Natural component and solid lipid microparticles of solar filter in sunscreen: Photoprotective and photostability effect enhancement

A topical formulation containing a natural compound (rutin), in association with UVA filter solid lipid microparticles (SLMs) was prepared aiming to decrease the photodegradation of the UV filter and evaluate whether the sunscreen's photoprotection was impaired by the microencapsulation process caused by UVA radiation. The SLMs were manufactured by spray congealing using a factorial central composite design. The optimum conditions for the preparation were a UVA filter content of 60.5%, flow rate of 6.76 mL/min, and airflow rate of 2.84 m³/min. SLMs presented a mean size of 29.6 μm, polydispersity index of 1.74, encapsulation efficiency of 100%. The topical formulation showed that the microencapsulation process and the free rutin were able to reverse avobenzone photodegradation. In addition, the formulation promoted photoprotection, showing that the microencapsulation process associated with the rutin is promising for use in sunscreens.