Abstract:

Quercetin is well known for its significant scavenging properties on oxidizing species, and can play a protective role against ultraviolet radiation-induced damage, thus improving skin condition and preventing skin aging. However, its low solubility in water is the main reason of its formulation difficulties. To overcome these problems, a proper and effective drug delivery system development is essential. Moreover, previous studies found that the solubility of quercetin in isopropyl lauroyl sarcosine could reach a maximum of （83.30±2.65） mg/g, which was much higher than other oils. Therefore, in this study, quercetin-loaded microemulsion was prepared by low energy emulsification method using isopropyl lauroyl sarcosine as the oil phase due to its good solubilizing capacity, and then some physicochemical properties （i.e., microscopic morphology, droplet size, pH, encapsulation efficiency, loading capacity, etc.） of the microemulsion system were evaluated. The microemulsion is found to be spherical in shape with an uniform size distribution, and the average droplet size, PDI, Zeta potential and pH value are measured to be （38.6±0.5） nm, 0.18±0.07, （-28.16±1.02） mV and 6.23±0.18, respectively. Meanwhile, the encapsulation efficiency and loading capacity of quercetin in the microemulsion system are calculated to be 98.85%±2.36% and 3.24%±0.12%, respectively. Additionally, it can be found that the microemulsion system presented non-Newtonian pseudoplastic fluid and predominantly elastic behaviors. The above results indicate that the microemulsion system comprising isopropyl lauroyl sarcosine as the dispersion phase has the potential to effectively improve the solubility and loading capacity of quercetin, which is of great significance for improving the efficacy of quercetin and reducing the used amount and frequency of the microemulsion system.

Key words: isopropyl lauroyl sarcosine, quercetin, microemulsion, high loading capacity