绞股蓝中6种多酚化合物的HPLC检测及其醇提液的抗氧化活性

采用高效液相色谱法分析野生(5叶、7叶和9叶3种生态类型)和人工种植(7叶)绞股蓝的叶及茎中6种多酚化合物的含量,并测定样品醇提液的总多酚含量及抗氧化活性。结果表明:色谱条件为色谱柱poroshell120 PFP(4.6 mm×100 mm,2.7μm),流动相1%甲酸(A)和乙腈(B),检测波长254 nm和350 nm,在此条件下绞股蓝样品中6种多酚单体可在35 min内得到较好分离,且重复性好(相对标准偏差(relative standard deviation,RSD)≤4.6%)、精密度高(RSD≤2.68%)、稳定性好(RSD≤2.45%)、加标回收结果准确可靠(平均回收率84%~99%,RSD≤4.02%)。6种多酚单体在不同的绞股蓝样品中含量差异较大,但均呈现出芦丁含量最高,对羟基苯甲酸含量最低。绞股蓝样品醇提液中总多酚及抗氧化活性在不同样品间差异较大,在野生绞股蓝(7叶)叶中最高(分别为75、39.65、70.48 mg/g),在其茎中最低(分别为2.81、2.1、3.7 mg/g)。总体而言,绞股蓝的叶中总多酚含量高于茎中,醇提液的抗氧化活性也强于茎。

Phenolic Contents and Antioxidant Activity in Methanol Extracts from Gynostemma pentaphyllum (Thumb.) Makino

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.