Characterization of Polyphenolic Content in the Aquatic Plants Ruppia cirrhosa and Ruppia maritima -A Source of Nutritional Natural Products.

Herein, the polyphenolic content in extracts of (Petagna) Grande and L.was fully characterized for the first time. High amounts of the main compound chicoric acid () (≤30.2 ± 4.3 mg/g) were found in both species. In addition, eight flavonoids, namely the 3--glucopyranosides and 3--galactopyranosides, as well as malonylated 3--glycosides of quercetin and isorhamnetin, were isolated and identified. The antioxidant activity of extracts and isolated compounds was investigated spectrophotometrically by a 1,1-diphenyl-2-picrylhydrazyl (DPPH·) radical scavenging assay. IC values were 31.8-175.7 μg/mL for extracts and 12.1-88.4 μg/mL for isolated flavonoids. Both individual and total phenolic and flavonoid content were quantified in crude extracts using analytical HPLC. The relative high amount of total flavonoids ranged from 5.9 to 14.7 mg/g in both species, with concentrations of individual flavonoids ranging from 0.4 to 2.9 mg/g dry weight. The content of chicoric acid was twofold more in than in . Seasonal variation of the quantitative content in was examined. Total flavonoid content ranged from 8.4 mg/g in October to 14.7 mg/g in August, whereas the highest concentration of chicoric acid was observed in March (29.2 mg/g).