RESUMO

There are relatively few studies concerning the use of coffee leaves for medicinal purposes and the composition of secondary plant substances. Therefore, we identified and quantitated polyphenolic compounds along with caffeine present in methanol extracts of Coffea arabica leaves from three different regions of Brazil (Ceará, Minas Gerais and São Paulo) by HPLC-ESI-MS. In addition, correlations between polyphenolic content of the coffee leaves and antioxidant assays DPPH, FRAP and ORAC were evaluated. Fifteen compounds belonging to three classes of polyphenols (xanthones, chlorogenic acids and flavonoids) along with the alkaloid caffeine were detected. The mean concentration of total polyphenolic compounds in the leaves of C. arabica, harvested from three different regions of Brazil was quite variable. The highest values were detected in the coffee leaves harvested in Minas Gerais (n = 4) at 40.80(13.00) g/kg (SD), followed by coffee leaves harvested in São Paulo (n = 20) at 24.79(20.19) g/kg, and the lowest in coffee leaves harvested in Ceará (n = 11) in the Northeast of Brazil at 10.30(5.61) g/kg. The three classes of polyphenols, all showed excellent correlations in the antioxidant assays. Coffee leaf tea, appears to be an excellent functional beverage, with its high content of polyphenolic compounds, which may render positive biologic effects, when inbibed as part of the normal human diet.

Assuntos

Cafeína/análise , Coffea/química , Suplementos Nutricionais , Flavonoides/análise , Folhas de Planta/química , Xantonas/análise , Antioxidantes/análise , Brasil , Ácido Clorogênico/análise , Cromatografia Líquida de Alta Pressão , Café/química , Extratos Vegetais/análise , Polifenóis/análise

RESUMO

Advanced glycation end products (AGEs) represent a set of molecules that contribute directly to the initiation and aggravation of diseases associated with ageing. AGEs are produced by the reaction between reducing sugars (or α-dicarbonyl compounds), proteins, and amino acid residues. Previous in vitro methods using non-enzymatic procedures described in the literature require an incubation period of 1⁻3 weeks to generate AGEs. In this study, the reaction time for the formation of AGEs (48 and 3 h) was significantly reduced by adaptation of methods previously described in the literature and coupling them to the free radical generation system termed hypoxanthine/xanthine oxidase assay. The incorporation of this assay into the experimental system accelerated the production of AGEs as a result of the formation of reactive oxygen species (ROS), as shown by increased fluorescence. The capacity of different classes of chemical compounds (aminoguanidine, chlorogenic acid, rutin, and methanol extracts of Hancornia speciosa Gomes) to inhibit protein glycation by acting as scavenging agents of α-dicarbonyl species was evaluated. Aminoguanidine and, especially, rutin identified in the leaf extracts of H. speciosa Gomes showed a high capacity to act as scavengers of reactive carbonyl species RCS-trapping, resulting in the inhibition of AGEs formation.