De rejeito industrial a ingredientes funcionais: composição química, atividade antioxidante e efeitos protetores em células humanas de extratos de sementes de uva (Vitis labrusca var. Bordeaux) e amora-preta (Rubus fruticosus L.)

Abstract

This study aimed to study the chemical composition and functional properties of burgundy grape (Vitis labrusca Bordeaux) and blackberry (Rubus fruticosus L.) seed oils, as well as to optimize the extraction of hydrophilic bioactive compounds from these seeds using a statistical approach. The thesis was designed in such a way that the objectives, methodology and results were segmented into two chapters: Chapter 1 presents the study of the lipid fraction, in which the total phenolic content, the antioxidant activity, the composition of fatty acids and phytosterols, the antimicrobial activity, as well as the cytotoxic activity of the non-polar extract of grape and blackberry seed were investigated; Chapter 2 addresses the optimization of the extraction of phenolic compounds with antioxidant activity by using a rotational composite design, using two factors (time and plant material:solvent ratio). The results showed that the non-polar seed extracts, obtained using the Bligh-Dyer (BD) method, showed the highest levels of total phenolic compounds and antioxidant activity, both for blackberry and grape, however, only the extracts obtained with hot solvent extraction (Soxhlet) showed an inhibitory effect against Escherichia coli (IAL 2064) and Staphylococcus aureus (ATCC 13565). Regarding cell viability, the non-polar extracts did not show cytotoxicity or antiproliferative effect on different cell lines at concentrations from 0 to 1000 μg/mL, which shows the relative toxicological safety of lipophilic extracts. When the extraction of phenolic compounds from grape and blackberry seeds was carried out, the optimized parameters for higher phenolic yield and antioxidant activity were: time (35.9 and 62.1 min, respectively), mass-solvent ratio (1:61, 28 and 1:64.1 g:mL, respectively) using 60% ethanol as solvent. The main phenolic compounds detected in the extracts were: grape seed ((-)-epicatechin – 833.1 mg/100g; epigallocatechin-3- gallate – 785 mg/100g; (+)-catechin – 573.8 mg/100g; quercetin – 231.7 mg/100g and quercetin-3-rutinoside - 72.6 mg/100g) and blackberry (catechin – 88.8 mg/100g; (-)- epicatechin – 81.5 mg/100g; quercetin-3 -glucoside - 35.3 mg/100g; 3,4- dihydroxybenzoic acid – 34.5 mg/100g and 2,5-dihydroxybenzoic acid;). Grape and blackberry seed extracts decreased intracellular generation of reactive oxygen species (ROS) in human adenocarcinoma (A549) and human colon carcinoma (HCT8) cells when exposed to H2O2. Similarly, the optimized grape and blackberry seed extracts showed a protective effect on human erythrocytes when subjected to hypotonic as well as isotonic conditions. Moreover, the extracts did not show hemolytic behavior in

relation to the tested concentration. Thus, considering the requirements of the 2030 Agenda and the need for sustainable ways of producing food ingredients, we conclude that grape and blackberry seeds can be used as sources of lipid antioxidants to be used in different technological applications.