pharmacological evaluation of a potential anti-diarrhoeal
agent.Castor oil causes diarrhoea due to its active
metabolite, recinolic acid (Ammon et al., 1974; Watson
and Gordon, 1962), which stimulates peristaltic activity in
the small intestine leading to changes in the electrolyte
permeability of the intestinal mucosa. The precise
mechanism of action of castor oil is through elevated
prostaglandin biosynthesis (Bruton, 1985; Galvez et al.,
1993). Prostaglandin contributes to the pathophysio-
logical functions in gastrointestinal tract (Sanders, 1984).
Inhibitors of prostaglandin biosynthesis delay castor oil
induced diarrhoea (Awouter et al., 1978). It has been
shown that E type of prostaglandins cause diarrhoea in
experimental animals as well as in human beings. The
mechanism has been associated with dual effects on
gastrointestinal motility as well as water and electrolyte
transport (Beubler and Juan, 1979). The maximal effect
produced by the extract was similar to that produced by
loperamide, which is at present one of the most
efficacious and widely employed antidiarrhoea drugs;
loperamide effectively antagonized diarrhoea induced by
castor oil (Niemegeers et al., 1974). Loperamide, apart
from regulating the gastrointestinal tract, is also reported
to slow down transit in the intestine, reduce colon flow
rate, and consequently any effect on colonic motility
(Theoderau et al., 1991). The therapeutic effect of
lopermide is believed to be due to its antimotility and
antisecretory properties (Couper, 1987).
Atropine and different doses of the extract significantly
decreased intestinal transit time. This is possible due to
its anticholinergic effect (Brown and Taylor, 1996),
atropine being less potent than the leaf extract at 200 and
400mg/kg body weight. The significant inhibition of the
castor oil- induced enteropooling in rats suggests that the
extract produced relief in diarrhoea by spasmolytic in vivo
and anti-enteropooling effects. It is also possible that
flavonoids present in the ethanolic leaf extract may be
responsible for the antidiarrhoeal activity .Flavonoids has
been ascribed to their ability to inhibit intestinal motility
and hydro-electrolytic secretion (DiCarlo et al., 1993). In
addition, flavonoids possess antioxidant properties, which
are presumed to be responsible for the inhibitory effects
exerted upon several enzymes including those involved
in the arachidonic acid metabolism.
The present study has shown that Verbena hastata
contains pharmacologically active substance(s) with
antidiarrhoea properties. Further study is to be carried out
to fractionate and purify the extract to fully investigate the
mechanisms responsible for the antidiarrhoeal activity
The authors are grateful to Mr. Sunday Dzama for his
technical assistance and Miss Ngozi Anyalewechi for her
Akuodor et al. 1627
Akah PA, Nwabie AI (1994). Evaluation of Nigerian medicinal plants
used for rheumatic inflammatory disorders. J. Ethnopharmacol.
Ammon PJ, Thomas PS (1974). Effects of oleic and recinoleic acids net
jejuna water and electrolyte movement. J. Clin. Invest. 53: 374-379.
Awouters F, Niemegeers CJE, Lenaerts FN, Janscen PA (1978). Delay
of castor oil diarrhoea in rats : a new way to evaluate inhibitors of
prostaglandin biosynthesis. J. Pharm. Pharmacol. 30: 41-45.
Beubler E, Juan H (1979). Effect of ricinoleic acid and other laxatives on
net water flux and prostaglandins E r elease exotoxin in transmucosal
water and electrolyte movement in canine jejunum. J. Pharm
Pharmacol . 31: 681-5.
Brown JH, T aylor P (1996). Muscarinic receptor agonists and
antagonist. In: Hardman JG, Limbird LE (Eds). Goodman and
Gilman’s the Pharmacological B asis of Therapeutics, 9th edition,
Macgrow Hill, New York.
Bruton (1985). L.L . Bruton, Agents affecting gastrointestinal water flux
and motility digestant: and bile acids. In: A.G. Gillman, T.W. Rail, A.S.
Nies and P. Taylor, Editors, Pharmacol. B asis of Therapeutics, 8th
ed, vol.2, McGraw, New York , p. 914.
Couper IM (1987). Opiod action on the intestine: the important the
intestinal mucosa. Life Sci. 41: 917-915.
DiCarlo G, Autore G, Izzo AA (1993). Inhibition of intestinal motility and
secretory by flavonoids in mic e and rats: structure activity
relationships. J. Pharm. Pharmacol. 45: 1054-1059
Galvez J, Zarzuelo A, Crespo ME (1991). Antidiarrhoeic activity of
Scleroarya birrea bark extract and its active tannin constituent in rats.
Phytother Res. 5: 276-278.
Galvez J, Zarzuelo A, Crespo ME, Lorente MD, Ocete MA, Jimenez J
(1993). Anti-diarrhoeal activity of Euphorbia hirta isolation of an
active flavonoidal constituent. Planta Med. 59: 33-36.
Longanga OA, Vercruysse A, Foriers A (2000). Contribution to the
ethnobotanical, phytochem.and pharmacol. studies of traditionally
used medicinal plant in the treatment of dysentery and diarroea in
Lomela area, Democratic Republic of Congo (DCR). J.
Ethnopharmacol. 71(3): 411-413.
Lork D (1983). A new approach to practical acute toxicity testing.
Archives of Toxicity 54: 275-287.
Mukherjee J, Das R, Balasubramania K, Saha M, Pal, Saha BP (1995).
Anti-diarrhoeal evaluation of Nelumbo nucifera rhizome extract,
Indian J. Pharmacol. 22: 262-264
National Research Council (1985). Guide for the care and use of
Laboratory Animals. NIH Publication no 85-23. The National
Academic press, Washington DC
Niemegeers CLE, Lenaerts FM, Janseen` PAJ (1974). Loperamide (R-
18553), a novel type of anti- diarrhoeal agent. Part 1: In vitro oral
pharmacology and acute toxicity.Comparison with morphine, codein,
diphenoxylate and dif enoxine. Arzeimittelforsc 24: 1633-1636.
Sanders KM (1984). Evidence that prostaglandins are local regulatory
agents in canine ilea circular muscles, AM. J. Physiology 246, PG
Synder JD, Merson MH (1982). The magnitude of the global problem of
acute diarrhea disease. A review of active surveillance data. Bull
WHO 60: 605-613.
Sofowora EA (1993). Med. plants and Traditional Med. in Afric a, 2nd ed.
Spectrum Books Ltd., Ibadan, Nigeria.
Theoderau V, Floramont J, H achet T, Bueno L (1991). Absorptive and
motor components of anti-diarrhoeal action of loperamide: an in vivo
study in pigs. Gut. 32: 1355-1359.
Treas GE, E vans MC (1989).Textbook of Pharmacognosy 13th ed.
Bailliere Tindal London. pp. 683-684
Tripathi KD (1994). Essentials of Med. Pharmacol. Jay pee Brothers
Watson WC, Gordon R (1962). Studies on the digestion absorption and
metabolism of castol oil. Biochem. Pharmacol. 11: 229-
World Health Organization, 1998 OECD. Principles on Good
Laboratory Practice (as revised 1997). Series on principles of Good
Laboratory Practic e and Compliance Monitoring No1 Organization for
Economic Cooperation and Development, Paris.