RESUMO
In this study, chitosan-coated liposomes were developed. To entrap lyophilized tamarind extract containing alpha-hydroxy acids (AHAs) together with tartaric acid, the reverse phase evaporation method was used to obtain well-formed liposomes loaded with the extract. The highest entrapment efficiency of 68.3 +/- 3.0% into the liposomes was obtained with liposomes consisting of phosphatidylcholine and cholesterol in a molar ratio of 2 : 1 after the extrusion process. The average particle size of the prepared liposomes was 158 +/- 26 nm showing a negative zeta potential of -6 mV. For the preparation of the chitosan-coated liposomes, two selected independent parameters were varied: chitosan concentrations of 0.1, 0.5 and 1.0% w/v and volumes of the chitosan solutions of 1, 2 and 3 mL, to study the effects of such parameters on the entrapment efficiency of the extract-loaded liposomes. Variation in the volumes of the chitosan solution did not affect the entrapment efficiency of the liposomes. However, the entrapment efficiency of the AHAs in the chitosan-coated liposomes significantly increased with increasing chitosan concentrations. The size of the chitosan-coated liposomes was in the range of 200-300 nm with a positive zeta potential in the range of 6-29 mV. An in vitro release study using dialysis technique was performed to evaluate the release profile of the tartaric acid from the chitosan-coated liposomes. The obtained results showed the effect of the chitosan-coated liposomes on the lower release rate and on the amount of tartaric acid in comparison with that of the uncoated liposomes. The study in an in vitro skin cell model indicated that the developed system could enhance the potential of tamarind's AHAs on the stimulation of human keratinocyte proliferation being two-fold higher than the solution of the tamarind extract.
