Experimental mixture design solvent effects on pigment extraction and antioxidant activity from coffea arabica L. leaves

High-performance liquid chromatography coupled with ultraviolet-visible spectroscopy, using a photodiode array detector (HPLC-PDA) were used to explore different pigments as well as their antioxidant activities in Coffea arabica leaves. Ethanol, dichloromethane and hexane were used for extraction following a simplex-centroid mixture design. Antioxidant capacity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay (DPPH). HPLC-PDA allowed identification of five pigments, pheophytin a, zeaxanthin, crocetin, beta-carotene and chlorophyll b. Pheophytin a showed the highest relative abundance followed by zeaxanthin and chlorophyll b with crocetin and beta-carotene having even lower amounts. All these pigments exhibited significant antioxidant activities. Ethanol extracts presented the highest relative abundance and antioxidant activities for all these pigments followed by an ethanol: dichloromethane mixture (50:50 v/v). On the other hand, pure hexane had no extraction capacity for zeaxanthin, crocetin, beta-carotene and chlorophyll b for the Coffea arabica leaves146713721CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES150107/2018-8não temThe authors acknowledge financial support of the Consórcio Brasileiro de Pesquisa e Desenvolvimento de Cafés, CNPq and CAPES, as well as for the scholarships granted (CNPQ, Process: 150107/2018-8). The authors are grateful to IAPAR – Agronomical Institute of Paraná (Londrina-Brazil) for the coffee leaves used in this wor