Formulation and evaluation of anise-based bioadhesive vaginal gels

Abstract

Various formulations of anise-based bioadhesive gels are prepared. Freeze-drying method was successfully employed and superporous scaffolds were obtained. The resulting porous microarchitectures are strongly influenced by the composition of hydrogel formulations and temperature of freezing. Anise-based hydrogels frozen in liquid nitrogen and lyophilized generate regular assembly of polyhedral pores. For Carbopol 934-based hydrogels it was determined G'>G'' for whole tested strain amplitude range indicating solid-like behaviour due to their dense network and entanglement and interaction through hydrogen bonds and van-der Waals forces. For sodium alginate-based hydrogels it was determined G''>G' for whole tested strain amplitude range accompanied by the extended linear viscoelastic region indicating liquid-like behaviour due to the formation of a stable "pseudo-gel" structure. Biocompatibility features of tested hydrogels were evaluated by contact angle measurements and determination of surface tension parameters. It was found that all anise-based hydrogel formulations manifest modest activity against S. aureus and S. lutea and no activity against tested Gram negative bacteria. Carbopol 934-based hydrogels containing anise exhibit antifungal activity against C. albicans, C. glabrata and C. Parapsilosis.

Keywords: Anise; Antimicrobial activity; Bioadhesive vaginal gels; Rheology; Surface morphology.