PHARMACOLOGICAL ASSESSMENT OF ANTISPASMODIC, ANTIOXIDANT AND FREE RADIADL SCAVENGING ACTIVITIES OF EXTRACTS, SOLUBLE FRACTIONS AND ISOLATED CONSTITUENTS FROM ALSTONIA CONGENSIS ENGL. (APOCYNACEAE) ROOT BARK

Cimanga K. R.*, Kikweta M. C., Tshodi E. M., Tona L. G., Tuenter E., Vlietinck A. J. and Pieters L.

ABSTRACT

The present study was initiated for the assessment of antispasmodic on acethylcholine and depolarization solution rich in KCl induced contractions on isolated guinea-pig ileum and antioxidant and free radical scavenging activities activities and a large game of reactive oxygen species (ROS) respectively of extracts, soluble fractions and isolated compounds from Alstonia congenesis root bark. In antispasmodic test, results revealed that aqueous and 80% methanol extracts produced inhibition of contractions induced by acetylcholine and depolarization solution rich in KCl on isolated guinea-pig ileum more than 80% as good activity while soluble fractions produced the same effect in producing 66.85±0.05 to 78.85±0.04% and 64.52±0.02 to 76.56±0.04% inhibition of contractions induced by the same agonist acethylcholine and depolarization solution rich in KCl on isolated organ respectively as moderate and good activity according the case. Isolated compounds boonein, echitamine, 6,7 secoangustilobine and β-amyrine inhibited contractions induced by acethylcholine on isolated organ with percentages from 70.54±0.02 to 82.65±0.00% as good actvity, and against depolarisation rich in KCl with percentages ranged from 68.75±0.04 to 80.48±0.06% as moderate and good activity according the case. In antioxidant testing, results revealed that aqueous and 80% methanol extracts inhibited the activities of all selected reactive oxygen species such, 1-diphenyl-2-picryl-hydrazyl (DPPH), 2,2’-azino-bis (3-ethylbenzthiazoline-6-sulphonate (ABTS), superoxide anions (O2●- ), hydroxyl ( HO.) and hydrogen peroxide (H2O2) (ROS) with inhibitory concentration 50 (IC50) < 10 μg/ml as pronounced, excepted aqueous extract bending hydrogen peroxide activity with a IC50 value of 11.07±0.04 μg/ml as good activities. Chloroform, ethylacetate, n-butanol and residual aqueous soluble fractions inhibited also ROS activities with IC50 values ranging from 7.05±0.04 to 15.32±0.04 μg/ml while total phenolic compounds reacted in the same manner by producing IC50 values < 10 μg/ml against all selected ROS as pronounced activity and can be considered as responsible for the observed antioxidant activity. These results showed that all tested samples possessed antispasmodic and antioxidant activities expressed at different magnitudes and can be used in treating of diarrhea and gestion of degenerative diseases such as cardiovascular diseases.

Keywords: Alstonia congensis, Apocynaceae, root bark, extracts, fractions, isolated constituents, polyphenols, flavonoids, antispasmodic and antioxidant activities.