Antioxidant Activity of Plant-Derived Colorants for Potential Cosmetic Application

Application of plant-derived colorants in products, i.e., cosmetics or food, apart from imparting the desired color without harming the environment, may provide other benefits. Valuable ingredients in cosmetic formulations include antioxidants showing an advantageous effect on the skin by neutralizing free radicals that accelerate the aging process and cause skin defects. Antioxidant activity can be determined by chemical-based methods. The aim of this study was to determine the antioxidant activity of plant-derived colorants (purple and red colorant) by two methods: CUPRAC and DPPH free-radical scavenging activity. Antioxidant activity evaluation using both methods for colorants samples was also performed after 5, 15, 30, and 60 min of exposure to UVC irradiation. The results obtained by CUPRAC method were for purple and red colorant unexposed samples as follows: 6.87 ± 0.09 and 4.48 ± 0.14 mg/100 mg colorant expressed as caffeic acid equivalent, respectively. UVC treatment did not affect the results of the antioxidant activity for red colorant and for the purple one only a slight influence was observed. DPPH free-radical scavenging activity for unexposed samples was 70.06 ± 7.74% DPPH/100 mg colorant for the red colorant and 96.11 ± 3.80% DPPH/100 mg colorant for the purple one.