**1. Introduction**

*Bletilla striata* (Thunb.) Reichb.f is a famous traditional Chinese herb that is widely used in the treatment of lung and stomach diseases such as pneumogastric hemorrhage, silicosis, tuberculosis, and gastric ulcer; it can also be used for the treatment of skin cracks, burns and freckles when combined with other traditional Chinese medicines. Numerous compounds have been identified from *Bletilla striata*, such as benzyls, phenanthrenes, dihydrophenanthrenes, anthracene, phenolic acid and polysaccharides [1,2]. Among these, polysaccharides are the most extensively and deeply studied, and their anti-ulcer [3], wound healing [4], homeostasis [5] and immune regulation [6] effects have represented most of the efficacy of *Bletilla striata*. However, in recent years, the pharmacological activities of the small molecular components in *Bletilla striata* have also attracted much attention. Liu [7] reported that the 80% ethanol elunt fraction of D101 macroporous resin significantly reduced bleeding time and increased the maximum platelet aggregation rate. Our previous research showed that the ethanol extract of *Bletilla striata* dose dependently inhibited alcohol induced gastric ulcer and silica induced silicosis in rats [8,9]. Furthermore, the ethanol extract of *Bletilla striata* significantly down regulated the serum level of IL-1β, TNF-α, transforming growth factor-β (TGF-β) and other inflammatory factors in rats with silicosis [9], thereby reducing the degree of pulmonary fibrosis, and this effect is far more effective than the polysaccharide of *Bletilla striata* [10]. However, its active components and underlying molecular mechanisms are unclear.

Silicosis is a type of systemic disease, characterized by chronic persistent inflammation and progressive fibrosis in lung tissue. The innate immune response mediated by alveolar macrophage plays a very important role in inflammatory reaction during the process of silicosis. The activated macrophages release proinflammatory mediators such as IL-6, IL-1β, TNF-α, TGF-β and platelet-derived growth factor (PDGF), etc. [11]. These inflammatory factors are recognized as key factors in pulmonary fibrosis, and the interruption of these factor pathways can alleviate or prevent fibrosis [12–14]. The classic LPS-induced RAW264.7 macrophage model can mimic the process of macrophage activation in vitro. One active compound 2,7-dihydroxy-4-methoxy-9,10-dihydrophenanthrene (coelonin) from *Bletilla striata* was separated and identified under the guidance of this cell model and combined with column chromatography.

Although few studies have described the anti-inflammatory effect of coelonin, but we found that this compound significantly down regulated IL-1β and IL-6 expression at 2.5 μg/mL on LPS-induced RAW264.7 cell. Hence, coelonin may be one of the main active components contributing to the anti-silicosis effect of *Bletilla striata*. In this study, we used a Phospho Explorer Antibody Array PEX100 to discover the potential target of the anti-inflammation effect of coelonin. The microarray results imply that coelonin may play an anti-inflammatory and cell-cycle regulation role through the PTEN/AKT pathway. Examining the down-stream signaling profile and cytokines secretion in RAW264.7 cells induced by LPS with or without coelonin or the PTEN inhibitor SF1670 suggests that coelonin blocked RAW264.7 cells in the G1 phase cell cycle in a PTEN- dependent manner, and PTEN may partially participated in coelonin inhibition on the secretion of inflammatory factors. Therefore, the potential molecular mechanism of the anti-inflammatory effect of coelonin remains to be addressed. Furthermore, as one of the main active ingredients of *Bletilla striata*, the anti-inflammatory activity of coelonin in vivo deserves further study.
