Application of natural deep eutectic solvents (Nades) for sappan wood (caesalpinia sappan l.) extraction to test for inhibition of dpp iv activity

Some natural deep eutectic solvents (NADES) can replace organic solvents that are toxic and harmful to the environment. The main flavonoid in sappan wood (Caesalpinia sappan L.) is brazilin. The aims of this study were to extract brazilin from sappan wood by using NADES and to evaluate the effect of the extract on inhibition of dipeptidyl peptidase IV (DPP IV) activity. The selected NADES compositions used choline chloride and betaine as hydrogen bond acceptors (HBA) with glycerol, xylitol, sorbitol, lactic acid, malic acid, and citric acid as various hydrogen bond donors (HBD). Ultrasound-assisted NADES extraction of brazilin was performed, and the content was measured by high-performance liquid chromatography (HPLC). Between selected NADES, betain–lactic acid gave the highest brazilin content of 4.49 mg/g. This result was comparable to conventional methods by a reflux using 96% ethanol that gave brazilin content of 5.43 mg/g. However, the reflux required 3 hours for three extraction cycle, while optimal extraction conditions by betain–lactic acid were 30 min. The sappan wood extract using choline chloride–lactic acid had a percent inhibition of 5.72% (2.03 ppm), and that using betaine–lactic acid had a percent inhibition of 7.74% (2.08 ppm) for DPP IV activity. These inhibitory activities were comparable to the brazilin standard which was 8.93% (2.2 ppm). Our results showed that two NADES compositions could extract brazilin from sappan wood and it showed potential DPP IV inhibitory activity.