| abstract |
Tricyclic compounds of formula (I) <IMAGE> (I) wherein X1 is a carboxyl or 5-tetrazolyl group X2 is carbonyl or methylene X3 is hydroxyl or a group -X4(CnH2n)X5 where X4 is oxygen or sulphur X5 is hydrogen or a group -OX6 where X6 is hydrogen, alkanoyl of 1 to 4 carbon atoms or a group -(CmH2m)X7 where X7 is hydrogen or a group -OX8 where X8 is hydrogen or alkanoyl of 1 to 4 carbon atoms and m and n are each, independently, an integer from 1 to 4, together with salts thereof, provided that when X5 is a group -OX6 then n is always greater than 1 and X4 and X5 are attached to different carbon atoms and that when X7 is a group -OX8 then m is always greater than 1 and no single carbon atom in the radical -(CmH2m)- is attached to two oxygen atoms. These compounds are of value in medicine in circumstances where it is desirable to provide a more effective delivery of oxygen to the tissues; in vivo applications include the relief or amelioration of tissue hypoxia as in, for example, cardiac or cerebral ischaemia while in vitro they maintain the oxygen-delivery capacity of stored red blood cells and prolong the cells' useful storage life. The invention is also directed to methods for the preparation of the compounds, to pharmaceutical formulations and other presentation forms containing them and the preparation thereof, to the use of the compound in medicine, and to novel intermediates for the said compounds and the preparation thereof. |