Cytotoxic Effect and antimicrobial action/antibiofilm of hybrids of curcouine and cinnamaldehyde on microorganisms of endodontic interest

Author(s)

Vanessa Rodrigues dos Santos

• Document type: Master's Dissertation
• Press: Araçatuba. 2019-05-10.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araçatuba
• Defense date: 2019-04-26
• Advisor: Cristiane Duque; Aimée Maria Guiotti

Abstract

Although conventional endodontic treatment significantly reduces the microbiota present inside the root canals, the permanence of microorganisms due to the anatomical complexity of the root canal system and their resistance to chemical-mechanical treatment can lead to persistent or secondary infections. Many studies have explored the use of phytochemicals, seeking to obtain new compounds that present pharmacological properties. Curcumin, a yellow pigment isolated from Curcuma longa rhizomes (Zingiberaceae), and cinnamaldehyde, the volatile substance responsible for the odor and taste of plant stems of the genus Cinnamomum (Lauraceae) are possible promising substances. The objective of the study was to evaluate the cytotoxic effect and antimicrobial action / antibiofilm of hybrid compounds of curcumin and cinnamaldehyde on microorganisms of endodontic interest. The minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBM) of cinnamaldehyde, curcumin and 23 hybrids on Enterococcus faecalis, Streptococcus mutans, Lactobacillus casei, Actinomyces israelii and Fusobacterium nucleatum were determined. The best compounds were evaluated on single biofilms (single bacterial strain) and dual-species biofilms (E. faecalis + L. casei, E. faecalis + S. mutans, E. faecalis + A. israelii, E. faecalis + F. nucleatum) in polystyrene plates to determine the effect on bacterial metabolism using the XTT assay and its viability by counting Colony Forming Units (CFUs) after 24 or 48 hours of exposure to the compound. Toxicity was also evaluated on fibroblasts (L929 cell line) using the methyltetrazolium (MTT) assay. In addition, mixed biofilms with the same bacterial species selected and multispecies with human biofilm samples were formed in the dentinal root of bovine teeth and after 48 hours treatment with the compound / control, they were evaluated by confocal microscopy. The data presented normal distribution and the differences between groups (antimicrobials and growth times - 1 or 2 weeks) were analyzed by ANOVA (One-way or Two-way) followed by the Tukey test. Of the 25 compounds tested, 9 of them had inhibitory effect for at least one of the bacterial species tested with MIC / MBC values ranging from 0.009 to 0.625 mg / mL. The LA11 compound and the chlorhexidine control (CHX) had the best inhibitory effect for all bacterial species tested and were therefore selected for subsequent assays. LA11 showed a higher concentration of chlorhexidine (CHX) in the fibroblasts and had a CHX-like or higher effect, reducing bacterial metabolism and viability in single and dual-species biofilms, with S. mutans biofilms being the most affected. For biofilms formed in root dentin, LA11 had a significant effect on mixed biofilms with a reduction of 85.93%, whereas in the multispecies biofilms, the microbial reduction was 33.76%. It is concluded that the hybrid compound LA11 presented cytocompatibility and antimicrobial effect and against biofilm of bacterial species related to root infections and could be an option of antimicrobial agent for application in endodontic treatment. (AU)

• FAPESP's process: 17/05892-8 - Cytotoxic effect and antimicrobial action/antibiofilm of curcumin and cinnamaldehyde hybrids on microorganisms of endodontic interest
• Grantee: Vanessa Rodrigues dos Santos
• Support Opportunities: Scholarships in Brazil - Master