Extraction,Isolation, and Identification of compound(s)responsible for anti-diarrhoeal activity of cassia Abbreviata-Oliv.

An aqueous decoction of the stem bark of the plant Cassia abbreviata-OHv., a native
Zambian plant, is traditionally used as an anti-diarrhoeal remedy by many contemporary
practitioners of traditional medicine in Zambia.The present work was undertaken based on the findings of preliminary investigations on Cassia abbreviata-Oliv. stem bark by Dr. S. Prakash.[13(i),13(ii)|
An ethanolic extract was prepared from the dried powdered stem bark of Cassia abbreviata-Oliv. by Soxhlet extraction and its anti-diarrhoeal activity was evaluated in-vitro on rabbitileum by the method of Perry et al [67]. The ethanolic extract was found to be a parasympathetic acetylcholine receptor, sympathetic ganglia and autonomic ganglia blocking agent as it antagonized the spasms induced by acetylcholine, histamine and nicotine, respectively. It was also found to have a direct inhibitory effect on the motility of the rabbit
ileum because it antagonized magnesium chloride and barium chloride induced spasms. The ethanolic extract was found to demonstrate potent anti-bacterial activity against Staphylococcus aureus, Shigella dysentrie, Proteus spp. and Bacillus spp. and its minimum inhibitory concentration (MIC) was also determined. The ethanolic extract was found to contain alkaloids, tannins and nitrogen. The ethanolic extract was separated on the basis of differences in polarity, pH, and solubility
of its components into 13 fractions and anti-diarrhoeal activities of each of these fractions were evaluated in-vitro.
The most potent anti-diarrhoea! fraction, extract 13, was found to be a neuromuscular and ganglion cell blocking agent as it antagonized the spasms induced by nicotine. It was also found to have a direct inhibitory effect on the motility of the rabbit ileum because it antagonized barium chloride induced spasms as well. However, it did not antagonize acetylcholine and histamine induced spasms. Extract 13 also exhibited potent anti-bacterial
activity, in-vitro, against Shigella dysentrie and Proteus spp. and its MIC was also determined. Extract 13 was subjected to bio-assay directed separation and purification by a combination
of analytical and preparative chromatographic techniques [73,74, 75,76]. At each stage of separation/purification the anti-diarrhoeal activity was monitored and only those fractions/eluates which demonstrated appreciable anti-diarrhoeal activity were chosen for further purification.Repetition of the process of chromatographic purification linked to evaluation of antidiarrhoeal
activity yielded a pure compound which was analysed by 500 MHz !H NMR spectrometry. The !H NMR data obtained was studied and chemical structure of the compound was proposed to be either 3-(3/-hydroxy-4' methoxphenyl)-2-propenoic acid or 3-
(4'-hydroxy-3'-methoxyphenyl)-2-propenoic acid.