Synthesis, Characterization and Antimicrobial Activity of Garcinol Coated Titanium Dioxide Nanoparticles

Background: Garcinol is a secondary metabolite derived from the plants of Clusiaceae Family. It has shown a broad range of bioactivities such as antimicrobial, antioxidant, anticancer and anti-inflammatory. Titanium dioxide nanoparticles (TiO2NPs) are known to have a significant photocatalytic activity and are widely used in medicine. In this study, garcinol was used to modify the surface of TiO2NPs to enhance the antibacterial activity. Objectives: To synthesize, characterize and determine antimicrobial activity of garcinol coated titanium dioxide nanoparticles G-TiO2NPs. Methods: Garcinol was isolated from the dried fruit rinds of Garcinia quaesita. TiO2NPs were coated by garcinol and characterized by using Scanning Electron Microscopy (SEM), Powder X-Ray Diffraction (XRD), and Diffused Reflectance Spectroscopy. Minimum Inhibition Concentration (MIC) was tested against five microbial species including Staphylococcus aureus (ATCC 25623), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922), Candida albicans (ATCC 10231) and clinical isolates of Methicillin Resistant Staphylococcus aureus (MRSA), using broth micro-dilution assay. Time-kill kinetic study was performed to determine the inhibition percentage of Staphylococcus aureus over time. Results: SEM images confirmed the spherical shape of G-TiO2NPs, diameter ranging from 20 - 200 nm. XRD data revealed the anatase phase and rutile phase of TiO2NPs. Formation of G-TiO2NPs caused a red shift of the absorption wavelength. G-TiO2NPs and TiO2NPs showed a MIC range of 250-500 μg/ml and 500-1000 μg/ml against the tested microbial species, respectively. In the time-kill kinetic studies, inhibition percentage (IP) of microbial growth was determined at 60 minute time intervals. TiO2NPs and G-TiO2NPs demonstrated inhibition over 50% at 3 hours. Conclusions: G-TiO2NPs presented a significant enhancement in antimicrobial activity against S. aureus compared to TiO2NPs. Surface modification of TiO2NPs with garcinol has created a synergistic antimicrobial effect against S. aureus. Acknowledgement: University Grant ASP/01/RE/SCI/2017/19