F. Martins, I. Camps, A. Doriguetto
Jul 1, 2008
Citations
1
Influential Citations
12
Citations
Journal
Helvetica Chimica Acta
Abstract
c ) a Garciniaphenone (¼ rel-(1R,5R,7R)-3-benzoyl-4-hydroxy-8,8-dimethyl-1,7-bis(3-methylbut-2-en-1- yl)bicyclo(3.3.1)non-3-ene-2,9-dione; 1), a novel natural product, was isolated from a hexane extract of Garcinia brasiliensis fruits. The crystal structure of 1 as well as the selected geometrical and configurational features were compared with those of known related polyprenylated benzophenones. Garciniaphenone is the first representative of polyprenylated benzophenones without a prenyl substituent at C(5). Notably, the absence of a 5-prenyl substituent has an impact on the molecular geometry. The tautomeric form of 1 in the solid state was readily established by a residual-electronic- density map generated by means of a difference Fourier analysis, and there is an entirely delocalized six- membered chelate ring encompassing the keto - enol moiety. The configuration at C(7) was used to rationalize the nature of the keto - enol tautomeric form within 1. The intermolecular array in the network is maintained by nonclassical intermolecular H-bonds. Introduction. - Garcinia brasiliensis (Mart.) Planch. and Triana , (Syn. Rheedia brasiliensis), commonly known as BbacupariC, is used in Brazil as traditional medicine for the treatment of urinary diseases and several types of tumors (1). Garcinia or Rheedia is the most abundant genus of the Guttiferae family, and it is known to be rich in oxygenated and prenylated phenol derivatives (2), including xanthones (3), flavonoids (4), phenolic acids (5), and benzophenones (6). Previous researchers have reported the presence of various biflavonoids including volkensiflavone and fukugetina (7), as well as of prenylated xanthones in MeOH extracts of G. brasiliensis roots (2). Polyprenylated benzophenones are biologically active compounds and common metabolites from the Guttiferae family. Some of them, as for instance guttiferone A (¼ rel-(1R,5R,7R,8S)-3-(3,4-dihydroxybenzoyl)-4-hydroxy-8-methyl-1,5,7-tris(3-meth- ylbut-2-en-1-yl)-8-(4-methylpent-3-en-1-yl)bicyclo(3.3.1)non-3-ene-2,9-dione), were isolated from Symphonia globulifera, Garcinia livingstonei, Garcinia ovalifolia, and Clusia rosea as HIV-inhibitory compounds (8). Consequently, numerous studies have screened such substances to uncover a range of pharmacological properties in various biological systems. As a result, it is agreed that polyprenylated benzophenones also possess radical-scavenging properties, inhibit iNOS and COX-2 expression in colon carcinoma, induce apoptosis, and can act as antiulcer, antioxidant, trypanocidal (9 - 13), anti-inflammatory (14), and antitumoral agents (15). Another natural polyprenylated