In vitro SPF and photostability assays of emulsion containing nanoparticles with vegetable extracts rich in flavonoids

The aim of study was to determine the in vitro sun protection factor (SPF) and the photostability profile of a topical formulation composed of nanoparticles loaded with vegetable extracts and to assess its physicochemical properties. Chitosan/tripolyphosphate (TPP) nanoparticles loaded with flavonoids-enriched vegetable extracts (Ginkgo biloba L., Dimorphandra mollis Benth, Ruta graveolens, and Vitis vinifera L.) were produced and characterized for their morphology, mean particle size, zeta potential, and encapsulation efficiency. A final topical formulation was obtained by dispersing chitosan/TPP nanoparticles in an o/w emulsion. Results showed that nanoparticles dispersion exhibited yellowish color, spherical shape, and uniform appearance. Extract-loaded chitosan/TPP nanoparticles showed a mean particle size of 557.11±3.1 nm, polydispersity index of 0.39±0.27, zeta potential of +11.54±2.1 mV, and encapsulation efficiency of 75.89% of rutin. The recorded texture parameters confirm that the developed formulation is appropriate for skin application. The SPF obtained was 2.3±0.4, with a critical wavelength of 387.0 nm and 0.69 UVA/UVB ratio. The developed formulation exhibited photostability, allowing the release of flavonoids from nanoparticles while retaining rutin into the skin in a higher extension.The authors acknowledge FAPESP (grant number 2015/25533-7 and 2017/14757-7), CAPES, and CNPq agencies for the financial support of this study. The authors also acknowledge the financial support received from the Portuguese Science and Technology Foundation (FCT/MCT) and from the European Funds (PRODER/COMPETE) under the project reference M-ERA-NET/0004/2015-PAIRED, co-financed by FEDER, under the Partnership Agreement PT2020.info:eu-repo/semantics/publishedVersio