This review, with 350 references, gives information on the chemical study of 234 naturally occurring tetraoxygenated xanthones in 12 families, 53 genus and 182 species of higher plants, and two which are described as fungal and lichen metabolites. The value of these groups of substances in connection with pharmacological activity and therapeutic use of some species is described. The structural formulas of 135 isolated compounds, and their distribution, are also given.

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Atherosclerosis can be defined as being a disease of coronary circulation. The present work evaluates the action of the naringenin, rutin, nicotinic acid, isolated and in association, on the metabolism of lipids. Cholesterol, cholesterol HDL, and triacylglycerols have been dosed after retreat of blood, following the administration of the compounds dissolved in propylene glycol by intraperitoneal route in doses of 5 mg kg-1 body wt. Results evidence that naringenin and nicotinic acid, isolated as well as their association with naringenin and nicotinic acid-rutin, present the largest percentual reduction of cholesterol. On the other hand, the best results for cholesterol-HDL have been obtained with naringenin, while rutin has shown the best triacylglycerols levels.

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The diterpene ent-kaur-16-en-19-oic acid (1) was identified as the trypanocidal component of the ethanolic extract from Mikania obtusata D. C. (Asteraceae). This compound presents an IC50 of 0.5 mg/ml (1.66 mM) against the trypomastigote blood form of the Trypanosoma cruzi, the causative agent of Chagas' disease (American trypanosomiasis).

The aim of this study was to examine the effects of 7-epiclusianone, a new prenylated benzophenone isolated from the plant Rheedia gardneriana, on some of the virulence properties of Streptococcus mutans associated with biofilm development and acidogenicity. The synthesis of glucans by glucosyltransferases B (GTF B) and C (GTF C) was markedly reduced by 7-epiclusianone showing more than 80% inhibition of enzymatic activity at a concentration of 100 microg mL(-1). Double-reciprocal analysis (Lineweaver-Burk plots) revealed that the inhibition of GTF B activity was noncompetitive (mixed) while GTF C was inhibited uncompetitively. The glycolytic pH drop by S. mutans cells was also disrupted by 7-epiclusianone without affecting the bacterial viability, an effect that can be attributed, in part, to inhibition of F-ATPase activity (61.1+/-3.0% inhibition at 100 microg mL(-1)). Furthermore, topical applications (1-min exposure, twice daily) of 7-epiclusianone (at 250 microg mL(-1)) disrupted biofilm formation and physiology. The biomass (dry-weight), extracellular insoluble polysaccharide concentration and acidogenicity of the biofilms were significantly reduced by the test agent (P<0.05). The data show that 7-epiclusianone disrupts the extracellular and intracellular sugar metabolism of S. mutans, and holds promise as a novel, naturally occurring compound to prevent biofilm-related oral diseases.

Vismia parviflora, planta da família Guttiferae, é uma espécie da tribo Vismeae encontrada na região de Ouro Preto MG. Dos extratos benzênico e etanólico dos galhos e etanólico dos frutos de um especimen desta planta, cromatografados em sílica gel, foram isolados sitosterol, ácido betulínico, lupeol, friedelina, β-friedelinol, ácido chiquímico, ácido 3,4-diidroxibenzóico, quercetina e as antraquinonas madagascina, ácido crisofânico, vismiaquinona-A e vismiaquinona-C, além das xantonas 1,7-diidroxixantona e 1,5-diidroxi-8-metoxixantona. Estas substâncias tiveram suas estruturas elucidadas com base nos seus dados espectrométricos de IV, UV, EM e RMN de 1 H e 13 C uni-(1D) e bidimensional-(2D).The stems and fruits of Vismia parviflora have been shown to contain sitosterol, betulinic acid, lupeol, friedelin, β-friedelinol, shikimic acid, 3,4-dihydroxybenzoic acid, quercetin, 1,7-dihydroxyxanthone, 1,5-dihydroxy-8-methoxyxanthone, madagascine, chrysophanic acid, vismiaquinone-A and its isomer vismiaquinone-C. The structures of these compounds have been elucidated by using spectroscopic data as MS, UV, IR, one-and two-dimensional NMR.

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