Optimization of acid hydrolysis of myricetin-3-o-rhamnoside using response surface methodology

Abstract

This study aimed to optimize the acid hydrolysis of glycosylated flavonols, to apply the optimum conditions for hydrolyzing Inga edulis extract (IEE), rich in glycosylated flavonols, and evaluating its impact on the antioxidant capacity. To evaluate the influence of three independent variables on the aglycone obtained after the reaction, the response surface methodology was applied using myricetin-3-O-rhamnoside (M3R) as a pure compound. The phenolic compound profile and antioxidant capacity were determined by high-performance liquid chromatography (HPLC) and the Trolox-equivalent antioxidant capacity (TEAC) assay, respectively. The maximum content of the aglycone myricetin (81.15%) occurred with 2.5 M HCl at 75 °C for 60 min. Under these conditions, the IEE produced the aglycones myricetin, quercetin and cyanidin. The TEAC values of the M3R samples and IEE before and after acid hydrolysis did not show significant differences (p > 0.05). These results suggest that the hydrolytic process is effective to produce aglycone flavonoids from leaf extracts of I. edulis, and probably for other plant extracts rich in M3R.