Optimized Extraction of Sargahydroquinoic Acid, Major Bioactive Substance, from Sargassum yezoense Using Response Surface Methodology

Abstract

Sargahydroquinoic acid (SHQA), a bioactive compound found in certain Sargassum species, exhibits significant health benefits. This study optimized the extraction of SHQA from Sargassum yezoense using response surface methodology (RSM) and evaluated its antioxidant effects through in vitro and in vivo assays. A Box-Behnken design (BBD) was effectively employed to investigate the effects of incubation temperature, time, and ethanol concentration on SHQA yield, achieving a high coefficient of determination (R² = 0.961). Analysis of variance (ANOVA) validated the model's reliability (F = 13.86, p = 0.005) and highlighted ethanol concentration as a highly significant factor (p < 0.001). Optimal extraction conditions were identified as 52.8 °C, 8.3 h, and 74.1% ethanol. The SHQA-maximized extract (SME) contained 67.8 ± 0.6 mg SHQA/g and 25.00 ± 1.01 mg phloroglucinol equivalent/g. SME exhibited antioxidant capacity of 26.45 ± 0.66 mg and 28.74 ± 2.30 mg vitamin C equivalent/g in ABTS and DPPH assays, respectively, and 0.29 ± 0.02 mM FeSO₄ equivalent/g in the FRAP assay. Additionally, SME at 50 µg/mL and SHQA at 1 µg/mL inhibited reactive oxygen species (ROS) generation in an H₂O₂-induced zebrafish model. This study presents the first optimization of SHQA extraction using RSM and demonstrates SHQA's ROS inhibition in a zebrafish model.

Keywords: Box–Behnken design; Sargassum yezoense; antioxidant; extraction yield; response surface methodology; sargahydroquinoic acid.

Figure 1

Effects of extraction variables on the sargahydroquinoic acid (SHQA) content in S. yezoense extracts: (a) temperature and time, (b) time and ethanol concentration, and (c) temperature and ethanol concentration.

Figure 2

The protective effect of sargahydroquinoic acid (SHQA)-maximized extracts from S. yezoense (SME) (a,b) and pure SHQA (c,d) on H₂O₂-induced ROS generation was evaluated in a zebrafish model. Panels (a) and (c) show microscopic fluorescence images of zebrafish embryos, while panels (b) and (d) display the corresponding relative fluorescence intensities, representing ROS levels. “NT” indicates the untreated control group. Different letters above the bar chart indicate significant differences (p < 0.05).