Abstract
Varieties and cultivars of the cruciferous vegetable Brassica oleracea are widely presumed to elicit positive influences on mammalian health and disease, particularly related to their indole and sulforaphane content. However, there is a considerable gap in knowledge regarding the mechanisms whereby these plant-derived molecules elicit their beneficial effects on the host. In this study, we examined the chemical variation between B. oleracea varieties and evaluated their capacity to both activate Nrf2 in the Drosophila intestine and elicit cytoprotection. Ten types of edible B. oleracea were purchased and B. macrocarpa was wild collected. Fresh material was dried, extracted by double maceration and green kale was also subjected to anaerobic fermentation before processing. Untargeted metabolomics was used to perform Principal Component Analysis. Targeted mass spectral analysis determined the presence of six indole species and quantified indole. Extracts were tested for their capacity to activate Nrf2 in the Drosophila intestine in third instar Drosophila larvae. Cytoprotective effects were evaluated using a paraquat-induced oxidative stress gut injury model. A "Smurf" assay was used to determine protective capacity against a chemically induced leaky gut. Extracts of Brussels sprouts and broccoli activated Nrf2 and protected against paraquat-induced damage and leaky gut. Lacto-fermented kale showed a cytoprotective effect, increasing survival by 20% over the non-fermented extract, but did not protect against leaky gut. The protective effects observed do not directly correlate with indole content, suggesting involvement of multiple compounds and a synergistic mechanism.