Incorporation of Achyrocline satureioides (Lam.) DC extracts into topical nanoemulsions obtained by means of spontaneous emulsification procedure

- Achyrocline satureioides liquid or dried extracts were incorporated in nanoemulsions.
- Formulations can be obtained by spontaneous emulsification procedure in a single step.
- The main flavonoids were simultaneously incorporated in nanoemulsions.
- 3-Methylquercetin release rate was influenced by the extract content in formulations.
- 3-Methylquercetin retention in porcine ear skin was shown using Franz diffusion cells.

Topical administration of flavonoids from Achyrocline satureioides extracts provides a promising opportunity in the treatment of various skin disorders. This study describes the simultaneous incorporation of quercetin, luteolin and 3-O-Methylquercetin (3-O-MQ) from liquid or dried ethanolic extracts into topical nanoemulsions by a spontaneous emulsification procedure. By using of liquid plant extract (up to 1% of extract dry residue), this procedure resulted in monodispersed nanoemulsions exhibiting a droplet size at a 200 nm range, as attested by transmission electron microscopy. Flavonoids seem to be located in the oil phase of nanoemulsions since they are not detected in the water phase after separation on ultrafiltration membranes. Similar results were obtained when freeze- or spray-dried ethanolic extracts were used. Regardless of the extract type, 3-O-MQ release rate was influenced by the extract content into nanoemulsion achieving approximately 90% released after 8 h of kinetics. First order model provides the most satisfactory fitting of the release data from extracts-nanoemulsions. Higher amount of 3-O-MQ was found in the porcine ear skin after topical application of nanoemulsions containing the extract before drying procedures. The involvement of others extract compounds in 3-O-MQ retention can be suggested. Such results indicate that nanoemulsions are potential carriers for skin delivery of Achyrocline satureioides flavonoids.