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Vasorelaxant activity of cyclic peptide, cyclosquamosin B, from Annona squamosa
Hiroshi Morita1, Toru Iizuka, Chee-Yan Choo
1Faculty of Pharmaceutical Sciences, Hoshi University, Shinagawa-ku, Tokyo, Japan. moritah@hoshi.ac.jp
Abstract:
A cyclic octapeptide, cyclosquamosin B (2), isolated from the seeds of Annona squamosa showed a vasorelaxant effect on rat aorta. It showed a slow relaxation activity against norepinephrine (NE)-induced contractions of rat aorta with/without endothelium. It showed inhibition effect on vasocontraction of depolarized aorta with high concentration potassium, but moderately inhibition effect on NE-induced contraction in the presence of nicardipine. These results showed that the vasorelaxant effect by 2 might be attributed mainly to inhibition of calcium influx from extracellular space through voltage-dependent calcium channels.
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