In vivo anti-inflammatory, anti-nociceptive, and in vitro antioxidant efficacy, and acute oral toxicity effects of the aqueous and methanolic stem bark extracts of Lonchocarpus eriocalyx (Harms.)

Gervason Apiri Moriasi; Anthony Muriithi Ireri; Elias Mandela Nelson; Mathew Piero Ngugi

doi:10.1016/j.heliyon.2021.e07145

In vivo anti-inflammatory, anti-nociceptive, and in vitro antioxidant efficacy, and acute oral toxicity effects of the aqueous and methanolic stem bark extracts of Lonchocarpus eriocalyx (Harms.)

Heliyon. 2021 May 28;7(5):e07145. doi: 10.1016/j.heliyon.2021.e07145. eCollection 2021 May.

Authors

Gervason Apiri Moriasi^{1

2}, Anthony Muriithi Ireri³, Elias Mandela Nelson⁴, Mathew Piero Ngugi²

Affiliations

¹ Mount Kenya University, Department of Medical Biochemistry, P.O BOX 342-01000, Thika, Kenya.
² Kenyatta University, Department of Biochemistry, Microbiology, and Biotechnology, P.O BOX 43844-00100, Nairobi, Kenya.
³ Kenyatta University, Department of Educational Psychology, P.O BOX 43844-00100, Nairobi, Kenya.
⁴ Mount Kenya University, Department of Biological Sciences, P.O. BOX 342-01000, Thika, Kenya.

Abstract

Oxidative stress causes and drives many agonising inflammatory conditions, which cause disability, financial burden, and emotional stress. The current anti-inflammatory, analgesic, and antioxidant agents are associated with adverse effects, inaccessibility, high costs, and low efficacies, thereby warranting the need for alternatives, especially from natural sources. Lonchocarpus eriocalyx plant is traditionally used in Kenyan communities to treat various inflammatory and oxidative stress-associated diseases; however, its pharmacologic efficacy and safety have not been empirically validated, hence this study. The in vivo antiinflamatory and antinociceptive efficacy of the aqueous and methanolic stem bark extracts of L. eriocalyx were determined using the xylene-induced ear oedema, and the acetic acid-induced writhing techniques, respectively, in experimental mice. Also, in vitro antioxidant activities of the studied plant extracts were investigated using the Thiobarbituric acid test for lipid peroxidation, 1, 1-diphenyl -2-picrylhydrazyl (DPPH), and Ferric reducing antioxidant power standard assay methods. Moreover, the studied extracts' acute oral toxicity effects were investigated according to the Organisation for Economic Corporation and Development (OECD) guidelines. The studied plant extracts showed significant dose-dependent inhibitions of oedema and writhing, depicting their anti-inflammatory and antinociceptive efficacy. Besides, the extracts revealed significant inhibitions of in vitro lipid peroxidation in varying degrees. Notably, the extracts demonstrated very strong DPPH radical scavenging and ferric-reducing antioxidant efficacies. Furthermore, the two studied plant extracts did not elicit acute oral toxicity, with LD₅₀ values of >2000 mg/kg BW, hence were considered safe. The anti-inflammatory, antinociceptive, and in vitro antioxidant efficacies of these extracts were attributed to antioxidant phytocompounds with diverse pharmacologic effects, especially through the amelioration of oxidative stress. Further studies on the anti-inflammatory, antinociceptive and antioxidant mechanism(s) and isolation and characterisation of responsible compounds are encouraged to spur the development of affordable, accessible, safe, and efficacious drugs.

Keywords: Acute oral toxicity effects; Anti-inflammatory activity; Antinociceptive activity; DPPH radical Scavenging activity; Ferric reducing antioxidant power; Lipid peroxidation; Lonchocarpus eriocalyx; Oxidative stress.