# Antioxidant Activity, Inhibition of Intestinal Cancer Cell Growth and Polyphenolic Compounds of the Seagrass Posidonia oceanica’s Extracts from Living Plants and Beach Casts

## TL;DR

This study explores how extracts from the seagrass Posidonia oceanica, both from living plants and beach casts, can inhibit cancer cell growth and have antioxidant properties.

## Contribution

The study identifies specific polyphenolic compounds in Posidonia oceanica and demonstrates their antiproliferative effects on intestinal cancer cells.

## Key findings

- Living leaves of Posidonia oceanica contain high levels of polyphenolic compounds like chicoric acid and rutin hydrate.
- Extracts from Posidonia oceanica inhibit intestinal cancer cell proliferation.
- Both living leaves and beach casts of Posidonia oceanica show antioxidant and antiproliferative activities, though with varying efficacy.

## Abstract

The aim of the present study was to investigate the use of Posidonia oceanica for making products beneficial for human health. Firstly, we demonstrated that the antioxidant defense (i.e., SOD and APX activity) of P. oceanica’s living leaves (LP) has low efficacy, as they partly neutralize the produced H2O2. However, high H2O2 levels led LP to produce, as a response to oxidative stress, high phenolic content, including chicoric acid, p-coumaric acid, caftaric acid, trans-cinnamic and rutin hydrate, as shown by UHPLC-DAD analysis. In addition, LP extracts inhibited intestinal cancer cell proliferation. Moreover, P. oceanica’s beach casts consisting of either Wet ‘Necromass’ (WNP) or Dry ‘Necromass’ (DNP) were used for preparing extracts. Both DNP and WNP exhibited antioxidant and antiproliferative activities, although lower as compared to those of LP extracts. Although both P. oceanica’s meadows and beach casts are considered priority habitats in the Mediterranean Sea due to their high ecological value, legislation framework for beach casts forbidding their removal is still missing. Our results suggested that both LP and DNP could be utilized for the production of high-added value products promoting human health, provided that a sustainability management strategy would be applied for P. oceanica’s meadows and beach casts.