Herbs are sold in many forms, as fresh plant material in the pro- duce department of a grocery store, and as dried plant material in bulk, tea bags, capsules, or tablets. Fresh or dried plant material can be prepared as extracts, either sold in liquid form, or dried and formu- lated into tablets or capsules, both hard and soft. Some basic botani- cal preparations and formulations are described in the appendix to this chapter.
The diversity in plant preparations is illustrated by those available for commercially supplied Asian ginseng roots, which are graded ac- cording to their source, age, part of the root, and method of prepara- tion (Bahrke and Morgan, 1994). The root can be used fresh, or pre- pared as “white” ginseng (peeled and dried) or “red” ginseng (steamed and dried). The fresh root is often thinly sliced and taken with or without honey, or it can be boiled in soup. White or red gin- seng can be powdered, extracted, or made into a tea (Yun and Choi, 1998). The different ginseng root preparations differ in their chemical composition. As an example, we know that the heating process in the production of red ginseng converts the malonylginsenosides to their ginsenoside counterparts and also results in other chemical transfor- mations (Chuang et al., 1995).
DOSE
The preparations described are, by definition, of different strengths and composition. Thus the type of preparation will have an influence on the recommended dose. Teas prepared with hot water are usually quite dilute in contrast with extracts that are more concentrated. So it follows that the type of preparation must be taken into account in de- termining the dose. For example, peppermint tea may be drunk by the cupful, while peppermint oil is administered in doses of five hun- dredths of a milliliter (Wren, 1988).
BIOAVAILABILITY
The type of preparation, and formulation of the preparation, will have an influence on the ability of the chemical components of the
herb to be assimilated into the body. This is especially a concern with tablets and capsules whose contents must first dissolve before being absorbed. Coatings on the surface of tablet or capsules may be de- signed to either accelerate or delay dissolution (release of chemical constituents) in the gastrointestinal tract.
As an example, garlic products often have enteric coatings to delay dissolution until the garlic preparation reaches the intestine. The rea- son for this is that garlic powder contains the enzyme allinase, which is necessary to produce the active constituent allicin, and that enzyme is destroyed by the acidic pH of the stomach. Studies on the effective- ness of Kwai garlic to reduce elevated serum cholesterol levels have been inconsistent. A review found a highly significant difference in effectiveness between studies conducted before 1993 and those con- ducted in 1993 and later. The authors found that the amount of allicin released under simulated gastrointestinal conditions correlated well with the success or failure of the tablets to lower serum cholesterol values. The sharp decline in the effectiveness of the tablets is paral- leled by sharp declines in both the acid resistance and the allicin re- lease from the tablets, apparently caused by a change in the coating of the tablet (Lawson, Wang, and Papadimitriou, 2001).
GUIDELINES
As demonstrated in this chapter, therapeutic effect is a result of the following variables: botanical identity, chemical profile, formulation, bioavailability, and dose. Therefore, characterization of botanical products, in publications and scientific studies, needs to include all of that information. An adequate description of botanical products is needed in order to ensure a consistent therapeutic effect. It is also needed to be able to compare products and to conduct statistical analy- ses on the results of multiple trials.
Editors of scientific, particularly medical, literature need to be cognizant of the breadth of information required. The Journal of Nat-
ural Products, published by the American Chemical Society and the
American Society of Pharmacognosy, provides guidance to its au- thors in the characterization of botanical substances. It requires that experimental biological material be authenticated as to its identity and that the herbarium which holds the voucher specimen be given along with the voucher number. It further requires that the scientific
name (genus, species, authority citation, and family) be given. It also requires authors who purchase dried “herbal remedies” or other ma- terials from companies to deposit a specimen in an herbarium, for fu- ture access. It requires that the extraction procedure be specified when studying a commercially available extract and that the identifi- cation of the extract be supported by an HPLC trace of known sec- ondary metabolite constituents (Journal of Natural Products, 2003).
NCCAM, in its guidelines for clinical trial grant applications, sug- gests that when plant material is used in a trial, it be accompanied by a botanical description, extraction procedure, the quantity of any known active constituent(s), as well as identity and stability tests. When a product is used, information about the manufacturing process, analy- sis for impurities, and quality controls for manufacturing must be in- cluded. In addition, disintegration/dissolution rates are required to es- timate bioavailability (NCCAM, 2003).
APPENDIX: PREPARATIONS AND FORMULATIONS