| abstract |
There are provided compounds of formula I, <IMAGE> I wherein R1, R2, R3, R4, R5 and R7 may be the same or different, and are hydrogen, hydroxy, alkoxy, alkoxy substituted by phenyl, acyl, amino, acylamino, alkenyl, halogen, or alkyl, provided that at least one of R1, R2, R3 and R7 are other than hydrogen and hydroxy, OR AN ADJACENT PAIR OF R1, R2, R3 and R7 represent a chain -COCH=CH-O-, X is a hydrocarbon chain containing from 2 to 10 carbon atoms and optionally substituted by a hydroxy group, and E is a carboxy group or a tetrazole group, AND PHARMACEUTICALLY ACCEPTABLE DERIVATIVES THEREOF. |