Correlation between chromatographic fingerprint and antioxidant activity of Turnera diffusa (Damiana).

摘要

In the present contribution, the partial least squares (PLS) method was used to establish a correlation between the antioxidant activity (obtained by DPPH assay) and chromatographic profiles of TURNERA DIFFUSA extracts. Chromatograms were obtained using HPLC-DAD. A model was constructed using 40 samples with 2550 X variables corresponding to the responses obtained at different times; the Y variables consisted of experimental values of antioxidant activity of each extract (measured as EC). Prior to this analysis, alignment of chromatograms was performed based on consideration of seven high-intensity signals present in all samples. The PLS1 model was validated by cross-validations; its capacity was evaluated using correlation parameters R(2), root mean square error of calibration (RMSEC), and root mean square error of prediction (RMSEP). The best results were achieved with zero order chromatograms using five-point smoothing (R(2) = 0.96, RMSEC = 3.31, and RMSEP = 7.86). Under these conditions, the optimal number of components was five. The model was applied to the prediction of antioxidant activity of commercial products; no significant differences were found between the experimental and predicted antioxidant activities for 83 % of them.