Pyrus ussuriensis Maxim, a pear commonly known as "Sandolbae" in Korea, is used as a traditional herbal medicine for
asthma,
cough, and
fever in Korea, China, and Japan. P. ussuriensis Maxim leaves (PUL) have
therapeutic effects on
atopic dermatitis (AD). However, there are no reports on the efficacy of specific components of PUL. In the present study, activity-guided isolation of PUL was used to determine the compounds with potent activity.
Astragalin was identified as the major component of the
chloroform-soluble fraction of PUL (PULC) using High-performance liquid chromatography (HPLC) analysis.
Astragalin and PULC were tested in vitro and in vivo for their effects against AD. PULC and
astragalin dose-dependently inhibited the production of
nitric oxide (NO) in mouse macrophage (RAW 264.7) cells, and
interleukin (IL)-6 and IL-1β in
tumor necrosis factor (TNF-α)/
interferon γ (IFNγ) induced HaCaT cells. In the AD mice model, PULC and
astragalin application significantly reduced
dermatitis severity, scratching behavior, and trans-epidermal water loss (TEWL) when compared to that of 2, 4-dinitrochlorobenzene-treated NC/Nga mice. Additionally, they normalized skin barrier function by decreasing
immunoglobulin E (
IgE) levels in the serum.
Filaggrin and
involucrin protein levels were normalized by PULC treatment in HaCaT cells and skin lesions. These results indicate that PULC and
astragalin ameliorate AD-like symptoms by alleviating both pro-inflammatory
cytokines and immune stimuli in vitro and in vivo in animal models. Therefore, PULC and
astragalin might be effective therapeutic agents for the treatment of AD.