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chaparral preparations containing leaves/stems or alcoholic extracts than with the ingestion of aqueous extracts (i.e., teas) because of the higher content of NDGA and other lipophilic compounds in the former preparations.

C. Data Gaps and Future Research Recommended

Detailed toxicity studies in animals are needed to explore the possible dose-response relationship in the development of hepatotoxicity and nephrotoxicity as the result of chaparral ingestion. In animal studies, pair feeding should be included in the experimental protocol due to possible aversion to the chow if NDGA has been added (Goodman et al., 1970). Ideally, studies should compare the different preparations of chaparral (i.e., powdered leaf, alcoholic extract, and water extract).

The differences in the chemical composition of the various preparations of chaparral need to be explored. The literature shows that a preponderance of toxicities were associated with preparations other than tea; hepatotoxicity was not reported in a clinical trial of cancer patients drinking chaparral tea. This suggests there that there are differences in the bioavailability of the various components of chaparral that result from differences in the chemical composition of the preparations. These differences need to be explored in detail.

In all further research, it is important to carry out careful product characterization. A qualified taxonomist should identify the plant material, and a botanical sample should be retained in an herbarium for future reference. It is important to carefully describe the plant part utilized. As an example, newer leaves should be distinguished from older leaves because newer leaves contain a higher proportion of the NDGA-containing resin. Chaparral roots contain a quinone not reported to be present in the aerial parts of the plants and, thus, roots should be carefully excluded. The plant material should be chemically profiled, including a quantitative determination of NDGA and other lignans. As a quality measure, there should be an analysis of metals since chaparral plants concentrate metals from the soil (Gardea-Torresdey et al., 2001). Furthermore, when reporting human experience with ingesting chaparral, the formulation is important to note. The formulation can best be critically evaluated if the manufacturer, date, and lot number are reported.

VI. LITERATURE SEARCH STRATEGY

This prototype focused monograph was prepared by excluding information not possibly related to hepatotoxicity after conducting a literature search for the full prototype monograph. This was probably a more effec-



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