Anti-Inflammatory Activity And The Mechanism Of Action Of Morinda Lucida Benth

Abstract

A commonly used medicinal plant in African folk medicine for the treatment of various diseases including inflammation is Morinda lucida Benth. However, scientific data supporting its antiinflammatory activity is scarce. In the current study, the anti-inflammatory activity of the hydroethanolic leaf extract of Morinda lucida Benth (HEML) was assessed using carrageenaninduced paw edema in female Sprague-Dawley rats (SDRs). The potential mode of action of HEML was determined by assessing its effect on the levels of PGE2, NO, IL-1β, TNF-α and IL- 10, and also expressional levels of COX-2 and iNOS in RAW 264.7 cells in vitro. Its phytochemical constituents were determined by standard methods, and its antioxidant activity was investigated by DPPH free radical scavenging assay. The ability of HEML to significantly reduce rat paw edema caused by carrageenan demonstrated its anti-inflammatory activity. HEML also inhibited paw edema induced by histamine or serotonin, and further suppressed LPSinduced fever in the SDRs, which indicates that both early and late phases of acute inflammation were affected by the extract. Persistence of the late phase mediators may plunge the organism into a chronic state of inflammation. Results obtained through the determination of levels of PGE2, NO, IL-1β, TNF-α and IL-10 in culture supernatant of LPS-activated RAW 264.7 cells showed that HEML reduced NO and PGE2 concentrations by downregulating iNOS expression but not COX-2. It also suppressed the levels of pro-inflammatory cytokines IL-1β and TNF-α possibly by boosting levels of the anti-inflammatory cytokine IL-10. HEML contained saponins, reducing sugars, polyphenolics including flavonoids. It possesses antioxidant activity, which may be due to its polyphenolic content, particularly flavonoids. The current findings provide evidence-based scientific data to support the anecdotal use of M. lucida as treatment agent for inflammation.