Desenvolvimento e caracterização de nanoemulsão com extrato de própolis marrom: estudo da atividade antioxidante e permeabilidade cutânea

Abstract

Propolis is recognized for its biological and therapeutic properties and is widely studied in Brazil, particularly the green and red varieties. However, brown propolis, originating from the southern region of the country, remains poorly investigated. This study aimed to chemically characterize the extract and purified fractions of brown propolis from Paraná, evaluate their antioxidant potential, and develop a facial serum with these bioactives encapsulated in a nanoemulsion. The hydroalcoholic extract (EEP) was obtained by exhaustive solid-liquid extraction using ethanol:water (80:20 v/v) and fractionated with solvents of increasing polarity: hexane, dichloromethane, ethyl acetate, butanol, and acetone. Antioxidant activity was evaluated using DPPH, ABTS, FRAP, and Folin-Ciocalteau (CFT) assays. The ethyl acetate (Fr-EtOAc), butanol (Fr-But), and acetone (Fr-Ace) fractions showed the highest antioxidant levels, with Fr-EtOAc 269.23 mg GAE/g and Fr-Ace 256.33 mg GAE/g standing out. Chemical characterization by HPLC-DAD and HPLC-Q-TOF identified the main compounds as cinnamic acid 169.36 mg/L-1 and ferulic acid 113.97 mg/L-1. Nanoemulsions were prepared via high-energy ultrasonication and characterized for mean droplet size, zeta potential, polydispersity index (IP), rheology, and encapsulation efficiency. Droplet sizes ranged from 278.58 nm (FB) to 46.78 nm (Fr-Ace), with efficient encapsulation of coumaric acid 89.67% in EEP and ferulic acid 88.13%. IP values ranged from 0.3 to 0.5, and zeta potential was negative. Preliminary stability was evaluated at 45 ºC and -5 ºC for 12 days. EEP showed visual and color changes, while pH and density remained stable. Spreadability increased for FB and Fr-Ace and decreased for EEP. Antioxidant activity of Fr-Ace ranged from 99,975 to 71,365 mg/L-1, and EEP from 70,969 to 24,829 mg/L-1 throughout the study, indicating an increase in antioxidant activity over the stability period. In conclusion, brown propolis nanoemulsions demonstrated good stability and promising antioxidant properties for cosmetic applications, supporting skin health.