Chemical Constitutions and Antioxidant Activities of Tomato Leaf Extracts

The present study aimed to determine the contents of five flavonols and two glycoalkaloids as well as the antioxidant activities of leaf ethanol extracts of 50 tomato accessions. The antioxidant activity was assessed using different tests: 2,2 -azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), 2,2-diphenyl-1-picryl hydrazyl (DPPH), nitric oxide (NO), and total polyphenol content (TPC). Flavonols and glycoalkaloids contents were determined using a high performance liquid chromatography-diode array detector system. Among five flavonols and two glycoalkaloids, naringenin and tomatine were detected in tomato leaves at high concentrations. Of the 50 tomato accessions, IT 229711, IT2365203, and IT 207224 were found to have the highest contents of quercetin, kaempferol, and tomatine, respectively. Leaf extract of IT189949 exhibited the highest relative antioxidant capacity index (RACI). Among the five flavonols, myricetin showed positive correlations with DPPH, ABTS, and NO, while isorhamnetin had positive correlation with DPPH. These results will expand the chemical constitution database and provide information on tomato leaves. They are valuable for the development of functional foods or feed-additives.