Antioxidants, Nutraceuticals and Functional Foods

by Robert Ronzio, Ph.D.

A variety of herbs and spices possess estrogen-like and progesterone-like properties

Extracts of over 150 different herbs, spices and foods were assayed in terms of their relative capacity to compete with either estradiol or progesterone binding to receptors for these hormones in cultured human breast cancers. Herbs and spices with the highest estrogen receptor binding activity (that is, with high levels of phytoestrogens) were soy, thyme, licorice, red clover, turmeric, hops and verbena. The six highest progesterone-binding herbs and spices (ie, highest in phytoprogestins) were thyme, oregano, verbena, turmeric, red clover and damiana. The abilities of extracts of these plants to regulate the growth of estrogen receptor-positive and estrogen receptor-negative breast cancer cell lines was also examined. Their abilities to regulate production of progestin-induced alkaline phosphatase, in progesterone receptor-positive cells were also compared. Herbal extracts, high in phytoestrogens that bound to estrogen receptors, either stimulated growth (that is, they functioned as estrogen agonists) or they had no activity (they were neutral). In contrast, extracts that were high in phytoprogestins either inhibited alkaline phosphatase (ie, they functioned as progesterone antagonists) or they had no effect (they were neutral) in these test systems.

Comment: Of the plant materials tested, culinary herbs and spices such as thyme, oregano, turmeric and hops contained relatively large amounts of estrogen receptor binding activity. Consequently, these herbs and spices may act as phytoestrogens in vivo, and foods containing them would be expected to possess mild estrogenic activity.

The most potent estrogen-binding products were soy milk, licorice and red clover. All three have been proposed to have chemopreventive properties. In addition, licorice, red clover and motherwort could be direct-acting estrogen agonists. Interestingly, dong quai, damiana, and black cohosh exhibited little estrogen receptor binding activity in these studies. However, these three herbs are often incorporated into protocols employed to normalize female hormone imbalances. It is not clear whether these latter herbs contain precursors that are converted to estrogens in vivo, or whether they mediate other receptor systems or modulate metabolism of endogenous hormones.

Zava DT et al. Estrogen and progestin bioactivity of foods, herbs and spices. PSEBM 1998; 217:369-78

Botanical antioxidants may counter the toxicity of certain chemotherapeutic agents

Tinospora cordifolia is widely used in botanical formulations in India and China. This study asked whether antioxidant properties could be associated with its physiological effects. Tinospora cordifolia extract (TCE) quenched superoxide radicals and hydroxyl radicals in vitro assays. The extract also inhibited lipid peroxidation in isolated liver microsomal fractions. The antioxidant properties of TCE were further studied in cell cultures. When incubated with activated macrophages, TCE inhibited the production of superoxide generated by the oxidative burst of these immune cells.

A variety of chemotherapeutic agents such as cyclophosphamide cause free radical-induced cytotoxicity as a side effect when they are activated by mixed function oxidases. Mice administered 10 doses of cyclophosphamide had a drastically suppressed bone marrow cell population. The action of Tinospora cordifolia was studied in this system. Treatment with cyclophosphamide and together with TCE (50 mg iv) entirely blocked the cyclophosphamide-induced cytotoxicity in bone marrow cells and in lymphocytes of mice. Furthermore, TCE

reduced lipid peroxidation due to drug exposure in the liver of test animals.

Comment: Tinospora cordifolia is reported to benefit the immune system in a variety of ways. These experiments suggest that its ability to scavenge free radicals and to block free radicals and to inhibit radical-induced membrane damage may be the underlying feature of many of the biological activities of this herb. Cyclophosphamide is inert until activated by cytochrome P450 to produce a DNA alkylating agent capable of killing cells. This process produces free radicals as a by-product and TCE may quench them, and thus limit oxidative damage associated with this agent. The key question remains, do these radical quenching effects occur when the herb is ingested orally?

Mathew S, Kuttan G. Antioxidant activity of Tinospora cordifolia and its usefulness in the amelioration of cyclophosphamide induced toxicity. J Exp Clin Cancer Res 1997; 16:407-11.

Culinary spices can inhibit several food-borne pathogens

The antibacterial properties of 21 plant essential oils were studied using five different pathogenic strains, including Campylobacter jejuni, Salmonella enteritis, Escherichia coli, Staphylococcus aureus and Listeria monocytogenes. Generally, the Gram-positive bacteria were more sensitive to inhibition by the plant oils than Gram-negative species. The oils prepared from bay, cinnamon, clove and thyme possessed the highest bacteriostatic properties, with effective concentrations of 0.075% or less.

Comment. There has been a significant increase in food-borne illness in recent years. For example, 82,041 cases of food-associated illness were reported in 1995. Bacterial pathogens account for a large percentage of these cases. For example, Campylobacter jejuni is a recently recognized food pathogen, yet it is currently the most common cause of infectious intestinal disease. Listeria monocytogenes is especially troublesome because this bacterium is able to multiply in refrigerated foods, unlike most other food-borne pathogens. While it is unlikely that concentrations of these oils of culinary herbs and spices can be routinely used in foods at sufficiently high concentrations to kill bacteria, this study suggests that concentrations sufficient to inhibit bacterial growth could improve food safety if the pathogen load is low.

Smith-Palmer A, et al. Antimicrobial properties of plant essential oils and essences against five important food-borne pathogens. Letters Applied Micobiol 1998; 26:118-22.

Pau d'arco may induce differentiation in de-differentiated cells

Pau d'arco tea, derived from the bark of a South American tree, has a long history of use in folk medicine. The authors developed a cell culture assay based upon the ability to induce differentiation in a mouse leukemia cell line in order to examine properties of water extracts of pau d'arco. Control compounds that induced differentiation in this assay included retinoic acid and butyric acid. Pau d'arco extracts contained two active components, one of which was identified as lapachol, a vitamin K analog. The half maximum response for cell differentiation was obtained at low lapachol concentration (0.1 mcg/ml). The concentrations of lapachol and pau d'arco required for differentiation were much less than required to demonstrate cytotoxicity. Vitamin K inhibited the differentiating activity of lapachol and pau d'arco extracts.

Comment. We usually think of vitamin K in the context of activation of prothrombin and blood clotting. However, vitamin K is needed for the post-translational modification (carboxylation) of a variety of precursor proteins to allow them to bind calcium so they can attach to receptors. The differentiation program of specialized cells is complex and in theory, conversion of a transformed cell type back to a differentiated form by pau d'arco could involve protein receptors, signal transduction systems, transcriptional controls and translational or post-translational control mechanisms. Since vitamin K blocked the action of lapachol and maintained the dedifferentiated state of mouse leukemia cells, this suggests lapachol inhibits a vitamin K-dependent step. The role of vitamin K in erythroid differentiation programs involves post-translation modification: Vitamin K is required for expression of a gene product called Axl. When over-expressed in tumor cells, Axl acts as a transforming gene, requiring vitamin K for its full effect. By inhibiting the reduction of vitamin K, lapachol may block vitamin K utilization and counter Axl over-expression in transformed cells. Because lapachol can inhibit vitamin K-dependent reactions generally, large amounts of pau d'arco could potentially interfere with blood clotting mechanisms and other K-dependent processes.

Dinnen RD, Ebisuzaki. The search for novel anticancer agents; a differentiation-based assay and analysis of a folklore product. Anticancer Research 1997; 17:1027-34.

What is the long term impact of genetically modified crops?

This is the fourth year in which genetically altered crops have been commercially available in the U.S. These crops include corn, cotton, soybeans and potatoes. The new plants represent genetically altered plants that produce their own pesticides, or resist the action of commercial herbicides. As an example of the complexity of this issue, the New Leaf potato marketed by Monsanto has been engineered to produce the organic pesticide Bt, which comes from a common soil bacterium. Bt has been used by organic growers for decades. It is very effective for potato beetles, one of the most damaging pests, and it is apparently safe for humans and animals.

In contrast to European countries, biotech foods are not identified as such on food labels in this country. Because Bt is a pesticide, it is exempt from FDA regulation, and information about pesticides is specifically excluded from food labels. New proteins engineered into foods are classified as food additives (if they are not pesticides), and the FDA has ruled that biotech plant foods need to be labeled only if they contain an allergen or if they have been "materially" modified- a gray area.

Future insect resistance to Bt is a concern expressed by several groups. They fear that use of Bt crops will become widespread, and so much Bt will be released into the environment that insects will become resistant to it. In recognition of this potential threat, the EPA and Monsanto developed a "resistance-management" program, in which certain portions of acreage must be given to non-Bt crops. Theoretically, Bt-resistant insects would most likely mate with nonresistant beetles, thus diluting any new gene for resistance. However, it is not clear how large refuges will have to be and in the case of New Leaf potatoes, the plan is voluntary for participating farmers. Non-potato fields become "refuges," though they may have been sprayed extensively with pesticides.

In planting a single type of potato, such as Red Russets demanded by fast food franchises, farmers may employ up to ten applications of chemical fertilizers and eight applications of potent fungicides such as Bravo in order to control fungal infection (late blight). Crops are also sprayed for aphids to block a viral infection that causes a cosmetic defect to potatoes destined for a market that demands unblemished french fries. To prevent such an infection, farmers may need extremely potent pesticides such as Monitor. By using a genetically engineered plant such as New Leaf, farmers can skip several pesticide sprayings, and avoid the use of Monitor at a significant savings. With small profit margins this is a powerful incentive to use genetically altered potatoes.

By license agreement with the farmer, Monsanto agents are free to test fields to determine whether the patented strains are being used as authorized. To further control use of patented plants, industry has used another biotech strategy. In partnership with the USDA, businesses have developed a gene complex called Terminator. When implanted into a crop, Terminator assures that seeds will be sterile. In other words, control of such new crops will pass to seed companies and their owners.

Comment: The average U.S. farmer grows enough food to meet the needs of 100 people. This enormous productivity requires a high technological input, including synthetic fertilizers, chemical pesticides, energy and machinery. As an example, a potato farmer may require $1965 per acre to pay for chemicals, energy, water and seed for a crop would potentially earn $1980 for the 20 tons of potatoes per acre. Elimination of a portion of the insecticide spraying now used would be an immediate financial boon. However, monoculture of genetically homogenous crops can increase vulnerability to pests and disease. In other words, biotechnology is being used to create magic bullets, rather than to examine ecological aspects of sustainable agriculture. While organic farming is labor intensive, crop rotation, the use of peas and alfalfa to attract beneficial insects or importing ladybugs entail only small outlays for chemicals. In addition, an organic potato farmer may plant eight different types of potatoes, out of the belief that biodiversity is the best defense against an imbalanced ecosystem.

Pollan, M. "Playing God in the garden." New York Times Magazine October 25, 1998