RESUMO
BACKGROUND: Echinacea is composed of three major groups of compounds that are thought to be responsible for stimulation of the immune system--the caffeic acid conjugates, alkylamides and polysaccharides. This study has focussed on the former two classes, as these are the constituents found in ethanolic liquid extracts. OBJECTIVE: To investigate the absorption of these two groups of compounds using Caco-2 monolayers, which are a model of the intestinal epithelial barrier. RESULTS: The caffeic acid conjugates (caftaric acid, echinacoside and cichoric acid) permeated poorly through the Caco-2 monolayers although one potential metabolite, cinnamic acid, diffused readily with an apparent permeability (Papp) of 1 x 10(-4) cm/s. Alkylamides were found to diffuse through Caco-2 monolayers with Papp ranging from 3 x 10(-6) to 3 x 10(-4) cm/s. This diversity in Papp for the different alkylamides correlates to structural variations, with saturation and N-terminal methylation contributing to decreases in Papp. The transport of the alkylamides is not affected by the presence of other constituents and the results for synthetic alkylamides were in line with those for the alkylamides in the echinacea preparation. CONCLUSION: Alkylamides but not caffeic acid conjugates are likely to cross the intestinal barrier.
Assuntos
Amidas/farmacocinética , Ácidos Cafeicos/farmacocinética , Echinacea/química , Amidas/química , Transporte Biológico , Células CACO-2 , Ácidos Cafeicos/química , Permeabilidade da Membrana Celular , Humanos , Extratos Vegetais/farmacocinéticaRESUMO
[figure: see text] In a number of Bactrocera species the penultimate step in the biosynthesis of spiroacetals is shown to be the hydroxylation of an alkyltetrahydropyranol followed by cyclization. The monooxygenases that catalyze this side chain hydroxylation show a strong preference for oxidation four carbons from the hemiketal center, to produce the spiroacetal. The hydroxy spiroacetals observed in Bactrocera appear to derive from direct oxidation of the parent spiroacetals and not from alternate precursors.
