Solvent polarity dictates the anti-inflammatory potency and mechanism of two purslane (Portulaca oleracea) seed extracts.

Abstract

This study aimed to assess the effect of solvent polarity on anti-inflammatory potency and the underlying mechanisms of two purslane seed extracts. Methanol and dichloromethane extracts were prepared using Soxhlet extraction and chromatographically analyzed. Antioxidant activities were assessed by different assays, while the anti-inflammatory potentials were assessed in RAW 264.7 macrophage cells. Methanol extraction yielded 15.5% water-soluble extract while dichloromethane produced 3.74% fixed oil. Nineteen phenolic compounds were chromatographically identified in methanol extract compared with 16 in the fixed oil including omega fatty acids and phytosterols. Methanol extract showed significantly higher capacity in radical scavenging assays (p < .001), but the fixed oil showed higher total antioxidant capacity (p < .001). Both extracts demonstrated anti-inflammatory potentials with different mechanisms, where the phenol-rich methanol extract significantly reduced TNF-α (p=.0371) and IL-1β (p=.0029) production through an antioxidant-mediated pathway, while the fixed oil inhibited COX1, COX2, and PGE2 gene expression through the upregulation of IL-10. PRACTICAL APPLICATIONS: Both purslane extracts presented herein demonstrated remarkable antioxidant/ anti-inflammatory potentials that could be safely utilized as natural antioxidants and inflammation remedies or as functional food products, particularly that they showed no cytotoxic effects.