Optimization, extraction, structure analysis and antioxidant properties of flavan-3-ol polymers: Proanthocyanidins isolated from Periploca angustifolia using surface response methodology

Periploca angustifolia roots condensed tannins (PATF) have been reported to have a various biological activities. In addition, response surface methodology was used to optimize the hot extraction parameters for condensed tannins from this plant. Through the analysis, temperature, pH and water-solid ratio were found to be the most important parameters. For this analysis, optimum conditions maximizing condensed tannins yield (35.62 %) were found to be temperature 80 degrees C, pH (9.5) and water/solid ratio 10:1 ml/g. Furthermore, analysis of PATF by HPLC, Fourier-Transform Infrared (FTIR) and 1D and 2D NMR Spectroscopy allowed the identification of two condensed tannins as catechin and epicatechin gallate. Moreover, Periploca angustifolia condensed tannins exhibited high total reducing power and considerable scavenging activities on DPPH, ABTS and NO radicals, in a concentration-dependent manner in vitro. Finally, PATF extract would be used as an important source of antioxidant activity.