Naturally complex: Perspectives and challenges associated with Botanical Dietary Supplement Safety assessment

The Potential Pharmacological Effects of Natural Product Withaferin A in Cancer: Opportunities and Challenges for Clinical Translation

Cancer is one of the biggest health concerns with a complex pathophysiology. Currently, available chemotherapeutic drugs are showing deleterious side effects, and tumors often show resistance to treatment. Hence, extensive research is required to develop new treatment strategies to fight against cancer. Natural resources from plants are at the forefront of hunting novel drugs to treat various types of cancers. Withaferin A (WA) is a naturally occurring withanolide, a biologically active component obtained from the plant Ashwagandha. Various in vitro and in vivo oncological studies have reported that Withaferin A (WA) has shown protection from cancer. WA shows its activity by inhibiting the growth and proliferation of malignant cells, apoptosis, and inhibiting angiogenesis, metastasis, and cancer stem cells (CSCs). In addition, WA also showed chemo- and radio-sensitizing properties. Besides the beneficiary pharmacological activities of WA, a few aspects like pharmacokinetic properties, safety, and toxicity studies are still lacking, hindering this potent natural product from entering clinical development. In this review, we have summarized the various pharmacological mechanisms shown by WA in in vitro and in vivo cancer studies and the challenges that must be overcome for this potential natural product's clinical translation to be effective.

Safety considerations for dietary supplement manufacturers in the United States

Due to significant dietary supplement use in the US, product manufacturers must understand the importance of implementing a robust approach to establishing safety for all ingredients, including dietary ingredients, components, and finished dietary supplement products. Different regulatory pathways exist by which the safety of dietary ingredients can be established, and thus allowed to be marketed in a dietary supplement. For individual dietary ingredients, safety information may come from a variety of sources including history of safe use, presence of the ingredient in foods, and/or non-clinical and clinical data. On occasion safety data gaps are identified for a specific ingredient, particularly those of botanical origin. Modern toxicological methods and models can prove helpful in satisfying data gaps and are presented in this review. For finished dietary supplement products, issues potentially impacting safety to consider include claims, product labeling, overages, contaminants, residual solvents, heavy metals, packaging, and product stability. In addition, a safety assessment does not end once a product is marketed. It is important that manufacturers actively monitor and record the occurrence of adverse events reported in association with the use of their products, in accordance with the law. Herein, we provide a comprehensive overview of considerations for assessing dietary supplement safety.

Non-targeted chemical analysis of consumer botanical products labeled as blue cohosh (Caulophyllum thalictroides), goldenseal (Hydrastis canadensis), or yohimbe bark (Pausinystalia yohimbe) by NMR and MS

Consumers have unprecedented access to botanical dietary supplements through online retailers, making it difficult to ensure product quality and authenticity. Therefore, methods to survey and compare chemical compositions across botanical products are needed. Nuclear magnetic resonance (NMR) spectroscopy and non-targeted mass spectrometry (MS) were used to chemically analyze commercial products labeled as containing one of three botanicals: blue cohosh, goldenseal, and yohimbe bark. Aqueous and organic phase extracts were prepared and analyzed in tandem with NMR followed by MS. We processed the non-targeted data using multivariate statistics to analyze the compositional similarity across extracts. In each case, there were several product outliers that were identified using principal component analysis (PCA). Evaluation of select known constituents proved useful to contextualize PCA subgroups, which in some cases supported or refuted product authenticity. The NMR and MS data reached similar conclusions independently but were also complementary.

Validation of a Toll-like Receptor (TLR)2/TLR1 Activation Assay for Biological Standardization of Arthrospira/Limnospira Immune-Enhancing Potency

Arthrospira/Limnospira is a popular botanical dietary supplement throughout the world and has been consumed as a food product for hundreds of years. Ongoing efforts from our research group are focused on evaluating the utility of a Limnospira-derived oral supplement (Immulina) in promoting resilience against influenza viral infection. Like other botanical extracts, Immulina is inherently a complex matrix with variation in the levels of its chemical constituents. Therefore, to ensure therapeutic consistency for future scientific research and clinical studies, we are developing standardization technology using a bioassay and chemical markers. Braun-type lipoproteins, a class of macromolecules that activate the Toll-like receptor (TLR)2/TLR1 signaling pathway, have been identified as a major active component within Immulina. Based on the mechanism of action of the Braun-type lipoproteins, an in vitro bioassay was established using the HEK-Blue hTLR2/TLR1 cell line to quantitate the immune-enhancing potency of Immulina. The objective of the current research was to validate that bioassay for Immulina activity quantification using the U.S. FDA guidance document for botanical drug development and U.S. Pharmacopeia recommendations. System suitability, reference standards and defining potency units were established. Validation of performance parameters included precision, specificity, accuracy, linearity, and range. Validating this bioassay for Immulina activity provides a tool for ensuring product consistency and quantifying the potency of this botanical for use in future research as well as material in the consumer market.

Horizon scan of DNA-based methods for quality control and monitoring of herbal preparations

Herbal medicines and preparations are widely used in healthcare systems globally, but concerns remain about their quality and safety. New herbal products are constantly being introduced to the market under varying regulatory frameworks, with no global consensus on their definition or characterization. These biologically active mixtures are sold through complex globalized value chains, which create concerns around contamination and profit-driven adulteration. Industry, academia, and regulatory bodies must collaborate to develop innovative strategies for the identification and authentication of botanicals and their preparations to ensure quality control. High-throughput sequencing (HTS) has significantly improved our understanding of the total species diversity within DNA mixtures. The standard concept of DNA barcoding has evolved over the last two decades to encompass genomic data more broadly. Recent research in DNA metabarcoding has focused on developing methods for quantifying herbal product ingredients, yielding meaningful results in a regulatory framework. Techniques, such as loop-mediated isothermal amplification (LAMP), DNA barcode-based Recombinase Polymerase Amplification (BAR-RPA), DNA barcoding coupled with High-Resolution Melting (Bar-HRM), and microfluidics-based methods, offer more affordable tests for the detection of target species. While target capture sequencing and genome skimming are considerably increasing the species identification resolution in challenging plant clades, ddPCR enables the quantification of DNA in samples and could be used to detect intended and unwanted ingredients in herbal medicines. Here, we explore the latest advances in emerging DNA-based technologies and the opportunities they provide as taxa detection tools for evaluating the safety and quality of dietary supplements and herbal medicines.

Have safety and efficacy assessments of bioactives come of age?

This article describes why the safety and efficacy assessment of non-nutrient bioactives for reducing chronic disease risk is so complicated, especially for dietary supplements and traditional medicines. Scientists, regulators, and the public have different and sometimes opposing perspectives about bioactives. Drug, food, and traditional medicine models used for bioactive safety assessment are based on different assumptions and use different processes. Efficacy assessment is seldom based on clinical trials of boactives' effects in reducing chronic disease risk. It usually consists of application of quality assurance measures and evaluation of label claims and commercial speech about ingredients or products to ensure conformity to regulations. Harmonization of safety and efficacy assessment on a global basis is difficult because of differences within and between regulatory systems. The recommendations provided may open the way for bioactives to play a larger health role in the future, fill gaps in data needed for crafting authoritative dietary guidance on intakes, and speed harmonization of global standards.

Mechanism-Driven and Clinically Focused Development of Botanical Foods as Multitarget Anticancer Medicine: Collective Perspectives and Insights from Preclinical Studies, IND Applications and Early-Phase Clinical Trials

Cancer progression and mortality remain challenging because of current obstacles and limitations in cancer treatment. Continuous efforts are being made to explore complementary and alternative approaches to alleviate the suffering of cancer patients. Epidemiological and nutritional studies have indicated that consuming botanical foods is linked to a lower risk of cancer incidence and/or improved cancer prognosis after diagnosis. From these observations, a variety of preclinical and clinical studies have been carried out to evaluate the potential of botanical food products as anticancer medicines. Unfortunately, many investigations have been poorly designed, and encouraging preclinical results have not been translated into clinical success. Botanical products contain a wide variety of chemicals, making them more difficult to study than traditional drugs. In this review, with the consideration of the regulatory framework of the USFDA, we share our collective experiences and lessons learned from 20 years of defining anticancer foods, focusing on the critical aspects of preclinical studies that are required for an IND application, as well as the checkpoints needed for early-phase clinical trials. We recommend a developmental pipeline that is based on mechanisms and clinical considerations.

A cross-sectional clinical study in women to investigate possible genotoxicity and hematological abnormalities related to the use of black cohosh botanical dietary supplements

Black cohosh (BC; Actaea racemosa L.), a top-selling botanical dietary supplement, is marketed to women primarily to ameliorate a variety of gynecological symptoms. Due to widespread usage, limited safety information, and sporadic reports of hepatotoxicity, the Division of the National Toxicology Program (DNTP) initially evaluated BC extract in female rats and mice. Following administration of up to 1000 mg/kg/day BC extract by gavage for 90 days, dose-related increases in micronucleated peripheral blood erythrocytes were observed, along with a nonregenerative macrocytic anemia resembling megaloblastic anemia in humans. Because both micronuclei and megaloblastic anemia may signal disruption of folate metabolism, and inadequate folate levels in early pregnancy can adversely affect neurodevelopment, the DNTP conducted a pilot cross-sectional study comparing erythrocyte micronucleus frequencies, folate and B12 levels, and a variety of hematological and clinical chemistry parameters between women who used BC and BC-naïve women. Twenty-three women were enrolled in the BC-exposed group and 28 in the BC-naïve group. Use of any brand of BC-only supplement for at least 3 months was required for inclusion in the BC-exposed group. Supplements were analyzed for chemical composition to allow cross-product comparisons. All participants were healthy, with no known exposures (e.g., x-rays, certain medications) that could influence study endpoints. Findings revealed no increased micronucleus frequencies and no hematological abnormalities in women who used BC supplements. Although reassuring, a larger, prospective study with fewer confounders (e.g., BC product diversity and duration of use) providing greater power to detect subtle effects would increase confidence in these findings.

Utility of fatty acid profile and in vitro immune cell activation for chemical and biological standardization of Arthrospira/Limnospira

Commercially cultivated Limnospira (species formerly classified to genus Arthrospira) is a popular food/supplement consumed by millions of people worldwide for health benefits. The objective of the current research was to advance the standardization technology for Limnospira. Quantitative methods were established to detect fatty acids as potential chemical markers and immune-enhancing activity. Analysis of 20 different batches of biomass obtained from one commercial grower demonstrated that there was a statistically significant relationship between the sum of two fatty acids (linoleic and γ-linolenic) and Toll-like receptor (TLR)2/TLR1-dependent activation (R² = 0.48, p = 0.0007). Investigation of 12 biomass samples sourced from growers in 10 different countries demonstrated that fatty acid content was again significantly correlated with biological activity (R² = 0.72, p = 0.0005) and the content of fatty acids varied by twofold and activity by 12.5-fold. This large variation between different samples confirms the need to use the present standardization methods to ensure consistent and properly characterized biomass for consumers and for future scientific research.

Exploration of facilitators and barriers to the regulatory frameworks of dietary and herbal supplements: a scoping review

Background

Over the last decade, the use of dietary and herbal supplements (DHSs) has expanded greatly across national healthcare settings for the prevention, management and/or treatment of a variety of health issues. Although regulatory policies for DHSs across different countries have been aimed towards evaluating safety and efficacy, performing quality controls, monitoring the manufacturing practices, and encouraging further research, significant safety issues have emerged from inappropriate regulatory classification, lack of suitable quality controls, and inadequate testing and labeling of these products. Therefore, the purpose of this scoping review was to identify facilitators and barriers to DHS regulation across different countries.

Methods

A scoping review was conducted and informed by the five-stage methodological framework proposed by Arksey and O’Malley and further enhanced by Levac et al. MEDLINE, EMBASE, AMED, and PsycINFO databases were systematically searched for eligible articles from database inception to September 29, 2020. Studies analyzing DHS regulatory frameworks were eligible for review. Relevant data from eligible articles were extracted and categorized into themes to provide a descriptive overview of the literature.

Results

Searches generated 4314 results, 1800 of which were duplicates, followed by 2472 that were excluded after screening the titles and abstracts of these articles. Of the remaining 42 full-texts, 15 eligible articles were included in this review. Themes identified include: (1) increased financial and human resources encouraging knowledge expansion as a facilitator to DHS regulation; (2) variances in DHS classification and regulatory requirements across countries as a barrier to DHS regulation, and (3) collaboration between various stakeholders (experts, policymakers, representatives of regulatory bodies, product companies and research institutions) facilitating DHS regulation.

Conclusion

The present scoping review identified facilitators and barriers to DHS regulation across different countries. We highlight that safety assessments of DHSs continue to be inadequate, and emerging technologies could potentially play a significant role in establishing common reference standards of herbal materials and products between regulatory agencies. Regulatory harmonization, increased scientific research, and collaboration could improve regulations globally through appropriate categorization and safe application of DHSs.

Integrative oncology: Addressing the global challenges of cancer prevention and treatment

The increase in cancer incidence and mortality is challenging current cancer care delivery globally, disproportionally affecting low- and middle-income countries (LMICs) when it comes to receiving evidence-based cancer prevention, treatment, and palliative and survivorship care. Patients in LMICs often rely on traditional, complementary, and integrative medicine (TCIM) that is more familiar, less costly, and widely available. However, spheres of influence and tensions between conventional medicine and TCIM can further disrupt efforts in evidence-based cancer care. Integrative oncology provides a framework to research and integrate safe, effective TCIM alongside conventional cancer treatment and can help bridge health care gaps in delivering evidence-informed, patient-centered care. This growing field uses lifestyle modifications, mind and body therapies (eg, acupuncture, massage, meditation, and yoga), and natural products to improve symptom management and quality of life among patients with cancer. On the basis of this review of the global challenges of cancer control and the current status of integrative oncology, the authors recommend: 1) educating and integrating TCIM providers into the cancer control workforce to promote risk reduction and culturally salient healthy life styles; 2) developing and testing TCIM interventions to address cancer symptoms or treatment-related adverse effects (eg, pain, insomnia, fatigue); and 3) disseminating and implementing evidence-based TCIM interventions as part of comprehensive palliative and survivorship care so patients from all cultures can live with or beyond cancer with respect, dignity, and vitality. With conventional medicine and TCIM united under a cohesive framework, integrative oncology may provide citizens of the world with access to safe, effective, evidence-informed, and culturally sensitive cancer care.

Working with the natural complexity: Selection and characterization of black cohosh root extract for use in toxicology testing

Black cohosh (Actaea racemosa L.) is a botanical supplement marketed to women of all ages. Due to paucity of data to assess the safe use, the National Toxicology Program (NTP) is evaluating the toxicity of black cohosh. The use of an authentic, quality material is imperative to generate robust data. Because botanical materials are complex mixtures with variable composition, the selection of a material is challenging. We describe selection and phytochemical characterization of an unformulated black cohosh root extract (i.e., an extract that serves as source material for a formulated product) to be used in the NTP assessments. A material was selected using a combination of non-targeted and targeted chemical analyses, including confirmation of authenticity, absence of contaminants and adulterants, and similarity to a popular black cohosh product used by consumers. Thirty-nine constituents covering three major classes, triterpene glycosides, phenolic acids, and alkaloids were identified. Among constituents quantified, triterpene glycosides made up approximately 4.7% (w/w) with total constituents quantified making up 5.8% (w/w) of the extract. Non-targeted chemical analysis followed by chemometric analysis of various materials sold as black cohosh, and reference materials for black cohosh and other Actaea species further confirmed the suitability of the selected extract for use.

NMR technique and methodology in botanical health product analysis and quality control

Botanicals have played an important role in maintaining human health and well-being throughout history. During the past few decades in particular, the use of botanical health products has gained more popularity. Whereas, quality, safety and efficacy concerns have continuously been critical issues due to the intrinsic chemical complexity of botanicals. Chemical analytical technologies play an imperative role in addressing these issues. Nuclear magnetic resonance (NMR) spectroscopy has proven to be a powerful and useful tool for the investigation of botanical health products. In this review, NMR techniques and methodologies that have been successfully applied to the research and development of botanical health products in all stages, from plants to products, are discussed and summarized. Furthermore, applications of NMR together with other analytical techniques in a variety of domains of botanical health products investigation, such as plant species differentiation, adulteration detection, and bio-activity evaluation, are discussed and illustrated with typical examples. This article provides an overview of the potential uses of NMR techniques and methodologies in an attempt to further promote their recognition and utilization in the field of botanical health products analysis and quality control.

Neurofibromatosis: Molecular Pathogenesis and Natural Compounds as Potential Treatments

The neurofibromatosis syndromes, including NF1, NF2, and schwannomatosis, are tumor suppressor syndromes characterized by multiple nervous system tumors, particularly Schwann cell neoplasms. NF-related tumors are mainly treated by surgery, and some of them have been treated by but are refractory to conventional chemotherapy. Recent advances in molecular genetics and genomics alongside the development of multiple animal models have provided a better understanding of NF tumor biology and facilitated target identification and therapeutic evaluation. Many targeted therapies have been evaluated in preclinical models and patients with limited success. One major advance is the FDA approval of the MEK inhibitor selumetinib for the treatment of NF1-associated plexiform neurofibroma. Due to their anti-neoplastic, antioxidant, and anti-inflammatory properties, selected natural compounds could be useful as a primary therapy or as an adjuvant therapy prior to or following surgery and/or radiation for patients with tumor predisposition syndromes, as patients often take them as dietary supplements and for health enhancement purposes. Here we review the natural compounds that have been evaluated in NF models. Some have demonstrated potent anti-tumor effects and may become viable treatments in the future.

Analysing Clusters of Consumers Who Use Medicinal and Aromatic Plant Products

The trend towards health and environmental protection has led to an increase in the consumption of medicinal and aromatic plant (MAP) products. The market for MAP products is influenced by consumer behaviour and therefore the aim of this study was to identify consumer segments that use MAP products for phytotherapeutic, cosmetic and personal care purposes according to their perceptions, attitudes and consumption habits and possible correlations between consumption of MAP products and interest in a healthy lifestyle and sustainable behaviour. Data collection was performed by administering a questionnaire to Cluj-Napoca residents. The final sample consisted of two groups of MAP consumers: the first with 231 respondents who use these products for phytotherapeutic purposes, the second group—with 297 respondents who use them as cosmetic and personal care products. The collected data were statistically analysed using the k-means clustering model, resulting in two distinct clusters in both consumer groups: cluster 1, the “Curious”, and Cluster 2, the “Knowledgeable”. For the consumers of the second cluster, consumption was positively correlated with healthcare and environmental protection, while they exhibited a growing interest in environmentally certified MAP products. The results obtained contribute to a better understanding of the MAP products consumption behaviour while tackling the practical implications for stakeholders in the pharmaceutical and cosmetics industry through the development and innovation of products tailored to consumer needs.

Biosynthesis and synthetic biology of psychoactive natural products

Psychoactive natural products play an integral role in the modern world. The tremendous structural complexity displayed by such molecules confers diverse biological activities of significant medicinal value and sociocultural impact. Accordingly, in the last two centuries, immense effort has been devoted towards establishing how plants, animals, and fungi synthesize complex natural products from simple metabolic precursors. The recent explosion of genomics data and molecular biology tools has enabled the identification of genes encoding proteins that catalyze individual biosynthetic steps. Once fully elucidated, the "biosynthetic pathways" are often comparable to organic syntheses in elegance and yield. Additionally, the discovery of biosynthetic enzymes provides powerful catalysts which may be repurposed for synthetic biology applications, or implemented with chemoenzymatic synthetic approaches. In this review, we discuss the progress that has been made toward biosynthetic pathway elucidation amongst four classes of psychoactive natural products: hallucinogens, stimulants, cannabinoids, and opioids. Compounds of diverse biosynthetic origin - terpene, amino acid, polyketide - are identified, and notable mechanisms of key scaffold transforming steps are highlighted. We also provide a description of subsequent applications of the biosynthetic machinery, with an emphasis placed on the synthetic biology and metabolic engineering strategies enabling heterologous production.

Xanthohumol Microbiome and Signature in Healthy Adults (the XMaS Trial): Safety and Tolerability Results of a Phase I Triple-Masked, Placebo-Controlled Clinical Trial

SCOPE

Xanthohumol, a prenylflavonoid from hops, has been extensively studied preclinically but has undergone limited research in human subjects. A triple-masked, placebo-controlled phase I clinical trial was conducted to examine the safety and tolerability of xanthohumol.

METHODS AND RESULTS

Thirty healthy volunteers were randomized to 24 mg day-1 xanthohumol (99.8% pure) or placebo for eight weeks. Comprehensive metabolic panels, complete blood counts, body weight, vital signs, and health-related quality of life questionnaires were assessed every two weeks. Participants were interviewed for adverse events (AEs) throughout the trial. Thirteen of 14 (93%) and 14 of 16 (88%) participants completed the trial in the placebo and xanthohumol groups, respectively. There were no withdrawals due to AEs. There were no clinically relevant, between-group differences in laboratory biomarkers, body weight, vital signs, or health-related quality of life. There were no severe or FDA-defined serious AEs, but non-serious AEs are documented in both the placebo (n = 42) and xanthohumol (n = 58) groups.

CONCLUSION

Over an eight-week period, 24 mg daily xanthohumol was safe and well-tolerated by healthy adults.

A Placebo-Controlled, Pseudo-Randomized, Crossover Trial of Botanical Agents for Gulf War Illness: Resveratrol (Polygonum cuspidatum), Luteolin, and Fisetin (Rhus succedanea)

A chronic multi-symptom illness of unknown etiology, Gulf War Illness (GWI) affects 175,000 to 250,000 veterans of the Gulf War. Because inflammation has suspected involvement in the pathophysiology of GWI, botanical treatments that target inflammation may be beneficial in reducing symptoms. No FDA-approved treatments currently exist for GWI, and rapid prioritization of agents for future efficacy testing is important. This study is part of a larger project that screened nine different botanical compounds with purported anti-inflammatory properties for potential treatment of GWI. We tested three botanicals (resveratrol [Polygonum cuspidatum], luteolin, and fisetin [Rhus succedanea]) on symptom severity of GWI in this placebo-controlled, pseudo-randomized clinical trial. Twenty-one male veterans with GWI completed the study protocol, which consisted of 1 month (30 days ± 3) of baseline symptom reports, 1 month of placebo, 1 month of lower-dose botanical, and 1 month of higher-dose botanical. Participants completed up to 3 different botanicals, repeating the placebo, lower-dose, and higher-dose cycle for each botanical assigned. Linear mixed models were used for analyses. Resveratrol reduced GWI symptom severity significantly more than placebo at both the lower (p = 0.035) and higher (p = 0.004) dosages. Luteolin did not decrease symptom severity more than placebo at either the lower (p = 0.718) or higher dosages (p = 0.492). Similarly, fisetin did not reduce symptom severity at either the lower (p = 0.504) or higher (p = 0.616) dosages. Preliminary findings from this screening study suggest that resveratrol may be beneficial in reducing symptoms of GWI and should be prioritized for future testing. Larger trials are required to determine efficacy, response rates, durability of effects, safety, and optimal dosage. This trial was registered on ClinicalTrials.gov (NCT02909686) on 13 September 2016.

National Center for Complementary and Integrative Health Perspectives on Clinical Research Involving Natural Products

The sales of dietary supplements continue to increase year after year. Despite their use by a large percentage of Americans, there is little evidence for the vast majority of products regarding their safety or efficacy. National Center for Complementary and Integrative Health supports a broad range of research on dietary supplements, including clinical trials. Our experience with these trials has shaped our current policies and priorities for clinical research. This perspective outlines those policies and priorities that are shaping our investments going forward. SIGNIFICANCE STATEMENT: The sales of dietary supplements continue to increase year after year. Despite their use by a large percentage of Americans, there is little evidence for the vast majority of products regarding their safety or efficacy. National Center for Complementary and Integrative Health supports a broad range of research on dietary supplements, including clinical trials. Our experience with these trials has shaped our current policies and priorities for clinical research. This perspective outlines those policies and priorities that are shaping our investments going forward.

A strategy for test article selection and phytochemical characterization of Echinacea purpurea extract for safety testing

Botanical dietary supplements (BDS) are used around the world for many purported therapeutic properties. The selection of an authentic product and it's phytochemical characterization is critical to generate robust safety data. Because botanicals are complex mixtures with variable quality, identification of a representative product for testing has been challenging. Echinacea is used for its purported immune stimulant properties and was listed as the 2nd top-selling BDS in 2018. However, there are limited safety data for Echinacea. Hence, the National Toxicology Program (NTP) has selected Echinacea for safety testing using rodent models. Here, we describe selection and comprehensive characterization of an Echinacea purpurea root extract to be used in the NTP testing program. Using non-targeted chemical analyses combined with chemometric analysis, a potential unfinished product (i.e., an extract that serves as source material for finished products) of Echinacea purpurea was selected. The product was then authenticated using chemical and DNA techniques and characterized, including the phytochemical composition. Among numerous constituents identified, caftaric acid, chicoric acid, chlorogenic acid and dodeca-2(E),4(E),8(Z),10(E/Z)-tetraenoic acid isobutylamide made up a small fraction of the extract. Based on these analyses, an approach is proposed for test article selection for Echinacea research which can be adapted to other botanicals.

Evaluating Sufficient Similarity of Botanical Dietary Supplements: Combining Chemical and In Vitro Biological Data

Botanical dietary supplements are complex mixtures with numerous potential sources of variation along the supply chain from raw plant material to the market. Approaches for determining sufficient similarity (ie, complex mixture read-across) may be required to extrapolate efficacy or safety data from a tested sample to other products containing the botanical ingredient(s) of interest. In this work, screening-level approaches for generating both chemical and biological-response profiles were used to evaluate the similarity of black cohosh (Actaea racemosa) and Echinacea purpurea samples to well-characterized National Toxicology Program (NTP) test articles. Data from nontargeted chemical analyses and gene expression of toxicologically important hepatic receptor pathways (aryl hydrocarbon receptor [AhR], constitutive androstane receptor [CAR], pregnane X receptor [PXR], farnesoid X receptor [FXR], and peroxisome proliferator-activated receptor alpha [PPARα]) in primary human hepatocyte cultures were used to determine similarity through hierarchical clustering. Although there were differences in chemical profiles across black cohosh samples, these differences were not reflected in the biological-response profiles. These findings highlight the complexity of biological-response dynamics that may not be reflected in chemical composition profiles. Thus, biological-response data could be used as the primary basis for determining similarity among black cohosh samples. Samples of E. purpurea displayed better correlation in similarity across chemical and biological-response measures. The general approaches described herein can be applied to complex mixtures with unidentified active constituents to determine when data from a tested mixture (eg, NTP test article) can be used for hazard identification of sufficiently similar mixtures, with the knowledge of toxicological targets informing assay selection when possible.

Development of a consensus approach for botanical safety evaluation - A roundtable report

Botanical safety science continues to evolve as new tools for risk assessment become available alongside continual desire by consumers for "natural" botanical ingredients in consumer products. Focusing on botanical food/dietary supplements a recent international roundtable meeting brought together scientists to discuss the needs, available tools, and ongoing data gaps in the botanical safety risk assessment process. Participants discussed the key elements of botanical safety evaluations. They provided perspective on the use of a decision tree methodology to conduct a robust risk assessment and concluded with alignment on a series of consensus statements. This discussion highlighted the strengths and vulnerabilities in common assumptions, and the participants shared additional perspective to ensure that this end-to-end safety approach is sufficient, actionable and timely. Critical areas and data gaps were identified as opportunities for future focus. These include, better context on history of use, systematic assessment of weight of evidence, use of in silico approaches, inclusion of threshold of toxicological concern considerations, individual substances/matrix interactions of plant constituents, assessing botanical-drug interactions and adaptations needed to apply to in vitro and in vivo pharmacokinetic modelling of botanical constituents.

Natural Compounds as a Strategy to Optimize "In Vitro" Expansion of Stem Cells

The efficient use of stem cells for transplantation is often limited by the relatively low number of stem cells collected. The ex vivo expansion of human stem cells for clinical use is a potentially valuable approach to increase stem cell number. Currently, most of the procedures used to expand stem cells are carried out using a 21% oxygen concentration, which is about 4- to 10-fold greater than the concentration characteristic of their natural niches. Hyperoxia might cause oxidative stress with a deleterious effect on the physiology of cultured stem cells. In this review, we investigate and critically examine the available information on the ability of natural compounds to counteract hyperoxia-induced damage in different types of stem cells ex vivo. In particular, we focused on proliferation and stemness maintenance in an attempt to draw up useful indications to define new culture media with a promoting activity on cell expansion in vitro.

Genotoxic properties of Betonica officinalis, Gratiola officinalis, Vincetoxicum luteum and Vincetoxicum hirundinaria extracts

Genotoxicity of B. officinalis, G. officinalis, V. luteum and V. hirundinaria extracts, which demonstrated strong antioxidant capacity, was tested using chromosome aberration, sister chromatid exchange (SCE), cytokinesis-block micronucleus and alkaline single-cell gel electrophoresis (comet) assays in human lymphocytes in vitro and Ames Salmonella/microsome test. All tested extracts were not mutagenic in S. typhimurium strains TA98 and TA100 with and without metabolic activation and did not induce chromosome aberrations in human lymphocytes in vitro. Extract from G. officinalis was the only one, which induced significant increase in micronuclei, indicating possible aneugenic effect. All investigated plant extracts induced DNA damage evaluated by the comet assay, while B. officinalis and V. luteum extracts induced slight increase in SCE values. The determined variation in response might be due to the plant extract tested and donor susceptibility.

Systemic exposure to Ginkgo biloba extract in male F344/NCrl rats: Relevance to humans

Ginkgo biloba extract (GBE) is a popular botanical dietary supplement used worldwide and the safety of use is a public health concern. While GBE is a complex mixture, the terpene trilactones and flavonol glycosides are believed to elicit the pharmacological and/or toxicological effects of GBE. In a National Toxicology Program (NTP) 2-year rodent bioassay with GBE, hepatotoxicity was observed in rodents (≥100 mg/kg in rats, ≥ 200 mg/kg in mice). Subsequently, questions arose about whether or not the GBE used in NTP studies was representative of other GBE products and how rodent doses are related to human doses. To address these, we generated systemic exposure data for terpene trilactones in male rats following oral administration of 30, 100, and 300 mg/kg GBE test article from the 2-year bioassay. Dose-normalized C_max and AUC_∞ for terpene trilactones from the current study were within 5-fold of published rodent studies using a standardized GBE preparation. Comparison of our rat systemic exposure data at 100 mg/kg GBE to published human data following ingestion of 240 mg GBE-containing product showed that the rat/human exposure multiple was 3-22, for terpene trilactones. These data demonstrate the relevance of NTP rodent toxicity data to humans.

Using Tox21 High-Throughput Screening Assays for the Evaluation of Botanical and Dietary Supplements

Introduction: Recent nationwide surveys found that natural products, including botanical dietary supplements, are used by ∼18% of adults. In many cases, there is a paucity of toxicological data available for these substances to allow for confident evaluations of product safety. The National Toxicology Program (NTP) has received numerous nominations from the public and federal agencies to study the toxicological effects of botanical dietary supplements. The NTP sought to evaluate the utility of in vitro quantitative high-throughput screening (qHTS) assays for toxicological assessment of botanical and dietary supplements.

Materials and Methods: In brief, concentration–response assessments of 90 test substances, including 13 distinct botanical species, and individual purported active constituents were evaluated using a subset of the Tox21 qHTS testing panel. The screen included 20 different endpoints that covered a broad range of biologically relevant signaling pathways to detect test article effects upon endocrine activity, nuclear receptor signaling, stress response signaling, genotoxicity, and cell death signaling.

Results and Discussion: Botanical dietary supplement extracts induced measurable and diverse activity. Elevated biological activity profiles were observed following treatments with individual chemical constituents relative to their associated botanical extract. The overall distribution of activity was comparable to activities exhibited by compounds present in the Tox21 10K chemical library.

Conclusion: Botanical supplements did not exhibit minimal or idiosyncratic activities that would preclude the use of qHTS platforms as a feasible method to screen this class of compounds. However, there are still many considerations and further development required when attempting to use in vitro qHTS methods to characterize the safety profile of botanical/dietary supplements.

Finding the bad actor: Challenges in identifying toxic constituents in botanical dietary supplements

Botanical-derived dietary supplements have widespread use in the general population. The complex and variable nature of botanical ingredients and reports of adverse responses have led to concern for negative human health impacts following consumption of these products. Toxicity testing of the vast number of available products, formulations, and combinations is not feasible due to the time and resource intensive nature of comprehensive testing. Methods are needed to assess the safety of a large number of products via more efficient frameworks. Identification of toxicologically-active constituents is one approach being used, with many advantages toward product regulation. Bioassay-guided fractionation (BGF) is the leading approach used to identify biologically-active constituents. Most BGF studies with botanicals focus on identifying pharmacologically-active constituents for drug discovery or botanical efficacy research. Here, we explore BGF in a toxicological context, drawing from both efficacy and poisonous plant research. Limitations of BGF, including loss of mixture activity and bias toward abundant constituents, and recent advancements in the field (e.g., biochemometrics) are discussed from a toxicological perspective. Identification of active constituents will allow better monitoring of market products for known toxicologically-active constituents, as well as surveying human exposure, two important steps to ensuring the safety of botanical dietary supplements.

Purification of two valepotriates from Centranthus ruber by centrifugal partition chromatography: From analytical to preparative scale

Considering chemical complexity of plant crude extracts, purification of natural products is a rate limiting process to identify new compounds as well as to obtain standard references for quantitative or qualitative purposes. In the present work, a centrifugal partition chromatography (CPC) method was developed to isolate and produce high quality reference standards of valtrate and 7-homovaltrate from Centranthus ruber L. roots. These two compounds are controversial aglycon iridioids regulated by the legislation on plant-based dietary supplements. A new biphasic solvent system suitable for CPC separation of valepotriates was developed. It was composed of methanol/hexane/water (5/5/0.8, v/v/v). It yielded a partition coefficient near 1 and a theoretical selectivity of 1.3 between both targeted compounds. Optimization of CPC experimental parameters at the analytical scale (50 mL- and 100 mL-column capacity) enabled compounds' separation with a flow rate of 8 mL/min at 2500 rpm. Then a scale up from a 100 mL-column capacity to a 1000 mL-column capacity has been studied using the "free-space between peaks" concept. It allowed an injected quantity 16 times higher in comparison to the maximal loading capacity of the 100 mL-column. Both valtrate and 7-homovaltrate were recovered in one single step with a purity over 97%. Further MS and NMR characterization allowed to confirm unambiguously the compounds' structures. The highly efficient CPC separation developed in this work provides valepotriates in amounts suitable for further study and strong bases for future industrial development.

Getting to the Root of the Matter: Challenges and Recommendations for Assessing the Safety of Botanical Dietary Supplements

The National Toxicology Program's (NTP) mission is "to evaluate agents of public health concern, by developing and applying the tools of modern toxicology and molecular biology." Botanical dietary supplements (BDS) represent agents of public health concern due to widespread exposure to high doses, a lack of safety data for most products, variable quality, and reports of adverse events. This commentary will address lessons learned in NTP testing activities with BDS and recommendations for moving forward.

Follow that botanical: Challenges and recommendations for assessing absorption, distribution, metabolism and excretion of botanical dietary supplements

Botanical dietary supplements are complex mixtures containing one or more botanical ingredient(s), each containing numerous constituents potentially responsible for its purported biological activity. Absorption, distribution, metabolism, and excretion (ADME) data are critical to understand the safety of botanical dietary supplements, including their potential for pharmacokinetic botanical-drug or botanical-botanical interactions. However, ADME data for botanical dietary supplements are rarely available and frequently inadequate to characterize their fate in vivo. Based on an assessment of the current status of botanical dietary supplements ADME research, the following key areas are identified that require robust data for human safety assessment: 1) phytochemical characterization including contaminant analysis and botanical authentication; 2) in vitro and/or in vivo data for identifying potential botanical-botanical or botanical-drug interactions and active/marker constituents; 3) robust ADME study design to include systemic exposure data on active/marker constituents using traditional or novel analytical chemistry and statistical approaches such as poly-pharmacokinetics; and 4) investigation of human relevance. A case study with Ginkgo biloba extract is used to highlight the challenges and proposed approaches in using ADME data for human safety assessment of botanical dietary supplements.

How similar is similar enough? A sufficient similarity case study with Ginkgo biloba extract

Botanical dietary supplements are complex mixtures that can be highly variable in composition and quality, making safety evaluation difficult. A key challenge is determining how diverse products in the marketplace relate to chemically and toxicologically characterized reference samples (i.e., how similar must a product be in order to be well-represented by the tested reference sample?). Ginkgo biloba extract (GBE) was used as a case study to develop and evaluate approaches for determining sufficient similarity. Multiple GBE extracts were evaluated for chemical and biological-response similarity. Chemical similarity was assessed using untargeted and targeted chemistry approaches. Biological similarity was evaluated using in vitro liver models and short-term rodent studies. Statistical and data visualization methods were then used to make decisions about the similarity of products to the reference sample. A majority of the 26 GBE samples tested (62%) were consistently determined to be sufficiently similar to the reference sample, while 27% were different from the reference GBE, and 12% were either similar or different depending on the method used. This case study demonstrated that approaches to evaluate sufficient similarity allow for critical evaluation of complex mixtures so that safety data from the tested reference can be applied to untested materials.