Abstract:
Purpose: An attempt was made to quantify comparative astringent powers among selected
substances taking tannic acid as the reference standard. The measurements were to be based
on composite astringent power of all contributing compounds present in extracts. Among the
folklore antimicrobial measures, consumption of black tea and black coffee in diarrheal
conditions are well established. Their effectiveness was to be determined through
demonstration of reduction in bacterial colony counts. Method: Astringent power of selected
materials were determined using standard egg albumin solution by titrating with different
astringent preparations. End points were determined when protein precipitation was
completed using UV absorption measurements and biuret test. To evaluate anti-microbial
activity of black tea and black coffee infusions, experiments on growth inhibition by a
reduction of colony forming units were carried out. Results: The strongest astringent activity
was found with Terminalia chebula (aralu) extract and the weakest with coriander extract.
Black tea and black coffee infusions showed a high percentage of inhibitory activity against
both Escherichia coli and Salmonella typhi in a range 70.83%±3.6 to 87.50%±0.00.
Conclusion: Using astringent power of substances, the Composite Astringent Index was
established. It was clear that consumption of black tea and black coffee infusions during
diarrheal states can achieve significant anti-diarrheal effects. Materials with greater
astringency showed greater anti-diarrheal effects. Materials with minimum end point values
for the protein precipitation assay yielded the lowest astringent power values
