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

Ananas comosus (pineapple) leaf is used in ethnomedicine to treat diarrhoea, inflammation, pain, bacterial infections and oedema. 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. Methanol ACLE was subjected to gas chromatography-mass spectrometry 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. 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. 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.