| abstract |
A compound of formula (I): <CHEM> or where appropriate a pharmaceutically acceptable salt thereof, wherein R<1> and R<2> each independently represent a moiety of formula (a): -(CH<2>)m-A (a) wherein m represents zero or an integer 1, 2 or 3, A represents a substituted or unsubstituted cyclic hydrocarbon radical; and R<3> represents hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl or a moiety of formula (a) as defined above; a pharmaceutical composition comprising such a compound a process for preparing such a compound and the use of said compound and said composition in medicine. |