Ethanolic extract of Parkia speciosa pods exhibits antioxidant and anti-inflammatory properties in lipopolysaccharide-induced murine macrophages by inhibiting the p38 MAPK pathway

Abstract

BackgroundParkia speciosa (PS) is commonly used in Southeast Asian cuisine and traditional medicine to treat diabetes, hypertension, dermatitis, and kidney diseases. PS has emerged as a subject of interest because of its potential antioxidation and anti-inflammatory properties. However, despite its historically long and wide usage, a comprehensive investigation of these properties in PS pods (PSp) have not been conducted. Aims of this studyThis study aimed to identify the phytochemical compounds in the ethanolic extract of PSp collected from Southern Thailand and assess whether PSp exhibit antioxidant properties and mitigate inflammation in a lipopolysaccharide (LPS)-induced RAW264.7 model. Materials and methodsThe ethanolic extract of PSp was comprehensively analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-mass spectrometry (GC/MS) to identify its phytochemical constituents. To assess the antioxidant activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS) assays were performed, and cytotoxicity was evaluated using the MTT assay. The effect of PSp on reactive nitrogen and oxygen species (RNS and ROS) was determined using a nitric oxide (NO) assay, and its effect on pro-inflammatory cytokines was assessed using enzyme-linked immunosorbent assay (ELISA) and real-time quatitvative polymerase chain reaction (qPCR). Morphological changes following treatment were observed using a microscope. Western blot analysis was performed to quantify MAPK pathway expression. ResultsPSp contain polyphenols, phytosterols, triterpenes, oxaloacetic acid, and unsaturated fatty acids. PSp demonstrated high antioxidant potential in scavenging free radicals and exhibited no cytotoxic effects on macrophages. Moreover, PSp effectively reduced NO release and inhibited pro-inflammatory cytokines such as IL1-β, TNF-α, and IL-6. PSp treatment induced notable morphological changes in macrophages, characterized by an increase in cell size and the presence of intracellular vacuoles. In addition, Western blot analysis showed the selective suppressive effect of PSp on the p38-MAPK pathway. ConclusionPSp possess strong antioxidant and anti-inflammatory properties, making it a potential therapeutic agent for the treatment of inflammatory disorders.