Anti-inflammatory activity and mechanism of action of ethanolic leaf extract of Morinda lucida Benth

Frederick Ayertey; Ebenezer Ofori-Attah; Stephen Antwi; Michael Amoa-Bosompem; Georgina Djameh; Nathaniel Lartey Lartey; Mistuko Ohashi; Kwadwo Asamoah Kusi; Alfred Ampomah Appiah; Regina Appiah-Opong; Laud Kenneth Okine

doi:10.1016/j.jtcme.2020.07.001

Anti-inflammatory activity and mechanism of action of ethanolic leaf extract of Morinda lucida Benth

J Tradit Complement Med. 2020 Aug 4;11(3):249-258. doi: 10.1016/j.jtcme.2020.07.001. eCollection 2021 May.

Affiliations

¹ Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Accra, Ghana.
² Department of Clinical Pathology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana.
³ Pharmacology, Toxicology Department, Center for Plant Medicine Research, Mampong, Akwapim, Ghana.
⁴ Department of Parasitology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana.
⁵ Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, South Africa.
⁶ Phytochemistry Department, Center for Plant Medicine Research, Mampong, Akwapim, Ghana.

Abstract

Background and aim: Most developing countries resort to medicinal plants for treating diseases, but few of these have scientific backing for their use. The aim of the study was to validate traditional use of Morinda lucida leaves in treating inflammation and determine the mechanism of action.

Experimental procedure: Effect of hydroethanolic leaf extract of M. lucida (HEML) on localized inflammation was evaluated using rat paw edema presented by sub-planter injections of λ-carrageenan, histamine or serotonin in separate experiments. Systemic inflammation was evaluated by lipopolysaccharide (LPS)-induced hyperthermia. Antioxidant activity of HEML was also evaluated using the free-radical scavenging assay.

Results and conclusion: No mortalities were recorded in acute toxicity assay after administering 5000 mg/kg HEML to rats. It showed very good activity against localized and systemic inflammation in inverse dose-dependent manner and caused reduction in nitric oxide and prostaglandin E-2 levels by affecting expression of inducible nitric oxide synthase, but not cyclooxygenases-2 in LPS-activated RAW 264.7 murine macrophages. HEML reduced pro-inflammatory cytokines interleukin (IL)-1β and tumor necrotic factor, but elevated levels of anti-inflammatory cytokine IL-10 in vitro. HEML contains saponins, reducing sugars, polyphenols and flavonoids and showed antioxidant activity with EC₅₀ = 0.6415 ± 0.0027 mg/ml. In conclusion, this study provides evidence that HEML possesses anti-inflammatory activity, possibly through modulation of production of early/late phase inflammation mediators.

Keywords: CPM, chlorpheniramine; CPMR, Centre for Plant Medicine Research; Cyclooxygenase-2; Cytokines; Edema; GRA, granisetron; HEML, hydroethanolic Morinda lucida; Inflammation; Nitric oxide; SFN, sulforuphane.