Chemodiversity and bioactivity assessment of phlorotannins from some Phaeophyta species from the Red Sea

Abstract

AbstractPhlorotannins are a unique and diverse category of secondary polyphenolic metabolites biosynthesized by brown seaweeds. They have revealed a huge potential for food and medicinal applications. In this study, five brown seaweed species were investigated: Polycladia myrica, Sirophysalis trinodis, Dictyota spiralis, Sargassum euryphyllum, and Turbinaria decurrens. All seaweed species contained considerable amounts of phlorotannins with P. myrica recording the highest content (as mg PGEs g−1 DW), followed by S. euryphyllum and then S. trinodis. The presence of phlorotannins was detected using UV–Vis spectroscopy analysis in the characterized range of 280 nm to 300 nm. All species exhibited highly significant antioxidant activity using four different techniques compared to ascorbic acid. For antidiabetic activity, the maximum α-amylase and α-glucosidase activity inhibition were recorded for P. myrica (68.79 ± 0.7%; 66.73 ± 0.5%), followed by T. decurrens (66.38 ± 0.6%; 61.34 ± 0.4%) and then D. spiralis (65.99 ± 0.5%; 60.58 ± 0.4%) compared to the acarbose standard drug (73.76 ± 0.6%; 68.38 ± 0.6%), which nominated these extracts as candidates for antidiabetic drugs. Moreover, the obtained results showed effective anti-inflammatory arthritis effects, with the maximum activity value of 86.02 ± 1.3% recorded for S. euryphyllum, followed by D. spiralis (86.23 ± 1.1%), and then P. myrica (85.94 ± 1.4%). On the other side, a low inhibition percentage of acetyl cholinesterase (AChE) activity was recorded for different phlorotannin extracts, indicating low potentiality as anti-alzheimer materials. Moreover, the P. myrica phlorotannins’ extract showed no toxicity on the WISH normal cell line by using the MTT assay. The same extract comprised a variety of phlorotannins, viz fucophlorethol, fuhalol, and phlorethol compounds, as revealed by UPLC-MS/MS analysis. Graphical Abstract