EXTRACTION OF FREE AND BOUND POLYPHENOLS FROM BRANS OF SORGHUM BICOLOR USING DIFFERENT SOLVENTS

Abstract

Sorghum is a drought tolerant, gluten–free cereal, which is known for the abundance of polyphenol compounds, including flavonoids. It is proved that these compounds have important health benefits as antioxidants and anti–inflammatory agents. They are found in seed walls in a free form or in a bound, esterified form, which affects their digestion and utilization. The main purpose of this research was to evaluate the ratio of free and bound polyphenols in sorghum brans extracted with different solvents, and see how the extraction step can influence the physiology importance of a sorghum extract. Solvents had significant effects on the polyphenol and flavonoid content of free polyphenol extracts, but there was not any difference in terms of their antioxidant activities. In case of bound fractions from different extractions, there were significant differences in all parameters, except for the flavonoid content. Correlation analysis showed strong connection between parameters, and there were differences in correlation between extraction. Among the two varieties, Alföldi1 had significantly higher content of total phenol, flavonoid and higher values of antioxidant capacity as well compared to Zádor in both extractions. In this research only the effect of the extraction solvent was evaluated, but further investigation is necessary to specify more extraction factors. This research aimed to emphasize the importance of extractant selection in determination of bioactive compounds from plants. Our results highlights that selecting the proper extractant is essential for determination of total polyphenolic content, however, the analysis if antioxidant power is not sensitive for extraction agents.