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Wen-Pi-Tang, a traditional Chinese prescription, has been widely used for the treatment of patients with moderate chronic renal failure in China. Although the protective effect of Wen-Pi-Tang on peroxynitrite (ONOO^-)-induced renal tubular epithelial LLC-PK₁ cell damage was elucidated in our previous research, the active components of Wen-Pi-Tang have not yet been fully clarified. Therefore in the present study, we investigated the active components by using a cellular ONOO^-generation system. As a result, p-coumaric acid, 4-(4'-hydroxylphenyl)-2-butanone 4'-O-glucopyranoside, gallic acid 3-O-(6'-O-galloyl)-β-d-glucopyranoside, procyanidin B-1, procyanidin B-3, and (+)-catechin were isolated as active compounds inhibiting cellular ONOO^- formation and cytotoxicity. In particular, the content of (+)-catechin was significantly higher than those of the other compounds, and the (+)-catechin structure was located in procyanidins B-1 and B-3. Therefore, the major bioactivity of Wen-Pi-Tang against ONOO^--induced cytotoxicity in LLC-PK₁ cells was thought to be mediated by (+)-catechin. Although we cannot disregard the synergetic effect of various components in Wen-Pi-Tang, (+)-catechin is a major active compound protecting against ONOO^--induced LLC-PK₁ cell damage and may be used as an index to qualify the ONOO^--inhibitory activity of Wen-Pi-Tang extract.

(+)-catechin is a flavanol that possesses various health and medicinal values, which include neuroprotection, anti-oxidation, antitumor and antihepatitis activities. This study investigated the modulatory effects of (+)-catechin on the lipopolysaccharides (LPS)-stimulated BV-2 cells. (+)-catechin attenuated LPS-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and inhibited microglial NO and ROS production. Additionally, (+)-catechin suppressed the production of tumor necrosis factor-α (TNF-α) and interleukin (IL)-6, while augmenting IL-4. (+)-catechin attenuated LPS-induced nuclear factor-κB (NF-κB) p65 nuclear translocation via the inhibition of IκB-α phosphorylation. Moreover, (+)-catechin blocked the activation of Akt and its inhibition was shown to play a crucial role in LPS-induced inflammation in BV-2 microglial cells. (+)-catechin also attenuated the LPS-induced phosphorylation of extracellular signal-regulated kinase (ERK1/2), and p-38 mitogen activated protein kinases (p38 MAPK) and specific inhibitors of ERK1/2 (UO126) and p38 MAPK (SB202190) subsequently down-regulated the expression of the proinflammatory mediators iNOS and COX-2. Further mechanistic study revealed that (+)-catechin acted through the amelioration of the LPS-induced suppression of adenosine monophosphate-activated protein kinase (AMPK) activity. Taken together, our data indicate that (+)-catechin exhibits anti-inflammatory effects in BV-2 cells by suppressing the production of proinflammatory mediators and mitigation of NF-κB through Akt, ERK, p38 MAPK, and AMPK pathways.