title: Inhibitory effect by new monocyclic 4-alkyliden-beta-lactam compounds on human platelet activation.
abstract: In the present study some new beta-lactam compounds were screened for their ability to inhibit human platelet activation. In particular four compounds differing in the group on the nitrogen atom of the azetidinone ring were investigated. A beta-lactam having an ethyl 2-carboxyethanoate N-bound group was demonstrated to inhibit, in the micromolar range, both the Ca(2+) release from endoplasmic reticulum, induced either by thrombin or by the ATPase inhibitor thapsigargin, and the Ca(2+) entry in platelets driven by emptying the endoplasmic reticulum. The compound also inhibited the platelet aggregation induced by a variety of physiological agonists including ADP, collagen, thrombin and thrombin mimetic peptide TRAP. The beta-lactam reduced the phosphorylation of pleckstrin (apparent MW 47 kDa), elicited by thrombin but not by the protein kinase C activator phorbol ester. Accordingly it did not significantly affect the aggregation evoked by phorbol ester or Ca(2+) ionophore. It was concluded that the beta-lactam likely exerts its anti-platelet-activating action by hampering the agonist induced cellular Ca(2+) movements. The beta-lactam concentration, which significantly inhibited platelet activation, only negligibly affected the cellular viability. Even if it is still premature to draw definitive conclusions, the present results suggest that this new compound might constitute a tool of potential clinical interest and the starting-point for the synthesis of new more beneficial anti-thrombotic compounds.
authors.affiliation: Department of Biological Chemistry, University of Padova, Italy.
authors.forename: Martina
authors.initials: M
authors.lastname: Pavanetto
authors.forename: Alessandro
authors.initials: A
authors.lastname: Zarpellon
authors.forename: Daria
authors.initials: D
authors.lastname: Giacomini
authors.forename: Paola
authors.initials: P
authors.lastname: Galletti
authors.forename: Arianna
authors.initials: A
authors.lastname: Quintavalla
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Cainelli
authors.forename: Alessandra
authors.initials: A
authors.lastname: Folda
authors.forename: Guido
authors.initials: G
authors.lastname: Scutari
authors.forename: Renzo
authors.initials: R
authors.lastname: Deana
mesh_terms: D001792:Blood Platelets / Q000378:metabolism*; D001798:Blood Proteins / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002273:Carcinogens / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008997:Monobactams / Q000494:pharmacology*; D010703:Phorbol Esters / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D015539:Platelet Activation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D019284:Thapsigargin / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology; D047090:beta-Lactams / Q000494:pharmacology*
chemical_list: D001798:Blood Proteins; D002273:Carcinogens; D004791:Enzyme Inhibitors; D008997:Monobactams; D010703:Phorbol Esters; D010750:Phosphoproteins; D010975:Platelet Aggregation Inhibitors; D047090:beta-Lactams; C039077:platelet protein P47; D019284:Thapsigargin; D013917:Thrombin; D002118:Calcium