Relative Inhibition of Lipid Peroxidation, Cyclooxygenase Enzymes, and Human Tumor Cell Proliferation by Natural Food Colors

TLDR

Water‑soluble natural food colors are mainly betacyanins and anthocyanins, while water‑insoluble colors include lycopene, bixin, beta‑carotene, and chlorophyll. Pure betanin, bixin, lycopene, chlorophyll, beta‑carotene, and cyanidin‑3‑O‑glucoside were isolated from their respective plants and tested alone and in mixtures for cyclooxygenase enzyme inhibition and dose‑dependent growth inhibition across five human cancer cell lines. Betanin, cyanidin‑3‑O‑glucoside, lycopene, and beta‑carotene inhibited lipid peroxidation; all pigments inhibited COX‑1 and COX‑2 and dose‑dependently suppressed growth of breast, colon, stomach, CNS, and lung tumor cells, but mixtures of anthocyanin and betanin reduced efficacy and did not enhance COX inhibition, marking the first comparative evaluation of these pigments alone and combined.

Abstract

The most abundant water soluble natural food colors are betacyanins and anthocyanins. Similarly, lycopene, bixin, beta-carotene, and chlorophyll are water insoluble colors. Pure betanin, bixin, lycopene, chlorophyll, beta-carotene, and cyanidin-3-O-glucoside were isolated from Beta vulgaris, Bixa orellana,Lycopersicum esculentum, Spinacia oleracea, Daucus carrota, and Prunus cerasus, respectively. These natural pigments, alone and in combination, were evaluated for their relative potencies against cyclooxygenase enzymes and tumor cell growth inhibition by using MCF-7 (breast), HCT-116 (colon), AGS (stomach), CNS (central nervous system), and NCI-H460 (lung) tumor cell lines. Among the colors tested, betanin, cyanidin-3-O-glucoside, lycopene, and beta-carotene inhibited lipid peroxidation. However, all pigments tested gave COX-1 and COX-2 inhibition and showed a dose-dependent growth inhibition against breast, colon, stomach, central nervous system, and lung tumor cells, respectively. The mixtures of these pigments were also evaluated for their synergistic effects and chemical interactions at various concentrations. The mixture of anthocyanin and betanin negated their efficacy in the cell growth inhibitory assay and did not enhance the COX enzyme inhibitory activity. This is the first report of a comparative evaluation and the impact on biological activities of these pigments alone and in combination.