In vitro Biological Activities of Azulene, Guaiazulene, and Sodium Guaiazulene Sulfonate and Its Application to Formulations through PEG-PCL Micelles

AbstractAtopic dermatitis (AD) is developed by complex interplay of various factors such as skin barrierdysfunction, immunological derangement, and oxidative stress, so multipronged approaches areneeded to treat AD. Azulene (AZ), guaiazulene (GA), and sodium guaiazulene sulfonate (GAS-Na) areknown to have biological activities. This study aimed to evaluate the bioactivities of AZ, GA, GAS-Na fromthe perspective of AD treatment. Anti-inflammatory properties were estimated by measuring inhibitoryeffect on IL-6 and IL-8 production of TNF-α treated HaCaT cells via enzyme-linked immunosorbent assay(ELISA). Antioxidant properties were estimated by measuring DPPH and ABTS+ radical scavenging activity.Based on the experimental results that GA showed a wider range of anti-inflammatory and antioxidanteffects than AZ and GAS-Na, we concluded that GA is the most suitable for treating both immunologicalderangement and oxidative stress. Furthermore, to overcome poor water solubility of GA hindering itsapplication to various cosmetic formulations, we developed 1% of GA loaded PEG-PCL micelles andconfirmed its stable characteristics via particle size, PDI, and zeta potential values. Through this study, wesuggest the widespread use of GA for the treatment of AD.