蜡菊中圣草酚和木犀草素含量测定、抗氧化活性及其反应动力学特性

目的 建立测定蜡菊中圣草酚和木犀草素含量的方法，并对圣草酚和木犀草素的体外抗氧化活性进行评价。方法 采用UPLC进行含量测定方法学研究，以维生素C和Trolox作为对照，通过测定圣草酚和木犀草素清除DPPH自由基的IC₅₀，比较抗氧化活性的强弱；通过4 h内清除自由基速度的变化，初步阐释二者清除DPPH自由基的反应动力学特性。结果 圣草酚和木犀草素分别在0.005 4~0.545 0，0.005 3~0.535 0 mg·mL^–1内，峰面积与浓度线性关系良好（R=0.999 7），方法精密度、稳定性、加样回收率结果满意。4种化合物清除自由基能力由高到低依次为木犀草素>圣草酚>维生素C>Trolox。不同于维生素C和Trolox，圣草酚和木犀草素清除自由基的过程总体呈现先快后慢的3个阶段。结论 含量测定方法较为简便，分析速度快，能用于蜡菊中圣草酚和木犀草素含量测定。圣草酚和木犀草素具有优异的抗氧化活性，蜡菊资源值得进一步开发。

Determination, Antioxidant Activity and Reaction Kinetics of Eriodictyol and Luteolin in Xerochrysum Bracteatum

OBJECTIVE To establish a method for the determination of eriodictyol and luteolin in Xerochrysum braeteatum, and to evaluate their antioxidant activities in vitro. METHODS UPLC was used to investigate the coutent determination methodologically. Vitamin C and Trolox were used as the control, the IC₅₀ values of eriodictyol and luteolin for scaving DPPH free radical were determined, and the antioxidant activity was compared. The kinetic characteristics of free radical scavenging reaction were preliminarily explained by the change of free radical scavenging rate within 4 h. RESULTS There was a good linear relationship (R=0.999 7) between the peak area and the concentration of eriodictyol in the range of 0.005 4-0.545 0 mg·mL^-1 and luteolin in the range of 0.005 3-0.535 0 mg·mL^-1. The precision, stability and recovery of the method were satisfactory. The scavenging ability of the 4 compounds from high to low was luteolin>eriodictyol>vitamin C>Trolox. Different from vitamin C and Trolox, the free radical scavenging process of eriodictyol and luteolin showed three stages:first fast and then slow. CONCLUSION The content determination method is simple and rapid, and can be used for the determination of eriodictyol and luteolin in Xerochrysum braeteatum. The resources of Xerochrysum braeteatum are worth further development because of their excellent antioxidant activities.