A comparative investigation of the interaction and pharmacokinetics of hemoglobin with berberine and its oxymetabolite

•Intravenous injection of berberine (BBR) can be metabolized to a new oxymetabolite (OBB).•Both of BBR and OBB exert much stronger interaction with hemoglobin than plasma, thus affect the pharmacokinetics.•BBR and OBB could change conformation of bovine hemoglobin with non-covalent bond.