Impact of Bougainvillea glabra on antioxidant activity by <i>in vitro</i> and <i>in silico</i> 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 <i>Bougainvillea glabra</i> was evaluated for its antioxidant, antimicrobial, and antidiabetic potential through both <i>in vitro</i> and <i>in silico</i> 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 <i>Staphylococcus aureus, Escherichia coli</i>, and <i>Pseudomonas fluorescens</i>, 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, <i>Bougainvillea glabra</i> 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.