# Inhibitory and Antioxidant Activities of Saccharina japonica Extracts Processed by Subcritical Water Extraction and Enterococcus faecalis Fermentation

## TL;DR

This study explores how processing Saccharina japonica seaweed with subcritical water and Enterococcus faecalis fermentation can produce extracts with strong enzyme-inhibiting and antioxidant properties.

## Contribution

The novel contribution is demonstrating the effectiveness of microbial fermentation in enhancing the bioactive properties of seaweed extracts.

## Key findings

- Fermented S. japonica extracts showed 78.69% inhibition of pancreatic lipase.
- Extracts exhibited 59.23% α-glucosidase inhibition and 65.60%–66.57% antioxidant activity.
- Subcritical water extraction yielded high concentrations of mannitol, laminarin, and phenolics.

## Abstract

Marine algae, notably Saccharina japonica, are valuable sources of essential nutrients, including carbohydrates, vitamins, and minerals, as well as bioactive compounds, such as phenols and pigments. In this study, subcritical water extraction of S. japonica, a brown seaweed, was conducted using a 10% (w/v) seaweed slurry at a temperature of 140°C for 10 min. The concentrations of mannitol, laminarin, and total phenolic content were determined to be 18.93 g/l, 10.79 g/l, and 1.94 mg GAE/g, respectively. The S. japonica fermented using Enterococcus faecalis (SFL) resulted in a maximum biomass production of 4.43 g dcw/l and exhibited an inhibitory activity of 78.69% against pancreatic lipase. The S. japonica fermented using E. faecalis (SFE) extracts exhibited α-glucosidase inhibitory and antioxidant activities of 59.23% and 65.60%–66.57%, respectively, at a concentration of 3.0 mg/ml. These results facilitate the development of functional seaweed food formulations derived from microbial fermentation.