Department of Pharmacology, Therapeutics & Toxicology (PTT), Faculty of Basic Medical Sciences, College of Medicine, University of Lagos, Idi-Araba Campus, P.M.B. 12003 Lagos, Nigeria.
Department of Pharmacology, Therapeutics & Toxicology (PTT), Faculty of Basic Medical Sciences, College of Medicine, University of Lagos, Idi-Araba Campus, P.M.B. 12003 Lagos, Nigeria.
J Ethnopharmacol. 2015 Dec 24;176:225-31. doi: 10.1016/j.jep.2015.10.035. Epub 2015 Oct 26.
Caladium bicolor (Araceae) is a horticulture plant also used by some traditional medicine practitioners in the treatment of diarrhoea and other gastrointestinal disorders. This study was conducted to evaluate the antidiarrhoeal activity of the aqueous leaf extract of C. bicolor and its possible mechanisms of action in rodents.
Normal and castor oil-induced intestinal transit and castor oil-induced diarrhoea tests were carried out in mice while gastric emptying and enteropooling tests were conducted in rats following the administration of distilled water (10 ml/kg, p.o.), C. bicolor extract (1-50mg/kg, p.o.) and loperamide (5mg/kg, p.o.). The probable mechanisms of action of C. bicolor was investigated following pre-treatment with yohimbine (10mg/kg, s.c.; α2-adrenoceptor antagonist), pilocarpine (1mg/kg, s.c.; non-selective muscarinic receptor agonist), prazosin (1mg/kg, s.c.; α1-adrenoceptor antagonist) and propranolol (1mg/kg, i.p.; non-selective β-adrenoceptor antagonist) 15 min prior to administration of C. bicolor extract (50mg/kg, p.o.). After 30 min of pre-treatment with these drugs, the mice were subjected to the castor oil-induced intestinal transit test.
C. bicolor extract did not produce significant (p>0.05) effect on normal intestinal transit unlike loperamide which caused significant (p<0.001) inhibition (61.57%). The extract caused significant (p<0.001) dose-dependent inhibition of castor oil-induced intestinal transit with peak effect, 100% inhibition, elicited at the dose of 50mg/kg compared to 86.97% inhibition for loperamide. Yohimbine and pilocarpine most significantly (p<0.001) reversed this effect of the extract. In the castor oil-induced diarrhoea test, the extract (1mg/kg) and loperamide significantly (p<0.05, 0.01) delayed the onset of diarrhoea. For diarrhoea score, the extract (1 and 50mg/kg) inhibited diarrhoea development (47.53% and 43.83% inhibition, respectively) like loperamide (5mg/kg; 54.94%). The in vivo antidiarrhoeal index of the extract at 1 and 50mg/kg was 50.07% and 42.81% respectively compared to 58.15% for loperamide.
The results obtained in this study suggest that the aqueous leaf extract of C. bicolor possess antidiarrhoeal activity due to its anti-motility effect possibly via antagonist action on intestinal muscarinic receptors and agonist action on intestinal α2-adrenoceptors. This justifies the use of the extract in traditional medicine for the treatment of diarrhoea.
五彩芋（天南星科）是一种园艺植物，也被一些传统医学从业者用于治疗腹泻和其他胃肠道疾病。本研究旨在评估五彩芋叶水提物的抗腹泻活性及其在啮齿动物中的可能作用机制。
在小鼠中进行了正常和蓖麻油诱导的肠道转运以及蓖麻油诱导的腹泻试验，而在大鼠中进行了胃排空和肠液蓄积试验，方法是给予蒸馏水（10ml/kg，po）、五彩芋提取物（1-50mg/kg，po）和洛哌丁胺（5mg/kg，po）。在给予五彩芋提取物（50mg/kg，po）前 15 分钟预先用育亨宾（10mg/kg，sc；α2-肾上腺素能受体拮抗剂）、毛果芸香碱（1mg/kg，sc；非选择性毒蕈碱受体激动剂）、哌唑嗪（1mg/kg，sc；α1-肾上腺素能受体拮抗剂）和普萘洛尔（1mg/kg，ip；非选择性β-肾上腺素能受体拮抗剂）预处理后，研究了五彩芋的可能作用机制。用这些药物预处理 30 分钟后，将小鼠置于蓖麻油诱导的肠道转运试验中。
与洛哌丁胺（引起显著的（p<0.001）抑制作用（61.57%）不同，五彩芋提取物对正常肠道转运没有产生显著的（p>0.05）影响。提取物对蓖麻油诱导的肠道转运具有显著的（p<0.001）剂量依赖性抑制作用，峰值作用为 50mg/kg 时抑制率为 100%，而洛哌丁胺的抑制率为 86.97%。育亨宾和毛果芸香碱最显著地（p<0.001）逆转了这种提取物的作用。在蓖麻油诱导的腹泻试验中，提取物（1mg/kg）和洛哌丁胺显著（p<0.05，0.01）延迟了腹泻的发作。对于腹泻评分，提取物（1 和 50mg/kg）抑制了腹泻的发展（分别为 47.53%和 43.83%的抑制作用），类似于洛哌丁胺（5mg/kg；54.94%）。提取物在 1mg/kg 和 50mg/kg 时的体内抗腹泻指数分别为 50.07%和 42.81%，而洛哌丁胺为 58.15%。
本研究结果表明，五彩芋叶水提物具有抗腹泻活性，这可能是由于其抗运动作用，可能通过对肠道毒蕈碱受体的拮抗剂作用和对肠道α2-肾上腺素能受体的激动剂作用。这证明了该提取物在传统医学中用于治疗腹泻的合理性。
