Nanoparticulate formulation of nitrosothiols aimed at improving nitric oxide bioavailability. Toxicological and pharmacological evaluation – NanoSNO

Formulation of RSNO was optimized by using nano-, micro-particles and in situ implants, all of them being based on biocompatible polymers, in order to present the best sustained profile of NO species release and payload (ratio of RSNO mass/polymers mass). Biocompatible and biodegradable polymers presently used were selected because of their approval by health authorities in other formulations. Numerous methodologies devoted to RSNO synthesis and formulation, physico-chemistry and bioanalysis of RSNO, and metabolic, toxicological and pharmacological evaluation of free and formulated RSNO were developed and validated by our lab or in relationship with partners : Pr R Schneider (Nancy) and Pr A Lamprecht (Besançon) and contractors de Duve Institute (Bruxelles) and Société ETAP (Nancy).

An original NO donor (it presents in its structure two chemical groups delivering NO) was synthesized by using a commercially available drug, i.e. bucillamine, as the starting material. Its high vasodilatation efficiency was demonstrated in comparison with S-nitrosoglutathione (GSNO), the main endogenous RSNO. Moreover, the proof-of-concept that a sustained release of NO species from in situ forming implants could significantly decrease blood pressure and inhibit platelet aggregation within five days in rats, was obtained. At last, the benefits of formulated GSNO vs. its free form were observed in a rat stroke model. These studies represent the first reported ones on RSNO formulations adapted to a sustained release and tested in physiological and pathophysiological (stroke) conditions.

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Ten publications (reviews, original contributions on methodologies and research data) in international scientific journals with peer review, numerous invited conferences, oral communications and posters in national and international symposia were useful for the diffusion toward the different communities to which belong the researchers implied in the NanoSNO project, of the “know-how” gained in various fields related to investigation of RSNO. The normalized methodologies developed in synthesis and (bio)analysis were easily transferred to other research laboratories.

The discovery of nitric oxide (°NO), awarded a Nobel Prize, has opened a wide field of investigation on this radical, its physiology and its role in therapy, particularly in the treatment of cardiovascular diseases. However, the °NO donors currently available have limited therapeutic uses despite their strong therapeutic potential. Indeed, the limits correspond to an early release of °NO, with low distribution and without targeting the induction of oxidative stress and the development of tolerance. Therefore, new °NO donors are developed, especially nitrosothiols which can liberate °NO over long periods without inducing oxidative stress or tolerance, with many possible beneficial effects on cardio-and cerebro-vascular diseases. However, these molecules are easily degraded under environmental conditions and require a formulation suitable to protect them. This project focuses on the formulation of nanoparticulate nitrosothiols (different sizes of nanoparticles will be investigated: 50 to 500 nm) to limit their biotransformation and facilitate their dissemination toward the vascular tissue. The choice of thiol carriers of °NO radical and polymers used for encapsulation will rely on a toxicological evaluation. Their pharmacological evaluation will use ex vivo models (relaxation of the aorta, cerebral ischemia, ...). This project will be managed between complementary skills primarily in the pharmaceutical field.