Metformin loaded silver nanoparticles were synthesized using ecofriendly method with extract of Azadiractha indica as reducing agent and two natural polymers; guar gum and xanthan gum, Sodium alginate, and a semi- synthetic polymer (AMS) as stabilizing agents. Twelve batches of nanoparticles were synthesized. Nanocomposites synthesized from AMS were designated as AMS 1% NANOmet, AMS3% NANOmet and AMS5% NANOmet. Guar gum stabilized nanoparticles were designated as GG1% NANOmet, GG3% NANOmet and GG5% NANOmet while Xanthan gum nanocomposites were coded as XG1% NANOmet, XG3% NANOmet and XG5% NANOmet respectively. Sodium alginate stabilized nanocomposites were designated as NaALG1% NANOmet, NaALG3% NANOmet and NaALG5% NANOmet respectively.
The percentage yield of nanocomposites was high with values ranging from 80 % to 99.87 %. The entrapment efficiencies of the samples ranged from 63.06 % to 80.22 % while the loading capacities were in the range of 7.24 % to 24.10%. Differential scanning calorimetry showed there was no interaction between the polymers and metformin. Characterization of the metformin nanocomposites using UV- v is spectroscopy, zeta sizer, scanning electron microscopy (SEM) and polydispersity were performed. The UV-vis spectroscopy showed surface plasmon resonance of 371nm for all the nanocomposites except XG5%NANOmet which had SPR of 335nm.
The mean particle size of GG1%NANOmet was ideal with a value of 188.7nm followed by AMS1%NANOmet (386.7nm). All the batches showed extended and sustained release profile with initial burst effect at the first 30 min of release studies. Release of metformin in SIF was predominantly higher than in SGF. The kinetics of release was mainly zero order for all the nanocomposites with the exception of NaALG5% NANOmet which released the drug by higuchi kinetics. Antimicrobial property of the optimized nanocomposites were similar (P>0.05). Generally, MIC values of the samples against the microorganisms tested ranged from 2500- 5000µg/ml.
In vivo anti hyperglycemic property of the optimized metformin nanocomposite using glucose hyperload model results showed GG5%NANOmet as the optimum batch. At equal doses it produced sustained and consistent significant (p
