Antidiarrheal effect of extract from the bark of Combretum leprosum in mice

Abstract This study investigated the effects of the ethanolic extract from the bark of Combretum leprosum (ECL) on intestinal transit and castor-oil induced diarrhea in mice. The oral administration of ECL (750 and 1000 mg/kg) slowed intestinal transit (ID50 of 455 mg/kg). The ECL (250-1000 mg/kg) reduced castor-oil induced diarrhea, in a time- and dose-dependent manner (p < 0.05). To determine if antidiarrheal effect of ECL involves α2-adrenergic or opioid receptor activation, the mice were pretreated with antagonists of these receptors, yohimbine or naloxone respectively. None of these drugs inhibited the antidiarrheal effect of ECL. To test if antidiarrheal effect of ECL is due to an antisecretory action, we realized the enteropooling assay on rats. The ECL increased bowel content and did not inhibit intestinal fluid secretion increase induced by misoprostol (100 µg/kg, s.c.). To determine if antimotility effect of ECL is due to a reduction on gastric motility, we realized the organ bath assay in the rat fundus stomach. Isotonic recordings show that the carbachol /KCl - induced contraction was not reversed by the addition of ECL. In conclusion, our results suggest that ECL contains antidiarrheal compounds and these compounds could induce a reduction of intestinal tract motility.

摘要 本研究探讨了麻风风车子（Combretum leprosum）树皮乙醇提取物（ECL）对小鼠肠道转运及蓖麻油诱导腹泻的影响。口服给予ECL（750与1000 mg/kg）可减缓小鼠肠道转运，其半数有效剂量（ID₅₀）为455 mg/kg。ECL在250~1000 mg/kg剂量范围内可呈时间与剂量依赖性减轻蓖麻油诱导的腹泻（p < 0.05）。为明确ECL的止泻作用是否涉及α₂-肾上腺素能受体或阿片受体激活，本研究分别采用育亨宾（yohimbine）与纳洛酮（naloxone）作为上述受体的拮抗剂预处理小鼠，但两类拮抗剂均未抑制ECL的止泻效应。为验证ECL的止泻作用是否源于抗分泌机制，本研究对大鼠开展肠积液实验：ECL可增加大鼠肠道内容物量，且未抑制米索前列醇（100 µg/kg，皮下注射，s.c.）诱导的肠液分泌增多。为探究ECL的抗转运作用是否由胃动力降低介导，本研究采用大鼠胃底器官浴槽实验进行验证：等张记录结果显示，卡巴胆碱（carbachol）/氯化钾（KCl）诱导的胃底平滑肌收缩并未因加入ECL而发生逆转。综上，本研究结果提示ECL中含有止泻活性成分，其作用机制可能为降低肠道蠕动。