Hu Feifei, Qin Ye, Zhou Yiqing, Li Lingyue, Wang Yingxi, Deng Zhangshuang
Key Laboratory of Functional Yeast, China National Light Industry & Hubei Key Laboratory of Natural Products Research and Development, College of Biological and Pharmaceutical Sciences, China Three Gorges University, Yichang 443002, China.
Hubei Key Laboratory of Tumor Microenvironment and Immunotherapy, Three Gorges University Medical College, China Three Gorges University, Yichang 443002, China.
Food Funct. 2022 May 10;13(9):4930-4940. doi: 10.1039/d2fo00513a.
Precipitation formation commonly occurs in the ageing step of fermented citrus vinegar. Hitherto, the chemical characteristics and biological properties of precipitates remain unveiled. This study focused on investigating the chemical profile, formation mechanism and biological repurposing of precipitates. Nine principal components, two flavonoid glycosides and their aglycones along with five polymethoxyflavones (PMFs), were identified from a methanol extract of precipitates. Using hydrolysis models, we demonstrated that insoluble aglycones were generated through the breakage of glycosidic bonds in flavonoid glycosides under acidic condition. Moreover, soluble bound-PMFs were destroyed by yeast-acid hybrid catalysis to release insoluble free-PMFs to form precipitates. A methanol extract of precipitates exhibited a potent anti-proliferative effect on MCF-7 cells (IC = 0.032 μg μL) inhibiting tubulin polymerization. This study will be helpful for the food industry to aid optimizing citrus vinegar brewing and for reutilizing precipitates for functional foods and health products. Furthermore, it also provides a green strategy of PMFs enrichment from citrus using an enzyme-acid hybrid system.
沉淀的形成通常发生在发酵柑橘醋的陈酿阶段。迄今为止，沉淀物的化学特性和生物学特性仍未明确。本研究聚焦于探究沉淀物的化学组成、形成机制及生物再利用。从沉淀物的甲醇提取物中鉴定出9种主要成分、2种黄酮糖苷及其苷元以及5种多甲氧基黄酮（PMFs）。利用水解模型，我们证明了在酸性条件下，黄酮糖苷中的糖苷键断裂会生成不溶性苷元。此外，可溶性结合型PMFs在酵母 - 酸混合催化作用下被破坏，释放出不溶性游离型PMFs以形成沉淀。沉淀物的甲醇提取物对MCF - 7细胞表现出强大的抗增殖作用（IC = 0.032 μg μL），可抑制微管蛋白聚合。本研究将有助于食品工业优化柑橘醋酿造，并将沉淀物重新用于功能性食品和保健品。此外，它还提供了一种利用酶 - 酸混合系统从柑橘中富集PMFs的绿色策略。
