Bioaccessibility and Potential Biological Activities of Lutein, Glucosinolates, and Phenolic Compounds Accumulated in Kale Sprouts Treated with Selenium, Sulfur, and Methyl Jasmonate

Glucosinolates, phenolic compounds, and carotenoids comprise a class of health-promoting compounds found in numerous vegetables, such as kale. Herein, the individual and combined effects of Se (40 mg/L), S (120 mg/L), and MeJA (25 mu M) on the content of carotenoids, phenolic compounds, and glucosinolates present in undigested extracts and intestinal-digested fractions of 7 day old Red Russian kale sprouts were evaluated. Moreover, the effect of undigested extract and digested kale on cellular antioxidant activity (CAA) and nitric oxide (NOx) production was assessed. Kale sprouts treated with Se showed higher levels of glucosinolates (53.2%) and lutein (149.3%), whereas phenolic content remained unchanged. After in vitro digestion, a significant liberation of lutein was observed in all samples, mainly the Se-treated sprouts (210.3%). On the other hand, phenolics and glucosinolates suffered significant losses after digestion in vitro. The treatments did not cause a significant change in phenolic content compared to control sprouts; however, Se treatment significantly preserved the concentration of glucoraphanin (70.8%%), glucobrassicin (58.2%), 4-methoxyglucobrassicin (41.6%), and total glucosinolates (63.2%) in kale compared with that in control sprouts. In correlation, the maximum percentage of CAA and NOx was achieved in the undigested extract and intestinal-digested fraction from kale sprouts treated with Se. Kale treated with Se, with higher levels of lutein and glucosinolates, may contribute to the defense against oxidant factors and modulate inflammation at the cellular level.