Abstract: 

Psoriasis is a common and chronic immune-mediated disorder that severely impacts the life quality of patients. Phosphodiesterase-4 (PDE4) inhibitors have attracted significant interests in the psoriasis treatment due to their ability to suppress the inflammatory cascades. In this study, extensive screening of an in-house library of 1200 Chinese medicinal plant extracts identified Platycladus orientalis (L.) Franco (P. orientalis) as a potent PDE4 inhibitor, exhibiting 42.7% inhibition at 0.2 μg/mL. Subsequent bioassay-guided isolation revealed flavonoids, particularly amentoflavone (AMF), as the principal component responsible for PDE4 inhibition. To enrich the effective ingredients, a purification protocol using microporous resin was developed, yielding a flavonoid-rich extract (FLDs) that efficiently increased AMF content from 6.2% to 72.3% and improved PDE4 inhibitory activity to 74.2% at 0.2 µg/mL. Notably, P. orientalis with favorable safety profiles demonstrated superior in vitro and in vivo anti-psoriasis effects to both AMF and the approved PDE4 inhibitor apremilast. These findings highlight the potential of P. orientalis as a novel therapeutic agent for psoriasis and provide valuable insights for its development in psoriasis treatment.

See more: https://www.sciencedirect.com/science/article/abs/pii/S1001841724013111