Determination of flavonols and phenolic acids in Puearia lobata (Kudzu) root by HPLC-PDA method

Abstract

Phenolic acids and derivatives of quercetin in Kudzu root were determined by high-performance liquid chromatography with diode array detector. The calibration curves were constructed using phenolic compounds standards (the coefficient of determination (R²) was 0.9990–0.9997 for phenolic acids and 0.9989–0.9994 for flavonols. respectively). Ethanol was the most efficient solvent in extracting flavonols and phenolic acids from dried Kudzu roots at the optimal extraction time 60 min. Due to acidic hydrolysis the content of free phenolic acids was increasing. The predominant phenolic acid in Kudzu root determined by HPLC-PDA method with hydrolysis digestion is p-hydrozybenzoic acid (39.57 ± 1.44 mg/g d.m.), next one was: p-coumaric acid (6.20 ± 0.11 mg/g d.m.), followed by ferulic acid (11.52 ± 0.21 mg/g d.m.).On the other hand, the highest content of flavonols was found for routine (6.13 ± 0.11 mg/g d.m.). The contents of the other flavonols in kudzu root are between 0.73 – 2.52 mg/g d.m. for Rh and Q.