Tree tomato (Solanum betaceum Cav.) from Madeira Island: a fruit with high potential to improve health status

Tree tomato (Solanum betaceum Cav.) is a typical edible fruit from Madeira Island which has about 4-10 centimetres long and it is egg shaped. Their colour ranges from yellow and orange to red and purple. The aim of this work was to determine the total phenolic compounds (TPC), total flavonoids content (TFC), antioxidant capacity and the content in vitamin C in the peel and pulp extracts of this fruit. Phenolic compounds were evaluated using the Folin-Ciocalteau method, the total flavonoids content was measured by the aluminium chloride colorimetric assay, antioxidant capacity was evaluated by the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) assay and β-carotene bleaching assay. TPC results were given in gallic acid equivalents (GAE) per 100 g and the results of total flavonoids in epicatechin equivalents (ECE) per 100 g. Vitamin C was determined by high performance liquid chromatography coupled with a diode array detector (HPLC-DAD). Tree tomato showed higher TPC and TFC in peel (133.5 mg GAE/100 g and 147.1 mg ECE/100 g, respectively) than in pulp (68.2 mg EGA/100 g and 40.3 mg EC/100 g, respectively). According to DPPH radical assay, peel presented also higher antioxidant activity (EC50 = 1.76 mg/mL) than pulp (EC50 = 3.57 mg/mL). Tree tomato pulp presented the two forms of vitamin C, ascorbic acid (25.0 mg/100 g) and dehydroascorbic acid (4.29 mg/100 g) while the peel presented only dehydroascorbic acid but in a concentration about 4 times higher than the pulp. Antioxidant compounds are related with the prevention of cancer, atherosclerosis, Alzheimer’s disease, inflammation, and rheumatoid arthritis as well as the delay of aging. Therefore, tree tomato can be considered with a great potential to prevent these diseases due to its antioxidant activity. However more studies must be carried out to identify and quantify other compounds, besides vitamin C, responsible for the tree tomato antioxidant activity.

This work was funded by National Institute of Health Dr. Ricardo Jorge (INSA), “Bioactive compounds and their health benefits” (2012DAN730). Denise Costa is grateful for the research grant under the project Rose4Pack (Biodegradable active packaging with rosemary extract (Rosmarinus officinalis L.) to improve food shelf-life), funded by the Foundation for Science and Technology (FCT) and COMPETE Program (FCOMP-01-0124-FEDER-028015). Tânia Gonçalves Albuquerque is grateful for research grant (BRJ/DAN-2012) funded by National Institute of Health Dr. Ricardo Jorge, I.P.