A tetrahydrocurcumin-based copolymeric micellar hydrogel for improved dermal delivery

Abstract

Tetrahydrocurcumin (THC) loaded monomethoxy poly(ethylene glycol)–poly(δ-valerolactone) micelles (THC-M) were developed as a local formulation with 12.45 wt% THC. The prepared THC-M were characterized by X-ray diffraction, particle size distribution, Fourier transform infrared spectroscopy, in vitro release and anti-tyrosinase activity experiments. They exhibited a slow and sustained THC release behavior, which caused slightly lower anti-tyrosinase activity than crude THC. More importantly, the THC-M loaded hydrogel (THC-M-H) was prepared with Carbopol 940 gelling material to prolong the retention of the drug at the skin administration site and improve skin penetration and accumulation. Its effect on the antioxidant activity and in vitro skin deposition of THC was evaluated. Like THC-M, THC-M-H also significantly improved the skin deposition of THC. The THC transdermal percentage in the THC-M group was 6.33%, while it was only 0.72% in the THC-M-H group. Both THC-M and THC-M-H showed good antioxidant activities. These results indicate that the investigated micelles-in-hydrogel enables the local skin delivery of hydrophobic drugs, making it a viable option for whitening or topical diseases treatment.