Aluminium and calcium lake pigments of Lac natural dye

This work presents the physicochemical properties of the prepared lac lakes. The study revealed the stability, cytotoxicity and use of lac lake pigment as a cosmetic colorant. SEM, XRD and DSC were used to study the characteristics of the lac lakes.. The color stability of lac dye and its lakes was investigated at ambient temperature and at 45 °C, in sunlight,fluorescent light and darkness, for 3 months. Cytotoxicity on human dermal skin fibroblast cell lines was tested using MTT assay and the use of the lakes as a colorant in lip color product was studied. Different metal salts resulted in lac lakes of different shades and appearance. SEM, XRD and DSC results indicated that the morphology and structure of lac dye were changed after reacting with metal salts which support the coordination of metal ion with lac dye. The lac lakes were not cytotoxic to human dermal skin fibroblast cells (0.78-100 µg/mL). Lac lakes exhibited less alteration of color shade over acidic and basic conditions when compared with the lac dye itself. Additionally, the lake pigments displayed better color stability than lac dye and produced an orange-brown shade of lip color product. The results suggest that lac lake pigments have good potential for use as cosmetic colorant.本研究报道了所制备紫胶色淀（lac lakes）的理化性质。本研究阐明了紫胶色淀颜料的稳定性、细胞毒性及其作为化妆品着色剂的应用潜力。本研究采用扫描电子显微镜（SEM）、X射线衍射（XRD）以及差示扫描量热法（DSC）对紫胶色淀的特性进行表征。本研究在室温、45℃条件下，分别于阳光照射、荧光照射及避光环境中，对紫胶染料（lac dye）及其色淀的颜色稳定性开展了为期3个月的考察。采用MTT比色法（MTT assay）检测了紫胶色淀对人真皮皮肤成纤维细胞系的细胞毒性，并探究了其作为唇彩产品着色剂的应用效果。不同金属盐可制备得到色调与外观各异的紫胶色淀。SEM、XRD及DSC表征结果显示，紫胶染料与金属盐反应后其形貌与结构发生改变，这一结果证实了金属离子与紫胶染料之间存在配位作用。在0.78~100 μg/mL的浓度范围内，紫胶色淀对人真皮皮肤成纤维细胞无细胞毒性。相较于纯紫胶染料，紫胶色淀在酸碱环境下的色调变化程度更低。此外，紫胶色淀颜料的颜色稳定性优于纯紫胶染料，且可制备出具橙棕色调的唇彩产品。上述研究结果表明，紫胶色淀颜料具备作为化妆品着色剂的良好应用潜力。