Profiling of phenolic compounds and antioxidant activities of Cissus rotundifolia (Forssk.) as influenced by ultrasonic-assisted extraction conditions

Cissus rotundifolia (Forssk.) is a wild plant belongs to the Vitaceae family, containing high levels of minerals, vitamins and amino acids. It has been used as a traditional medicine for the treatment of several diseases. In this work, the effects of different ultrasound-assisted extraction parameters including solvent type and concentration, sonication time, power, temperature, and sample to solvent ratio on the total phenol compounds (TPC) and antioxidant activities of C. rotundifolia leaves extract were investigated. The leaves extract showed high phenolic compounds content and antioxidant activity. Under the optimal conditions (acetone as a solvent, with a concentration of 40%, sonication time of 40min, power of 150W, temperature of 40 degrees C, and sample to solvent ratio of 1:50w/v), TPC of 15.68 gallic acid equivalents/gram dry weight (g DW) was attained. Regarding the antioxidant activities, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azino-bis-(3-ethylbenzothioline-6-sulphonic acid)-di-ammonium salt (ABTS) were 59.35% and 20.34mg Trolox/g DW, respectively. There was a significant correlation between TPC, DPPH, and ABTS with the extraction conditions in particular solvent type and concentration. The scanning electron microscopy revealed that the ultrasound affected the walls of plant cells, and thus facilitated solvent penetration for phenolic compounds extraction. Liquid chromatography-mass spectrometry analysis showed that C. rotundifolia leaves extract contained various phenolic compounds characterized by their potential applications in several medical and pharmaceutical purposes.