Development and biological evaluation of Gymnema sylvestre extract-loaded nonionic surfactant-based niosomes

Aim: To develop and characterize Gymnema sylvestre extract-loaded niosomes using nonionic surfactants, and to evaluate their antihyperglycemic efficacy in comparison with the parent extract. Materials & methods: Nonionic surfactant-based G. sylvestre extract-loaded niosomes were prepared using the thin-film hydration method. The optimized formulation was screened for entrapment efficiency of the constituents, as well as other parameters such as release kinetics, vesicle size, zeta-potential and stability studies. The parent extract and optimized niosomal formulation were evaluated for their antihyperglycemic potential in an alloxan-induced diabetic animal model. Results: Niosomes prepared using Span T 40 (SD Fine Chemicals Ltd, Mumbai, India) provided sterically stable vesicles 229.5 nm in size with zeta-potential and entrapment efficiency of 150.86 mV and 85.3 +/- 4.5%, respectively. The surface morphology of vesicles was confirmed to be spherical by scanning electron microscopy studies. An in vitro release study demonstrated 77.4% of phytoconstituents release within 24 h. The niosome formulation demonstrated significant blood glucose level reduction in an oral glucose tolerance test, and increased antihyperglycemic activity compared with the parent extract in an alloxan-induced diabetic model. Conclusion: This study reveals the merits of G. sylvestre extract-loaded niosomes, and justifies the potential of niosomes for improving the efficacy of G. sylvestre extract as antidiabetic.