Total Phenolics Levels and Antioxidant Properties in Methanol Extracts from Several Vietnamese Wild Plants

The aim of this study was to determine total phenolics (TP) content, total flavonoids (TF) level, and antioxidant activity of methanol extracts from leaf parts of 15 Vietnamese wild plants. TP content showed the highest amount in methanol extracts from Altenanthera sessilis ($409.7{\pm}1.4$ ppm), and followed by Eclipta prostrata ($183.6{\pm}3.8$ ppm) and Cassia tora ($159.3{\pm}5.7$ ppm). The highest TF level also was found in A. sessilis ($156.3{\pm}1.7$ ppm), followed by E. prostrata, and C. tora, showing similar tendency to TP. Methanol extracts of A. sessilis, E. prostrate and C. tora at 1000 ppm exhibited the highest DPPH radical scavenging activity by 94.5, 92.6 and 92.7%, respectively. The methanol extracts from A. sessilis showed the highest ABTS and nitrite scavenging activities by 97% and 92%, respectively. The highest correlation coefficient ($r^2$) was 0.9522 between TP and TF, and followed by 0.8919 between DPPH and ABTS activities. However, polyphenols and antioxidant activities showed low correlation coefficients, ranging from $r^2=0.4114$ to 0.4826. It was concluded that Vietnamese wild plants contain polyphenol compounds with antioxidant activities depending on plant species.