From neat compounds to complex mixtures: A potential screening strategy for cardiotoxic potential of botanicals

Abstract

Natural products, such as botanical dietary supplements, are used globally and in some regions growing in popularity. Ensuring the safety of these products is an important public health priority. Botanical dietary supplements are naturally complex, with varying chemical compositions due to factors such as differences in growing conditions, extraction processes, and/or changes to the finished product. Conventional in vivo rodent models are generally not suitable for detecting acute cardiotoxicity of chemicals and have significant differences in electrophysiology in comparison to humans. Additionally, in vitro testing schemes are designed to test single chemicals, not complex mixtures. Because of the chemical variability and a reliance on history of use data, toxicity data for many botanical dietary supplements are lacking, and few tools have been tested for their suitability for these complex mixtures.

A global, cross-sector effort is working to evaluate assays for botanicals. A battery of in vitro assays already used for single chemical toxicity testing was selected to evaluate each tool’s suitability for botanicals. For cardiotoxicity testing, assays and endpoints including microelectrode assays, cardiac contractility screening, and voltage/or calcium sensitive dyes were selected. Botanicals with well documented cardiotoxicity or neuroactive potential were sourced, chemically characterized, and used across the assays. These botanicals include aconite, ephedra, oleander, yohimbe, and thunder god vine, along with those expected to be negative, like milk thistle and Asian ginseng. Initial data using human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) show promising results for cardiotoxicity screening of complex botanical mixtures.

Electrophysiology measurements indicate that acute treatment with aconite and ephedra at 2 μg/ml induced significant changes in action potential duration at 90 % of repolarization (ADP90), whereas botanicals without reported cardiotoxicity (e.g., ginseng) did not cause changes in APD90 at the highest concentration tested (7 μg/ml). These results indicate that assays currently available and validated by an international multi-site effort led by HESI and the FDA for single chemicals are suitable for cardiotoxicity screening of botanicals. Further work will include testing more botanicals and different preparations (e.g., different solvents) to better understand the applicability of these tools for cardiotoxicity testing of botanicals.