Modern HPTLC--a perfect tool for quality control of herbals and their preparations.

Herbals and herbal preparations are complex mixtures with numerous natural compounds in an uncharacterized matrix--truly multicomponent systems. This is in contrast to most of the samples of the pharmaceutical and, in part, the food industry, where primarily single compounds have to be analyzed. Recently, models for the characterization of multicomponent systems with near-IR, NMR, and MS combined with chemometric tools have been developed. However, the complexity and sophistication of such methods still prevent their general applicability to the QC of herbals. On the other hand, modern TLC is a well-established method with a long tradition. The typical chromatograms visualize even complex multicomponent systems in a special manner. The technique is rapid, comparatively simple, robust, and extremely versatile. HPTLC can not only confirm but also establish identity. It is also an ideal screening tool for adulterations and is highly suitable for evaluation and monitoring of cultivation, harvesting, and extraction processes and testing of stability. To substantiate these claims, several examples taken from daily work are provided and discussed in this paper.

Reduction of safrole and methyleugenol in Asari radix et rhizoma by decoction.

INTRODUCTION: Asari radix et rhizoma (Xixin, Manchurian Wildginger, Asarum spp) is a herbal drug commonly used as an ingredient in traditional Chinese medicine (TCM). Many species of Asarum contain safrole and methyleugenol as the main components of their volatile oils. However, toxicological studies have shown that safrole and methyleugenol may be a hepatocarcinogen and/or genotoxic leading to concerns regarding the habitual consumption of this herbal drug. MATERIALS AND METHODS: An HPLC method was established to assess the levels of safrole and methyleugenol in five batches of Asari radix et rhizoma and two TCM formulae containing this herbal drug as an ingredient. Analyses showed that the content of safrole in the dried herbal drugs tested ranged from 0.14-2.78 mg/ g whilst the content of methyleugenol ranged from 1.94-16.04 mg/g. RESULTS: The present study demonstrated that following a 1-hour decoction, the amount of safrole was decreased by more than 92% resulting in the equivalent of no more than 0.20 mg/g safrole remaining in the aqueous extract. Similarly, the content of methyleugenol was decreased to the equivalent of 0.30-2.70 mg/g. Furthermore, both TCM formulae, after decoction, showed negligible amounts of safrole (maximum, the equivalent of 0.06 mg/ g), and only 1.38-2.71 mg/g of methyleugenol. CONCLUSIONS: The present study shows that a decoction procedure, similar to that traditionally used for Chinese herbal preparations, is able to effectively reduce the amount of safrole and methyleugenol effectively. Such a reduction in the content of safrole should be acceptable for therapeutic use.

Reduction of beta-asarone in acori rhizoma by decoction.

Beta-asarone, the major constituent of the essential oil from the traditional Chinese herbal drug "Acori rhizoma" is regarded as carcinogenic in rodents and potentially genotoxic. Thus, the limit for the ingestion of this constituent from herbal medicinal products has been set at 0.115 mg beta-asarone/person/day. The present study demonstrates that a decoction procedure, traditionally used for Chinese herbal preparations and intended as the standard procedure in Ph. Eur., was able to significantly reduce the amount of beta-asarone. HPLC analysis indicated that the content of beta-asarone in dried herbal drug ranged from 15.22 to 25.34 mg/g. During a 1-hour decoction, the amount of beta-asarone decreased more than 85 % and the aqueous extract contained the equivalent of only 0.46-2.19 mg beta-asarone per gram of herbal drug. If this aqueous extract was heated for a further 2 hours, the final content of beta-asarone was reduced to the equivalent of no more than 0.005 mg per gram of herbal drug. This low level of beta-asarone should be acceptable for therapeutic use. It was noted that decoction of Acori rhizoma in the presence of other herbal substances impaired, to some extent, the reduction in beta-asarone.