Iridoids from Crescentia alata.

Four new 11-nor-iridoids, 6beta,7beta,8alpha,10-tetrahydroxy-cis-2-oxabicyclo[4.3.0]nonan-3-one (1), 6beta,7beta,8alpha,10-tetra-p-hydroxybenzoyl-cis-2-oxabicyclo[4.3.0]nonan-3-one (2), 1beta,6beta,7alpha,8alpha,10-pentahydroxy-cis-2-oxabicyclo[4.3.0]nonane (3), and 6beta-hydroxy-2-oxabicyclo[4.3.0]Delta8-9-nonen-1-one (4), were isolated from the pulp of the fruits of Crescentia alata. Although a limited number of Crescentia species have been studied chemically, iridoids lacking C-11 have been isolated from the fruits of these species, and the isolation of compounds 1-4 from C. alata is in accordance with the constituents of the species previously analyzed. The structures of these compounds were established on the basis of IR, UV, 1H and 13C NMR, DEPT, COSY, HSQC, HMBC, MS, and X-ray data.