Broccoli, carcinogenicity

Apart from activators and inhibitors which bind to the active site of HDACs, there are also compounds which modulate the HDAC expression level in human body. One notable example is 3,3 -diindollylmethane (DIM, Fig. 23). DIM is an anti-carcinogenic compound mainly available in cruciferous vegetables with genus Brassica, like cabbage, broccoli, cauliflower, collard green etc. 

Fahey JW, Zhang Y, Talalay P. (1997) Broccoli sprouts An exceptionally rich source of inducers of enzymes that protect against chemical carcinogens. Proc Natl Acad Sci USA 94 10367-10372. 

Some secondary plant compounds have proven carcinogenic in laboratory rodents. These include D-limonene in orange juice 5-8-methoxypsoralen in parsley and parsnips and caffeic acid in coffee, but also in smaller amounts in apples, apricots, broccoli, Brussels sprouts, cabbage, cherries, kale, peaches, pears, and plums (Ames and Gold, 1990 Ames etal., 1990). How dangerous these compounds can be to human health, is still being debated. 

A related glucosinolate glucoraphanin is found in broccoli, and is associated with beneficial medicinal properties of this vegetable. This is hydrolysed to the isothiocyanate sulforaphane, which is believed to induce carcinogen-detoxifying enzyme systems. 

The present results also point to differences between the mammary tumor model and the ACT model for evaluating the potential cancer protective effects of Se in broccoli. A previous study (17) showed that high-Se broccoli florets decreased the number of DMH-induced ACT. Similarly, in the present study high-Se broccoli sprouts decreased DMH-induced ACT, but low-Se broccoli sprouts alone did not have any effect (Table 3). In the mammary tumor model, however, broccoli alone, similar to garlic alone (3), reduced the number of tumors (Table 1). This contrasting effect could be the result of a difference between tumor and preneoplastic lesion models, a difference between carcinogens, or a difference between mammary and colonic tissues. 

Nestle M (1997) Broccoli sprouts as inducers of carcinogen-detoxifying enzyme systems Clinical, dietary, and policy implications. Proc Natl Acad Sci USA 94, 11 149-11 151. 

Examples of phytochemicals and their biological effects include isothiocyanates and sulforaphane which are found in vegetables such as broccoli and have been shown to trigger enzyme systems that block or suppress cellular DNA damage and reduce tumor size in animal studies (4) Allylic sulfides, found in onions and garlic, can enhance immune function, increase the production of enzymes that help to excrete carcinogens, decrease the proliferation of tumor cells, and reduce serum cholesterol levels (5). Isoflavonoids in soy have also been shown to reduce serum cholesterol levels in humans (6). 

Products and Uses A chemical that triggers enzymes known to neutralize carcinogens in cells. Primarily found in cruciferous vegetables, broccoli, brussels sprouts, cabbage, and cauliflower. 

Zhang, Y. etal. (1992) A major inducer of anti-carcinogenic protective enzymes from broccoli isolation and elucidation of structure. Proc Natl Acad Sci USA 89 (6), 2399-2403... 

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