Natural plant colourants used for hair dye applications and phytochemical profile by LC-MS/MS analysis

This study explores plant extracts’ potential as natural hair dye colourants, emphasising its eco-friendly advantages and antioxidant qualities. DPPH tests, reducing power, and phenolic and flavonoid content analysis were used to assess antioxidant activity. The LC-MS/MS analysis revealed the highest concentration of tannic acids in Juglans regia L. extract. Quinic acid, protocatecchuic acid, and quercetin were identified in the majority of extracts. Protocatecchuic acid was most abundant, especially in Allium cepa L. extract (220.14 mg/g DW). The greatest phenolic content (684.5 µg GAE/mg) and DPPH scavenging activity (78%–93% inhibition) were found in onion peel. Oxalic acid was added to dye compositions containing these extracts to boost colour intensity and wash fastness; CIEL ab values verified the better outcomes. The findings suggest that plant-based dyes, with their strong antioxidant properties, provide an effective, safe, and sustainable alternative to synthetic dyes, delivering vibrant colours while supporting hair health and environmental sustainability.