In Vitro Evaluation of GLP-1R-Associated Activity of a Sustainable Standardized Phospholipid-Formulated Bergamot Extract

Background: Metabolic syndrome is characterized by dysregulated glucose metabolism and is a major risk factor for type 2 diabetes mellitus and cardiovascular disease. Although glucose-lowering therapies such as glucagon-like peptide-1 receptor (GLP-1R) agonists are effective, their use may be limited by cost, administration route, side effects and tolerability. Bergamot (Citrus bergamia Risso et Poiteau) extract, rich in flavanones, has shown favorable metabolic effects in clinical studies, although its mechanisms of action remain insufficiently defined. This study aimed to investigate the potential glucose-modulating mechanisms of a standardized phospholipid-formulated bergamot extract (BP) (Vazguard™) in vitro. Methods: GLP-1R activation was assessed in a U2OS cell line expressing cyclic adenosine monophosphate (cAMP)-sensitive Nomad Biosensors™. Dipeptidyl peptidase-4 (DPP4) activity was evaluated using a cell-free enzymatic assay, while Glucose transporter type 4 (GLUT4)-mediated glucose uptake was assessed in CHO-K1 cells stably expressing human GLUT4 using an adenosine triphosphate (ATP)-based readout. Cytotoxicity was also using lactate dehydrogenase (LDH), MTT, and nuclei count assays. Results: BP exhibited a dose-dependent (0.31–5 mg/mL) increase in cAMP biosensor fluorescence, consistent with GLP-1R-associated signaling and a maximal response of approximately 60% relative to the positive control (GLP-1R agonist II). No cytotoxic effects were observed. In contrast, BP showed no inhibitory effect on DPP4 activity and did not alter GLUT4-mediated glucose uptake under the experimental conditions tested. Conclusions: These findings provide novel mechanistic evidence that phospholipid-formulated bergamot extract suggests a possible involvement in GLP-1R-associated signaling in vitro, without detectable effects on DPP4 or GLUT4 pathways under the conditions tested. This suggests a mechanism consistent with weak agonist or allosteric modulation of GLP-1R and supports further investigation of bergamot formulated with phospholipids as potential natural adjuncts in metabolic health management.