<i>Momordica charantia</i>Ameliorates Atopic Dermatitis by Inhibiting the Expression of Inducible Nitric Oxidase Synthase in NC/Nga Mice

Introduction: Momordica charantia (MC) has been reported to possess various beneficial effects. Improvement in natural aging of the skin has been observed with the use of MC. However, few studies have detailed the effects of MC on atopic dermatitis (AD). Therefore, in this study, we investigated the effects of MC on the skin symptoms of AD. Methods: Specific pathogen-free and conventional NC/Nga mice were orally administered a 50 mg/kg/day dose of MC every day for 2 weeks. Results: The expression levels of lipopolysaccharide (LPS), inducible nitric oxidase synthase (iNOS), and prostaglandin E2 (PGE2) remarkably increased in AD, but were suppressed by MC administration. As a result, the degradation of filaggrin by PGE2 was suppressed. Furthermore, in AD, iNOS induced macrophage type 1 and increased NO levels. In contrast, due to suppression of iNOS with MC administration, macrophages shifted to type 2 and an increase in L-ornithine was observed, which subsequently promoted filaggrin synthesis. Conclusions: These findings indicate that the AD-like skin symptoms were decelerated by MC via the regulation of the LPS/iNOS/PGE2/filaggrin and LPS/iNOS/Arginase 1/L-ornithine/ filaggrin signaling pathways.