Cymodocea nodosa, growing at low water depth, is affected by various environmental changes and is expected to adapt to oxidative stress. Oxidative stress in living leaves (LC) and beach deposits (NC) of C. nodosa activated superoxide dismutase (SOD), which was higher in LC, leading to significant neutralization of the produced H2O2 and destruction of protein generation. Higher antioxidant capacity (using a UV/Vis spectrophotometer) to scavenge 2.2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS•+) (IC50: 5 in LC vs. 22 μg mL−1 in NC) and OH• (hydroxyl) radicals (IC50: 132 in LC vs. 281.7 μg mL−1 in NC), compared to 2,2-diphenyl-1-picrylhydrazyl (DPPH•) (IC50: 63 in LC vs. 45 μg mL−1 in NC) and superoxide anion (O2•−) radicals (IC50: 190 in LC vs. 94 μg mL−1 in NC), and similar reducing power (RP) were recorded in LC compared with NC extracts (IC50: 53 in LC vs. 52 μg ml−1 in NC). Phenolic compounds were not significantly lost during plant exposure on shores (mean value: 57.00 in LC vs. 45.48 mg g−1 d.w. in NC). Phenolic compounds identified, using UHPLC-DAD analysis, in both LC and NC extracts were chicoric, trans-ferulic, caftaric, p-coumaric, sinapic, and trans-cinnamic acid and rutin hydrate, whereas caffeic acid, in traces, was identified in NC extracts. NC showed higher cytotoxic activity in inhibiting LS 174 colon cancer cells than LC. In cases of plant cultivation or management plans for seagrass meadows and their beach deposits, with the least possible impacts, both LC and NC extracts could be exploited for their antioxidant and anticancer properties. In a ‘case study’, the amounts of individual phenolic compounds that can be produced from NC utilization were estimated.
Kevrekidou et al. (2026) studied this question.