Mustard (Brassica juncea) belong to the Cruciferae family. The seeds of this plant are widely used as a traditional pungent spice, a source of edible oil and protein and as medicine. It is an indispensable component of curry powders, pungent sauces. The pungent flavor is developed when the seeds are ground with water initiating the hydrolysis of the thioglucosides present in the seeds by the enzyme myrosinase. The hydrolytic conditions affect the composition and yield of the mustard essential oil, the main component of which is allyl isothiocyanate (AITC).

Isothiocyanates (ITCs) are present in a number of cruciferous plants such as cabbage, cauliflower, broccoli, brussel sprouts in the form of glucosinolates are thus part of regular human diet. Glucosinolate levels have been estimated to be as high as 180 mg/g in some vegetables.

To date, the most important biological property of ITCs is their ability to prevent chemical carcinogenesis. More than 20 ITCs have been shown to inhibit tumorigenesis induced by a variety of chemical carcinogens in animal models, inhibiting tumorigenesis in the lung, stomach, colon, liver, esophagus, bladder and mammary glands. Several epidemiological studies suggest that humans who consume higher amounts of ITCs (through food) might be less likely to develop lung and colon cancer.

Mechanistic studies have shown that the remarkable anticarcinogenic property of ITCs stem from their ability to disrupt multiple steps in the carcinogenic process - reducing genetic damage by inhibition of carcinogen activating enzymes and induction of carcinogen detoxifying enzymes, inhibiting proliferation of genetically damaged cells as a result of induction of apoptosis and cell cycle arrest and inducing the differentiation of malignant cells.

Exposure of cancer cells to AITC and other ITCs for just 3 h was long enough for the inhibition of cell growth. - a fantastic performance indeed!

The anticarcinogenic potential of AITC and other ITCs is further strengthened by the finding that their metabiolites formed in vivo possess similar, if not more potent, anticarcinogenic activity in cultured cells and animal models

The ITCs are rapidly metabolized mainly through the mercapturic acid pathway in both humans and animals to produce various dithiocarbamate metabolites. These dithiocarbamates are merely carriers of ITCs as they are unstable and dissociate readily to ITCs.