随着消费者健康意识的提高，天然环保的植物染发剂已成为市场的发展趋势。然而，与化学染发剂相比，植物染发剂普遍存在色稳定性差的问题。染色后的头发在光照下容易出现光褪色等退行性变化。目前国内外对染发的光稳定性研究尚停留在物理表型的描述阶段，缺乏对其光老化机制的深入系统研究。因此，对于如何科学评价染发的光老化程度以及如何采取合适的防护手段，仍存在不少争议。生活中，日光中的紫外辐射是导致头发颜色改变的最主要环境因素之一。本项目拟以紫外光敏化产生活性氧为切入点，通过人工染发光老化模型的建立和活性氧的定量分析，结合对头发中特征光降解产物（色素、角蛋白成分的变化）与物理表征（颜色、微观形态、机械张力）的综合分析，探讨散沫花醌和苏木精等植物染发成分在头发光老化中的作用机制，并通过比较不同配方及媒染剂对染发光化学稳定性的影响，为未来天然染护发产品的优化研发提供重要的实验基准数据。

With increasing health concerns regarding the use of synthetic hair dyes, natural and environment-friendly botanical colorants from plant sources are favored by consumers. However, comparing with the artificial colors, hairs treated with natural dyes are poor in colorfastness and are subject to photofading over extended exposure to light. Current scientific reports on the photoageing and photostability of dyed human hairs are mainly physical descriptions without interpretation of the underlying mechanisms. Controversies are arising on how to evaluate the photodamage of dyed human hairs scientifically during photoageing as well as the appropriate preventions. Since the ultraviolet radiation is one of the major environmental factors that affect hair color, the proposed project is committed to elucidate the role and mechanism of botanical hair dyeing colorants such as lawsone and hematoxylin in the photoageing process of dyed human hairs. To achieve this goal, an artificial photoaging model for dyed human hairs is constructed, in which the UV-sensitized generation of reactive oxygen species can be quantified, together with a comprehensive analysis of photoproducts of hair protein and colorants as well as the physical characterizations (including changes of color, morphology and mechanical tension). The effects of different dye formula and mordanting agents on the photochemical stability of human hairs are also assessed to provide important experimental basis for the optimized R&D of future natural hair dyes and after-dye products.