OPTIMIZATION OF SOLVENT MIXTURES FOR EXTRACTION FROM BARK OF Schinus terebinthifolius BY A STATISTICAL MIXTURE-DESIGN TECHNIQUE AND DEVELOPMENT OF A UV-VIS SPECTROPHOTOMETRIC METHOD FOR ANALYSIS OF TOTAL POLYPHENOLS IN THE EXTRACT

A statistical mixture-design technique was used to study the effects of different solvents and their mixtures on the yield, total polyphenol content, and antioxidant capacity of the crude extracts from the bark of Schinus terebinthifolius Raddi (Anacardiaceae). The experimental results and their response-surface models showed that ternary mixtures with equal portions of all the three solvents (water, ethanol and acetone) were better than the binary mixtures in generating crude extracts with the highest yield (22.04 +/- 0.48%), total polyphenol content (29.39 +/- 0.39%), and antioxidant capacity (6.38 +/- 0.21). An analytical method was developed and validated for the determination of total polyphenols in the extracts. Optimal conditions for the various parameters in this analytical method, namely, the time for the chromophoric reaction to stabilize, wavelength of the absorption maxima to be monitored, the reference standard and the concentration of sodium carbonate were determined to be 5 min, 780 nm, pyrogallol, and 14.06% w v(-1), respectively. UV-Vis spectrophotometric monitoring of the reaction under these conditions proved the method to be linear, specific, precise, accurate, reproducible, robust, and easy to perform.