Herbs Phytochemicals

Dr. Meskin s major areas of research interest include (1) hepatic drug metabolism and the effects of nutritional factors on drug metabolism and clearance (2) nutrient-drug interactions (3) the role of bioactive non-nutrients (phytochemicals, herbs, botanicals, and nutritional supplements) in disease prevention and health promotion (4) fetal pharmacology and fetal, maternal, and pediatric nutrition (5) nutrition education and (6) the development of educational programs for improving science literacy and combating health fraud. 

The dense fluid that exists above the critical temperature and pressure of a substance is called a supercritical fluid. It may be so dense that, although it is formally a gas, it is as dense as a liquid phase and can act as a solvent for liquids and solids. Supercritical carbon dioxide, for instance, can dissolve organic compounds. It is used to remove caffeine from coffee beans, to separate drugs from biological fluids for later analysis, and to extract perfumes from flowers and phytochemicals from herbs. The use of supercritical carbon dioxide avoids contamination with potentially harmful solvents and allows rapid extraction on account of the high mobility of the molecules through the fluid. Supercritical hydrocarbons are used to dissolve coal and separate it from ash, and they have been proposed for extracting oil from oil-rich tar sands. 

A wide diversity of herbal remedies have purported abilities to stimulate defense functions. Complexes of carbohydrate and lignin, which are present in some herbs, modulate enteric immune functions (Kiyohara et al, 2000), and the changes in cytokine secretion (Matsumoto and Yamada, 2000) can trigger systemic responses. The polysaccharides present in other herbal medicines augment production of immunoglobulin (Ig) A by the Peyer s patches in the small intestine (Sakushima et al, 1997 Yu et al, 1998). The responses of the enteric immune system to lectins are variable (Pusztai 1993), and can elicit systemic responses (Lavelle et al, 2000). Other phytochemicals provide protection by inducing detoxification pathways in mucosal cells (Williamson et al, 1998). 

Because of the great diversity of phytochemicals in fruits, vegetables, herbs and spices, only the major structural classes in the most common food plants, have been selected for discussion (see below and Figs. 15.2 and 15.3, for example, phytochemicals). These are also the phytochemicals for which there is generally the greatest information on food composition and health effects. 

This chapter reviews recent findings about the health benefits of phytochemicals present in fruits, vegetables, nuts, seeds, and herbs, including phenolics, carotenoids, sterols, and alkaloids. These phytochemicals are extracted using emerging technologies such as supercritical carbon dioxide (SC-CO2) extraction, PEF, MWE, HPP, UE, and OH. The impact of important parameters related to sample preparation (particle size and moisture content) and extraction process (temperature, pressure, solvent flow rate, extraction time, and the use of a cosolvent) on the efficiency of extraction and on the characteristics of the extracted products is evaluated based on an extensive review of recent literature. The future of extraction of phytochemicals is certainly bright with the... 

Table 9.4. Extraction of phytochemicals from herbs using emerging technologies.

Temperature and pressure. Most of the studies for the extraction of phytochemicals from herbs using SC-CO2 were performed at temperatures of 40-70°C and pressures of 14 10 MPa (see Table 9.4). The influence of temperature and pressure using... 

Flow rate and extraction time. No report was found for the effect of flow rate in the extraction of phytochemicals from herbs. Extractions at lower pressures and/or temperatures required prolonged time and large amounts of CO2 to achieve the same yield as reported for the extraction of caffeine, theophylline, and theobromine from mate tea leaves (Saldana and others 1999,2002a). 

Duke, J.A. Handbook of Phytochemical Constituents of Grass, Herbs, and Other Economic Plants (Boca Raton. FL CRC Press, 1992). 

A recent publication by James A. Duke lists the phytochemical constituents of generally-regarded-as-safe (GRAS) herbs (Duke, 2000a). It is also available as a searchable database on disk (WordPerfect 5.1 macros). There is also a volume dealing with 365 herbs having medicinal or folklore medicinal properties (Duke, 2000b). 

H. serrata and its related genera have been used as folk herbs for the treatment of memory disorder and schizophrenia in the east of China. Phytochemical studies disclosed that these plants contained mainly serratene-type triterpenes and Lycopodium alkaloids.In the early 1970s, Chinese scientists reported that the total alkaloids of H. serrata could relax the striated muscle and alleviate the symptom of myasthenia gravis on the animal model. Biodirected assay caused the phenolic alkaloids fraction to be spotlighted and the following chemical component isolation resulted in the finding of HA. ... 

Research in our laboratory has focused on cancer prevention in colon and skin by phytochemicals. We have recently studied apigenin, a tri-hydroxy flavone that is widely distributed in plants and resveratrol, a phytoalexin that is found in grapes, wine, peanuts, and Asian herbs. We initially found that topical apigenin inhibited chemically and ultraviolet (UV)-light induced skin cancer and that it was most effective in preventing cancer promotion. 

Duke J. A. (1992) Handbook of Phytochemical Constituents of GRAS Herbs and other Economic Plants. CRC Press, Boca Raton. 

This last category of saw palmetto product is a recent introduction to the world of herbs. Standardized products are manufactured to contain specific amounts of phytochemicals that the producers believe may be active constituents or that act as marker chemicals (a specific, easy-to-test-for component of the herb). The idea is that every capsule contains the exact same measure of the active substance. There are both pros and cons concerning this type of product and we will discuss them further in chapter 5. 

Tanninan acid phytochemical found in most tree barks. Tannins act as astringents, reducing secretions. Tincturea hydryalcoholic extract of herbs. 

Beckstrom-Sternberg SM, Duke JA. Potential for synergistic action of phytochemicals in spices. In Charalambous G, ed. Spices, Herbs, and Edible Fungi. New York Elsevier Sciences B.V., 1994. 

Duke 1992 A Duke, Jamnes A. 1992. Handbook of phytochemical constituents of GRAS herbs and other economic plants. Boca Raton, FL. CRC Press. 

While the first essential is to establish the identity of the plant, it cannot be assumed that correct identity alone guarantees efficacy and safety for a particular herb. The activity of the plant is due to the presence of one or more groups of phytochemicals. Various factors influence the amount of these phytochemicals in the plant. 

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