Impact of Bougainvillea glabra on antioxidant activity by in vitro and in silico investigation of the insulin signaling pathway

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by persistent hyperglycemia, often resulting from insulin resistance and oxidative stress. With the limitations of current pharmacological treatments, there is growing interest in identifying plant-derived compounds that can modulate key components of the insulin signaling pathway. In this study, the methanolic leaf extract of Bougainvillea glabra was evaluated for its antioxidant, antimicrobial, and antidiabetic potential through both in vitro and in silico approaches. Phytochemical profiling using Gas Chromatography–Mass Spectrometry (GC-MS) revealed the presence of bioactive compounds, including 2-propenoic acid, 2-ethylhexyl ester and 3,4-dihydro-4-(1,3-dioxolan-2-yl)-5,7-dimethoxy-1(2H)-benzopyran-2-one. The antioxidant potential of the extract was assessed using the DPPH radical scavenging assay, which showed a concentration-dependent activity with a maximum inhibition of 77.57% at 50 µL. Antibacterial activity was demonstrated against several microbial strains, notably Staphylococcus aureus, Escherichia coli, and Pseudomonas fluorescens, with enhanced zones of inhibition observed at higher extract concentrations. Molecular docking studies were carried out targeting insulin signaling proteins GLUT-4, IRS-1, and SREBP-1c. Among these, GLUT-4 showed the strongest binding affinity with the key phytocompounds, with docking scores of –8.7 and –7.9 kcal/mol, along with multiple hydrogen bond interactions. Pharmacokinetic and toxicity predictions using SwissADME and pkCSM indicated high gastrointestinal absorption, low mutagenicity, and favorable drug-likeness profiles for most compounds, supporting their therapeutic potential. In conclusion, Bougainvillea glabra demonstrated significant antioxidant, antimicrobial, and antidiabetic properties. The high binding affinity of its phytocompounds to GLUT-4 and their favorable ADMET profiles highlight their promise as candidates for plant-based drug development in the management of Type 2 Diabetes Mellitus.