Optimization of ultrasound-assisted extraction method of Syzygium cumini leaves based on extraction yield, content of bioactive compound, and inhibition of dipeptidyl peptidase IV enzyme activity using response surface methodology

Abstract

Syzygium cumini leaves show potential to be developed as herbal medicine products against diabetes mellitus due to their high polyphenol contents. S. cumini was optimized using response surface methodology and Box–Behnken design with solvent solid ratio, solvent concentration, time and temperature, extraction yield, total flavonoid content (TFC), total phenolic content (TPC), and dipeptidyl peptidase IV (DPP-IV) enzyme inhibitory activity to obtain an effective and optimal extraction method. The conditions were achieved using a 70% ethanol solvent for the extraction, with a solvent–solid ratio of 21 v/w and run at 20°C for 30 min. The results showed an extraction yield of 83.875%, with TFCs measuring at 3.068 mg QE/g, TPCs of 65.029 mg GAE/g, and DPP-IV enzyme inhibition activity of 66.079%. Further analysis of the phytochemical profile using untargeted liquid chromatography-high-resolution mass spectrometry showed the presence of amine, amide, and fatty acid derivatives as major constituents. In addition, major flavonoids observed were myricetin and myricitrin, accounting for 0.2%. Ursolic acid and 25-azacholesterol accounted for 1.03% of the phenolics detected.