# Ultrasonic-Assisted Hot-Water Extraction Optimization, Preliminary Characterization and Antioxidant Activity of Polysaccharides from Zingiber striolatum

## TL;DR

This study optimizes the extraction of antioxidant-rich polysaccharides from Zingiber striolatum and evaluates their potential health benefits.

## Contribution

The study introduces an optimized ultrasonic-assisted hot-water extraction method for Z. striolatum polysaccharides and evaluates their antioxidant properties.

## Key findings

- Optimal extraction conditions yielded 19.96% polysaccharides with a molecular weight of 56.3 kDa.
- The polysaccharide ZS-P1-1 showed significant DPPH· and ·OH scavenging capacities and reducing ability.
- ZS-P1-1 reduced oxidative stress markers and protected against liver and kidney damage in mice.

## Abstract

Polysaccharides serve as the main bioactive compounds of Zingiber striolatum (Z. striolatum). However, their structures and functions require further research. The present work used response surface methodology (RSM) for optimizing polysaccharide extraction conditions from Z. striolatum through ultrasonic-assisted hot-water extraction and evaluating the antioxidant properties of Z. striolatum polysaccharides. According to our findings, optimal Z. striolatum polysaccharide extraction conditions included ultrasonic power of 200 W, extraction temperature of 79 °C, extraction duration of 2.5 h, and ultrasonic time of 20 min, with the extraction yield reached 19.96% ± 0.18%. The molecular weight (MW) of the purified polysaccharide ZS-P1-1 isolated from Z. striolatum was 5.63 × 104 kDa, mainly composed of galactose (Gal), galacturonic acid (GalA) and glucuronic acid (GlcA) in a 0.453:0.162:0.114 molar ratio. Typically, 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·) and hydroxyl radical (·OH) scavenging capacities and total reducing ability reached 30.49% ± 1.82%, 28.51% ± 1.40% and 0.64 ± 0.07 of ZS-P1-1 at 0.5 mg/mL, respectively. Moreover, ZS-P1-1 increased the reduced glutathione (GSH) level, enhanced the total superoxide dismutase (T-SOD), reduced the malondialdehyde (MDA) level, and alleviated the liver and kidney damage caused by oxidative stress in mice. Our results suggest that ZS-P1-1 shows excellent antioxidant properties and provides a certain theoretical foundation for developing and utilizing Z. striolatum polysaccharides.