Research Topic

Bioassays for Assessing Traditional Medicines: Promises and Pitfalls

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Traditional Medicines (TMs) including traditional Chinese medicines, Ayurveda, Kampo and African medicines, have a long history of use in health maintenance and in disease prevention and treatment. With a complex system with numerous unknown components and chemical analyses, the current main strategies for ...

Traditional Medicines (TMs) including traditional Chinese medicines, Ayurveda, Kampo and African medicines, have a long history of use in health maintenance and in disease prevention and treatment. With a complex system with numerous unknown components and chemical analyses, the current main strategies for assessing TMs quality are insufficient in identifying all components and explaining the relationship between its components and bioactivities. That is, the current chemical analyses face big challenges in assessing TMs quality.

TMs have the following characteristics: multi-component, multi-targeted and multiple ways to be potentially effective. Drug quality is the basis of ensuring clinical efficacy and bioassays could reflect the overall effectiveness of TMs. It has the advantages of relating bioactivity and/or clinical efficacy, and make up for the deficiency of conventional chemical analyses in assessing TMs quality. Therefore, bioassays are one of the key directions involved in TMs development, particularly with new biochemical methodologies quality assessment using bioassays that could offer novel strategies for quality control. These strategies could potentially promote the ability of TMs’ quality evaluation and ensure the clinical efficacy of TMs.

Unfortunately, methodological system and guidelines for TMs bioassays that correlates clinical efficacy has not yet been established. For example, in vitro bioassay (thrombin activity) could be detected for the bioactivity of promoting blood circulation and disperse stasis (a traditional function) of leech. However, extrapolating and translating the in vitro results to the in vivo situation remains a challenge. Due to the lack of consensus, bioassay has so far not received the attention it deserves and has not been widely used in the field of TMs. Specifically, some key issues including the role, biochemical principle, experimental system, application scope, limitations and common pitfalls of bioassays in TMs quality evaluation are unclear, which seriously impede the improvement of clinical efficacy and the process of internationalization of TMs. For any of these bioassays to become a valid tool, it will have to be accepted by the relevant authorities like EMA (European Medicines Agency) or the China Food and Drug Administration (CFDA). Therefore, it is necessary to establish a consensus on the bioassays for assessing TMs, especially when aiming to form a relationship between traditional function, modern pharmacology and bioassay.

This Research Topic is intended to address opportunities and problems related to bioassays for assessing TMs quality, including experimental system (model organisms like tissue, living cells, protein, etc., and positive & negative controls), principles and methods of advanced biochemical technologies, in vivo / in vitro correlation analysis and mechanism elucidation, sample processing, data analysis, limitations, common pitfalls and so forth. Promises as well as pitfalls will be dealt with the aim to test what tools could be implemented for evaluating the quality of TMs. For this purpose, we would like to welcome contributors that tackle the new developments of bioassay technologies, experimental systems and their mechanism researches in this Research Topic.

Papers presented to this Research Topic are expected to be linked to the following fields of research:
- Selections of model organisms (tissue, living cells, proteins, etc.) and positive & negative controls (TMs extractions, pharmaceutical chemicals, etc.).
- Advanced technologies for bioassay.
· New detection technologies for TMs identification and analysis like interdisciplinary technologies fluorescence, super-resolution microscopy, Raman, electrochemistry, microfluidic devices, nanofluidic devices.
· Nucleic-acid based identification, e.g. DNA barcodes, transcriptomes, NGS sequencing.
· Single molecule measurement technologies (optical tweezers, magnetic tweezers, etc.).
· New dynamic monitoring methods like bio-characteristic profiling living cell dynamics, enzyme activity, electric chemistry, isothermal titration calorimetry.
· Instrumentation (automation, miniaturization, etc.) of detection apparatus.
- Sample processing associated with clinic for bioassays (total extractions, bionic extraction, drug-containing serum, etc.).
- Experimental design and data analysis, e.g. test type (qualitative/quantitative), deviation analysis, chemometrics.
- Mechanism underlying bioassay related to effectiveness and/or safety.
- Influence factors, limitations and common pitfalls of bioassays.
- Adoption of such assays by regulatory bodies and the specific requirements in this context

This Research Topic welcomes different kinds of articles such as Reviews, Original Research Articles, Short Communications, Perspectives, Commentaries and Protocols.

The four pillars of best practice in ethnopharmacology

With these guidelines we define in detail what constitutes best practice for manuscripts submitted to Frontiers in Pharmacology; Section Ethnopharmacology. They provide a basis for the peer review and build on the general requirements of Frontiers in Pharmacology.

1) Pharmacology

a) The manuscript (MS) must report a substantive body of ethnopharmacological research, to be considered as an independent addition to the literature. In general, we expect that such studies are based on local / traditional uses of plants or other natural substances which need to be spelled out clearly.

b) For pharmacological studies, the model used must be one which is either generally accepted in the field as valid or a credible alternative whose general development, and application in the reported instance, has been justified.

Specifically antioxidant activity must be based on a pharmacologically relevant in vivo or cell based model. Simple in silico and pharmacologically irrelevant assays for antioxidant activity (e.g. the DPPH assay, FRAP (Ferric Reducing Ability of Plasma), ABTS (2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) are not acceptable as a main tool for assessing an extract or a compound for activity.

c) Similarly, simple screening for anti-microbial effects of crude extracts is no longer state-of-the-art. Authors must follow the widely accepted standards for microbiological testing (cf. Cos et al. 2006 Anti-infective potential of natural products: How to develop a stronger in vitro ‘proof-of-concept’ Journal of Ethnopharmacology 106: 290–302) and subsequent methods papers. Such research is only meaningful if it contributes to our mechanistic understanding of anti-microbial effects, its specificity or identifies novel leads.

d) The dose ranges must be therapeutically relevant. While it will be impossible to define an exact cut-off, the literature in the field is now replete with studies which test extracts at implausibly high doses. Single dose studies will only be of relevance in exceptional circumstances (e.g. in case of specific complex pharmacological models). And of course, positive and negative controls must be included.

e) In order to establish therapeutic benefits, selectivity data are essential. How specific is the effect? Many compounds have non-selective in vitro effects and research on common compounds must be justified in terms of the potential therapeutic benefits. While such research may be relevant and have potential applications, authors will need to assess the specificity of a single compound or an extract rich in a well-studied compound (like rutin, curcumin, or quercitin) and provide evidence for the relevance and novelty of the approach.

f) Docking studies must be justified with affinity experiments, or other well established experimental methods to support a proposed mechanism of action. Algorithmic docking studies will not be accepted; these indicate if a compound will "fit" into a binding site but do not indicate the binding affinity or the ability to induce a conformational change.

2) Composition:

a) Botanical:

The identification of the study material must be described well. All species are fully validated using Kew MPNS portal or The Plant List initiative or Plants of the World Online Of course, full botanical documentation is essential (i.e. a voucher specimen deposited in a recognised herbarium). A scan of the voucher(s) is welcome as supplementary material and encourage authors to include the coordinates of the location where the material had been collected.

b) Chemical

- The composition of the study material must be described in sufficient detail. Chromatograms with a characterisation of the dominating compound(s) are preferable. If preparations are used which are available commercially quality parameters provided in pharmacopoeia must be provided. The material under study must be characterised using the methods of the relevant monograph

- If ‘pure’ compounds are used sufficient information on the level of purity must be included. Especially in in vitro models, the authors must be confident that the compounds are stable under the conditions used (for example, they do not degrade due to high concentrations of DMSO). A critical aspect that should be considered is how these assays and extraction protocols are linked to local and traditional uses. In this way, variables such as the solubility of the compound in the traditional preparation and in the analytical extraction protocol should be taken into consideration

- All chemical line structures must be drawn using a internationally accepted structure drawing programme, must be consistent and - if possible and relevant - the stereochemistry needs to be given.

c) Multiherbal preparations:

Very often multiherbal preparations are used. Full information on their composition (in terms of the botanical drugs / species included) and information on the rationale for studying this preparation needs to be included. It is essential that in these cases sufficient details are provided on the botanical (2a) and chemical (2b) characterisation.

3) Basic requirements and research ethics

Frontiers has very well developed guidelines relating to ethical aspects of a MS. Specifically, for Frontiers in Pharmacology (Ethnopharmacology) the following key requirements are essential:

a) The objectives of the research reported must be spelled out clearly and in detail. All MS must critically assess the scientific basis of the work and provide meaningful conclusions, which are based on a clear hypothesis / research question as defined in the introduction. Ethnopharmacological research must assess whether a compound or plant extract has a certain effect and it cannot be about ‘confirming an extract’s or compound’s effects or efficacy’.

b) Research must add new and scientifically substantive knowledge to our understanding of the pharmacology and use of medicinal plants. A key basis for this is a review of literature relevant to the pharmacological activity already reported on the species including possibly related taxa or compounds. This must be up-to-date, and clearly demonstrate the substantive addition to the literature the MS submitted represents. Simply using advanced measurements/techniques/protocols reproducing previous studies of the same plant product will only be accepted in exceptional circumstances (e.g. previously unknown, highly active components are discovered).

c) Compliance with all international ethical standards is essential. In the context of ethnopharmacology, the Convention on Biological Diversity and, most recently, the Nagoya Protocol are of particular relevance (

d) Research in ethnopharmacology is based on local and traditional knowledge often passed on orally over generations. Ultimately, research in this field must therefore benefit those populations who are or were the original keeper of this knowledge.

e) The use of animals must be justified in the context of novelty (see also part 1). It is ethically not acceptable to have yet another in vivo study on an already well-studied species, demonstrating some common activity (e.g. an anti-inflammatory effect studied in the rat-paw edema). The same is true for species which are chemically very similar (and generally are rich in common ingredient) to ones already studied pharmacologically. Such studies must ‘meet(s) the standards of rigor’ we expect in ethnopharmacology as defined in the Frontiers’ guidelines.

4) Other specific requirements

a) Studies focusing on local and traditional uses of plants (ethnopharmacological field studies) must be based on substantial, original data. The relevance of the MS in the context of previous studies in the geographical region must be spelled out clearly and it must contribute to the understanding of the therapeutic uses of plant species and inform experimental or clinical studies This includes an adequate presentation and discussion of the data. Also, social science centered studies (e.g. ethnobotanical studies or health system research of local and traditional medical systems) are welcome. This journal subscribes to the ConSEFS standards including any updates.

b) In case of reviews, we expect clearly defined scientific aims (objectives), a comprehensive, critical and specific assessment of the relevant information linking local and other medical uses to the biomedical and bioscientific evidence. Reviews need to define future research needs and priorities. It is essential that the scientific quality of the original articles cited is assessed. If pharmacological studies are reviewed, particular attention must be paid to assessing the quality of the studies.

c) Food plants are commonly reported to have pharmacological effects. Frontiers in Ethnopharmacology focuses on therapeutic benefits of such species and not on the general food/nutritional properties.

Keywords: Biotechnology, effect mechanism, drug metabolism, clinical efficacy, traditional Chinese medicine

Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.

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