p-Coumaric-Acid-Containing Adenostemma lavenia Ameliorates Acute Lung Injury by Activating AMPK/Nrf2/HO-1 Signaling and Improving the Anti-oxidant Response

Abstract

Adenostemma lavenia is a perennial herb belonging to the Compositae family and is widely distributed in the tropical parts of Asia. It has been widely used as medicine in Taiwan with the whole plant used to treat pulmonary congestion, pneumonia, bacterial infections of the respiratory tract, edema, and inflammation. This study sought to investigate the anti-inflammatory effects of A. lavenia in vitro and in animal models. The anti-inflammatory effects of ethyl acetate fractions of A. lavenia (EAAL) were stimulated with lipopolysaccharide (LPS) murine macrophages (RAW 264.7) and lung injury in mice. EAAL reduced proinflammatory cytokine responses. Preoral EAAL alleviated LPS-induced histological alterations in lung tissue and inhibited the infiltration of inflammatory cells and protein concentrations in bronchoalveolar lavage fluid (BALF). EAAL prevented protein expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2); phosphorylation of I$\kappa$B-$\alpha$, MAPKs, and AMP-activated protein kinase (AMPK); and activated anti-oxidant enzymes (catalase, SOD, and GPx), heme oxygenase-1 (HO-1), and nuclear factor E2-related factor 2 (Nrf2) in LPS-stimulated cells and lung tissues. Fingerprinting of EAAL was performed with HPLC to control its quality, and $p$-coumaric acid was found to be a major constituent. This study suggests that EAAL is a potential therapeutic agent to treat inflammatory disorders.

Keywords: AMPK/Nrf2/HO-1 Pathways; Acute Lung Injury; Adenostemma lavenia; Lipopolysaccharide; MAPK; $p$-Coumaric Acid.