Anti-diabetic effect of the ethyl acetate fraction of Clerodendrum volubile: protocatechuic acid suppresses phagocytic oxidative burst and modulates inflammatory cytokines

The antidiabetic effects of the ethyl acetate (EtOAc) fraction of Clerodendrum volubile leaves was investigated in this study. EtOAc was also fractionated to isolate the active compounds. The structure of the isolated compound (Protocatechuic acid) was established using 1H and 13C NMR spectroscopies and mass spectrometry. Protocatechuic acid was investigated for its anti-oxidative burst in polymorphonuclear neutrophils (PMNs) and macrophages. It was also docked with α–glucosidase and TNF-α. Acute treatment with EtOAc fraction of Clerodendrum volubile leaves significantly (p < 0.05) decreased blood glucose level and hepatic biomarkers, and significantly (p < 0.05) increased serum insulin level and β–cell function. It had little or no effect on serum lipid profile and atherogenic indices. Protocatechuic acid significantly (p < 0.05) suppressed phagocytic oxidative burst and docked well with α–glucosidase and TNF-α. These results indicate the therapeutic effect of EtOAc fraction of C. volubile on type 2 diabetes and its complications, which can be attributed to the main bioactive compound, protocatechuic acid.