Preparation of a ferulic acid–phospholipid complex to improve solubility, dissolution, and B16F10 cellular melanogenesis inhibition activity

Li et al. Chemistry Central Journal (2017) 11:26 DOI 10.1186/s13065-017-0254-8 Open Access RESEARCH ARTICLE Preparation of a ferulic acid– phospholipid complex to improve solubility, dissolution, and B16F10 cellular melanogenesis inhibition activity Li Li, Yanhong Liu, Yan Xue, Jun Zhu, Xiaoyue Wang and Yinmao Dong* Abstract Background: We aimed to enhance the solubility, dissolution properties, and skin-whitening ability of ferulic acid (FA) by preparing a ferulic acid–phospholipid complex (FA–PC). The properties and melanogenesis inhibition activities of FA–PC were then elucidated. Methods: We characterized the complex via differential scanning calorimetry, Fourier transform infrared spectroscopy, scanning electron microscopy, solubility, and oil–water partition coefficient. A Strat-M® membrane, a synthetic membrane possessing diffusion characteristics that are well-correlated with human skin, was used for the diffusion studies of FA–PC. Results: We found that the lipophilicity of FA improved when complexed with phospholipids, allowing FA–PC to release FA in a controlled pattern. In the same time, complexing with phospholipids also obviously enhanced inhibition of B16F10 cellular melanogenesis. Conclusions: FA–PC is a promising material for medicinal and cosmetic usages. Keywords: Ferulic acid, Phospholipid, Solubility, Transdermal permeation, Melanin inhibition Background Ferulic acid (FA; 4-hydroxy-3-methoxycinnamic acid) is present in many foods, including wheat, rice, barley, oats, citrus fruits, and tomatoes [1]. FA has been shown to afford significant skin protection against UV-induced oxidative stress [2]. It reverts chronic UVB-induced oxidative damage in mice skin tumors by modulating the expression of vascular endothelial growth factor (VEGF), inducible nitric oxide synthase (iNOS), tumor necrosis factor (TNF)-α, and interleukin (IL)-6 [3]. It also modulates the expression of mutated p53, Bcl-2, and Bax in UVB-induced mice skin tumors [4]. Several studies have established that FA inhibits the expression of cytotoxic *Correspondence: Beijing Key Laboratory of Plant Resources Research and Development, Beijing Technology and Business University, Haidianqufuchenglu 11hao dongqu8haolou 214shi, Beijing 100048, People’s Republic of China and inflammation-associated enzymes [5] and matrix metalloproteinases (MMPs), and attenuates the degradation of collagen fibers [6]. Phospholipid complexes are widely used in the pharmaceutical industry. They have good permeability and safety and are receiving increasing attention for application in cosmetics. Because phospholipids are biofunctional surfactants with good solubilizing properties, they can be used as carrier systems for less soluble drugs [7], improving transdermal permeation and cumulative penetration rate of topical drugs [8]. Transdermal permeation of drugs involves dissolution, distribution, and diffusion into the skin. Physical and chemical properties, especially the oil–water partition coefficient of the drug to be administered, affect this process [9]. Unfortunately, FA is a poorly soluble compound. We attempted to improve its solubility, skin penetration properties, and ability to inhibit melanogenesis © The Author(s) 2017. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/ publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Li et al. Chemistry Central Journal (2017) 11:26 Page 2 of 8 by creating a novel ferulic acid–phospholipid complex (FA–PC) via a solvent evaporation method. The prepared FA–PC was then evaluated for various physical–chemical parameters. Differential scanning calorimetry (DSC; used to measure thermal behavior), Fourier transforms infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), were utilized. Solubilities were measured and oil–water partition coefficients were calculated. In addition, a Strat-M® membrane was used to evaluate skin permeability, and the ability for FA–PC to inhibit B16F10 cellular melanogenesis was investigated. complexing rate was expressed as mg of FA equivalents per g of dry weight. Methods Screening for optimal reaction time for FA–PC preparation Materials FA and phospholipids at a molar ratio of 1:1 were added to a 100 mL round-bottom flask and dissolved in anhydrous ethanol (FA, 2.0 mg/mL). The mixtures were constantly stirred constantly at 40 °C for 15, 30 min, 1, 2, 3, or 4 h and then dried by rotary evaporation at 40 °C. Afterward, they were placed in desiccators in preparation for determination of FA content. Powdered FA and arbutin (purity >99%) were purchased from Beijing HWRK Chem Co., Ltd. Soy lecithin (phosphatidylcholine, PC; purity >98%) was purchased from Shanghai Taiwei Co., Ltd. A Strat-M® membrane was purchased from Merck Millipore (Darmstadt, Germany). Other chemical reagents were of analytical grade. Physical mixture (PM) was prepared by putting equimolar amount of ferulic acid and phospholipids into mortar and grinding the mixed material sufficiently. Cell culture Mouse melanoma B16F10 cells were purchased from the Cell Bank of the Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences. Cells were cultured in Dulbecco’s modified Eagle medium (DMEM) that was supplemented with 10% fetal bovine serum (BioWhittaker, Walkersville, MD, USA) and 1% penicillin– streptomycin (Gibco BRL, NY, USA). The cultures were incubated at 37 °C in a humidified atmosphere containing 5% CO2. Preparation of FA–PC using solvent evaporation Screening for optimal proportion of ferulic acid and phospholipids FA and phospholipids at molar ratios of 2:1, 1:1, 1:2, 1:3, and 1:4 were added to 100 mL round-bottom flasks and dissolved in anhydrous ethanol (FA, 2.0 mg/mL). The mixtures were stirred constantly at 40 °C for 1 h, and then the anhydrous ethanol was removed by rotary evaporation. The dried FA–PC complexes were placed in a desiccator for 24 h. To determine the optimal ratio of FA to phospholipid, we measured the complexing rate of FA by UV spectrophotometry (UV-3150; Shimadzu, Japan). Briefly, the absorbance of prepared FA–PC samples in ethanol was determined at 323 nm. An equal amount of phospholipids dissolved in ethanol was used as a control, and a standard curve was constructed using FA. The Screening for optimal reaction temperature for FA–PC preparation FA and phospholipids at a molar ratio of 1:1 were added to 100 mL round-bottom flasks and dissolved in anhydrous ethanol (FA, 2.0 mg/mL). The mixtures were stirred constantly at 20, 40, 60, or (...truncated)