Enhancement in antifungal activity of eugenol in immunosuppressed rats through lipid nanocarriers

In the present study eugenol loaded solid lipid nanoparticles (SLN) was prepared and characterized for particle size, polydispersity index, zeta potential, encapsulation efficiency, in vitro release and in vivo antifungal activity. Effect of addition of liquid lipid (caprylic triglyceride) to solid lipid (stearic acid) on crystallinity of lipid matrix of SLN was determined by using Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. Transmission electron microscopy (TEM) was carried out to determine the morphology of SLN. In vivo antifungal activity of eugenol loaded lipid nanoparticles was evaluated by using a model of oral candidiasis in immunosuppressed rats. Particle size results showed that d90 of SLN1 (single lipid matrix) and SLN2 (binary lipid matrix) was 332 ± 14.2 nm and 87.8 ± 3.8 nm, respectively. Polydispersity index was found to be in the range of 0.27–0.4 which indicate moderate size distribution. Encapsulation efficiency of SLN2 (98.52%) was found to be more than that of SLN1 (91.80%) at same lipid concentration (2%, w/v). Increasing of the solid lipid concentration from 2% (w/v) to 4% (w/v) resulted in increase in encapsulation efficiency and the particle size. SLN2 shows faster release of eugenol than that of SLN1 due to smaller size and presence of liquid lipid which provide less barriers to the diffusion of drug from matrix. TEM study reveals the spherical shape of SLN. FT-IR, DSC and XRD results indicate less crystallinity of SLN2 than that of SLN1. In vivo studies show no significant difference in log cfu value of all the groups at 0 day. At 8th day, log cfu value of group treated with saline (control), standard antifungal agent, eugenol solution, SLN1 and SLN2 was found to be 3.89 ± .032, 2.69, 3.39 ± .088, 3.19 ± .028 and 3.08 ± 0.124, respectively. The in vivo study results indicate improvement in the antifungal activity of eugenol when administrated in the form of SLN.

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► In the present study, eugenol loaded SLN were prepared by using single lipid and binary lipid mixtures.
► Eugenol loaded SLN made of binary lipid mixture showed the smaller particle size and less crystallinity than that of single lipid.
► Eugenol loaded SLN extended the release of eugenol and follow fickian diffusion.
► Eugenol loaded SLN improved the oxidative stability of eugenol.
► Eugenol loaded SLN enhanced the in vivo antifungal activity of eugenol in oral candidiasis in immunosuppressed rat model.