Validated ultra performance liquid chromatography method for simultaneous quantitative analysis of antioxidant compounds in the leaves of Persicaria barbata (L.) H. Hara var. barbata

Abstract

The optimized hydrolysis process of Persicaria barbata (L.) H. Hara var. barbata leaves produced two antioxidant compounds (gallic acid and quercetin) confirmed by their chromatographic fingerprints. A method for the simultaneous quantitative analysis of gallic acid and quercetin using ultra performance liquid chromatography (UPLC) was developed and validated. Good linearity ranges of gallic acid and quercetin were 0.22–8.56 μg/mL and 0.40–16.08 μg/mL, respectively. The repeatability and intermediate precision were acceptable with relative standard deviations of less than 5%. The mean recovery values of gallic acid and quercetin were 99% and 98%, respectively, suggesting acceptable accuracy. The contents of gallic acid and quercetin in P. barbata leaves collected from Sa Kaeo province, Thailand analyzed using the validated UPLC method were 1.90 ± 0.18 g/100 g of crude extract and 5.29 ± 1.20 g/100 g of crude extract, respectively. Based on its speed, precision, reliability and sensitivity, the proposed UPLC method is suitable for future routine analysis of the gallic acid and quercetin contents in P. barbata leaf raw material and its commercial products. Quercetin was isolated and its chemical structure confirmed using various chromatographic and spectroscopic techniques.