Three New Cholestane Bisdesmosides from Nolina recurvata Stems and Their Inhibitory Activity on cAMP Phosphodiesterase and Na⁺/K⁺ ATPase

Abstract

Fresh stems of Nolina recurvata were found to contain three new cholestane bisdesmosides. Their structures were determined on the basis of spectroscopic data and acid-catalyzed hydrolysis to be (22S)-cholest-5-ene-1β, 3β, 16β, 22-tetrol 1-O-β-D-glucopyranoside 16-O-α-L-rhamnopyranoside (1), (22S)-cholest-5-ene-1β, 3β, 16β, 22-tetrol 1, 16-di-O-β-D-glucopyranoside (2) and (22S)-cholest-5-ene-1β, 3β, 16β, 22-tetrol 1-O-{O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside} 16-O-α-L-rhamnopyranoside (3), respectively. The prominent downfield shift of the aglycone 19-Me of 3, compared with that of 1 and 2, is likely caused by the interaction between the 19-Me and 6'''-Me of the rhamnose attached to C-2 of the inner glucose, evidence for which was provided through molecular mechanics and molecular dynamics calculation studies and by the nuclear Overhauser effect (NOE) correlation spectrum. The isolated compounds and their derivatives were evaluated for their inhibitory activity on cAMP phosphodiesterase and Na⁺/K⁺ ATPase.