AQUEOUS FRACTION

Background: The blood pressure-lowering effect of aqueous leaves extract of Phyllanthus amarus has been reported in earlier work in normotensive albino rabbits. The effects of organic solvent fractions were evaluated in Wistar rats.
Methods: The aqueous fraction obtained from the crude extract of the leaves was evaluated for blood pressure-lowering effect in anaesthetized normotensive Wistar rats, at the graded doses of 2.5-40 mg/kg after which it was subjected to vacuum liquid chromatography (VLC) using combinations of chloroform, ethyl acetate, methanol and water. This yielded eleven fractions which were bulked into six samples (A-F) after thin layer chromatograph analysis, and samples A, B and C were evaluated for activities on the blood pressure of hypertensive Wistar rats at the graded doses of 5 to 20 mg/kg. Fraction “C” showed the highest blood pressure lowering effect and was further subjected to column chromatographic and VLC analysis, to obtain fraction (BVLC2) which was evaluated for possible blood
pressure lowering effect in hypertensive Wistar rats.

Results: The aqueous fraction caused a dose dependent decrease in the blood pressure of normotensive Wistar rats, decreasing the mean arterial blood pressure (MAP) from a basal level of 104.58 ± 8.29 mmHg to 45.22 ± 6.71 mmHg (p<0.0001; 66.4%) at the dose of 40 mg/kg. Fraction “C” caused significant decrease in the MAPfrom 116.99 ± 10.28 mmHg to 68.33 ± 6.78 mmHg (p < 0.001; 0.01%) at the dose of 20 mg/kg, while the fraction BVLC2 decreased the MAPfrom 146.11 ± 8.29 mmHg to 79.33 ± 6.18 mmHg (***p< 0.001) at the dose of 10 mg/kg, indicating a trend of increasing potency along the course of purification.

Conclusion: The aqueous fraction of the leaves of Phyllanthus amarus yielded column chromatographic sample (BVLC2), that might possibly serve as a lead sample from which pure active hypotensive constituent(s) could be isolated.

Waltheria indica is used in many medicinal preparations in ethnomedical practice in Nigeria. Its use in treating diarrhea has been scientifically validated and reported. The present work examined the probable intestinal relaxant effects of organic solvent fractions obtained from the methanol extract of the leaves. The methanol extract (90 g) was suspended in water and partitioned repeatedly with chloroform (200 mL x 5) in a separating funnel. The aqueous and the chloroform fractions were concentrated under pressure and separately evaluated for relaxant effects on 80µg Ach-induced ileum contractility at concentrations of 20, 40 and 80 mg. The aqueous fraction was further subjected to vacuum liquid chromatography (vlc) using dichloromethane with increasing concentrations of ethyl acetate and later methanol. Seven fractions obtained were tested for effects on Ach-induced ileum contractions at concentrations of 10, 20 and 40mg and compared with atropine 20 µg. Both the aqueous and dichloromethane fractions significantly (p<0.0.5) inhibited the contractile effect of Ach on the isolated ileum. However, the inhibitory effect of the aqueous fraction was more pronounced particularly at 80mg as the Cmax of Ach was reduced to 11.23 ± 1.00 % in contrast to 58.37 ± 3.16% produced by the chloroform fraction. The vlc fractions (fraction 2 and to some extent fraction 4) obtained from the aqueous fraction produced remarkable relaxant effects on the ileum particularly fraction 2 which at 20mg, completely abolished the contraction produced by the Ach, similar to the effect of Atropine (20 µg). The extract of W. indica especially the aqueous fraction contains bioactive constituents that can be separated and purified for improved relaxant effects on the intestine. The results further provide evidence for the ethno-medical use of the plant in treating diarrhea.