ABSTRACT
Essential oils from aerial parts of Piper aduncum (Matico) and Piper obliquum (Anis del Oriente) of ecuadorian origin were analyzed by GC-FID, GC-MS, (13)C NMR and their biological and pharmacological activities were assessed. Chemical composition proved to be unusually different from previous reports for safrole-rich P. obliquum (45.8%), while P. aduncum main constituent was dillapiol (45.9%). No genotoxic activity was found in the Ames/Salmonella typhimurium (TA98 and TA100) assay, either with or without S9 activation. Mutagen-protective properties, evaluated using sodium azide, 2-nitrofluorene and 2-aminoanthracene as mutagens/promutagens, was observed against promutagen 2-aminoanthracene, likely in consequence of microsomial deactivation. Antimicrobial assays have been performed on Gram+/Gram- bacteria, dermatophyte and phytopathogenic fungi and best results were provided by P. aduncum against fungal strains with complete inhibition at 500µg/ml. Preliminary analgesic and antithrombotic activities evidenced the absence of the former in hot plate and edema assays and a limited antiplatelet action against three different agonists (ADP, AA and U46619). Both oils have a very limited antioxidant capacity.
ABSTRACT
Ocotea quixos essential oil was shown to possess significant inhibitory activity of platelet aggregation and clot retraction in rodent plasma. This study is aimed at fully characterizing the antiplatelet activity of the whole essential oil and its main components trans-cinnamaldehyde and methyl cinnamate also in human plasma, at investigating the mechanism underlying such activity and at evaluating the potential antithrombotic activity of subacute treatment of mice with Ocotea essential oil. In vitro Ocotea essential oil and trans-cinnamaldehyde inhibited arachidonic acid-, U46619-, ADP-, phorbol12-myristate13-alcetate-, collagen-induced platelet aggregation and thrombin-induced clot retraction in human and rodent plasma; Ocotea oil and trans-cinnamaldehyde competitively antagonized contractions induced by thromboxane A2 receptor agonist U46619 in rat isolated aortic ring (K(B) = 18 and 3.2 microg ml(-1), respectively). In vivo Ocotea oil, orally administered in a subacute treatment (30-100 mg kg(-1) day(-1) for 5 days) to mice, prevented acute thrombosis induced by collagen-epinephrine intravenous injection. This antithrombotic activity was not accompanied by pro-haemorragic side effect, as detected by the inactivity in bleeding test, thus showing a favourable safety profile compared to the conventional antiplatelet agent, acetylsalicylic acid. Present findings indicate that Ocotea essential oil possesses potent and safe antithrombotic activity attributable to its antiplatelet and vasorelaxant effects. The main constituent trans-cinnamaldehyde seems to be the primary responsible for this activity through a putative mechanism involving the inhibition of thromboxane A2 receptors.