ABSTRACT
An acetylenic fatty acid: 9,12,15-octadecatrien-6-ynoic acid (dicranin) was extracted from Dicranum Scoparium and preincubated with platelets which were then stimulated by exogenous arachidonic acid (20:4 n-6). This molecule at 10(-4) M weakly inhibited the cyclooxygenase activity as assessed by measurement of 12-hydroxy-heptadecatrienoic acid (HHT) In contrast, the 12-hydroxy-eicosatetraenoic acid (12-HETE) synthesized by the 12-lipoxygenase was strongly increased by about 650%. The same effects were observed with 10(-5) M and with 10(-6) M of dicranin but to a lesser extent. Platelet hydroxylated dicranin metabolites were also found and the structure of the main compound determined by GC-MS was a 13-hydroxy derivative. Its origin has not yet been elucidated. Platelet aggregation induced by 1 microgram/ml of U46619, a structural PGH2 analogue was completely abolished in the presence of dicranin. Platelet aggregation induced either by thrombin or by arachidonic acid was inhibited by 10(-4) M of dicranin only after preincubation. This observation indicates that the formation of metabolites of dicranin are necessary to effect this inhibition. Dicranin is thus a new inhibitor of platelet aggregation and may prove to be useful for elucidating the effects of 12-HETE in biological systems.
Subject(s)
Arachidonic Acid/blood , Blood Platelets/metabolism , Cyclooxygenase Inhibitors/pharmacology , Linolenic Acids/pharmacology , Platelet Aggregation Inhibitors/pharmacology , 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid , Blood Platelets/drug effects , Fatty Acids, Unsaturated/biosynthesis , Humans , Hydroxyeicosatetraenoic Acids/biosynthesis , In Vitro Techniques , Lipoxygenase Inhibitors/pharmacologyABSTRACT
An acetylenic fatty acid: 9,12,15-octadecatrien-6-ynoic acid (dicranin), extracted from Dicranum Scoparium was preincubated with platelets stimulated by exogenous arachidonic acid (20:4 n-6). Dicranin (10(-4) M) weakly inhibited the cyclooxygenase activity as assessed by measurement of 12-hydroxy-heptadecatrienoic acid (HHT) In contrast, the 12-hydroxy-eicosatetraenoic acid (12-HETE) synthesized by the 12-lipoxygenase was strongly increased by about 650%. The same effects were observed with 10(-6) M of dicranin but to a lesser extent. The main platelet hydroxylated dicranin metabolite determined by GC-MS was a 13-hydroxy derivative Platelet aggregation induced either by thrombin or by arachidonic acid or by U46619, an structural PGH2 analogue was inhibited by 10(-4) M of dicranin.
Subject(s)
Arachidonic Acid/blood , Blood Platelets/metabolism , Cyclooxygenase Inhibitors/pharmacology , Linolenic Acids/pharmacology , Platelet Aggregation Inhibitors/pharmacology , Platelet Aggregation/drug effects , 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid , Blood Platelets/drug effects , Fatty Acids, Unsaturated/biosynthesis , Humans , Hydroxyeicosatetraenoic Acids/biosynthesis , In Vitro Techniques , Lipoxygenase Inhibitors/pharmacologyABSTRACT
The polyphenol composition of some traditional herbal remedies is reviewed. Polyphenols probably act in such remedies by virtue of their astringent action and current views on the molecular basis of this property are outlined and discussed.
Subject(s)
Flavonoids , Phenols/metabolism , Plants, Medicinal , Polymers/metabolism , Chemical Phenomena , Chemistry , Cyclodextrins/metabolism , Humans , Polyphenols , Protein BindingABSTRACT
Using vesicles from the plasma membrane of hog thyroid, we have characterized its Na+-dependent I- transport system. We have found it to be totally Na+ dependent; K+ cannot substitute and Li+ can partially substitute for Na+; the Na+:I- flux ratio is larger than one; the system is electrogenic, being stimulated by a delta psi negative inside the vesicles. A number of large, lipophilic anions are fully-competitive inhibitors of Na+-dependent I- uptake; the closer their atomic radii are to that of iodine, the smaller their Ki values.
Subject(s)
Cell Membrane/metabolism , Iodine/metabolism , Sodium/metabolism , Thyroid Gland/metabolism , Animals , Anions/metabolism , Biological Transport/drug effects , Cations/metabolism , Kinetics , Swine , Valinomycin/pharmacologySubject(s)
Anthocyanins/analysis , Edible Grain/analysis , Flavonoids/analysis , Proanthocyanidins , PolymersABSTRACT
Cortex Betulae contains (+)-catechin-7-beta-D-xylopyranoside. Except for its occurrence in elm bark, this biologically active substance is so far unknown as a natural product.
