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Operating and compositional variables for preparation of betulinic acid nanoemulsions

Abstract:

Betulinic acid is a triterpene with remarkable biological activities, including anticancer and highlights the anti -HIV activity. In recent years, nanoemulsions have been used as delivery systems to improve the bioavailability of lipophilic bioactive compounds. In this work response surface methodology (RSM) by a central composite design was employed to evaluate the effects of emulsification power, ultrasonication time, emulsifier concentration in the characteristics of betulinic acid nanoemulsions. Optimal conditions for nanoemulsions formation were obtained and different emulsifiers and oils as the dispersed phase were studied. The effect of pH on globule size and zeta potential of betulinic acid nanoemulsions was studied. The statistical model used for globule size effectively fitted the experimental data with a R2 of 0.94. Operating conditions (power and emulsification time) and the quadratic terms, had significant effects on globule size. The optimal conditions to prepare nanoemulsions with an mean diameter of 64 nm were using 15% emulsifier (tween 60), and an ultrasonication power of 20 W during 220 s. Nanoemulsions prepared with medium chain oil as the dispersed phase had the lowest mean globule size; however, after storage time, nanoemulsions with the mixture medium chain oil:olive oil, the globule size remained unaltered. The pH variation changed the globule surface charge, values from -30 mV were obtained, and after storage time there was no significant change in the zeta potential.