# Structural Characterization and Anti-Inflammatory Properties of an Alginate Extracted from the Brown Seaweed Ericaria amentacea

## TL;DR

This study extracts and characterizes sodium alginate from a brown seaweed, showing it has strong anti-inflammatory and antioxidant properties suitable for biomedical use.

## Contribution

The novel contribution is the sustainable extraction and characterization of sodium alginate from Ericaria amentacea waste with demonstrated anti-inflammatory effects.

## Key findings

- Extracted sodium alginate has an M/G ratio of 2.33 and a molecular weight of 1 × 10⁴ g/mol.
- The alginate shows significant antioxidant and anti-inflammatory effects, including inhibition of iNOS gene expression in macrophages.

## Abstract

Brown algae of the Cystoseira genus are recognized as valuable sources of bioactive compounds, including polysaccharides. Within the framework of current restoration efforts regarding damaged Ericaria amentacea populations in the Mediterranean Sea, the valorization of apices derived from ex situ cultivation waste represents a sustainable opportunity for industrial and biomedical applications. In this study, sodium alginate (SA) was extracted from E. amentacea apex by-products using a hydrothermal–alkaline method and subsequently chemically characterized. FTIR analysis showed O-H, C-H, and COO- stretching compatible with commercial alginates, while 1H-NMR spectroscopy indicated high β-D-mannuronic acid content, with an M/G ratio of 2.33. The extracted SA displayed a molecular weight of 1 × 104 g/mol and a polydispersity index of 3.5. The bioactive properties of the SA extract were investigated in chemico and in vitro. SA exhibited remarkable antioxidant activity, showing significant DPPH and nitric oxide-radical-scavenging capacity. Furthermore, SA demonstrated a strong anti-inflammatory effect in LPS-stimulated macrophages through modulation of several inflammatory mediators (i.e., IL-6, IL-8/CXCL5, MCP-1, and TNF-α). In particular, SA promoted a striking iNOS gene expression inhibition, which, paired with its direct NO-scavenging ability, paves the way for future pharmacological use of E. amentacea derivatives, particularly if sustainably obtained from restoration activity waste.