title: Relaxing activity of two linear diterpenes from Cystoseira brachycarpa var. balearica on the contractions of intestinal preparations.
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 microM 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 x 10(-6) M) and haemoglobin (3 x 10(-6) M). Tetraethylammonium (TEA), furosemide, N omega-nitro-L-arginine methyl ester (L-NAME), indomethacin, alpha-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 beta 2-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.
authors.affiliation: Dipartimento di Scienze dell'Ambiente e del Territorio, Università degli Studi di Pisa, Italy.
authors.forename: F D
authors.initials: FD
authors.lastname: Pietà
authors.forename: M C
authors.initials: MC
authors.lastname: Breschi
authors.forename: R
authors.initials: R
authors.lastname: Scatizzi
authors.forename: F
authors.initials: F
authors.lastname: Cinelli
mesh_terms: D000818:Animals; D004224:Diterpenes / Q000494:pharmacology*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007422:Intestines / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects
chemical_list: D004224:Diterpenes; C027930:eleganolone; C081083:elegandiol