Fabio Trento

Antithrombin activity of an algal polysaccharide.

In an effort to reduce the risks of a possible iatrogenic transmission of bovine spongiform encephalitis (BSE) through the use of bovine-derived medicinal products, we patented in the USA in 1999 a polysaccharide from brown algae, endowed with interesting pharmacological activities: (a) concentration-dependent inhibition of thromboplastin or cephalin-kaolin-induced thrombin generation from platelets, (b) concentration-dependent inhibition of thrombin-induced platelet aggregation, (c) thrombin has hypotensive effect, which was blunted and zeroed by our fucansulfate in a dose-dependent way, (d) when aortae are stimulated with thrombin, they become stickier for polymorphonucleated leukocytes (PMNs); our fucansulfate decreased concentration-dependently, PMNs sticking to autologous rabbit aortae, (e) dose-dependent inhibition of thrombin-induced thrombosis. All the above data suggest that our fucansulfate could be a heparin substitute endowed with antithrombotic and anti-inflammatory activities, devoid or the problems caused to heparin by its animal origin, i.e., possible prion protein contamination.

Chronic Oral Defibrotide Counteracts Hypercholesterolemia Noxious Effects on Cardiovascular Function in the Rabbit

The aim of the present work was to assess if the cardioprotective drug defibrotide could counteract the hypercholesterolemia noxious effects on cardiovascular function. Aortas and hearts from normal- or cholesterol-fed rabbits, treated or not with chronic oral defibrotide (100 mg/kg/day) for 45 days, were used in in vitro tests throughout the experiment. Hypercholesterolemia worsened: aorta stickiness toward polymorphonuclear leukocytes, aorta relaxation to acetylcholine, heart left ventricular end-diastolic pressure and coronary perfusion pressure, heart left ventricular diastolic pressure, acetylcholine and endothelin-1 activity on coronary perfusion pressure, and heart generation of 6-Keto-prostaglandin F1alpha. Oral defibrotide counteracted and/or obliterated the above hypercholesterolemia noxious effects. Particularly, oral defibrotide counteracted the parameters associated with early endothelial cell disfunction: that is, increased adherence of leukocytes to endothelium and endothelial vasorelaxation induced by acetylcholine, which acts through the release of endothelium-derived relaxing factor. These activities of defibrotide are probably exerted through the increased generation of prostacyclin. The fact that acetylcholine induced vasorelaxation is partially protected by oral defibrotide points to a partial rescue of endothelial ability to generate endothelium-derived relaxing factor, as acethylcoline acts through the release of endothelium-derived relaxing factor, by defibrotide itself. Defibrotides endothelial protection could, in turn, explains why defibrotide protected cardiovascular function. This is not surprising as, in a few cases, endothelial dysfunction, observed in hypercholesterolemia, was found to be prevented or reversed, pharmacologically, by PN-2001-10, a calcium channel blocker, dipyridamole, and lovastatin.

Defibrotide Normalizes Cardiovascular Function Hampered by Established Atherosclerosis in the Rabbit

In a previous paper we gave evidence that chronic oral defibrotide antagonizes the noxious effect of developing atherosclerosis in the cardiovascular system. In the present paper we give evidence that defibrotide is still capable of exerting beneficial effects on cardiovascular function once atherosclerosis is established. In fact, there was statistically significant amelioration by defibrotide infusion in the following, all of which were hampered by established atherosclerosis: in rabbit aorta relaxation to acetylcholine, prostaglandin E2, and 6-keto-prostaglandin F1alpha generation from rabbit aortas, rabbit heart left ventricular end-diastolic pressure, coronary perfusion pressure, and left ventricular developed pressure, vasopressor activity of acetylcholine and endothelin-1 on coronary perfusion pressure, and 6-keto-prostaglandin F1alpha generation from the rabbit heart. Since prostacyclin takes part in NO generation, is cellular protective, and inhibits 5-lipoxygenase product synthesis, its increase, caused by defibrotide, could explain defibrotide cardioprotective activity. Prostacyclin activity could be backed by prostaglandin E2, another cardioprotective prostaglandin.

Pharmacodynamics of the anticoagulant activity (APTT) of an algal polysaccharide

Recently, in a previous paper [1], we have described the antithrombin and antithrombotic activity of a novel fucansulfate extracted from brown algae and patented in the USA in 1999 [2]. The reason why such a fucansulfate was developed and patented is because it is free of the problems (such as bovine spongiform encephalitis, BSE) that antithrombotic and anticoagulant polysaccharides of animal origin might have [1]. In the present paper, we give the evidence that our novel fucansulfate, when given by subcutaneous route, has a better absorption than calcium heparin, as far as activated partial thromboplastin time (APTT) is concerned.