Herbal Drugs: Their Collection, Preservation, and Preparation; Evaluation, Quality Control, and Standardization of Herbal Drugs

Botanical samples are often freeze-dried (lyophilized) for use in research studies, and a variety of freeze-dried botanicals are marketed to the public. In both instances, there is an underlying assumption that freeze-drying properly preserves the medicinal qualities of plants, and is superior to other preservation methods. In fact, little systematic research has been done to verify this assumption. A review of the existing research, done primarily by the food and spice industry, indicates that freeze-drying has unanticipated and significant effects on the constituent profiles of medicinal plants that puts into question whether freeze-drying necessarily is the best method to preserve botanical medicines.This research review finds there is insufficient information to conclude that freeze-drying has negative effects on the medicinal qualities of plants. But, because existing research indicates that freeze-drying imperfectly preserves important classes of medicinal compounds (such as volatiles, phenolics and carotenoids), may increase the mutation rate in unicellular organisms and may diminish some medicinal plant actions, researchers and practitioners should carefully consider how the use of freeze-dried material may affect pharmacological and clinical study results. Copyright (c) 2005 John Wiley & Sons, Ltd.

As all medicines, herbal medicinal products are expected to be safe, effective, and of appropriate quality. However, regulations on herbal medicinal products vary from country to country, and herbal preparations do occur not only in the form of medicinal products but also as less strictly regulated product groups like dietary supplements. Therefore, it is not always easy for the consumers to discriminate high-quality products from low-quality products. On the other hand, herbal medicines have many special features that distinguish them from conventional medicinal products. Plants are complex multicomponent mixtures; in addition, their phytochemical composition is not constant because of inherent variability and a plethora of external influences. Therefore, the production process of an herbal medicinal product needs to be strictly monitored. First of all, the starting materials need to be correctly authenticated and free of adulterants and contaminants. During plant growth, many factors like harvest season and time, developmental stage, temperature, and humidity have a strong impact on plant metabolite production. Also, postharvest processing steps like drying and storage can significantly alter the phytochemical composition of herbal material. As the production of many phytopharmaceuticals includes an extraction step, the extraction solvent and conditions need to be optimized in order to enrich the bioactive constituents in the extract. The quality of finished preparations needs to be determined either on the basis of marker constituents or on the basis of analytical fingerprints. Thus, all production stages should be accompanied by appropriate quality assessment measures. Depending on the particular task, different methods need to be applied, ranging from macroscopic, microscopic, and DNA-based authentication methods to spectroscopic methods like vibrational spectroscopy and chromatographic and hyphenated methods like HPLC, GC-MS and LC-MS. Also, when performing pharmacological and toxicological studies, many features inherent in herbal medicinal products need to be considered in order to guarantee valid results: concerning in vitro studies, difficulties are often related to lacking knowledge of ADME characteristics of the bioactive constituents, nuisance compounds producing false positive and false negative results, and solubility problems. In in vivo animal studies, the route of administration is a very important issue. Clinical trials on herbal medicinal products in humans very often suffer from a poor reporting quality. This often hampers or precludes the pooling of clinical data for systematic reviews. In order to overcome this problem, appropriate documentation standards for clinical trials on herbal medicinal products have been defined in an extension of the CONSORT checklist. This article is part of a Special Issue entitled "Botanicals for Epilepsy".

Ingredients of commercial herbal medicines are assessed for quality primarily to ensure their safety. However, as complex mixtures of different groups of plant secondary metabolites, retention of overall phytochemical consistency of herbal medicines is pivotal to their efficacy. Authenticity and homogeneity of the herbs and strict regimes of physical processing and extract manufacturing are critical factors to maintain phytochemical consistency in commercial products. To ensure both safety and efficacy of herbal medicines, implementation of and adherence to good agricultural and collection practice (GACP), good plant authentication and identification practice (GPAIP), good manufacturing practice (GMP) before and during the manufacturing process, and good laboratory practice (GLP) in analysis are necessary. Establishment and application of harmonized multilaboratory-validated analytical methods and transparency in the supply (value) chain through vendor audits are additional requirements in quality assurance. In this article, we outline steps of a comprehensive quality assurance paradigm aimed at achieving and maintaining safety, consistent phytochemical composition, and clinical efficacy of ingredients of herbal medicines. This article is part of a Special Issue entitled Botanicals for Epilepsy.