Degraded limonoids from Melia azedarach and biogenetic implications.

The roots of Melia azedarach yielded three new degraded limonoids: teracrylmelazolide A, melazolide A and teracrylmelazolide B, possessing a previously undescribed skeleton. The known pyroangolensolide, fraxinellone and its three derivatives, 30-hydroxyfraxinellone, 9 alpha- and 9 beta-hydroxyfraxinellone, were also isolated. Their stereochemisty was elucidated on the basis of spectral data and chemical reactions.