In-vivo and In-vitro Mechanistic Study in The Antidiarrheal Activity of Hydro-alcoholic Extract of Ocimum lamiifolium HOCHST. EX BENTH Leaves.
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Date
2023
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Addis Ababa University
Abstract
Ocimum lamiifolium is used in the management of various diseases such as fever, malaria,
headache, cough, and gastrointestinal disease (diarrhea). This study was undertaken to evaluate
the in-vivo and in-vitro mechanistic studies in the antidiarrheal activity of hydro-alcoholic
extracts of the leaves of O. lamiifolium. The anti-diarrheal activity was assessed using a castor-
oil-induced diarrhea model, charcoal meal test, and entero-pooling test in mice. The standard
drug loperamide 3 mg/kg was given to the positive control. Different doses of the hydro-
alcoholic extract of O. lamiifolium (100, 200, and 400 mg/kg were given to the test groups, and
distilled water (10 ml/kg) was given to negative controls. The ex-vivo spasmolytic activity was
evaluated using organ bath perfusion in isolated guinea pig ileum. The mechanistic study was
also explored using a castor-oil-induced diarrheal model in the presence of naloxone (opioid
antagonist). In the mechanistic study, the test group received 400 mg/kg extract with naloxone 2
mg/kg, the positive control received loperamide 3 mg/kg with naloxone 2 mg/kg, and the negative
control received distilled water 10 ml/kg with naloxone 2mg/kg. In the castor oil-induced
diarrhea model, all the tested ingredients significantly prolonged the onset of diarrhea and
reduced the number of defecation (p<0.05). However, the mean weight of wet and total feces was
significantly reduced by only the higher doses (200 and 400 mg/kg) (p<0.05). All doses also
produced a significant (p<0.01) reduction in mean weight and mean volume of intestinal
contents in the entero-pooling study. Similarly, in the charcoal meal test, all the study doses of
the substance also produced significant (p<0.001) antimotility effects. In the mechanistic studies,
the percentage inhibition of diarrhea by 400 mg/kg of the extract in the presence of naloxone (2
mg/kg) is 64.69%. In this case, charcoal meal traverse is significantly reduced by the extract
compared to the control p<0.001. However, in the presence of naloxone (2mg/kg), the
percentage inhibition by loperamide 3mg/kg is 6.89%. In the ex-vivo studies, the percentage of
response or relaxation produced by the extract was 20%, 65%, and 75% at the doses of 0.1, 0.2,
and 0.4 ml respectively. The doses that produced 50% maximal relaxation (EC50) by the extract
were 0.18 ml or 1.8 mg of hydro-alcoholic extracts of O. lamiifolium. In conclusion, this study
revealed that the hydro-alcoholic leaf extract of O. lamiifolium exhibits considerable anti-
diarrheal activity because of its inhibitory effect on gastrointestinal motility and secretion. This
is partly mediated through blockage of muscarinic acetylcholine receptors but not opioid
receptors.
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Keywords
O. lamiifolium, castor-oil-induced antidiarrheal activity, antimotility, anti-entero- pooling, spasmolytic activities, 80% methanol extraction.