There is provided a compound comprising a steroidal ring system and a group R.sup.1 selected from any one of a sulphamate group, a phosphonate group, a thiophosphonate group, a sulphonate group or a sulphonamide group; wherein the D ring of the steroidal ring system is substituted by a group R.sup.2 of the formula --L-R.sup.3, wherein L is an optional linker group and R.sup.3 is an aromatic hydrocarbyl group.