Introduction: Zinc oxide nanoparticles (ZnOn) have been used as carriers and sun-protecting agents for Teucrium polium L. extract to enhance sun protection. ZnOn was synthesized by hydrolyzing zinc acetate using sodium hydroxide with mean particle diameter less than 500 nm.
Materials and methods: Top flowerings of T. polium L. were extracted by percolation method with petroleum ether, chloroform, and 80% methanol consecutively. Methanolic extract was lyophilized and used as a flavonoid-rich fraction. Sunscreen was prepared by the reconstitution of 0.5 g of the lyophilized extract in water and mixing with 0.5 to 2 g zinc-oxide (ZnO). Sun protection factor (SPF) of the aqueous extract of T. polium, the prepared gel, as well as the zinc oxide suspension alone and in combination with each other was determined spectrophotometrically based on a modified Transpore(®) tape method.
Results and conclusion: Obtained results showed that the T. polium extract has a wide band of ultraviolet radiation (UV) spectrum absorption ranging from 250 nm to 380 nm. SPF of the combination product in the ultraviolet B (UVB) area was greater than 80, revealing a synergistic action between ZnO and T. polium. The adsorption of flavonoids of T. polium on Zinc-oxide nanoparticles (ZnOn) slowed down their release thereby lengthening their persistence on the skin and contributing to further duration of action.
Keywords: Nanomedicines; Sun protection factor; Teucrium polium.