【专题：红豆属植物多样性保育研究】响应面法优化小叶红豆总黄酮提取工艺及抗氧化活性研究

Optimization of extraction process and antioxidant activity of total flavonoids from Ormosia microphylla by response surface methodology

关键词:  珍稀濒危，小叶红豆，总黄酮，响应面法，抗氧化水平，超声辅助提取

Key words:  rare and endangered, Ormosia microphylla, total flavonoids, response surface methodology, antioxidant activity, ultrasound-assisted extraction

摘要:

小叶红豆（Ormosia microphylla）为国家一级重点保护野生植物，隶属于豆科红豆属，野生种群日渐稀少，但其相关的研究报道较少。为明确小叶红豆不同部位的抗氧化能力，该研究采用超声辅助提取技术结合响应面分析法，对小叶红豆总黄酮的提取工艺进行优化，并探究其不同部位的总黄酮含量差异，并分析和评估其抗氧化能力。结果表明：（1）小叶红豆总黄酮最佳提取工艺为乙醇浓度68%、提取时间60 min、提取温度71 ℃、料液比1∶70 g·L-1。（2）在最佳提取工艺下，小叶红豆不同部位的总黄酮含量存在显著差异，具体表现为枝>皮>叶>去皮材>根，为5.05%~1.53%，表明小叶红豆的枝干和树皮部位是黄酮类物质的主要富集部位，且黄酮在植株表皮组织中的分布可能与其防御功能密切相关。（3）小叶红豆5个不同部位抗氧化活性对比中，枝干中总黄酮DPPH·清除率最强，为77.96%；根中总黄酮·OH清除率最强，为63.75%；小叶红豆去皮材、根、皮、枝4个部位具有良好的还原能力。（4）小叶红豆不同部位的抗氧化活性并不完全与总黄酮含量呈正比，可能存在其他活性成分及其协同作用对自由基清除能力的贡献。该研究结果为小叶红豆如何通过黄酮类化合物提高自身抗旱、抗病和抗逆能力研究提供科学数据，同时为小叶红豆的综合保护提供理论依据。

Abstract:

Ormosia microphylla, a species of the genus Ormosia in the Fabaceae family, is listed as a nationally protected Class I wild plant in China. Its wild populations are gradually declining, yet relevant research remains limited. To clarify the antioxidant capacity of different plant parts of O. microphylla, this study employed ultrasound-assisted extraction combined with response surface methodology to optimize the extraction conditions for total flavonoids. Furthermore, the variation in total flavonoid content and antioxidant activity among different parts of the plant was analyzed and evaluated. The results were as follows: (1) The optimal extraction conditions for total flavonoids were 68% ethanol concentration, 60 min extraction time, 71℃ extraction temperature, and a material-to-liquid ratio of 1∶70 g·mL-1. (2) Under these optimal conditions, the total flavonoid content varied significantly among different plant parts, in the order of branch > bark > leaf > debarked stem > root, ranging from 5.05% to 1.53%. This indicates that flavonoids are primarily accumulated in the branch and bark tissues of O. microphylla, and their distribution in epidermal tissues may be closely related to the plant’s defensive functions. (3) In a comparison of antioxidant activities among the five plant parts tested, total flavonoids from the branches showed the strongest DPPH· radical scavenging activity (77.96%), while those from roots exhibited the highest ·OH radical scavenging activity (63.75%). The debarked stem, root, bark, and branch also demonstrated good reducing power. (4) The antioxidant activity of different plant parts was not entirely proportional to their total flavonoid content, suggesting that other active compounds and synergistic effects may contribute to free radical scavenging. Flavonoids play an important role in plant self-protection mechanisms. The findings of this study provide scientific evidence for understanding how O. microphylla enhances its resistance to drought, disease, and other environmental stresses through the accumulation of flavonoids. Moreover, the results offer a theoretical foundation for the integrated conservation of this endangered species.