Transdermal nanoemulsions of Foeniculum vulgare Mill. essential oil: Preparation, characterization and evaluation of antidiabetic potential

Foeniculum vulgare Mill., family Umbelliferae, is well known for its essential oil. One of the major components of F. vulgare seed's essential oil is trans-anethole. F. vulgare (fennel) possesses antioxidant and antidiabeic activities. Transdermal nanoemulsions (NEs) were employed to encapsulate fennel essential oil (FEO) with the aim of attaining effective prolonged antidiabetic action. A large NE existence area was obtained on phase diagrams employing oleic acid; oil phase and Tween20/propylene glycol; Smix in the ratios 1:1, 2:1 and 3:1 and water. Encapsulation efficiency was evaluated for trans-anethole (TA) by HPLC analysis and reached 64% in the prepared NEs. NEs were characterized for thermodynamic stability, conductivity, pH, particle size and zeta potential. Values obtained were promising. Permeation profiles for 24 h showed the superiority of FEO NE, F1, which showed also a high potential of reducing plasma glucose levels in rats which continued for 7-days after a single topical application of a dose of 120 mg/kg of FEO. These results highlight the high efficiency of F1, formed of 2% FEO, 5.6% oleic acid, 68% Smix (1:1) and distilled water, in bringing glucose levels to normal in diabetic rats.

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