Saponin and sapogenol. XXIV. The structure of Mi-saponin C, a bisdesmoside of protobassic acid from the seed kernels of Madhuca longifolia (L.) Macbride.

The structure of a minor saponin named Mi-saponin C (10), which was previously isolated together with two major saponins Mi-saponin A (4) and Mi-saponin B (5) from the seed kernels of Madhuca longifolia (L.) MACBRIDE (Sapotaceae), has been investigated. On the basis of chemical and physicochemical evidence, the structure of Mi-saponin C has been established as 3-O-β-D-glucopyranosyl-28-O-{[3-O-α-L-rhamnopyranosyl-4-O-β-D-glucopyranosyl]-β-D-xylopyranosyl (1→4)-α-L-rhamnopyranosyl (1→2)-α-L-arabino-pyranosyl}-protobassic acid (10). Mi-saponin A (4), B (5), and C (10) are bisdesmosides of an olean-12-ene-type sapogenol protobassic acid (1).