In the present research, the effect of clove essential oil (CO) and its major constituent, eugenol, formulated in water-based microemulsions, was studied on fatty liver and dyslipidemia in high-fructose-fed rats. Plasma and liver lipids, oxidative stress, inflammatory biomarker, and liver function were the assessed criteria. CO dispersed in water as conventional cloudy emulsion was also subjected to the same biological evaluations for comparison with the microemulsified form of this oil. Results showed that the particle size of CO microemulsion (COM) and eugenol microemulsion (EM) was 8.0 nm and 8.9 nm, respectively. Excess dilution and incubation of these microemulsions in 1.2 N HCl, that mimic stomach juice (without lipase), for 5 hours at 37 °C lead to the establishment of second population of larger particles with average diameter>100.0 nm. Biological evaluation revealed that rats of high fructose control group exhibited significant dyslipidemia, high plasma tumor necrosis factor-α, and elevated malondialdehyde. The same group of rats showed significant high liver total fat, triglycerides and cholesterol, and liver dysfunction compared to control normal rats fed balanced diet. Daily oral administration of CO conventional emulsion, COM, and EM produced significant improvement of all studied parameters. No significant change in all biochemical parameters was noticed when the groups given the different formulations were compared with each other. The study concluded that administration of CO conventional emulsion, COM, or EM produced significant improvement in fatty liver and dyslipidemia with consequent expected protection from cardiovascular diseases and other complications of fatty liver. Formulation of CO in microemulsion having particle size ∼ 8.0 nm did not enhance the protective effect compared with the same dose of CO dispersed in water as conventional macroemulsion, probably due to the ease of absorption of these bioactives in their native states. However, formulation in microemulsion provides a delivery system for oral administration of CO or eugenol in homogeneous, water-based, and thermodynamically stable dosage form during storage.
Keywords: clove oil; eugenol; fatty liver; microemulsions; protective effect.