The invention provides compounds of formula I: (I) wherein A, B, W, Y, Z, R1, R3 and R4 have any of the meanings defined in the specification and their salts as well as additional compounds and their salts. The invention also provides pharmaceutical compositions comprising a compound of the invention, processes for preparing compounds of the invention, intermediates useful for preparing compounds of the invention, and therapeutic methods for treating cancer, a bacterial infection or a fungal infection using compounds of the invention.
