Not in factory trim and I don't know of any aftermarket like the S&A for Colt.
Most of the southpaws I know depress the magazine catch with their trigger finger.
Heck I wish that the mag release was on the opposite side. As far as I'm concerned it's already a left hander because you can use your index finger to depress the button without moving your hand to use the thumb which as a right hander I have to do.
I love the Walther P99 because it has a ambi release and I can use my right finger.
I was concerned about inadvertently releasing the mag while firing, as I would be wrapping around the button with my hand. Thanks for "unconcerning me"