Abstract:
Leaf extracts of Murraya koenigii (L.) Spreng., Coccinia grandis (L.) Voigt and flower extracts of Senna auriculata (L.) Roxb. is traditionally used for the treatment of hyperglycaemia. Although the glucose-lowering activity of these plants is scientifically proven, poor pharmacokinetic properties and formulation difficulties have hindered their development as therapeutic agents. This study attempted to load M. koenigii, C. grandis and S. auriculata extracts into gelatin nanoparticles and to assess their glucose-lowering activity using a high-fat diet fed, streptozotocin-induced diabetic Wistar rat model (5-7 weeks old, n=6/group). Aqueous, ethanol, and aqueous ethanol 70% v/v extracts of M. koenigii, C. grandis, and S. auriculata prepared by ultrasonication (40 0C, 40 kHz, 30 min) were dried and loaded into gelatin nanoparticles. The optimized nanoparticles were screened in vivo using rats with chemically induced type 2 diabetes mellitus and oral glucose tolerance tests (OGTT, 3 g/kg) were conducted. The glucose-lowering activity was evaluated using the total area under the OGTT curve (TAUC). The most active nanoformulations were characterized by particle size, zeta potential, and Fourier-transform infrared (FTIR) spectroscopy. The optimum loading of plant extracts into gelatin nanoparticles was achieved at concentrations ranging from 30─50 mg/mL. The particle size and zeta potential values of nanoparticles exerting the highest glucose-lowering potential ranged from 467.9─519.9 nm and (–14.7)─(–34.3) mV. The entrapment of phenolic compounds in the gel matrix via physical interactions was evident in the FTIR spectra. Gelatin nanoparticles encapsulated with M. koenigii, C. grandis, S. auriculata aqueous extracts, and M. koenigii aqueous ethanol 70% v/v extract showed significant reductions of TAUC by 16.5%(p=0.002), 13.3%(p=0.005), 17.4%(p=0.002) and 19.0%(p=0.000) respectively compared to the respective non-encapsulated extracts. It can be concluded that the glucose-lowering activity of M. koenigii, C. grandis and S. auriculata aqueous extracts, and M. koenigii aqueous ethanol 70% v/v extract is enhanced by encapsulation into gelatin nanoparticles.
