UV-A AND -B BLOCKING AGENTS FOR PSORIASIS PHOTOTHERAPY

Abstract

UV-A and –B blocking agents are essential components for the formulation of topical cream for psoriasis phototherapy. In this research, many natural compounds were discovered as potent UV-A and UV-B blocking agents, but small number could absorb narrowband UV-B. Quercetin hydrate, oxyresveratrol and curcumin were good UV-A blocking agents, while catechin, hesperetin, lutein and naringenin were proper for UV-B blocking agents. Berberine chloride hydrate, demethoxycurcumin and mansonone G were UV-A and –B blocking agents. From random combination, the mixture of mansonone G 0.010 % w/v and quercetin hydrate 0.0025 % w/v was disclosed to be a right choice for this developed topical cream. The combination of truly two natural products as quercetin and mansonone G has never been reported for psoriasis phototherapy. In addition, this combination revealed no difference in cytotoxicity at low concentration from combination of avobenzone and octinoxate (standard compounds). For photostability test, the combination of these two compounds exhibited the same absorption at 311 nm as the unexposed compounds for the period no longer than 30 min. These two compounds were eventually formulated to produce yellow cold topical cream.