CHARACTERIZATION OF SEMISOLID FORMULATIONS ENRICHED WITH COPAIBA OIL AND ITS ANTIBACTERIAL ACTIVITY AGAINST Streptococcus agalactiae

Streptococcus agalactiae (Group B Streptococcus – GBS) is a leading cause of invasive infections in neonates and intrapartum-antimicrobial prophylaxis (IAP) remains an important measure for infection control. However, resistance in GBS to penicillin, erythromycin, and clindamycin that are used for IAP, has been described worldwide. There is a need to discover new antimicrobials and natural products are a rich source of molecules with several biological activities. Moreover, hydrogels have been explored in drug delivery research for their physical properties, like high water content, softness, flexibility, and biocompatibility. Therefore, the aim of this study was to develop a hydrogel enriched with copaiba oil with antibacterial activity against planktonic cells of GBS. Reference strain ATCC 13813 and nine GBS strains from the bacterial collection of the Laboratory of Clinical Microbiology of the Universidade Estadual de Londrina (UEL) were employed in this study. The oleoresin from Copaifera officinalis was commercially obtained from an industry with filling certification. Nine formulations with or without copaiba oil were prepared based on three different polymers, carbomer, hydroxyethyl cellulose and sodium acrylates copolymer plus lecithin. The antibacterial activity of all formulations was evalued on Tryptic Soy Agar (TSA) surface. Planktonic cells of all GBS strains were spread on TSA and an aliquot of formulations with or without copaiba oil were spread over the inoculum. After 24 hours of incubation at 37 °C, the hydrogel which promoted total inhibition of GBS growth, compared to the untreated control, were selected for following assays. The characterization of formulation determined its stability, organoleptic and physical-chemical characteristics, and rheological profile. Among the formulations, only copaiba oil formulation based on carbomer with copaiba oil 1.0% (COF1 1.0%) preserved the bactericidal activity, inhibiting planktonic GBS growth. After centrifugation, COF1 1.0% did not show phase separation, or any instability sign. Copaiba oil formulation was homogeneous and showed a slight turbidity, due to oil presence. The pH value of 5.48 and density of 1.0658 g/mL were detected for COF1 1.0%. Rheological analysis showed a non-Newtonian behavior and pseudoplastic profile, suggesting improved retention on vaginal mucosa. The results showed COF1 1.0% has antimicrobial activity against GBS planktonic cells, suitable pH, and rheological profile which improves the vaginal treatment.