3-Methoxy-catalposide inhibits inflammatory effects in lipopolysaccharide-stimulated RAW264.7 macrophages

Pseudolysimachion rotundum var. subintegrum is utilized as a traditional herbal remedy to treat cough, bronchitis, and asthma in Korea, Russia, China, and Europe. Here, we show that 3-methoxy-catalposide, a novel iridoide glycoside isolated from P. rotundum var. subintegrum has the anti-inflammatory activity in lipopolysaccharide (LPS)-stimulated macrophages. The chemical structure of 3-methoxy-catalposide was determined by NMR, optical rotation and HRESIMS. In in vitro experiment, RAW264.7 cells were treated with 3-methoxy-catalposide for 2h before exposure to LPS for different times. Inflammatory gene and protein expressions were assayed using RT-PCR and ELISA. Activities of signal proteins were examined using western analysis. Our results demonstrated that 3-methoxy-catalposide significantly inhibits the expression of cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) in RAW264.7 cells stimulated by LPS, thereby suppressing the release of prostaglandin E2 (PGE₂) and nitric oxide (NO). Moreover, 3-methoxy-catalposide markedly reduced the LPS-induced expression of pro-inflammatory genes, such as interleukin (IL)-6, IL-1β, and TNF-α. Further, 3-methoxy-catalposide inhibited both LPS-induced activation of three MAP kinases (ERK 1/2, JNK, and p38) and the nuclear translocation of NF-κB and AP-1. These results support that 3-methoxy-catalposide may be a promising candidate for inflammation treatment.