Hydroalcoholic extract of Pycnocycla spinosa is a relaxant of rat ileum (IC₅₀=40±7.3 µg/ml) and at dose of 1mg/kg inhibits diarrhoea in mice (Sadraei et al., 2003a). The hydroalcoholic extract of P. spinosa is composed of alkaloid, flavonoid and saponin components. Alkaloid fraction of P. spinosa contains the most active constituents (Sadraei et al., 2003b). Therefore, the aim of this research was to further separate fractions from alkaloid extract of P. spinosa and screen for their spasmolytic activity on rat isolated ileum.

Alkaloid fraction of P. spinosa was separated by fractional liberation technique (see Sadraei et al., 2003b). The concentrated alkaloid extract were spotted on coated Silicagel plates and chromatographed in saturated chamber containing CHCl₃:MeOH:NH₃ (10:4:1) solvent mixture for 1.5 hours. T hin layer chromatography resolved four fractions, identified by their Rf value as F1 (0-0.4), F2 (0.43-0.47), F3 (0.52-0.70) and F4 (0.80-0.85) respectively.

Male Wistar rats (200-250g), were killed by a blow on the head and their ileum were removed and secured in Tyrode’s solution in an organ bath at 37 °C and gassed with O₂. Isotonic contractions induced by KCl (80mM), were recorded before and after addition of the extracts. A full cumulative concentration-response curve was obtained for the alkaloid extract and the separated fractions. All experiments were conducted in parallel with time-matched controls adding an equivalent volume of vehicle. Ileum contractions were measured 10min after addition of the each concentration of the extracts and expressed as % inhibition of the initial response for each tissue. Mean ± s.e.mean values were calculated for each group of results and significance of differences between the means were calculated by two-tailed unpaired Student's t-test.

Alkaloid extract of P. spinosa in a concentration-dependent manner inhibited the ileum contraction induced by 80mM KCl with an IC₅₀ value of 11 ± 1.1 µg/ml (n=6). With 20 µg/ml bath concentration response to KCl was almost abolished. In a similar way F4 fraction inhibited the tonic contraction to KCl (IC₅₀=10 ± 0.8 µg/ml, n=6). The F1 fraction (IC₅₀=27 ± 6.5 µg/ml, n=6), F2 fraction (IC₅₀=32 ± 4 µg/ml, n=6) and F3 fraction (IC₅₀=34 ± 5 µg/ml, n=6) at relatively higher concentrations had inhibitory effect on ileum contractions.

From this study it can be concluded that all four fractions separated from alkaloid extract of P. spinosa contribute to the spasmolytic activity of this herbal plant. However, as F4 fraction seems to containing the most active ingredients, it is suggested that the chemical compounds in this fraction to be identified.

Sadraei , H. et al., (2003a). Phytother. Res., 17(6), 645-649.
Sadraei, H. et al., (2003b). J. Ethnopharmacol., 86, 187-190.