Abstract

Antioxidant activity of 19 different mixed herbal infusion as it was calculated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays was correlated using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and chemometrics. The spectral region 1538- 843 cm-1 in 2nd derivative mode and the partial least squares (PLS) regression were used. The correlation coefficient, the root-mean-square error of calibration (RMSEC) and the root-mean-square error of prediction (RMSEP) for the DPPH assay were 0.97, 130 and 118 respectively. The corresponding values for the ABTS assay were 0.99, 148 and 121. The above results show that it is possible to estimate the antioxidant activity according to DPPH and ABTS assays of different mixed herbal infusions using ATR-FTIR spectroscopy. Furthermore the proposed methods are simple, rapid and economical.

Key words: Antioxidant activity; ATR-FTIR; chemometrics; herbal infusions; PLS