Is there any problem using brass screws to fit zinc hinges?
If it gets wet at all, you will run into problems with galvanic corrosion that will eat away at the hinges.  Your best bet is to use materials of similar anodic index (near the bottom of this page on galvanic corrosion).  If you absolutely must pair brass and zinc, either ensure that the connection between the two will never get wet (using grease or some sort of coating) or that the two metals never actually come into contact with one another (using, say, a nonmetallic washer).