Bioactive compounds accumulation in Brassica sprouts grown under microgravity and darkness: A novel approach to functional foods.

Sprouts, rich in bioactive phytochemicals, are good candidates for functional food. This study brings novel evidence on the impact of microgravity and darkness conditions on the growth and bioactive compounds' synthesis in Brassica sprouts. In microgravity grown sprouts, the 50 to 80 % increase in abscisic acid (stress phytohormone) amount was noted, in comparison to control. Microgravity combined with darkness caused 2-fold increase in polyphenolics' synthesis in broccoli sprouts, and 3-fold increase in sulfur compounds' synthesis in kohlrabi sprouts. In contrast, kale showed the greatest response to microgravity alone, while Brussels sprouts responded the least. Kohlrabi sprouts revealed the best antioxidant effect (6.48 to 23.30 μM Fe/100 g dw), enhanced by microgravity and darkness conditions. The observed changes in polyphenolics' and glucosinolates' amounts in most cases correlated positively with the increase in the activity, of phenylalanine ammonia-lyase, and cytochrome P450 enzymes, being key drivers of biosynthesis of these compounds, respectively.