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A study published today in the Journal of Agricultural & Food Chemistry claims that spraying broccoli with a plant hormone called methyl jasmonate, normally used in plant defence, can intensify its anti-cancer potential. Broccoli is known as a ‘super food’, contributing positively to a healthy diet. There are many claims, backed up by studies including animal models, that broccoli and broccoli sprouts can be protective against cancer. Some studies suggest that eating broccoli regularly can lead to lower rates of prostate, colon, breast, lung and skin cancers, although it should be noted that it can be difficult to be unambiguous about claims that eating broccoli can directly affect cancer incidence or progression.

These claims have centred mainly on the phytonutrient glucoraphanin (4-methylsulfinylbutyl glucosinolate), which is present in significant amounts in broccoli and is metabolised in vivo to the biologically active sulforaphane. Sulforaphane has been shown to target self-renewal in cancer stem cells (CSCs) in different cancer types via modulation of signalling intermediates including NF-κB, SHH, epithelial-mesenchymal transition and Wnt/β-catenin. Sulforaphane has also been tested pre-clinically in combination with chemotherapy with promising results. Such studies have led to interest in developing broccoli varieties which are enriched in glucoraphanin and therefore capable of making more sulforaphane.

In the current Journal of Agricultural & Food Chemistry study, sprays of methyl jasmonate were used in an attempt to alter glucosinolate composition, including glucoraphanin levels, in five commercial broccoli hybrids. The researchers from the University of Illinois in the USA found that sprays of methyl jasmonate significantly increased expression of several glucosinolates, including glucoraphanin, and of their hydrolysis products, including sulforaphane and several other glucosinolate derivatives with likely cancer-fighting potential. This was associated with increased quinone reductase (QR). QR is a member of the family of phase II enzymes which mediate detoxification processes of chemical carcinogens which can prevent the start of carcinogenesis. As well as the effect of methyl jasmonate, year-associated weather variables were also important.

These studies offer potential to maximise the cancer-fighting enzymes levels of broccoli and gives insight into the environmental elements that impact on this process. It seems there are potentially very compelling reasons why we should ‘eat our greens’.

Sources

KU, K.M, JEFFERY, E.H. and JUVIK, J.A. , 2013. Influence of Seasonal Variation and Methyl Jasmonate Mediated Induction of Glucosinolate Biosynthesis on Quinone Reductase Activity in Broccoli Florets. Journal of Agricultural and Food Chemistry, 2013; DOI: 10.1021/jf4027734

DE FIGUEIREDO, S.,M. et al., 2013. The anti-oxidant properties of isothiocyanates: a review. Recent Patents On Endocrine, Metabolic & Immune Drug Discovery, 7(3), pp. 213-225

JAMES, D. et al., 2012. Novel concepts of broccoli sulforaphanes and disease: induction of phase II antioxidant and detoxification enzymes by enhanced-glucoraphanin broccoli. Nutrition reviews, 70(11), pp. 654-665

LI, Y. and ZHANG, T., 2013. Targeting cancer stem cells with sulforaphane, a dietary component from broccoli and broccoli sprouts. England: Future Medicine Ltd.

American Chemical Society. "Maximizing broccoli's cancer-fighting potential." ScienceDaily, 16 Oct. 2013. [Accessed 16 Oct. 2013].