Commercially available herbal products of creosote and yerba mansa differ in chemical composition

A8

Herbal product use is one of the most common complementary and alternative medical practices in the Hispanic community. While many nutritional supplements have standardization or quality information on their labeling, this information is not present on most herbal product labels. To assess how variable commercial herbal products were, we characterized the chemical composition of extracts and dried plant material for two different common medicinal plants used by Hispanics in the Southwest, Anemopsis californica (yerba mansa) and Larrea tridentata (creosote, chapparal, gobernadora). Both of these plants are used for a variety of symptoms and conditions; some traditional uses include treatment of cancers. Extracts were prepared from plants collected from wild local populations, as well as from dried plants purchased from commercial suppliers. Extracts were also purchased from commercial sources. The chemical composition of A. californica roots and commercial tinctures prepared from roots were characterized using GC/MS. The bioactive compounds in this plant are presumed to be in the essential oil. In the case of L. tridentata, nordihydroguaiaretic acid (NDGA) is presumed to be the principal bioactive compound. The abundance of this lignan in extracts of various plant parts and commercial sources was determined using HPLC.
 For A. californica, the concentrations of the four most abundant compounds, piperitone, thymol, methyeugenol and elemicin were quantified in two commercial tinctures. The concentrations of piperitone and elemicin were similar in the commercial sources, while the concentrations of thymol and methyeugenol varied significantly; 233 mg/L for methyleugenol in one sample vs 600 mg/L in another, for thymol, 6 mg/L vs 18 mg/L. These four compounds were the most abundant compounds in essential oils prepared from dried roots of A. californica in the lab, although again significant differences in the concentrations were observed.
 For L. tridentata, similar results were observed. Tinctures of this plant were obtained from three commercial suppliers and dried plant matter from four commercial suppliers. There were significant differences in the concentration of NDGA detected in the commercial tinctures. The NDGA content was the highest in extracts prepared from plant material collected locally. The NDGA content was lower in extracts prepared from commercial sources of dried L. tridentata leaves. Antimicrobial bioassays were also conducted to compare the commercial sources of this herbal product. Again significant differences were observed in the IC50 concentrations for different sources of the extract against Staphylococcus aureus, and Candida kefyr, among other organisms.
 As Hispanics are more likely to purchase and use herbal plant products it is especially important that information about the chemical and biological variability of these products be provided to them so that they can make informed decisions.