Determination of Phenolics and Biological Activity of Viola dalatensis Gagnep. by High-Performance Liquid Chromatography (HPLC) and Multivariate Analysis.

Viola dalatensis, belonging to the Violaceae family, is an endemic species to Vietnam. The present study aimed to determine phenolic compounds in extracts from aerial parts of the plant species using high performance liquid chromatography with diode-array detection (HPLC-DAD). In addition, free radical scavenging and bovine albumin denaturation inhibition assays were performed to evaluate the antioxidant and in vitro anti-inflammatory activities of the extracts. Most of the phenolic compounds in the methanolic extract were detected at the greatest concentrations compared to the other extracts, which was also supported by the highest total phenolic content (26.70 ± 0.1059 mg GAE/g). In general, the antioxidant activities of the methanolic and ethanolic extracts were found to be stronger than those of the other extracts. The aqueous extract exhibited the most potent inhibitory effect on albumin denaturation (IC50 = 90.39 ± 8.415 µg/mL), comparable with that of diclofenac. Through principal component analysis, 88.60% of the total variance in the phenolic dataset was explained. The correlation analysis showed that chlorogenic acid, ferulic acid, epigallocatechin gallate, rutin, and kaempferol may play important roles in antioxidant activity while gallic acid could contribute to in vitro anti-inflammatory activity of the extracts. The findings of this study provide the first evidence of the bioactive compounds present in V. dalatensis and shed light on the potential health-promoting properties linked to its aerial parts. [ABSTRACT FROM AUTHOR]