Natural products for cancer prevention: a global perspective
Introduction
Mortality that results from the common forms of cancer is still unacceptably high. Despite many therapeutic advances in the understanding of the processes in carcinogenesis, overall mortality statistics are unlikely to change until there is a reorientation of the concepts for the use of natural products as new chemopreventive agents. Natural or semisynthetic compounds may be used to block, reverse, or prevent the development of invasive cancers. Cellular carcinogenesis forms the biologic basis for the identification of preventive products, the assessment of their activity, and ultimately the success or failure of a therapy.
As long ago as 480 BC, Hippocrates recognised that several aspects of what we now call “lifestyle” must come together to produce a healthy body. He said, “Positive health requires a knowledge of man's primary constitution and the powers of various foods, both those natural to them and those resulting from human skill.” What Hippocrates called “man's primary constitution,” we today call “genetics,” and we can infer that foods “resulting from human skills” can be equated with today's diet.
Cancers may be caused in one of three ways, namely incorrect diet, genetic predisposition, and via the environment. At least 35% of all cancers worldwide are caused by an incorrect diet, and in the case of colon cancer, diet may account for 80% of the cases. When one adds alcohol and cigarettes to their diet, the percentage may increase to 60%. Genetic predisposition to cancer lends itself to ∼20% of cancer cases, thus leaving the majority of cancers being associated with a host of environmental carcinogens. Doll and Peto (1981) reported that in the United States the major environmental carcinogens include air and water pollution, radiation, and medication.
Section snippets
Carcinogens
The majority of human cancers result from exposure to environmental carcinogens; these include both natural and manmade chemicals, radiation, and viruses. Carcinogens may be divided into several classes, as shown in Table 1. (1) Genotoxic carcinogens, if they react with nucleic acids. These can be directly acting or primary carcinogens, if they are of such reactivity so as to directly affect cellular constituents. (2) Alternatively, they may be procarcinogens that require metabolic activation
Epidemiological studies
A recent United States study was conducted involving 628 men under the age of 65 years with newly diagnosed prostrate cancer. They were placed on a trial of fruit and vegetables for 5 years. It was found that while fruit was not protective, vegetables, especially cruciferous vegetables (cabbage, broccoli, brussel sprouts, and cauliflower), reduced risk. Tomatoes containing lycopene are protective against prostrate cancer, and when α-tocopherol (a variety of vitamin E) is added to lycopene,
Natural products and defense against carcinogenesis
The literature indicates that many natural products are available as chemoprotective agents against commonly occurring cancers occurring worldwide. A major group of these products are the powerful antioxidants, others are phenolic in nature, and the remainder includes reactive groups that confer protective properties. These natural products are found in vegetables, fruits (Table 3), plant extracts, and herbs (Table 4). Although the mechanism of the protective effect is unclear, the fact that
Mechanisms of action of natural products on carcinogenesis
In the last decade, advances in cancer research have enhanced our understanding of cancer biology and genetics. Among the most important of these is that the genes that control apoptosis have a major effect on malignancy through the disruption of the apoptotic process that leads to tumor initiation, progression, and metastasis. Therefore, one mechanism of tumor suppression by natural products may be to induce apoptosis (Table 4), thereby providing a genetic basis for cancer therapy by natural
Summary
The top two causes of cancer are related to dietary habits and tobacco smoke, and as such, it is largely a preventable disease. The incidence of cancer can thus be substantially reduced by diet modification. Diets rich in vegetables, fruits, and legumes contain large quantities of antioxidants that protect against the deleterious action of free radicals that may lead to cancer development. Consumption of reduced amounts of red meats, saturated fat, salt, and sugar and the avoidance of tobacco
Acknowledgements
We are particularly grateful to the Medical Research Council and the National Research Foundation, South Africa for research grant support.
References (115)
- et al.
Modulation of omega-3/omega-6 polyunsaturated ratios with dietary fish oils in men with prostate cancer
Urology
(2001) - et al.
Antimutagenicity profiles of some natural substances
Mutat Res
(1992) - et al.
Mitochondrial glutathione depletion by glutamine in growing tumor cells
Free Radic Biol Med
(2000) - et al.
Conjugation position of quercetin glucuronides and effect on biological activity
Free Radic Biol Med
(2000) - et al.
Pilot study of dietary fat restriction and flaxseed supplementation in men with prostate cancer before surgery: exploring the effects on hormonal levels, prostate-specific antigen, and histopathologic features
Urology
(2001) - et al.
Dietary strategies to counteract the effects of mycotoxins: a review
J Food Prot
(2001) The evolving role of carotenoids in human biochemistry
Nutrition
(2001)- et al.
Evaluation of butylated hydroxyanisole, myo-inositol, curcumin, esculetin, resveratrol, and lycopene as inhibitors of benzo[a]pyrene plus 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced lung tumorigenesis in A/J mice
Cancer Lett
(1999) - et al.
Potent growth inhibitory activity of a novel Ornithogalum cholestane glycoside on human cells: induction of apoptosis in promyelocytic leukemia HL-60 cells
Cancer Lett
(1996) - et al.
Resveratrol and quercetin inhibit angiogenesis in vitro
Cancer Lett
(2001)
The contribution of endogenous sources of DNA damage to the multiple mutations in cancer
Mutat Res
Activation of caspase cascades in Korean mistletoe (Viscum var. coloratum) lectin-II-induced apoptosis of human myelo U937 cells
Gen Pharmacol
Resveratrol isolated from Polygonum cuspidatum root prevents tumor growth and metastasis to lung and tumor-induced neovascularization in Lewis lung carcinoma-bearing mice
J Nutr
SELECT: the next prostrate cancer prevention trial. Selenium and vitamin E cancer prevention trial
J Urol
Resveratrol suppresses hepatoma cell invasion independently of its anti-proliferative action
Cancer Lett
Berberine complexes with DNA in the berberine-induced apoptosis in human leukemic HL-60 cells
Cancer Lett
An investigation on the antimutagenic properties of South African herbal teas
Mutat Res
Intake of specific carotenoids and risk of lung cancer in 2 prospective US cohorts
Am J Clin Nutr
Resveratrol reverses tumor-promoter-induced inhibition of gap-junctional intercellular communication
Biochem Biophys Res Commun
Glutamine potentiates TNF-α-induced tumor cytotoxicity
Free Radic Biol Med
Don't thank fiber; blame meat and milk
Am J Gastroenterol
Beta-carotene at high concentrations induces apoptosis by enhancing oxy-radical production in human adenocarcinoma cells
Free Radic Biol Med
In vitro antimutagenic and in vivo anticlastogenic effects of carotenoids and solvent extracts from fruits and vegetables rich in carotenoids
Mutat Res
Vitamin C augments chemotherapeutic response of cervical carcinoma HeLa cells by stabilizing p53
Biochem Biophys Res Commun
Redox environment of the cell as viewed through the redox state of the glutathione disulfide/glutathione couple
Free Radic Biol Med
Inhibition of malignant trophoblastic cell proliferation in vitro and in vivo by melatonin
Life Sci
Docetaxel compared with sequential methotrexate and 5-fluorouracil in patients with advanced breast cancer after anthracycline failure: a randomised phase III study with crossover on progression by the Scandinavian Breast Group
Eur J Cancer
The natural tyrosine kinase inhibitor genistein produces cell cycle arrest and apoptosis in Jurkat T-leukemia cells
Leuk Res
Carotenoids and carotenoids plus vitamin E protect against ultraviolet light-induced erythema in humans
Am J Clin Nutr
Docetaxel versus doxorubicin in patients with metastatic breast cancer who have failed alkylating chemotherapy: a preliminary report of the randomized phase III trial. 303 Study Group
Semin Oncol
Role of diet modification in cancer prevention
Biofactors
In vivo anti-cancer activity of RC-18: a plant isolate from Rubia cordifolia, Linn. against a spectrum of experimental tumour models
Chemotherapy
Anticarcinogenic effect of a polyphenolic fraction isolated in human prostrate carcinoma DU145 cells: modulation of cell cycle regulators and induction of G1 arrest
Mol Carcinog
Green tea constituent epigallocatechin-3-gallet and induction of apoptosis and cell cycle arrest in human carcinoma cells
J Natl Cancer Inst
Resveratrol causes WAF-1/p21-mediated G1-phase arrest of cell cycle and induction of apoptosis in human epidermoid carcinoma A431 cells
Clin Cancer Res
Soy diets containing varying amounts of genistein stimulate growth of estrogen-dependent (MCF-7) tumors in a dose-dependent manner
Cancer Res
Effects of the flavonoid drug quercetin on the response of human prostate tumours to hyperthermia in vitro and in vivo
Int J Hypertherm
Structure function relationship of the dietary anticarcinogen ellagic acid
Carcinogenesis
Whey protein concentrate (WPC) and glutathione modulation in cancer treatment
Anticancer Res
Valepotriates, a new class of cytotoxic and antitumor agents
Planta Med
Suppression of angiogenesis, tumor growth, and wound healing by resveratrol, a natural compound in red wine and grapes
FASEB J
Antimutagenic activity of natural phenolic compounds present the common bean (Phaseolus vulgaris) against aflatoxin B1
Food Addit Contam
Natural antitumor compounds of vegetable origin
G Batteriol Virol Immunol
Clinical pharmacokinetics of irinotecan
Clin Pharmacokinet
Mode of action of GCE: an active anticancer principle isolated from an indigenous plant Gymnosporia rothiana laws
Indian J Exp Biol
Effects of aflatoxin and carotenoids on growth performance and immune response in mule ducklings
Comp Biochem Physiol Toxicol Pharmacol
The in vitro cytotoxicity of ascorbate depends on the culture medium used to perform the assay and involves hydrogen peroxide
Antioxid Redox Signal
Molecular mechanisms of anticancer activity of natural dietetic products
J Mol Med
Echinacea purpurea and melatonin augment natural-killer cells in leukemic mice and prolong life span
J Altern Complement Med
Oral glutamine in the prevention of fluorouracil induced intestinal toxicity: a double blind, placebo controlled, randomised trial
Gut
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