Spectrophotometric and Chromatographic Assessment of Contributions of Carotenoids and Chlorophylls to the Total Antioxidant Capacities of Plant Foods

Abstract

Carotenoids and chlorophylls are photosynthetic compounds and also efficient antioxidants. This study aims to identify and quantify carotenoids and chlorophylls in some vegetables (carrot, tomato, spinach), to measure the total antioxidant capacity (TAG) of these samples with two spectrophotometric methods, to correlate TA C data with carotenoid structure, and to compare the TAG results with HPLC findings. Separation of the individual antioxidant pigments was achieved on a C-30 column using a developed gradient elution program involving methanol acetonitrile (50:50, v/v) with 0.1% (v/v) triethylamine (TEA) (A) and acetone (B) mobile phases. Total antioxidant capacities of the acetone extracts of studied samples, in trolox and beta-carotene equivalents, were in the order: spinach > tomato > carrot by both CUPRAC and ABTS methods. CUPRAC responded favorably to both chlorophylls a and b. The TAG calculated with aid of combined HPLC spectrophotometry was very close to the spectrophotometric value (93-108%) for real samples and synthetic mixtures.