Enhanced stability and reduced irritation of 4-n-butylresorcinol via nanoemulsion formulation: Implications for skin pigmentation treatment.

4-n-butylresorcinol (4-nBR) is a valuable ingredient to lighten skin and reduce pigmentation, contributing to an even skin tone and a more youthful appearance. However, its poor solubility, low stability, and strong irritation to the skin limit its application. In this study, 4-nBR was prepared into 4-n-butylresorcinol nanoemulsion (4-nBR-NE) for the first time, enhancing the solubility and stability of 4-nBR while greatly reducing its skin irritation. The relationship between the viscosity of nanoemulsion and the formulation process, as well as the impact of surfactant ratio on the formability of 4-nBR-NE were further studied. This led to the successful development of a nanoemulsion with adjustable viscosity (AV-NE) and with a low surfactant content. The particle size of 4-nBR-NE was 13.34 ± 0.16 nm with a PDI of 0.0853 ± 0.0191, indicating a uniform particle size distribution. The encapsulation rate of 4-nBR-NE was determined to be 80.05 ± 0.75 % via UV-Vis spectrophotometry. In addition, 4-nBR-NE demonstrated excellent stability over several months, with negligible changes in particle size. Cellular and transdermal evaluations confirmed that the preparation of 4-nBR-NE effectively reduced the original irritation cause by 4-nBR on cells and skin. Then, 4-nBR-NE was incorporated into an essence. This advancement enhances the applicability of 4-nBR in treating pigmentation disorders such as melasma and freckles, thereby increasing its applicability in pharmaceutical and cosmetic industries.

Preparation and characterization of agarose-sodium alginate hydrogel beads for the co-encapsulation of lycopene and resveratrol nanoemulsion.

In the study, lycopene and resveratrol nanoemulsion hydrogel beads were prepared by using agarose­sodium alginate as a carrier and the semi-interpenetrating polymer network technique, characteristics and morphologies were evaluated by scanning electron microscopy, fluorescence microscopy, rheological measurement. The synergistic antioxidant effect of lycopene and resveratrol was confirmed, the best synergistic antioxidant performance is achieved when the ratio of 1:1. To increase the solubility and improve the stability, the lycopene was prepared as solid dispersion added to the nanoemulsion. The encapsulation rate of lycopene and resveratrol reached 93.60 ± 2.94 % and 89.30 ± 1.75 %, respectively, and the cumulative release showed that the addition of agarose slowed down the release rate of the compound, which improves the applicability of lycopene and resveratrol and development of carriers for the delivery of different bioactive ingredients.