Ocular Toxicity and Mechanistic Investigation for Berberine and Its Metabolite Berberrubine on Zebrafish

Berberine (BBR) has seen growing application in ophthalmology, yet the ocular toxicity of BBR and its metabolites remains poorly understood. This study aimed to evaluate the ocular toxicity of BBR and its major metabolite M1 and unravel their underlying mechanisms. Ocular toxicity was evaluated in human corneal epithelial cells and wild-type AB zebrafish. Mechanistic studies utilized fluorescence imaging, biochemical quantitative assays, and qPCR analyses in AB zebrafish and transgenic mitochondrial fluorescent zebrafish (strain Tg(Xla.Eef1a1:mlsEGFP)). Both BBR and M1 induced significant ocular toxicity across models, with BBR showing higher toxicity than M1. Mechanistic analyses revealed their toxicity stemmed from photoreceptor cell damage and Sirtuin 3 (SIRT3) inhibition, triggering a cascade of pathological events: mitochondrial dysfunction, oxidative stress, autophagic dysfunction, apoptosis, and inflammation. This study provides a reference for individualized risk assessment and clinical management of BBR-based therapies and paves the way for developing BBR derivatives with reduced ocular toxicity.