Triterpenes degradation products

The third and in many ways most creative phase of George Buchi s career had its roots in his doctoral work at ETH, where he had undertaken the synthesis of degradation products of certain triterpenes. Synthetic studies on natural products has always flourished in George s laboratory at MIT, but with his growing interest in complex alkaloid came the opportunity to ex-... 

Collagenase production and release are partly responsible for the joint destruction that characterises human rheumatoid arthritis. Triterpenes from the lupane and a-amyrin groups have been studied in vitro to examine their effects on the release of the arthritic joint degradative enzyme collagenase using the rat osteosarcoma. This test and the rat synovial granuloma of adjuvant arthritis are similar both models are based on connective tissue tumours with bone-invasive properties. The pentacyclic triterpenes assayed have been shown to possess general antiproteolytic effects that can explain the anti-arthritic effects in adjuvant arthritis in rats [71,103]. 

Quassinoids are natural products formed by oxidative degradation of triterpene derivatives their biosynthetic precursors are similar to those of limonoids but the biosynthetic pathways of quassinoids have not been established so far [1]. At least 351 different natural quassinoids have been described in the literature (Fig. 125.1), and a large number of semisynthetic and synthetic analogues have been prepared for synthesis or medicinal chemistry purposes, mostly in last 30 years [see, for example, 2-4]. Several base skeletons have been described in the literature, and these can be classified into five distinct groups according to the number of atoms of the main chain (Fig. 125.1). 

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