ABSTRACT
Twenty-one lignans including three new ones (1, 2 and 13) were isolated from Justicia procumbens. The chemical structures of the new lignans were determined by spectroscopic means including 1D and 2D NMR analysis. These compounds were evaluated for their cytotoxic and anti-HIV activities. The new secoisolariciresinol dimethyl ether acetate (13) exhibited anti-HIV-1 activity with an IC value of 5.27 μmol·L and a selective index (SI) value of 2.2. The known arylnaphthalene lignan procumbenoside A (3) and diphyllin (8) demonstrated inhibitory activity against HIV-1 with IC values of 4.95 (SI > 6.2) and 0.38 μmol·L (SI = 5.3), respectively.
ABSTRACT
<p><b>BACKGROUND</b>Cathepsin L (CatL) is a cysteine protease with strong matrix degradation activity that contributes to photoaging. Mannose phosphate-independent sorting pathways mediate ultraviolet A (UVA)-induced alternate trafficking of CatL. Little is known about signaling pathways involved in the regulation of UVA-induced CatL expression and activity. This study aims to investigate whether a single UVA irradiation affects CatL expression and activity and whether mitogen-activated protein kinase (MAPK)/activator protein-1 (AP-1) pathway is involved in the regulation of UVA-induced CatL expression and activity in human dermal fibroblasts (HDFs).</p><p><b>METHODS</b>Primary HDFs were exposed to UVA. Cell proliferation was determined by a cell counting kit. UVA-induced CatL production and activity were studied with quantitative real-time reverse transcription polymerase chain reaction (RT-PCR), Western blotting, and fluorimetric assay in cell lysates collected on three consecutive days after irradiation. Time courses of UVA-activated JNK and p38MAPK signaling were examined by Western blotting. Effects of MAPK inhibitors and knockdown of Jun and Fos on UVA-induced CatL expression and activity were investigated by RT-PCR, Western blotting, and fluorimetric assay. Data were analyzed by one-way analysis of variance.</p><p><b>RESULTS</b>UVA significantly increased CatL gene expression, protein abundance, and enzymatic activity for three consecutive days after irradiation (F = 83.11, 56.14, and 71.19, respectively; all P < 0.05). Further investigation demonstrated phosphorylation of JNK and p38MAPK activated by UVA. Importantly, inactivation of JNK pathway significantly decreased UVA-induced CatL expression and activity, which were not affected by p38MAPK inhibition. Moreover, knockdown of Jun and Fos significantly attenuated basal and UVA-induced CatL expression and activity.</p><p><b>CONCLUSIONS</b>UVA enhances CatL production and activity in HDFs, probably by activating JNK and downstreaming AP-1. These findings provide a new possible molecular approach for antiphotoaging therapy.</p>