The Methionine 549 and Leucine 552 Residues of Friedelin Synthase from Are Important for Substrate Binding Specificity.

Friedelin, a pentacyclic triterpene found in the leaves of the Celastraceae species, demonstrates numerous biological activities and is a precursor of quinonemethide triterpenes, which are promising antitumoral agents. Friedelin is biosynthesized from the cyclization of 2,3-oxidosqualene, involving a series of rearrangements to form a ketone by deprotonation of the hydroxylated intermediate, without the aid of an oxidoreductase enzyme. Mutagenesis studies among oxidosqualene cyclases (OSCs) have demonstrated the influence of amino acid residues on rearrangements during substrate cyclization: loss of catalytic activity, stabilization, rearrangement control or specificity changing.

Crude leaf extracts of Piperaceae species downmodulate inflammatory responses by human monocytes.

In this study, we aimed to evaluate the immunomodulatory effects of crude leaf extracts from Piper gaudichaudianum Kunth, P. arboreum Aub., P.