Evaluation of anthocyanins extraction from Gynura crepioides Benth. using conventional method

Gynura crepioides is one of the natural resources of flavonoid compounds, including anthocyanins (ACs). The anthocyanins, extracted from the leaves of G. crepioides, provide a lot of nutritional values to human and preferred in most of the food industries as a natural colourant. Limited studies have been reported on the determination of parameters for the solid-liquid extraction process and the kinetic study in ensuring its efficient performance. In this present study, freeze drying method is recommended prior to extraction to ensure high recovery of useful bioactive compounds for later use. The chemical characteristics of the G. crepioides leaves are studied using proximate analysis. Next, investigations were done to determine the effect of various extraction parameters in order to achieve high anthocyanins yield from the leaves by using the conventional solid-liquid extraction method. Those extraction parameters included the effect of solvent selection, solvent volume, methanol to aqueous HCl ratio, HCl concentration, extraction temperature, and time. The highest yield of ACs from the freeze dried leaves of G. crepioides with the use of the conventional solid-liquid extraction method was 25.89 0.50 mg/L that extracted at 50 for 15 minutes by using acidified methanol. The kinetics of extraction is also studied and the data observed corresponded well to second-order reaction. The activation energy is calculated as 18.45 kJ mol-1, which is an indication of an endothermic process. The highest initial extraction rate is observed as 16.64 mg L-1 min-1 at 333K. The extract of the leaves was subjected to DPPH scavenging activity and cytotoxicity tests. Lastly, the extract of leaves, with the presence of anthocyanins, shows a good DPPH scavenging activity and cytotoxicity. The findings suggest that extract of G. crepioides is a valuable anthocyanins sources that maybe beneficial to the industry.