Total coffee leaves samples phenolic content from different Brazilian States

The phenolic compounds are associated with several biological activities, among them antioxidant¹, antiprolifetarive², bactericidal3, anti-inflammatory4. Plants produce secondary metabolite for their own benefit that depends on the phenotype. The aim of this work was to evaluate the phenolic compounds content from Coffea arabica leaves ethanol extracts (70%) collected from the Brazilian States: São Paulo (SP), Minas Gerais (MG), Espírito Santo (ES), and Paraná (PR). The Total Phenolic content (TP) was spectrophotometrically determined by the modified Folin-Ciocalteu assay5,6. A calibration curve for the standard caffeic acid (5-100μg/ml) was used to obtain a correlation between sample absorbance and standard concentration, and total phenolic contents were expressed in terms of caffeic acid equivalent, CAE (standard curve equation: y = 153,79x - 4,5292, R² = 0,9877). The coffee extracts were evaluated in six concentrations (1000 - 31,25 µg/mL). In a 96 wells plate, 20 µl/mL (of sample, blank or standard) was mixed with 100 µl/mL of the Folin-Ciocalteu reagent (1:10) and 80 µl/mL of a sodium carbonate solution (7.5% m/v), in triplicate for each concentration. The mixture was incubated at 45 °C for 15 min, and after 30 min at 25°C, absorbance readings were performed at 765 nm, on a UV-Vis spectrophotometer. In decreasing order of concentration were MG sample with higher phenolic content (195 ± 12,03µg of CAE/mg), followed by PR harvest 1 (C1) (136,10 ± 4,82µg of CAE/mg), SP (134,75 ± 5,63µg of CAE/mg), ES (111,56 ± 3,46µg of CAE/mg) and the last PR harvest 2 (C2) (101,84 ± 2,43µg of CAE/mg). The phenolic compounds and others secondary metabolites of plant composition can be influenced by collection date, local, environmental or climatic conditions.7,8. Here in the TP of four different states harvested at the same month of the year, but at different stages of maturation is reported. The MG sample showed the highest component content. For Paraná we performed a collection during the fruit ripening (C1) and another during the fruit harvest (C2) verifying a variability of the phenolic compounds content. Further tests will be performed to characterize the ethanol extracts and verify the influence of the phenolic compounds concentration on biological activities.