The Genus Brassica as Source of Bioactive Compounds

The genus Brassica includes many species of great economic importance as a source of seed oil (B. rapa, B.oleracea, B. napus…), and are also known to be a good source of bioactive compounds such as glucosinolates, polyphenols, carotenoïds and vitamins (Valeria et al., 2013). These bioactive compounds found in Brassicaceae crops are known to have a beneficial effects on human nutrition and health, including, anti-oxidant, anti-inflammatory, anti-microbial, anti-allergic and cytotoxic anti-tumor activity (Cartea et al., 2011). It was provided that the consumption of a diet rich in Brassica vegetables has been associated with inhibitions of chemically induced carcinogenic in laboratory animals and human (Ioana et al., 2012).

Brassica tournefortii (Brassicaceae), called African mustard is an annual herb plant growing wild in the Mediterranean regions in North Africa and the Middle East (Minnich and Sandres, 2000). It’s growing, especially in the sandy soils and the regions with the eolian sediment (Sanchez-Flores, 2007). Little information is available in the literature about B. tournefortii chemical composition and biological activities. Formerly, B. tournefortii was collected and used as cooked legume with traditional meals. Our preliminary work, have shown that collected B. tournefortii leaves accumulated low secondary metabolite levels and displayed a weak bioactivity (unpublished data). Hence, we planned to subject B. tournefortii samples to short term Kombucha fermentation in order to track potential production of new metabolites and to evaluate their bioactivity.

Kombucha is a refreshing drink obtained by fermentation procedure, for about 14 days with a symbiotic culture of several indigenous bacteria (Acetobacter and Gluconobacter) and yeasts (Saccharomyces spp and non-Saccharomyces spp) (Malbasa et al., 2014). Most of the studies suggest that ‘tea fungus’’ return’s back from the Southeast of Asia, Japan, Tibet or Mauchuria and date of thousands years ago (Jarrel et al., 2000). A floating cellulosic pellicle layer and the sour liquid broth are the two portions which compose the ‘tea fungus’’. Many works reported that Kombucha beverage consumption claimed to be a prophylactic agent to the beneficial health effect (Chen and Liu, 2000; Srihari and Satyanarayana, 2012). Nowadays, the preparation of Kombucha doesn’t limit its self in the cultivation of sweetened black tea. However, other substrates take place to be used instead of the tea, such as; fruit drink, wine, milk and herbal teas, lemon balm tea, green tea. Some of these new substrates have shown to have better stimulation effect on Kombucha fermentation compared to the original Kombucha tea (Vitas et al., 2013). In the current study, B. tournefortii dried leaves were incubated for two weeks with Kombucha “tea fungus” under controlled conditions. At the end of treatment, fermented extracts were compared with unfermented control ones in terms of their (i) total phenolic content (ii) antioxidant, anti-Alzheimer, anti-xanthine oxidase and cytotoxic activities. Obtained data were discussed to highlight the fermentation-related changes on chemical composition and bioactivity of B. tournefortii leaves.