Ultrasound-assisted intensified aqueous extraction of phenolics from waste Syzygium cumini leaves: Kinetic studies and evaluation of antioxidant, antidiabetic and anticancer potential

Abstract

This is the first report illustrating the extraction of total phenolic compounds (TPC) using the ultrasound-assisted aqueous extraction (USAE) technique from waste Syzygium cumini leaves (WSCL). A kinetic study indicated that Peleg's model was appropriately fitted to the experimental data when the effect of different parameters was checked on extraction with respect to time. Extraction yields of total phenolic contents (TPC) and total flavonoid contents (TFC) were 78.38 mg GAE/g, and 10.15 mg CE/g, respectively, at optimized parameters of 1:25 WSCL: water, 35 °C temperature, 134 W power, 50% duty cycle and in 9 min of sonication time. Cumulative yields of TPC and TFC obtained by 5 sequential stirred batch extraction were 79.36 mg GAE/g and 10 mg CE/g, respectively. The cost and energy requirement of the USAE process was around 3000 times less than that of the Soxhlet technique. SEM images showed the changes in the morphology of the WSCL surface area before and after ultrasonic extraction. FTIR analysis showed the presence of O-H, N-H, C-H, C=C, and halogenated functional groups. The obtained WSCL extract showed antioxidant potential with an IC50 value of 15.64 μg/mL. IC50 values of extract for α-amylase and α-glucosidase inhibitions were 8.3 and 6.64 μg/mL. Antiproliferation activity against breast, cervical, and lung cancer showed the potential with GI50 values 252.8, 112.5, and 97.8 μg/mL, respectively. Aqueous extract of Syzygium cumini leaves can be used to treat oxidative stress, diabetes, and cancer.