Abstract
Organogels (ORGs) are semi-solid materials, in which an organic phase is immobilized by a three-dimensional network composed of self-organized system, forming the aqueous phase. In this context, lipid–Pluronics (PLs) ORGs form a two-phase system which can be effectively used as skin delivery systems, favoring their permeation across the skin. In this study, we presented the development of ORG skin drug-delivery systems for curcumin (CUR), a liposoluble phenolic pigment extracted from the turmeric rhizome. In special, we designed the formulation compositions in order to carry high amounts of CUR soluble in oleic acid (OA), as organic phase, entrapped into an aqueous phase composed of micellar PL-based hydrogels by associating two polymers with different hydrophilic–lipophilic balances, Pluronic F-127 (PL F-127), and Pluronic L-81 (PL L-81), to enhance the permeation across the skin. Results revealed that the incorporation of PL L-81 favored the CUR incorporation into micelle–micelle interface. CUR insertion into OA-PL F-127/L-81 reduced both G’/G” relationship (∼16 x) and viscosity values (η* ∼ 54 mPa.s, at 32.5°C), disturbing the ORG network structural organization. In vitro permeation assays through Strat-M® skin-model membranes showed that higher CUR-permeated amounts were obtained for OA-PL F-127/L-81 (4.83 µg.cm−2) compared to OA-PL F-127 (3.51 μg.cm−2) and OA (2.25 μg.cm−2) or hydrogels (∼1.2 μg.cm−2, p < 0.001). Additionally, ORG formulations presented low cytotoxic effects and evoked pronounced antileishmanial activity (IC50 < 1.25 µg.ml−1), suggesting their potential use as skin delivery systems against Leishmania amazonensis. Results from this study pointed out OA-PL-based ORGs as promising new formulations for possible CUR topical administration.
Highlights
The clinical efficacy of this type of administration depends on the drug physico-chemical and pharmacological properties, as well as its bioavailability at the site of action, which is limited by the low permeability of the stratum corneum (Godin and Touitou, 2007; Prausnit and Langer, 2008)
ORG morphology was characterized by wrinkles distributed for all surface, which can be attributed to the incorporation of the organic phase (OP) into the hydrogels forming a system with low water content resulting in a different morphology from hydrogels
This feature can be attributed to the presence of oleic acid (OA) as OP, FIGURE 1 | Micrographs for organogels and hydrogel formulations obtained from atomic force microscopy (AFM). (A) F-127/L-81-H, (B) F-127/L-81-CUR-H, (C) OA-F-127/L-81, and (D) OA-F-127/L-81-CUR
Summary
Curcumin (CUR) and its derivatives have shown a wide variety of biological activities, such as anti-oxidant (Dall’Acqua et al, 2016), anti-inflammatory (Zhu et al, 2016), anti-tumor (Han et al, 2011), antimicrobial (Cetin-Karaca and Newman, 2015), and antiparasitic effects (Morais et al, 2013), as well as for the treatment of ulcers (Magalhaes et al, 2009) and skin diseases (Patel et al, 2009; Rachmawati et al, 2015), among others (Aggarwal and Harikumar, 2009). CUR extensive first-pass biotransformation and low aqueous solubility became an interesting molecule for skin delivery (Anand et al, 2008) In this context, skin delivery is an important strategy for drug administration, since this procedure is non-invasive and avoids first-pass biotransformation and enables the use of self-administered pharmaceutical forms, improving patient compliance. Considering that most skin pathological processes occur locally, CUR topical application may offer the advantage for delivering the molecule into the site of action. Nanocarrier systems such as gels and nanoemulsions can provide the chemical stabilization and permeation of the CUR molecule (Rachmawati et al, 2015)
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