Qualitative and Quantitative Analysis of Phenolics in Tetrastigma hemsleyanum and Their Antioxidant and Antiproliferative Activities

The phenolic profiles of Tetrastigma hemsleyanum leaf extracts by different solvents (80% methanol, ethyl acetate and hexane) and their antioxidant and antiproliferative activities were investigated. Thirteen phenolic compounds (3-caffeoylquinic acid, 5-caffeoylquinic acid, 1-caffeoylquinic acid, 5-p-coumaroylquinic acid, isoorientin-2″-O-rhamnoside, isoorientin, orientin-2″-O-rhamnoside, orientin, 1-p-coumaroylquinic acid, vitexin-2″-O-rhamnoside, isovitexin-2″-O-rhamnoside, vitexin and isovitexin) were identified in T. hemsleyanum leaves for the first time, and six of them were quantified using a combination of LC-QTOF-MS and LC-QqQ-MS techniques. It was found that 80% methanol extract exhibited the highest antioxidant activities (DPPH, 3.32 mmol of Trolox/g DW; ABTS, 1.38 mmol of Trolox/g DW; FRAP, 1.85 mmol of FeSO4/g DW), while the hexane extract had the lowest (1.23, 0.43 and 0.13, respectively). Total phenolic contents (TPC) of various extracts of T. hemsleyanum leaves ranged from 28.95 to 275.71 mg of GAE/g DW. Also, total antioxidant activities as evaluated by ABTS, FRAP and DPPH assays were correlated well with TPC. In addition, 80% methanol extract provided antiproliferative activity on HepG2 cells (IC50 = 524 μg/mL). This paper provides a complete picture of phenolics in T. hemsleyanum leaves and relates them to their antioxidant and antiproliferative activities.