J. Cosmet. Sci., 64, 9–17 ( January/February 2013) 9 Preparation and characterization of cosmeceutical liposomes loaded with avobenzone and arbutin JUN-JEN LIU, SAMI NAZZAL, TZU-SHAN CHANG, and TSUIMIN TSAI, School of Medical Laboratory Science and Biotechnology, Taipei Medical University, Taipei 110, Taiwan (J.-J.L.), Department of Basic Pharmaceutical Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, LA 71201 (S.N.), and Graduate Institute of Biomedical Materials and Engineering, Taipei Medical University, Taipei 110, Taiwan (T.-S.C., T.T.). Accepted for publication May 9, 2012. Synopsis The objective of this study was to develop and characterize a liposome delivery system coencapsulating two cosmeceutical ingredients, avobenzone (AVO) and arbutin (AR). Two different liposome preparation meth- ods, that is, thin fi lm hydration and reverse-phase evaporation, were evaluated. To obtain the optimal formu- lation, various ratios of lipid to AVO or AR were tested. The effects of liposome formulation and preparation method on particle size, entrapment effi ciency (EE), and skin permeation rate were studied. The mean par- ticle size of the liposome formulations obtained by the thin fi lm hydration method was smaller than that obtained by the reverse-phase evaporation method. The EE of AR and AVO in liposomes prepared by the thin fi lm method, however, was lower than that prepared by the reverse-phase evaporation method. No differences in membrane permeation were observed between the two preparation methods. A large portion of AR perme- ated through the membrane into the receptor chamber. On the other hand, AVO remained in the donor chamber or accumulated in the membrane. The results of this study revealed that liposomes are a promising delivery system for coencapsulated AR and AVO. Liposomes may aid in retaining the sunscreen (AVO) at the surface of the skin for sun protection meanwhile facilitating the penetration of the whitening agent (AR) into the deeper layers of the skin for whitening effect. INTRODUCTION Ultraviolet radiation (UVR) emitted by sun can damage collagen fi bers and accelerate skin aging and is a major cause of skin cancer. To prevent skin damage by sunlight, physical coverage, such as clothing and sunglasses, is the most effective way to prevent sunburn and skin cancer caused by UVR. Applying sunscreens is also helpful in protecting the skin. An effi cient sunscreen product, however, should provide effective broad-spectrum protection across the UVR range (280–400 nm). An example of a highly effective sunscreen ingredi- ent with broad-spectrum protection is butyl methoxydibenzoylmethane or avobenzone Address all correspondence to Tsuimin Tsai at tmtsai00@tmu.edu.tw.

JOURNAL OF COSMETIC SCIENCE 10 (AVO) (trade name Parsol 1789), which is one of the most frequently used ingredients in sunscreens products. Sunscreens have also been used along with whitening agents to main- tain light skin tone. Whitening agents protect the skin against the negative effects of UVR including skin blemishes and brown spots. Arbutin (AR), a potent tyrosinase in- hibitor and an antioxidant (1), has been widely used as a skin-whitening agent. It can ef- fectively restrain the activity of tyrosinase and the formation of melanin in the skin (2,3). Although AVO and AR are widely used as sunscreen and whitening agents, respectively, their physicochemical properties limit their effectiveness, especially when used concur- rently. AVO, for example, undergoes photodegradation under sunlight illumination and therefore loses part of its protection capacity during usage (4,5). AR, on the other hand, is very hydrophilic and therefore has limited permeability across the outermost epidermis through the hydrophobic stratum corneum into the deeper layers of the skin (6). Several strategies have been reported to address some of these limitations. The addition of photostabilizing agents, complexation with cyclodextrins, and encapsulation in poly- meric or lipid microparticles were used to enhance the stability of AVO (7,8). Studies have shown that inclusion of a carrier in sunscreen formulations may enhance photopro- tection by reducing both skin penetration and photodecomposition of UV absorbers (9). Carriers such as liposomes have also been used to facilitate the penetration of hydrophilic compounds such as AR through the skin. Liposomes are spherical, bilayered structures composed mainly of phospholipids and have been widely used in drug delivery and cos- metic applications (10). Liposomal formulations emerged as attractive alternatives for the topical delivery of drugs and cosmetic ingredients not only because of their biocompati- bility, nontoxicity, and suitability for encapsulation of both hydrophilic and lipophilic compounds but also because of their ability to enhance skin penetration. The objective of this study was, therefore, to address the physical properties of AVO and AR that limits their use in cosmetic applications by coencapsulating the two ingredients into liposomal formulations. Due to their differences in lipophilicity, two liposome preparation meth- ods, that is, thin fi lm hydration and reverse-phase evaporation, were used to coencapsu- late AVO and AR. The physical properties of liposomes prepared by each method were compared, and their in vitro permeation was evaluated using the Franz diffusion cells. MATERIAL AND METHODS MATERIALS AR was purchased from Alfa Aesar (Ward Hill, MA), AVO was purchased from Merck KGaA (Darmstadt, Germany), and L-α-phosphatidylcholine (EPC) was purchased from Avanti (Alabaster, AL). Sephadex cartridges prepacked with G-50 gel were obtained from Pharmacia Biotech (Uppsala, Sweden). Cellulose acetate membranes (pore diameter 2 μm) were purchased from Millipore (Bedford, MA). SPECTRAL ANALYSIS OF AR AND AVO The absorption spectra of AR and AVO alone or in combination were carried out in 95% ethanol or methanol. Absorption spectra were measured using Hitachi U-3300