METHODS: Different parts of the plants were subjected to sequential extraction method. Cytotoxicity of the extracts was determined by dimethylthiazol-2-yl)- 2,5diphenyl tetrazolium bromide (MTT) assay on 2 human cancer (colon and breast) and normal (endothelial and colon fibroblast) cells. Anti-angiogenic potential was tested using ex vivo rat aortic ring assay. DPPH (1,1-diphenyl-2-picrylhydrazyl) assay was conducted to screen the antioxidant capabilities of the extracts. Finally, total phenolic and flavonoid contents were estimated in the extracts using colorimetric assays.

RESULTS: The results indicated that out of 6 plants tested, 4 plants (Nicotiana glauca, Tephrosia apollinea, Combretum hartmannianum and Tamarix nilotica) exhibited remarkable anti-angiogenic activity by inhibiting the sprouting of microvessels more than 60%. However, the most potent antiangiogenic effect was recorded by ethanol extract of T. apollinea (94.62%). In addition, the plants exhibited significant antiproliferative effects against human breast (MCF-7) and colon (HCT 116) cancer cells while being non-cytotoxic to the tested normal cells. The IC50 values determined for C. hartmannianum, N. gluaca and T. apollinea against MCF-7 cells were 8.48, 10.78 and 29.36 μg/ml, respectively. Whereas, the IC50 values estimated for N. gluaca, T. apollinea and C. hartmannianum against HCT 116 cells were 5.4, 20.2 and 27.2 μg/ml, respectively. These results were more or less equal to the standard reference drugs, tamoxifen (IC50 = 6.67 μg/ml) and 5-fluorouracil (IC50 = 3.9 μg/ml) tested against MCF-7 and HCT 116, respectively. Extracts of C. hartmannianum bark and N. glauca leaves demonstrated potent antioxidant effect with IC50s range from 9.4-22.4 and 13.4-30 μg/ml, respectively. Extracts of N. glauca leaves and T apollinea aerial parts demonstrated high amount of flavonoids range from 57.6-88.1 and 10.7-78 mg quercetin equivalent/g, respectively.

AIM OF THE STUDY: This study aimed to elucidate the possible mechanism(s) of antidiarrhoeal activity of methanol leaf extract of Combretum hypopilinum (MECH) in mice.

MATERIALS AND METHODS: Phytochemical screening and acute toxicity study were conducted according to standard methods. Adult mice were orally (p.o) administered distilled water (10 ml/kg), MECH (1000 mg/kg) and loperamide (5 mg/kg). The probable mechanisms of antidiarrhoeal activity of MECH were investigated following pretreatment with naloxone (2 mg/kg, subcutaneously), prazosin (1 mg/kg, s.c), yohimbine (2 mg/kg, intraperitoneally), propranolol (1 mg/kg, i.p), pilocarpine (1 mg/kg, s.c) and isosorbide dinitrate (150 mg/kg, p.o) 30 min before administration of MECH (1000 mg/kg). The mice were then subjected to castor oil-induced intestinal motility test.