Abstract
Black cohosh extract (BCE) is a popular botanical dietary supplement marketed to relieve symptoms of various gynecological ailments. Studies conducted by the National Toxicology Program (NTP) showed that BCE induces micronucleated erythrocytes in female rats and mice. Subsequently, the NTP showed that a variety of BCEs, including the sample that induced micronuclei (MN) in vivo (“NTP BCE”) had a similar effect in human TK6 cells. Further testing with the MultiFlow® DNA Damage Assay revealed that TK6 cells exposed to NTP BCE, as well as a BCE reference material (BC XRM), exhibited a signature consistent with aneugenic activity in TK6 cells. Results from experiments reported herein confirmed these in vitro observations with NTP BCE and BC XRM. We extended these studies to include a novel test system, the MultiFlow Aneugen Molecular Mechanism Assay. For these experiments, TK6 cells were exposed to NTP BCE and BC XRM over a range of concentrations in the presence of fluorescent Taxol (488 Taxol). After 4 h, nuclei from lysed cells were stained with a nucleic acid dye and labeled with fluorescent antibodies against phospho‐histone H3 (p‐H3) and Ki‐67. Whereas BCEs did not affect p‐H3:Ki‐67 ratios (a signature of aneugenic mitotic kinase inhibitors), 488 Taxol‐associated fluorescence (a tubulin binder‐sensitive endpoint) was affected. More specifically, 488 Taxol‐associated fluorescence was reduced over the same concentration range that was previously observed to induce MN. These results provide direct evidence that BCEs destabilize microtubules in vitro, and this is the molecular mechanism responsible for the aneugenicity findings. Environ. Mol. Mutagen. 2019. © 2019 The Authors. Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.
Highlights
Due to public concern with regard to the safety of botanical dietary supplements, the National Toxicology Program (NTP) is evaluating a number of botanicals for toxicological effects (Abdel-Rahman et al 2011; National Toxicology Program 2017; Rider et al 2018)
We extended the work by evaluating NTP black cohosh extract (BCE) and BC extract reference material (BC XRM) in a new test system known as the MultiFlow Aneugen Molecular Mechanism (AMM) Assay (Bernacki et al 2019)
The lowest effective concentration was 250 μg/mL in each case. When both exponential and Hill models are considered, Benchmark dose (BMD) estimates for NTP BCE were observed to range from 154–158 μg/mL, whereas both models produced a value of 247 μg/mL for BC XRM (Fig. 1c, d)
Summary
Due to public concern with regard to the safety of botanical dietary supplements, the National Toxicology Program (NTP) is evaluating a number of botanicals for toxicological effects (Abdel-Rahman et al 2011; National Toxicology Program 2017; Rider et al 2018). BCE is prepared from the root of the plant (Actaea racemosa) and is one of the top 10 selling botanical dietary supplements in the United States (Smith et al 2018). It is primarily marketed to older women with the stated intention of alleviating symptoms of menopause and is represented as an alternative to hormone replacement therapy. BCE is used by younger women with the goal of alleviating symptoms of premenstrual syndrome (PMS) and to regulate the menstrual cycle (Gafner 2016). In 90-day repeat-dose rodent studies conducted by the NTP, BCE administered by oral gavage significantly increased micronucleated reticulocytes and micronucleated erythrocytes in the peripheral blood of female B6C3F1/N mice and micronucleated reticulocytes in the peripheral blood of female Wistar Han rats (Mercado-Feliciano et al 2012). The observation that BCE is genotoxic in vivo, coupled with widespread use, led the NTP to investigate whether BCE is carcinogenic the 2-year rodent cancer bioassay (currently on test; National Toxicology Program 2019)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
