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Inhibition of carcinogenesis by some minor dietary constituents
Abstract:
Previous work has shown that food contains a large number of minor dietary constituents that can inhibit the occurrence of cancer. Additional inhibitors from four different natural sources will be the subject of this presentation. 1. Citrus fruit oils. Orange, tangerine, lemon, and grapefruit oils given p.o. induce increased glutathione (GSH) S-transferase activity in tissues of the mouse. When fed in the diet prior to and during the course of administration of benzo(a)pyrene (BP), the four citrus fruit oils inhibit formation of tumors of both the forestomach and lungs of mice. When fed either before or after the administration of 7,12-dimethylbenz(a)anthracene (DMBA) orange oil inhibits mammary tumor formation. 2. Garlic oil. Allyl methyl trisulfide (AMT), a constituent of garlic oil, has been synthesized recently. When given p.o. 96 and 48 hr prior to BP, AMT inhibits the occurrence of forestomach tumors in mice. 3. Green coffee beans. Two diterpene esters, kahweol palmitate and cafestol palmitate, which are potent inducers of GSH S-transferase activity have been isolated from coffee beans. When administered p.o. prior to DMBA the two diterpene esters inhibit mammary tumor formation. 4. Cruciferous vegetables. Several glucosinolates occur in cruciferous vegetables. Efficient procedures for the isolation of these compounds have been developed recently. The inhibitory effects of three of these i.e. glucobrassicin, glucotropaeolin, and glucosinalbin were studied in several animal models. Glucobrassicin caused substantial inhibition of BP-induced neoplasia of the lung and forestomach of the mouse and DMBA-induced neoplasia of the breast in rats. Glucosinalbin and glucotropaeolin are less active in these systems. In addition to protective effects, indoles derived from the hydrolysis of glucobrassicin have potential harmful properties. The implications of multiple properties and factors which may determine their consequence will be discussed.
Insights
Natural compounds from citrus oils, garlic, coffee beans, and cruciferous vegetables show promise in inhibiting cancer formation by boosting glutathione S-transferase activity. Further research is needed to explore their full potential and any risks.
Area of Science:
- Nutritional Biochemistry
- Chemoprevention
- Natural Products Chemistry
Background:
- Dietary constituents play a role in cancer prevention.
- Identifying novel natural inhibitors is crucial for chemoprevention strategies.
Purpose of the Study:
- To investigate the cancer-inhibitory effects of four natural sources: citrus fruit oils, garlic oil, green coffee beans, and cruciferous vegetables.
- To evaluate the impact of these natural compounds on carcinogen-induced tumor formation in animal models.
Main Methods:
- Administration of citrus oils, allyl methyl trisulfide (from garlic), diterpene esters (from coffee beans), and glucosinolates (from cruciferous vegetables) to mice and rats.
- Assessment of tumor incidence following exposure to carcinogens like benzo(a)pyrene (BP) and 7,12-dimethylbenz(a)anthracene (DMBA).
- Measurement of glutathione S-transferase (GSH S-transferase) activity in animal tissues.
Main Results:
- Citrus oils increased GSH S-transferase activity and inhibited BP-induced forestomach and lung tumors, and DMBA-induced mammary tumors.
- Allyl methyl trisulfide inhibited forestomach tumors induced by BP.
- Diterpene esters from coffee beans inhibited DMBA-induced mammary tumors.
- Glucobrassicin from cruciferous vegetables significantly inhibited lung, forestomach, and breast tumors, while glucotropaeolin and glucosinalbin showed less activity.
Conclusions:
- Citrus oils, garlic oil constituents, coffee bean diterpenes, and specific glucosinolates possess significant cancer-inhibitory properties.
- These natural compounds demonstrate potential as chemopreventive agents through mechanisms including the induction of GSH S-transferase.
- Further investigation into the beneficial and potentially harmful properties of derived compounds, such as indoles from glucobrassicin, is warranted.