PHARMACOLOGICAL RATIONALE FOR FOLKLORIC USES OF THE LEAVE EUPHORBIA HIRTA, LINN
PHARMACOLOGICAL RATIONALE FOR FOLKLORIC USES OF THE LEAVE EUPHORBIA HIRTA, LINN
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Date
1992-11
Authors
JOHNSON, PATRICIA BIANCA LENA
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Abstract
Water and ethanol extracts of the leaves of Euphorbia hirta were subjected to in vivo
and in vitro studies. Water extract (0.025 - 2.5 mg/ml), ethanol extract (0.25 - 1 mg/ml);
fraction 28 of ethanol extract (0.1 - 0.5 mg/ml) and adrenaline (2.5 - 250 ng/ml) produced
concentration - dependent relaxations of the rabbit jejunum. Ethanol extract also caused
concentration -related contractions of the same tissue. The relaxations produced by the
extracts and adrenaline were not affected by atropine (10 nM) but blocked by propranolol (1
/xM). The extracts and fraction 28 have shown bacteriostatic rather than bactericidal effect.
Low concentrations of water extract (10 - 100 μg/ml) and ethanol extract (0.05-5
mg/ml) had no observable aggregatory effect on human platelets. However, PAF (50 -
1OOOnM) and adrenaline (1-10 μg/ml) caused a concentration-related aggregation of human
platelets. Both extracts had no observable effects on aggregation induced by PAF and
adrenaline. Water extract (0.2 - 1 mg/ml) produced concentration-related aggregation of
human platelets maintained in plasma. Indomethacin (0.014 - 0.14 μM) produced a
concentration-related inhibition of water extract-induced platelet aggregation and this was also
reduced by nifedipine (0.23/μM) whilst WEB 2086 had no observable effect.
The water extract (0.05 - 5 mg/kg) and the ethanol extract (0.5 - lmg/kg) produced
dose-dependent decrease in the mean arterial blood pressure (MABP) of the cat. These
effects were partially blocked by atropine (5.0 and 10 μg/kg) and pirenzepine (5 mg/kg)
while propranolol (1 μM/kg) had no effect. Further investigation of the mechanism using
methroctramine (0.6 μM) caused a blockade of water (0.5 mg/ml), acetylcholine (1 μg/ml)
and choline (0.5 mg/ml) which had earlier produced maximum relaxation on the guinea pig
atrium.
The diuretic effects of the extracts were assessed using acetazolamide and frusemide
as standard drugs. Water extract (50 and 100 mg/kg) and ethanol extract (50 and 100
mg/kg) produced time-related and significant increase in urinary output. Electrolyte
excretion was also significant especially for bicarbonate ions (HCO3"). The water extract and
acetazolamide have similar spectrum of diuresis.
The acute toxicity test was carried out to determine the safety margin of the water and
ethanol extracts of Euphorbia hirta. The LD50 values were 1.13 ± 0.21 for water extract and
1.61 ± 0.24 g/kg for ethanol extract. These values fall within the slightly toxic range. The
mechanism of E.hirta induced-death supports the presence of compounds (eg. leukotrienes)
which cause respiratory distress.
These studies on E.hirta have provided data supporting the folkloric use of the plant
in the treatment of diarrhoea and possibly dysentery, and also as a diuretic remedy.
However, no pharmacological basis was found for the traditional use of the plant as an
anti-asthmatic agent. This was further supported by the acute toxicity test. Pharmacological
screening revealed the presence of a hypotensive principle(s).
Description
A THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL AHMADU
BELLO UNIVERSITY IN PARTIAL FULFILMENT OF THE
REQUIREMENT DEGREE OF MASTER SCIENCE IN
PHARMACOLOGY
Department of Pharmacology & Clinical Pharmacy
Faculty of Pharmaceutical Sciences
Ahmadu Bello University, Zaria.
NOVEMBER, 1992
Keywords
RATIONALE,, PHARMACOLOGICAL,, FOLKLORIC,, LEAVE EUPHORBIA HIRTA,, LINN