Analysis of Polygonum Aviculare and Polygonum Maritimum for Minerals by Flame Atomic Absorption Spectrometry (FAAS), Polyphenolics by High-Performance Liquid Chromatography-Electrospray Ionization – Mass Spectrometry (HPLC-ESI-MS), and Antioxidant Properties by Spectrophotometry

Abstract

Polygonum aviculare and Polygonum maritimum, commonly known as knotgrass and sea knotgrass, have been widely used for several purposes. Leaves, stems, and roots of these species were evaluated for mineral composition, phytochemical contents, and antioxidant properties. The minerals were characterized by flame atomic absorption spectrometry (FAAS). The polyphenolics were investigated colorimetrically and by high-performance liquid chromatography-electrospray ionization – mass spectrometry (HPLC-ESI-MS). The antioxidant potential was evaluated by total antioxidant capacity (TAC), DPPH-radical scavenging activity, and reducing power (RPA). The mineral contents differed remarkably between and within species. For P. maritimum, the leaves showed the highest sodium, potassium, calcium, and magnesium contents while the roots accumulated the highest iron. The stems of P. aviculare contained higher Na, K, Ca and Fe compared to roots and leaves. P. maritimum extracts contained higher phytochemical contents compared to P. aviculare. The stems and leaves of P. maritimum were the richest in polyphenols and flavonoids while the roots possessed the highest condensed tannins. For P. aviculare, the stems contained the highest phenolics. HPLC-ESI-MS determined 20 phenolics including quinic acid, gallic acid, protocatechuic acid, (+)-catechin, quercetin-3-O-galactoside, and cirsiliol. P. maritimum extracts contained more antioxidants than P. aviculare. The results suggest that the selected species may be important sources of bioactive molecules.