Antioxidant, Total Phenol and Flavonoid Contents of Two Pedicularis L. Species from Eastern Azerbaijan, Iran

Abstract

Introduction: Pedicularis sibthorpii and P. wilhelmsiana are endemic species mainly found in North-West of Iran. Plants of genus Pedicularis produce some important polyphenols and flavonoids. In the present work, total phenol and flavonoid contents of the mentioned species as well as their antioxidant capacity have been evaluated. Methods:  Methanol extract of samples was fractionated by SPE method using an ODS cartridge and their ¹H-NMR spectra were recorded. Total phenols and flavonoids of methanol extracts were determined using Folin- Ciocalteu and aluminum chloride methods. For determining antioxidant activity of the extracts and fractions, bleaching of purple colour methanol solution of 1, 1-diphenylpycryl hydrazyl (DPPH) was measured by spectrophotometric assay. Results: Total phenols of Pedicularis sibthorpii and P. wilhelmsiana were in the range of 8-30 mg g^-1 and 9-20 mg g-1, respectively. The 40% and 60% fractions of P.sibthorpii and the 20%, 40% and 60% fractions of P. wilhelmsiana showed higher amounts of phenolic compounds. The total flavonoid contents of P. sibthorpii and P. wilhelmsiana were in the range of 0-215 mg g^-1 and 0-177 mg g^-1, respectively, whereas the 40% and 60% fractions showed higher flavonoid amounts. Antioxidant activity of P. sibthorpii and P. wilhelmsiana were in the range of 0.01-0.7 mg mL^-1 and 0.01-1.02 mg mL^-1. In the same manner, the 20% and 40% fractions of P. sibthorpii and the 40% and 60% fractions of P. wilhelmsiana had lower RC₅0 than that of other fractions. Conclusion:  Fractions with lower RC₅₀ had higher contents of phenolic and flavonoid compounds. The results of NMR spectra were parallel with these findings and show that it is worth to do phytochemical studies on P. sibthorpii and P. wilhelmsiana.

Keywords: Pedicularis sibthorpii, Pedicularis wilhelmsiana, Antioxidants, Polyphenols, Polyphenols