1 Department of Pharmacology, Faculty of Pharmacy.
2 Department of Pharmacognosy, Obafemi Awolowo University, Ile-Ife, 220005, Osun State, Nigeria.
3 Department of Chemical and Physical Sciences, Faculty of Natural Sciences, Walter Sisulu University, NMD Campus, Mthatha, South Africa.
4 Department of Chemistry, Faculty of Science and Agriculture, University of Fort Hare, Alice, South Africa.
Research Article
GSC Biological and Pharmaceutical Sciences, 2021, 14(02), 064-076.
Article DOI: 10.30574/gscbps.2021.14.2.0030
Received on 15 January 2021; revised on 05 Februay 2021; accepted on 08 Februay 2021
Objectives: This study determined the chemical composition of essential oil obtained from fresh leaf of Plectranthus aegyptiacus, and evaluated it for novelty-induced behavioural (NIB) and determine its mechanism(s) of action in mice.
Methods: The oil was hydro-distillated, and analyzed using gas chromatography-mass spectrometry. The effects of the oil (50, 100 and 150 mg/kg; i.p., n=6) on novelty-induced behavioural was assessed using open field test and head dipping on hole board. Probable mechanism(s) were evaluated using antagonists: flumazenil, naloxone and cyproheptadine at 2 mg/kg each, atropine and yohimbine at 5 mg/kg and 1 mg/kg respectively.
Key Findings: The LD50 values obtained were 2154 and 490 mg/kg for oral and intraperitoneal routes respectively. The oil (50, 100 and150 mg/kg) significantly (p<0.05, 0.01 and 0.01) inhibited all NIB and head dips. Flumazenil significantly (p<0.05) reversed the effect of the oil on NIB; atropine, naloxone and cyproheptadine significantly (p<0.01, 0.01 and 0.001) potentiated inhibitory effect on NIB respectively, while yohimbine showed no significantly effect. The analyzed oil showed 61 compounds, and the major compounds were carvacrol, germacrene-D, p-cymene and [1,1'-Bicyclopentyl]-2,2'-diol.
Conclusions: The study concluded that the oil possessed central nervous system depressant activity, which could be mediated mainly through augmentation of GABAergic neurotransmission, while cholinergic-(muscarinic), adrenergic and serotonergic pathways may be involved.
Acute toxicity; Carvacrol; Essential oil; Novelty-induced behavior; Plectranthus aegyptiacus
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Enimeya Dressman Akuegbe, Idris Ajayi Oyemitan, Ifeoluwa Isaac Ogunlowo, Gugulethu Mathew Miya, Opeoluwa Oyehan Oyedeji and Adebola Omowumi Oyedeji. Behavioural activities and chemical composition of fresh leaf essential oil of Plectranthus aegyptiacus from Southwest Nigeria in mice. GSC Biological and Pharmaceutical Sciences, 2021, 14(2), 064-076. Article DOI: https://doi.org/10.30574/gscbps.2021.14.2.0030