Phenolic fingerprints of the Pacific seagrass Phyllospadixtorreyi - Structural characterization and quantification of undescribed flavonoid sulfates

Abstract

Four undescribed flavonoid sulfates were isolated from Phyllospadix torreyi S. Watson foliar tissue. In addition, nine known flavonoid sulfates and three phenolic acids were isolated from the same extract, of which seven had never been reported for the genus Phyllospadix. Structural elucidation of individual phenolics was assigned using complementary informations from their spectral evidence (HPLC-DAD, LC-MS, NMR, and UV) and chemical behavior. The inter-annual variation in phenolic concentrations was determined by quantitative HPLC-DAD over a three-year period. The results showed a relative constancy of phenolic content over time and the high prevalence of flavonoid disulfates (70–90% of the total flavonoids detected). All samples were found dominated by the unreported nepetin 7, 3′-disulfate and 5-methoxyluteolin 7, 3′-disulfate, followed by luteolin 7, 3′-disulfate. Considering the economic potential of flavonoid sulfates in the pharmaceutical and nutraceutical segments, a sample of detrital leaves was also analyzed. The same phenolic pattern was found and the concentration of the individuals, although lower than in fresh material, makes this abundant biomass of interest for dietary and pharmaceutical applications.