Editor's Note
This review examines the utility of alkaloids as biomarkers and chemical markers in the evaluation of quality, efficacy, and safety of medicinal herbs and their commercial products. The paper discusses the fundamental roles played by alkaloids as chemical and biomarkers in assessing the essential parameters of the quality of botanical ingredients. The review concludes that the use of alkaloids as biomarkers to determine the efficacy-linked pharmacokinetic parameters is limited to studies on human subjects.
Abstract

Background
Selecting the appropriate chemical and bio-markers for monitoring the quality, efficacy, and safety is critical for efficient and reliable assessment of traditional medicines derived from botanical sources. Chemical markers have been implicated primarily in establishing the analytical methodologies aiming at verification of the botanical sources of the raw materials, the extracts, and the finished products such as botanical  dietary supplements  and  nutraceuticals . In addition, they have been employed in differentiation between crude or raw (unprocessed) and processed  plant extracts , and identification as well as determination of potential toxicants and adulterants in herbal medicines. Additionally, these chemical markers are utilized for selection of efficient methods for extraction of plants. Further, biomarkers have been exploited in determination of the pharmacokinetic properties of bioactive herbal constituents. Alkaloids , unlike other plant constituents, are uniquely characterized by having basic properties, and possessing substantial and diverse pharmacological effects. These features make alkaloids attractive components for functioning as chemical and biomarkers in determining the quality of botanical ingredients where this class of  phytochemicals  prevail or is responsible for lending  biological effects .

Purpose
The aim of the review is to exhibit the function of alkaloids as biomarkers and chemical markers in the evaluation of quality, efficacy, and safety of medicinal herbs and their commercial products.

Methods
Literature acquisition was accomplished using the most commonly accessed scholarly  search engines  including SciFinder,  PubMed , and Google Scholar. Secondly, the full-texts which are relevant to the topic were included in this review. This was followed by a thorough and detailed analysis of the collected information.

Results
The literature search with main emphasis on the roles of alkaloids in the evaluation of quality, efficacy and safety of herbal medicines was evaluated to provide all succinct information in one place. Compilation of such critical information is expected to help the reader to appreciate alkaloids as important markers in the quality control of  herbal drugs  and products.

Conclusion
The current review article covers the fundamental roles played by alkaloids as chemical and biomarkers in assessing the essential parameters of the quality of botanical ingredients, as briefly described earlier. The utilization of alkaloids as biomarkers to determine the efficacy-linked pharmacokinetic parameters is limited to reviewing studies on human subjects.