Abstract: A new high performance liquid chromatography (HPLC) method was used to analyze the contents of 6 selected phenolic compounds and total phenolics in the leaves and stems of wild (five-leaf, seven-leaf and nine-leaf) and cultivated (seven-leaf) Gynostemma pentaphyllum (Thumb.) Makino. The total phenolics and antioxidant activity of the methanol extracts of these plant samples were determined. The chromatographic column used was poroshell 120 PFP (4.6 mm × 100 mm, 2.7 μm) and the mobile phase was composed of 1% formic acid (A) and acetonitrile (B). The detection wavelengths were set at 254 and 350 nm. The results showed that the six phenolic compounds could be separated well within 35 min, with good repeatability (relative standard deviation (RSD) ≤ 4.6%), high precision (RSD ≤ 2.68%), good stability (RSD ≤ 2.45%) and reliable recovery (average recovery rate 84%–99%, RSD ≤ 4.02%). The contents of the phenolic compounds and total phenolics and antioxidant activities in G. pentaphyllum varied greatly among different varieties. For all the samples, rutin was the most dominant phenolic constituent whereas p-hydroxybenzoic acid was the least dominant one. Total phenols content and antioxidant activity were both highest in the leaves (respectively 75, 39.65, 70.48 mg/g) and lowest in the stems (respectively 2.81, 2.1, 3.7 mg/g) of wild G. pentaphyllum among the 8 samples. In general, the content of total phenols and antioxidant activity in the leaves were higher than in the stems of G. pentaphyllum.

Key words: G. pentaphyllum, phenolic compounds, total phenols, high performance liquid chromatography (HPLC), antioxidant activity