Anti-inflammatory potential of Trifolium pratense L. leaf extract in LPS-stimulated RAW264.7 cells and in a rat model of carrageenan-induced inflammation

This study evaluated the anti-inflammatory potential of a 40% prethanol extract of Trifolium pratense leaves (40% PeTP) using in vitro (RAW264.7 cells) and in vivo (carrageenan-induced inflammation model) experiments. Pretreatment with 40% PeTP significantly inhibited the LPS-induced expression of nitric oxide (NO), prostaglandin E2 (PGE2), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and inflammatory cytokines, including tumour necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 in RAW264.7 cells, without inducing cytotoxicity. The inhibitory effects of 40% PeTP are mediated through suppression of the nuclear translocation of nuclear factor (NF)-κB and the phosphorylation of mitogen-activated protein kinases (MAPKs). Oral administration of 40% PeTP at 50, 100, and 200 mg/kg of body weight suppressed carrageenan-induced oedema in a dose-dependent manner. Collectively, our results suggested that 40% PeTP exerts potential anti-inflammatory effects by suppressing the activation of the NF-κB and MAPK pathways in vitro, and by reducing carrageenan-induced paw oedema in vivo.