Abstract The antioxidant activity and the structure-activity relationship of aqueous phase bio-oil (APBO), obtained from hydrothermal treatment (HTT) combined with pyrolysis of biomass, have been investigated in this study. HTT increased the relative content of phenolic compounds and reduced the relative content of acids. Phenolic compounds possessed as the dominant chemical components in APBO, representing up to 61.68 %. 2-methoxyphenol (guaiacol) and its derivatives were the major components of phenolic compounds. HTT promoted the antioxidant activity of APBOs and APBO-180 showed higher antioxidant activity than that of commercial chemical antioxidant (butylated hydroxyl toluene) with IC50 values of 0.402 mg/mL of reducing power, 0.132 mg/mL of DPPH free radical scavenging capacity and 0.405 mg/mL of hydroxyl free radical scavenging capability. The antioxidant activity of APBO was affected by its chemical composition. Phenols exhibited a promotion effect on antioxidant activity, while acids showed an inhibition effect. In addition, the substituent structure of phenols played a key role in antioxidant activity. Phenols with the shorter carbon side chain showed higher antioxidant activity (e.g. 2-methylphenol>2-methoxyphenol, 4-methyl-2-methoxyphenol>4-ethyl-2-methoxyphenol). This study suggested that APBO could be developed as the natural feed additives or alternative antioxidant, providing a new strategy for efficient utilization of APBO.

中文翻译：

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水热预处理增强水相生物油抗氧化活性及其构效关系

摘要 本研究研究了水热处理（HTT）结合生物质热解获得的水相生物油（APBO）的抗氧化活性和构效关系。HTT增加了酚类化合物的相对含量并降低了酸的相对含量。酚类化合物是APBO的主要化学成分，占比高达61.68%。2-甲氧基苯酚（愈创木酚）及其衍生物是酚类化合物的主要成分。HTT促进了APBOs的抗氧化活性，APBO-180表现出比商业化学抗氧化剂（丁基化羟基甲苯）更高的抗氧化活性，IC50值为0.402 mg/mL的还原能力、0.132 mg/mL的DPPH自由基清除能力和0.405 mg/mL 的羟基自由基清除能力。APBO的抗氧化活性受其化学成分的影响。酚类对抗氧化活性有促进作用，而酸类则有抑制作用。此外，酚类的取代基结构在抗氧化活性中起关键作用。具有较短碳侧链的酚表现出较高的抗氧化活性（例如2-甲基苯酚>2-甲氧基苯酚、4-甲基-2-甲氧基苯酚>4-乙基-2-甲氧基苯酚）。该研究表明，APBO 可以作为天然饲料添加剂或替代抗氧化剂开发，为 APBO 的有效利用提供了新的策略。酚的取代基结构在抗氧化活性中起关键作用。具有较短碳侧链的酚表现出较高的抗氧化活性（例如2-甲基苯酚>2-甲氧基苯酚、4-甲基-2-甲氧基苯酚>4-乙基-2-甲氧基苯酚）。该研究表明，APBO 可以作为天然饲料添加剂或替代抗氧化剂开发，为 APBO 的有效利用提供了新的策略。酚的取代基结构在抗氧化活性中起关键作用。具有较短碳侧链的酚表现出较高的抗氧化活性（例如2-甲基苯酚>2-甲氧基苯酚、4-甲基-2-甲氧基苯酚>4-乙基-2-甲氧基苯酚）。该研究表明，APBO 可以作为天然饲料添加剂或替代抗氧化剂开发，为 APBO 的有效利用提供了新的策略。