Quassinoids: Structural diversity, biological activity and synthetic studies

Abstract

Quassinoids are bitter constituents of Simaroubaceae and the secondary metabolites characteristic of this family. The generic term quassinoids arises from quassin, the name of the first structurally identified member of this class isolated from specimen Quassia amara. Quassinoids can be divided into distinct groups according to their basic skeletons C 18 , C 19 , C 20 , C 22 and C 25 . The chemistry and biogenesis of quassinoids have been reviewed several times. They remain exclusively of Simaroubaceous origin and biogenetically can be regarded as degraded triterpenoids and are almost certainly derived from tetracyclic triterpenes. Several quassinoids have been isolated and structurally elucidated and the majority of them have been biologically tested, including antifeedant, inseticidal, herbicidal, antiparasitic, antimalarial and anticancer activities. The interest in the chemistry of quassinoids has accelerated rapidly with the American National Cancer Institute finding in early1970s, showing that these compounds display marked antileukemic activity (e.g. bruceantin). Chemical modifications of biologically inactive quassinoids have been performed, attempting to yield active ones, either by esterification or conversion of glycosides to the corresponding aglycones. Many studies on semisynthesis of rings member, intermediates and total synthesis of the molecular backbones or same leads such as bruceantin have been published. This review covers the structural variations, biological activity and some quassinoids synthetics studies. © 2006 Elsevier B.V. All rights reserved.