Seasonal variation in the levels of the main phenolics in Copaifera langsdorffii leaves

The main phenolics found in Copaifera langsdorffii leaves (Fabaceae, Caesalpinioideae) are galloylquinic acids (GQAs) and flavonoids (Fs). To verify their variation according to seasons and climatic factors, for further standardization of plant raw material, leaf samples of 10 different populations of C. langsdorffii cultivated under the same conditions in Cajuru, SP, Brazil were collected monthly in 2012. Then, they were analyzed by HPLC-UV, using analytical method previously validated to quantify nine GQAs and two Fs. Climatic data for radiation rate (R), temperature (T), humidity (H), and pluviometric precipitation (P) were provided by the National Institute of Meteorology, Brazil. Multivariate analysis was performed to correlate climatic and chemical variables. RDA was carried out using the software CANOCO 4.5 (DCA gradient< 0.5, Monte Carlo analysis p < 0.05), and grouped C. langsdorffii populations by month and not by origin. The results of CDA followed by Jackknifed test (Percentage of correct classification = 100%), confirmed the clustering proposal for four distinct groups: I, May-Jul (negative correlation with R, T, and chemical variables – low levels of phenolics); II, Aug-Sep (negative correlation with P and H); III, Jan (positive correlation with R, T, and chemical variables, especially Fs); IV, Feb-Apr, and Oct-Dec (positive correlation with T, P, H, and chemical variables, especially in February – high levels of phenolics). On one hand, all 10 populations gave similar qualitative and quantitative chemical composition in a particular month, when cultivated under the same conditions; on the other hand, the seasonal variations played an important role on quantitative content of the analyzed phenolics. Therefore, a standardized extract may be produced independently of the chosen cultivated population.