Relaxing Activity of Two Linear Diterpenes fromCystoseira brachycarpavar.balearicaon the Contractions of Intestinal Preparations

Publisher Website
Google Scholar
Abstract
Eleganolone (1) and elegandiol (2), two linear diterpenes isolated from Cystoseira brachycarpa var. balearica, were tested on guinea-pig intestinal preparations. Both these compounds inhibited the contractile activities of acetylcholine (Ach) and histamine (Hist) on ileum musculature; the relative pIC50 values of eleganolone were found to be 4.60 ± 0.03 and 4.84 ± 0.20, respectively, while those of elegandiol were 4.71 ± 0.18 and 5.18 ± 0.01, respectively. Furthermore, 1 and 2 dose-dependently relaxed the same preparations precontracted with 300 µM BaCl2(pIC50 = 4.34 ± 0.18 for 1 and pIC50 = 4.34 + 0.02 for 2) or with 60 mM KCl (pIC50 = 4.73 ± 0.18 and 4.47 ± 0.06, respectively). On colon smooth muscle, the diterpenes inhibited the spontaneous contractile tone and this effect was reversed by both methylene blue (3 × 10-6M) and haemoglobin (3 × 10-6M). Tetraethylammonium (TEA), furosemide, N ω-nitro L-arginine methyl ester (L-NAME), indomethacin, α-chymotrypsin, and metoprolol were unable to block the eleganolone and elegandiol relaxing action on colonic musculature, but rather potentiated this response. On the contrary, the β2-blocker butoxamine partially inhibited the diterpenes activity. These results suggest that Cystoseira diterpenes act at a second messenger cyclase system rather than at a receptor level.

This publication has 0 references indexed in Scilit: