5α/5β Stereochemistry of Spirostanol and Furostanol Saponins

Steroidal saponins constitute an important class of plant secondary metabolites and are mostly found in monocotyledonous angiosperms. These compounds are known to possess a vast array of bioactivities, including anticancer, adjuvant, immunostimulant, anti-inflammatory, antimicrobial, hypocholesterolaemic, antimicrobial and antioxidant^1,2. Structurally, steroidal saponins are classified as spirostanol and furostanol glycosides³. A third and relatively less common class of steroidal saponins is furospirostanols. The saponins of this class generally have a polyoxygenated A-ring and/or one or more double bonds present in the rings A and B⁴.