Triterpenoid Saponins of Sapotaceae Plants and Their Bioactivities

Abstract

Naturally occurring triterpenoid saponins reported in the plants of six genera, i.e., Argania, Madhuca, Mimusops, Sideroxylon, Tieghmella, and Vitellaria, of the family Sapotaceae are reviewed together with their biological activities. Most of the triterpenoid saponins found in these Sapotaceae plants are bisdesmosides with sugar chains at the C-3 and C-28 positions, and their aglycone is either protobassic acid, 16a-hydroxyprotobassic acid, bayogenin, or bassic acid, all belonging to the d12-oleanane series. The most frequently encountered sugar chain bound to C-3 of the aglycone is the single glucose residue (¬Glu) followed by the dissaccharide chain of apiosyl-glucose (¬Glc4¬Api), while that attached to C-28 is the linear tetrasaccharide chain of rhamnosyl-xylosyl-rhamnosyl-arabinose (¬Ara2¬Rha4¬Xyl3¬Rha). Arganine C (16a-hydroxy Mi-saponin A) has been found to be the most common saponin of the Sapotaceae plants. The biological activities such as anti-inflammatory, cytotoxicity, antioxidant, melanogenesis-inhibitory, anti-tumor promoting, antiviral, and antifungal activities of these saponins are discussed.