Application of Natural Deep Eutectic Solvents (NADES) for Sappan Wood (Caesalpinia sappan L.) extraction to test for inhibition of DPP IV activity

Abstract

Some natural deep eutectic solvents (NADES) can replace organic solvents that are toxic and harmful tothe environment. The main flavonoid in sappan wood (Caesalpinia sappan L.) is brazilin. The aims of this study were toextract brazilin from sappan wood by using NADES and to evaluate the effect of the extract on inhibition of dipeptidylpeptidase IV (DPP IV) activity. The selected NADES compositions used choline chloride and betaine as hydrogen bondacceptors (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 highperformance liquid chromatography (HPLC). Between selected NADES, betain–lactic acid gave the highest brazilincontent of 4.49 mg/g. This result was comparable to conventional methods by a reflux using 96% ethanol that gavebrazilin content of 5.43 mg/g. However, the reflux required 3 hours for three extraction cycle, while optimal extractionconditions by betain–lactic acid were 30 min. The sappan wood extract using choline chloride–lactic acid had a percentinhibition of 5.72% (2.03 ppm), and that using betaine–lactic acid had a percent inhibition of 7.74% (2.08 ppm) for DPPIV activity. These inhibitory activities were comparable to the brazilin standard which was 8.93% (2.2 ppm). Our resultsshowed that two NADES compositions could extract brazilin from sappan wood and it showed potential DPP IVinhibitory activity.