamnopyranosyl-(1 → 2)-[4- O-di-α-L-rhamnopyranosyl-3,16-dihydroxy-10-oxo-hexadecanoyl]-α-D-fucopyranoside and (2) 3- O-β-D-galactopyranosiduronic acid echinocystic acid 28- O-β-D-galactopyranosyl-(1 → 2)-α-L-arabinopyranosyl-(1 → 2)-[β-D-xylopyranosyl-(1 → 4)]-α-L-rhamnopyranosyl-(1 → 2)-[4- O-di-α-L-rhamnopyranosyl-3,16-dihydroxy-10-oxo-hexadecanoyl]-β-D-fucopyranoside. The surfactant properties of saponins, probably involved in the cytotoxic activity of CS5 and their exclusive localization in the external part or the corm, indicate their possible role as phytoprotectans. The similarity of their structural compositions to that of other triterpenoid saponins which are of special use in the pharmaceutical industry suggest a new application for C. sativus crops through the exploitation of corm for saponin extraction. © 2011.