||Curcumin has anti-bacterial, anti-inflammatory, anti-oxidative, and free radical scavenging abilities. Medium-chain fatty acids also have antimicrobial activity. Both curcumin and lauric acid had been found in the inhibition of Propionibacterium acnes and Staphylococcus epidermidis. The aims of this study were to investigate the preparation of transdermal delivery microemulsion with antibacterial activity.
Curcumin was loaded in the microemulsions that lauric acid as an oil phase, polyoxyethylene sorbitan monolaurate (tween 20) as a surfactant, transcut0l as a cosurfactant, and water as an immiscible phase. The tween 20 and transcutol were mixed in various ratios to propose the phase diagram. The characterizations of microemulsions including particle size, morphology, conductivity, and pH were analyzed.
The particle sizes of the microemulsions decreased from 79.02 nm to 16.05 nm with increasing in transcutol; all conductivities were increased from 6.02 to 45.9 μS but pH value decreased from pH 5.6 to 4.4 by the increasing in their water contents. The transdermal delivery abilities of curcumin-containing microemulsions were analyzed using porcine ear skin mounted on a Franz diffusion cell. The microemulsion (ME2) of tween20: transcutol (1:2) with the best transdermal delivery rate was about 73 μg/cm2/72hr. The inhibitory activities of curcumin, lauric acid, and curcumin-containing microemulsion to Propionibacterium acnes and Staphylococcus epidermidis were also determined. The results showed that the antimicrobial activity of curcumin-containing microemulsion was better than free curcumin in the same concentration due to the additive effect of lauric acid. Using the MTT assays to identify the toxicity of microemulsion to fibroblasts, the cytotoxicity of curcumin-containing microemulsion was low and from curcumin. Microemulsion, loaded with curcumin and lauric acid, is an effective vehicle for transdermal delivery, and has an antibacterial effect but low cytotoxicity.