Phytochemical Composition and Antitumor Activities of New Salad Greens: Rucola (Diplotaxis tenuifolia) and Corn Salad (Valerianella locusta)

Abstract

D. tenuifolia and V. locusta, two greens, were analyzed for active compounds and antitumor actions on colorectal cancer cells. Phenolics were determined by UHPLC-Orbitrap-MS; carotenoids and glucosinolates by HPLC-MS; and sterols and fatty acids by gas-liquid chromatography (GLC). For antitumor effects, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) tests were run on HT-29 colorectal cancer cells, and in CCD-18 untransformed enterocyte cells. Six main carotenoids were identified in both vegetables, while total carotenoids accounted for 3520 and 2970 mu g center dot g(-1) dry weight in D. tenuifolia and V. locusta, respectively. Six phenolics were detected in D. tenuifolia (68,600 mu g center dot g(-1) dry weight) and five in V. locusta (139,000 mu g center dot g(-1) dry weight). Three glucosinolates (GSL) were found in D. tenuifolia (1960 mu g center dot g(-1) dry wt. total). Low-polarity extracts from V. locusta and D. tenuifolia showed IC50 similar to 150 and similar to 200 mu g center dot mL(-1) on HT-29 cells, while both plants lacked actions on CCD-18 cells. V. locusta inhibited HT-29 cancer cells viability more efficiently than D. tenuiofolia, but induced less cytotoxicity. This work highlights the importance of functional foods for colorectal cancer prevention.