Liquid-crystalline systems as a potential strategy for vaginal administration of p-coumaric acid on the treatment of vulvovaginal candidiasis

Author(s)

Paula Scanavez Ferreira

• Document type: Master's Dissertation
• Press: Araraquara. 2020-04-23.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Farmacêuticas. Araraquara
• Defense date: 2020-01-24
• Advisor: Marlus Chorilli

Abstract

Vulvovaginal candidiasis (VVC) is the most common type of acute vaginitis among women, caused by fungi of the genus Candida spp. Candida albicans is the species responsible for 80-90% of cases, however in recent years, there has been an increase in the number of cases involving other species, with Candida glabrata being the second most reported and most resistant to conventional treatments. Existing therapies for VVC have disadvantages due to the side effects of the antifungal agents used and the prevailing fungal resistance. As an alternative, natural compounds such as p-cumaric acid (p- CA) have been studied due to their potential antifungal activity. However, its lipophilic character hinders its solubility in water, reducing its effectiveness. The incorporation of p-CA in a drug delivery system (DDS), such as liquid crystals (LCs), can assist in its topical administration, and thus increase its solubility, effectiveness, reduce systemic side effects and enhance its activity on the vaginal mucosa. Thus, this work aimed to develop liquid-crystalline systems with mucoadhesive properties for controlled release of p-cumáric acid in the treatment of vulvovaginal candidiasis, via topical administration. The antifungal activity of p-CA was analysed by assays of minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC), biofilm formation and in vivo assay against strains of C. albicans (SC5314), C. glabrata (ATCC 2001) and C. krusei (ATCC 6528). For the development of the formulations, two phase-diagrams were constructed consisting of oleic acid and cholesterol (5: 1 v / v), a dispersion of poloxamer 16% and two substances were tested: triethanolamine (TEA) and triethanolamine oleate (TEA-Oleato). After a pre-evaluation of the selected points of each diagram, two systems (P24 and P29) from the TEA-Oleato diagram were characterized visually, by polarized light microscopy, rheology, texture profile analysis, in vitro mucoadhesion analysis and release, permeation and retention profiles. In addition to the original systems, their respective dilutions in artificial vaginal mucus (30% and 100%) were evaluated in order to mimic the application site and to check possible changes in the LCs when in contact with the vaginal mucus. MIC values were 5000μg.mL-1 for p-CA, 1.0μg.mL-1 for amphotericin B (Amph. B) and both strains were resistant to fluconazole (Fluco). The MFC value for p-CA was 6000μg.mL-1. In the in vitro and in vivo biofilm assays, the MFC value of p-CA was used both to test the free and the incorporated drug; while for Fluco and Amph. B, the concentration used was 1000x MIC. From the in vitro results, it was observed that p-CA demonstrated better inhibition of mature biofilms than Amph. B and Fluco. While p-CA inhibited 98% of the C. albicans biofilm and 92% of C. glabrata, only with its CFM value, Amph. B demonstrated inhibition rates of 96% and 65% respectively, but with its MIC value increased by 1000x. At 1mg.mL-1, Fluco was still less effective, inhibiting only 30-40% of biofilms. The incorporated systems presented mucoadhesive profile, characteristic structures of LCs (Malta crosses and striations), high structural organization and pseudoplasticity, desirable parameters for topical formulations. The systems presented controlled release profiles in 12h (46% - 50% of released p-CA) when compared to the free drug (87%). The LCs also decreased the permeation of the compound in the vaginal mucosa from 38% to 9%, which can avoid systemic effects. In the in vivo therapeutic assay, the LCs increased the antifungal activity of Fluco and p-CA, decreased the presence of filamentous forms, and, at the end of the experiment, the LCs incorporated with p-CA showed results similar to those incorporated with Fluco. From the results obtained, p-CA proved to be a natural compound with antifungal activity against species of the genus Candida spp. From the present work, it was possible to obtain LCs with characteristics suitable for vaginal administration of p-CA and potential as a drug delivery system for the treatment of vulvovaginal candidiasis. (AU)

• FAPESP's process: 17/22928-6 - Liquid-crystalline systems as a potential strategy for vaginal administration of p-coumaric acid in the treatment of vulvovaginal candidiasis
• Grantee: Paula Scanavez Ferreira
• Support Opportunities: Scholarships in Brazil - Master