In silico assessment of the endocrine disrupting and genotoxic potential of bisguaiacols as possible bisphenol A alternatives

Introduction

Bisguaiacols (BGs) are proposed as safer and more sustainable alternatives to bisphenol A (BPA), largely due to structural modifications like methoxy substituents on the benzene ring of bisphenols (as in BGs) resulting in reduced estrogenic potential. However, the full toxicological profile of BGs remains insufficiently characterised. This study focuses on genotoxicity and endocrine disruption (ED) as key endpoints. The aim is to provide in silico predictions for seven BGs and compare these with three bisphenols (BPs), and to integrate these predictions with New Approach Methodologies (NAMs) to support hazard identification.

Methods

ED was evaluated using QSAR models and molecular docking. Genotoxicity was assessed using QSAR models. Selected BGs were further evaluated using NAM-based assays, including CALUX assays targeting nuclear receptors and an integrated genotoxicity battery.

Results

QSAR results for estrogen receptor binding were variable, while androgen receptor predictions were consistent. Docking indicated receptor-specific binding preferences and thyroid receptor interactions not captured by QSAR models. CALUX assays confirmed lower or absent endocrine activity for selected BGs compared to BPA across multiple receptors, supporting in silico trends.

QSAR models predicted BPs and corresponding BGs non-mutagenic. Two models for predicting micronucleus activity yielded conflicting results both for BPs (with good reliability) and BGs (with moderate reliability). The model for chromosomal aberration indicated limited activity, with only BGP acid predicted active with low reliability. In vitro NAM-based genotoxicity assays supported these predictions, showing ROS, DNA lesions, clastogenic activity and secondary genotoxicity for BPA and at reduced level for BGs.

Conclusions

BGs show a lower or comparable receptor-dependent ED potential as BPs. QSAR models for genotoxicity are unable to distinguish BGs from BPs. The integration of QSAR tools, docking, and NAMs provides complementary evidence, reduces uncertainty in early hazard assessment, and enables prioritisation of candidate substances as safer BPA alternatives.