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The L. (HML) Medic, an edible hibiscus of the Malvaceae family, is abundant with flavonoids. The study investigated how --31-assisted pretreatment affects the extraction and bioactivity of flavonoids from HML. The fiber structure of the fermented flavonoid sample (RFF) appears looser, more porous, and more disordered than the unfermented flavonoid sample (RUF). RFF demonstrates milder conditions and yields higher extraction rates. According to the Box-Behnken response surface optimization experiment, the optimal conditions for RFF include a material-liquid ratio of 1:41 g/mL, a 2 h extraction time, a 57% ethanol concentration, and an extraction temperature of 800 °C, resulting in a 3.69% extraction yield, which is 39.25% higher than that of RUF. Additionally, RFF exhibits greater activity than RUF in the radical-scavenging system. The IC50 values for DPPH, OH, and ABTS radicals are 83.43 μg/mL and 82.62 μg/mL, 208.38 μg/mL and 175.99 μg/mL, and 108.59 μg/mL and 75.39 μg/mL for RUF and RFF, respectively. UPLC-QTOF-MS analysis of the active components in the HML flavonoid sample revealed significant differences in the chromatograms of RUF and RFF, indicating that biofermentation led to substantial changes in composition and content from HML.

洛神花（HML）是锦葵科的一种可食用芙蓉，富含黄酮类化合物。该研究调查了 -31 辅助预处理如何影响从 HML 中提取黄酮类化合物及其生物活性。发酵黄酮类样品（RFF）的纤维结构比未发酵黄酮类样品（RUF）显得更松散、多孔且无序。RFF 显示出更温和的条件并产生更高的提取率。根据 Box-Behnken 响应面优化实验，RFF 的最佳条件包括料液比 1:41 g/mL、提取时间 2 小时、乙醇浓度 57% 和提取温度 800 °C，提取率为 3.69%，比 RUF 高 39.25%。此外，RFF 在自由基清除系统中比 RUF 表现出更大的活性。RUF 和 RFF 对 DPPH、OH 和 ABTS 自由基的 IC50 值分别为 83.43 μg/mL 和 82.62 μg/mL、208.38 μg/mL 和 175.99 μg/mL、108.59 μg/mL 和 75.39 μg/mL。对 HML 黄酮类样品中的活性成分进行 UPLC-QTOF-MS 分析，结果显示 RUF 和 RFF 的色谱图存在显著差异，表明生物发酵导致 HML 的成分和含量发生了实质性变化。

需注意，原文中“800 °C”可能有误，一般提取温度不会达到这么高，可根据实际情况修正后理解。