JOURNAL OF COSMETIC SCIENCE 236 membrane to ions varies considerably (25). Protons and hydroxyl ions pass rapidly across liposo- mal membrane. However, the permeability of liposome membranes to divalent and multivalent ions is slower than monovalent ions. This could be due to the charge increasing and the hydra- tion shell of ions. IMPROVEMENT OF MAGNESIUM CHLORIDE DETOXIFICATION ACTIVITY Ex vivo study of the MCCL effi cacy to improve the skin availability of active mole- cules was performed. Because of its destabilization in contact with 12% of MgCl2, noncoated liposomes were not tested in this ex vivo test. Indeed, MgCl2 was entrapped in coated liposomes, and its effect on P-gp skin explants activity was evaluated versus non-entrapped MgCl2. Acrylates/xanthan (1:0.5 w/w) gel containing 3% of MCCL or an equivalent amount of free MgCl2 (0.36%) was used to evaluate the P-gp activity in a model of normal human skin explants. Figure 5 presents the quantity of ATP consumed by P-gp per μg of proteins. Compared to the nontreated explants (control), placebo and free MgCl2 did not have signifi cant effect on the consumption of ATP by P-gp transporter. However, MCCL increased the consumption of ATP (p = 0.06) sig- nifi cantly, followed by the activity of P-gp transporter. P-gp is a transmembrane bio- logical target involved in cell detoxifi cation system and waste elimination (26–28). Hamada and Tsuruo (7) found that magnesium is essential for P-gp ATPase activity. However, high concentrations of Mg2+ inhibited the ATPase activity of P-gp (7). Ac- cording to this fi nding, we can conclude that 0.36% of MgCl2 inhibited the ATPases activity of P-gp transporter. Figure 5 shows that coated liposomes improved the pen- etration of MgCl2 through skin explants signifi cantly compared to nonentrapped MgCl2. We can suppose that the entrapment of MgCl2 decreased its concentration in external aqueous medium of coated liposome suspension and then increased the ac- tivity of ATPase. During the incubation time, the long-lasting release of MgCl2 re- duced potential metabolism inhibition of P-gp ATPase in the presence of high salt contents. Figure 5. P-gp activity in human normal skin explants model (MCCL: Magnesium chloride coated liposomes).

NEW RESISTANT LIPOSOME COATED WITH POLYSACCHARIDE FILM FOR COSMETIC APPLICATION 237 CONCLUSION The development of a resistant liposome coated with hydrophobized polysaccharide increased its stability in cosmetic formula composed of high amounts of surfactants and/or electrolytes. Alkyl chains of hydrophobized polysaccharides were inserted into the bilayer membrane of liposomes, and then the polysaccharide surrounded the ves- icle surface. We conclude that polysaccharide fi lm surrounded liposomes did not re- duce their delivery property and then the penetration of MgCl2 into the skin. Unlike noncoated liposomes, the coated ones allowed entrapment of high amounts of MgCl2 (12%) and then to limit the decrease of viscosity in cosmetics formulas. Compared to the free MgCl2, the entrapment into coated liposomes increased the P-gp activity implicated in cell detoxifi cation signifi cantly and then its skin bioavailability. Thus, the coating maintains delivery property of liposomes. With this new generation of biomimetic vector, new cosmetic formulations can be achieved with higher effi cacy and stability. ACKNOWLEDGMENTS The authors would like to thank Barbara Trouiller for her technical support in this project. REFERENCES (1) N. Weiner, L. Lieb, S. Niemiec, C. Ramachandran, Z. Hu, and K. Egbaria, Liposomes: A novel topical delivery system for pharmaceutical and cosmetic applications, J. Drug Target., 2, 405–410 (1994). (2) N. Weiner, F. Martin, and M. Riaz, Liposomes as a drug delivery system, Drug Develop. Ind. Pharm., 15, 1523–1554 (1989). (3) K. Egbaria and N. Weiner, Liposomes as a topical drug delivery system, Adv. Drug Deliv. Rev., 5, 287– 300 (1990). (4) B. Maherani, E. Arab-Tehrany, M. R. Mozafari, C. Gaiani, and M. Linder, Liposomes: A review of manufacturing techniques and targeting strategies, Curr. Nanosci., 7, 436–452 (2011). (5) E. Proksch, H. P. Nissen, M. Bremgartner, and C. Urquhart, Bathing in a magnesium-rich Dead Sea salt solution improves skin barrier function, enhances skin hydration, and reduces infl ammation in atopic dry skin, Int. J. Dermatol., 44, 151–157 (2005). (6) M. Denda, C. Katagiri, T. Hirao, N. Maruyama, and M. Takahashi, Some magnesium salts and a mix- ture of magnesium and calcium salts accelerate skin barrier recovery, Arch. Dermatol. Res., 291, 560–563 (1999). (7) H. Hamada and T. Tsuruo, Characterization of the ATPase activity of the Mr 170,000 to 180,000 mem- brane glycoprotein (P-glycoprotein) associated with multidrug resistance in K562/ADM cells, Cancer Res., 48, 4926–4932 (1988). (8) S. Chakraborty, Q. Qiang, P. Deo, and J. Wang, Surfactants, polymers and their nanoparticles for per- sonal care applications, J. Cosmet. Sci., 55, S1–S17 (2004). (9) D. Bais, A. Trevisan, R. Lapasin, P. Partal, and C. Gallegos, Rheological characterization of polysaccharide–surfactant matrices for cosmetic O/W emulsions, J. Colloid Interface Sci., 290, 546–556 (2005). (10 ) N. Deo and P. Somasundaran, Mechanism of mixed liposome solubilization in the presence of sodium dodecyl sulfate, Colloids Surf. A Physicochem. Eng. Asp., 186, 33–41 (2001). (11 ) M. Carafa, C. Marianecci, V. Annibaldi, A. Di Stefano, P. Sozio, and E. Santucci, Novel O- palmitoylscleroglucan-coated liposomes as drug carriers: Development, characterization and interac- tion with leuprolide, Int. J. Pharm., 325, 155–162 (2006).