The diarrhoeogenic and antidiarrhoeal bidirectional effects of rhubarb and its potential mechanism.
OBJECTIVE
The present study investigated the pharmacological effects of different extracts of rhubarb on intestinal function of mice, further to explore possible reasons for the adverse effects of long-term use of rhubarb as a purgative.


METHODS
The total extract of rhubarb (TR) was extracted with 60% ethanol and the total anthraquinones extract (TA), total tannins extract (TT) and remaining components extract (RC) of rhubarb were separated from TR using macroporous resin. The pharmacological effects of each extract on the intestinal function of mice were evaluated by defecation test and the antidiarrhoeal activity of rhubarb tannins as well as its mechanism was studied by different animal models and histopathological examination.


RESULTS
Both TR and TA produced purgative activities, but the purgative activity of TA was stronger than that of TR. Successive administration of TT produced an antidiarrhoeal activity in a time- and dose-dependent manner. Besides, successive administration of RC showed no significant effect on the intestinal function of mice. The antidiarrhoeal activity of rhubarb tannins was confirmed directly for the first time and its mechanism was probable that rhubarb tannins generated protein-precipitating reaction to the gastrointestinal mucosa due to its protein-precipitating action.


CONCLUSIONS
The results confirmed that rhubarb had the diarrhoeogenic and antidiarrhoeal bidirectional effects due to the coexistence of anthraquinones and tannins. The bidirectional effects might be the reason or one of the reasons for the adverse effects of long-term use of rhubarb as a purgative.
Integrative Medicine Center of 302 Military Hospital, China Military Institute of Chinese Materia Medica, Beijing 100039, PR China.
Yi
Y
Qin
Jia-bo
JB
Wang
Wei-jun
WJ
Kong
Yan-ling
YL
Zhao
Hui-yin
HY
Yang
Chun-mei
CM
Dai
Fang
F
Fang
Lin
L
Zhang
Bao-cai
BC
Li
Cheng
C
Jin
Xiao-he
XH
Xiao
D000818:Animals; D003672:Defecation / Q000187:drug effects; D003967:Diarrhea / Q000139:chemically induced* / Q000188:drug therapy*; D004305:Dose-Response Relationship, Drug; D005772:Gastrointestinal Transit / Q000187:drug effects; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D010936:Plant Extracts / Q000009:adverse effects* / Q000494:pharmacology / Q000627:therapeutic use*; D012250:Rheum / Q000737:chemistry*
D010936:Plant Extracts