Vasodilator Effects of the Extract of the Leaves of Cistus populifolius on Rat Thoracic Aorta

✍ Scribed by B. Somoza; V. R. Sanchez de Rojas; T. Ortega; A. M. Villar

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 444 KB
• Volume: 10
• Category: Article
• ISSN: 0951-418X
• DOI: 10.1002/(sici)1099-1573(199606)10:4<304::aid-ptr848>3.0.co;2-b

✦ Synopsis

The effects of different extracts of Cktus populifolius L. on smooth muscle were studied. The aqueous extract inhibited in a dose dependent manner the noradrenaline (NA) (10-'-1.03 X M) and CaCI, (2 X 10-4-l.28 X lo-' M)-induced contractions in rat thoracic aorta. Furthermore, this extract induced relaxant effects in rat aorta precontracted with NA (lo-' M) and with K' (80 mM). Two different vasodilator responses were observed on NA-induced contractions: one an endothelium-dependent response abolished by methylene blue but not by indomethacin, and the other an endothelium-independent response unaffected by methylene blue and indomethacin similar to that obtained with a flavone, luteolin (lo-' M).

The search for active constituents included a bioactivity-directed fractionation of the lyophilized aqueous extract (LAE) using vascular reactivity experiments. Four different fractions (CI,CH,, Me,CO, MeOH, H20) were analysed at two different concentrations (1 and 2 mg (dry plant)/mL). The methanol fraction was the most active on NA precontracted vascular segments with endothelium, whereas the water fraction was the most active on segments without endothelium. These relaxant effects were less on K' (80 mM)-induced contractions. Due to these results we suggest that this plant contains interesting hydrophilic compounds with strong pharmacological action. The endothelium-independent relaxant effect is probably related to flavonoid constituents. However we cannot relate the endothelium-dependent relaxation to known natural compounds in Cistus species. The presence of these constituents with relaxing properties on smooth muscle could account for the use of Cistus plant in traditional medicine.