Glucobrassicin is a type of glucosinolate that can be found in almost all cruciferous plants, such as cabbages (e.g.broccoli), mustards, cress, and woad. As for other glucosinolates, degradation by the enzyme myrosinase is expected to produce an isothiocyanate, indol-3-ylmethylisothiocyanate. However, this specific isothiocyanate is expected to be highly unstable, and has indeed never been detected. The observed hydrolysis products when isolated glucobrassicin is degraded by myrosinase are Indole-3-carbinol and thiocyanate ion (plus glucose, sulphate, and hydrogen ion), which are envisioned to result from a rapid reaction of the unstable isothiocyanate with water. However, a large number of other reaction products are known, and indole-3-carbinol is not the dominant degradation product when glucosinolate degradation takes place in crushed plant tissue (Agerbirk et al., 2009) or in intact plants (Clay et al., 2009; Bednarek et al., 2009).
Indole-3-carbinol or products of additional reactions such as diindolylmethane may help prevent cancer, but the effect is still not completely understood. Some adverse effects may in fact be expected, at least at high doses (probably higher than you would get by eating vegetables).
Glucobrassicin is also known to be a highly active egg-laying stimulant of cabbage white butterflies such as the small white (Pieris rapae) and the large white (Pieris brassicae).
Several derivatives of glucobrassicin are known.
The compound itself was first isolated from Brassica plants, hence the ending of the name. When a second, similar natural product was discovered, it was named neoglucobrassicin. When further derivatives were discovered, a more systematic nomenclature was used.
Currently, the following five derivatives are known from plants:
- 1-methoxyglucobrassicin (=neoglucobrassicin),
- 1,4-dimethoxyglucobrassicin, and
The existence of a sixth derivative, 1-acetylglucobrassicin, has been suggested, but the data were insufficient so whether this compound exists or not in nature is not known (by 2008).
The three first mentioned derivatives are as frequent in crucifers as glucobrassicin itself. The additional two derivatives appear to be rare in nature. 4-methoxyglucobrassicin was recently reported to be a signal molecule involved in plant defence against bacteria and fungi (Clay et al., 2009; Bednarek et al., 2009).
Agerbirk, N., De Vos, M., Kim, J. H., Jander, G. (2009) Indole glucosinolate breakdown and its biological effects. Phytochemistry Reviews 8, 101-120.
Clay, N. K., Adio, A. M., Denoux, C., Jander, G., Ausubel, F. M. (2009) Glucosinolate metabolites required for an Arabidopsis innate immune response. Science 323, 95-101.
Bednarek, P., Pislewska-Bednarek, M., Svatos, A., Schneider, B, Doubsky, J., Mansurova, M., Humphry, M., Consonni, C., Panstruga, R., Sanchez-Vallet, A., Molina A., Schultze-Lefert, P. (2009) A glucosinolate metabolism pathway in living plant cells mediates broad-spectrum antifungal defense. Science 323, 101-106.