Comparison of antioxidant and antiproliferative activities of extracts from Brussels and Savoy cabbage (Brassica oleracea L. var. sabauda) sprouts

A large number of epidemiological studies have consistently shown that the daily consumption of plant-based foods is associated with the reduction of risk factors for chronic diseases, such as cardiovascular diseases, diabetes, and obesity. Germination is an inexpensive and effective way to accumulate bioactive compounds in pulses, cereal, vegetable, fruit, flower and medicinal plant seeds [1]. The concentration of different bioactive compounds increased during seed germination, providing to sprouts many bioactivities such as antioxidant, antidiabetic, anti-inflammatory, hypolipidemic and anticarcinogenic activities [1]. Sprouts have attracted an increasing interest by nutritionists, as they possess a higher nutritional value than adult plants. Broccoli sprouts, in fact, have higher level of glucosinolates [2], vitamins (C and E), GABA [3], phenolic compounds [4], and a higher phase 2 inducing activity [5] than adult plants. Glucosinolates and their hydrolysis products isothiocyanates, are considered to have an important role in cancer chemoprevention. These compounds, in fact, are reported to have a chemo-preventive activity in a variety of cell and animal models, probably due to their capacity to induce phase 2 detoxification enzymes [6]. The present investigation was planned to compare the antioxidant and antiproliferative activity of aqueous and hydroalcoholic extracts of two Brassica genus, Savoy cabbage (Brassica olearea L.var. sabauda) and Brussels (Brassica olearea L.var. gemmifera) sprouts. The in vitro antioxidant activity of extracts was tested using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,20-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging assays. The antiproliferative activity of extracts was tested against human breast adenocarcinoma cells (MDA-MB 231) and human colon carcinoma cells (HCT116). The MTT (3- (4,5-dimethyl-2-thiazolyl) - 2,5-diphenyl-2H-tetrazolium bromide) assay was used as relative measure of cell viability. The results highlight a higher content of polyphenols in the aqueous extract of Savoy cabbage sprouts compared to the aqueous extract of Brussels sprouts with a greater scavenger activity especially against the radical ABTS+. The incubation of tumor cell lines in presence of different concentrations of aqueous and hydroalcoholic sprout extracts of two varieties of plants shows a significant inhibition of cellular proliferation. Savoy cabbage sprouts present highest antiproliferative activity on HCT116 cell line with IC50 value of 96.52 µg/ml by hydroalcoholic extract. Studies are in progress to characterize the single components responsible for the observed effects in the sprout extracts. [1] Gan RY, Lui WY, Wu K, Chan CL, Dai SH, Sui ZQ, Corke H. Bioactive compounds and bioactivities of germinated edible seeds and sprouts: An updated review. Trends Food Sci Tech. 2017;59:1-14. [2] Pérez-Balibrea S, Moreno DA, García-Viguera C. Improving the phytochemical composition of broccoli sprouts by elicitation. Food Chem. 2011;129:35-44. [3] Nakamura K, Koyama M, Ishida R, Kitahara T, Nakajima T, Aoyama T. Characterization of bioactive agents in five types of marketed sprouts and comparison of their antihypertensive, antihyperlipidemic, and antidiabetic effects in fructose-loaded SHRs. J Food Sci Technol. 2016;53:581-590. [4] Singh J, Upadhyay AK, Prasad K, Bahadur A, Rai M. Variability of carotenes, vitamin C, E and phenolics in Brassica vegetables. J Food Compos Anal. 2007;20:106-112. [5] Fahey JW, Zhang Y, Talalay P. Broccoli sprouts: An exceptionally rich source of inducers of enzymes that protect against chemical carcinogens. P Nat Acad Sci USA. 1997;94:10367-10372. [6] Plumb GW, Lambert N, Chambers SJ, Wanigatunga S, Heaney RK, Plumb JA, Williamson G. Are whole extracts and purified glucosinolates from cruciferous vegetables antioxidants? Free Radical Res. 1996;25:75-86.