Phytochemical characterization, anti-diarrhoeal, analgesic, anti-inflammatory activities and toxicity profile of Ananas comosus (L.) Merr (pineapple) leaf in albino rats

Abstract

Ethnopharmacological relevance: Ananas comosus (pineapple) leaf is used in ethnomedicine to treat diarrhoea, inflammation, pain, bacterial infections and oedema.

Aim of the study: The aim of this study was to investigate the anti-diarrhoeal, anti-inflammatory and analgesic effects as well as the toxicity profile of the aqueous Ananas comosus leaf extract (AACLE) in rats.

Methods: Methanol ACLE was subjected to gas chromatography-mass spectrometry (GC-MS) analysis. In the acute toxicity study, a single oral dose of up to 5000 mg/kg AACLE was administered. In the subacute toxicity study (28 days), rats in groups 2-4 received AACLE orally. The anti-diarrhoeal effect was studied using charcoal meal and castor oil-induced diarrhoea. Anti-inflammatory and analgesic tests were measured using egg albumin-induced paw oedema and acetic acid-induced writhing methods, respectively. For the subacute toxicity, anti-diarrhoeal, analgesic, and anti-inflammatory studies, AACLE was administered orally to rats at doses of 200, 400, and 600 mg/kg body weight.

Results: Hexadecanoic acid methyl ester, 2-methoxy-4-vinylphenol, n-hexadecanoic acid and n-heptadecanol-1 were identified among other compounds with known pharmacological activities by GC-MS analysis. No deaths, behavioural changes, or signs of toxicity were observed in the acute toxicity study. Treatment with AACLE (28 days) decreased aspartate aminotransferase, alanine transaminase, total cholesterol, triglycerides, and low-density lipoprotein cholesterol, while high-density lipoprotein cholesterol, glutathione, and catalase increased when compared with control (P < 0.05). Treatment with AACLE did not cause significant changes in haematological or renal function parameters. Treatment with AACLE inhibited gastrointestinal motility and castor oil-induced diarrhoea in rats. Treatment with AACLE resulted in a dose-dependent (200-600 mg/kg) significant (P < 0.05) anti-diarrhoeal, analgesic, and anti-inflammatory effect compared to standard drugs.

Conclusion: Our study revealed that ACLE is not toxic but contains bioactive compounds with anti-diarrhoeal, anti-inflammatory, antimicrobial, and hepatoprotective activity. AACLE has antidiarrhoeal, analgesic and anti-inflammatory activity in rats, which justifies its therapeutic use in traditional medicine.

Keywords: Analgesic; Anti-diarrhoeal; Anti-inflammatory; Pineapple leaf; Toxicity.