I found info. about Mango & Pumpkin . . . but not a thing about Papaya. I find that odd, since Papayas are known to contain enzyme that help in the digestion o f meat, & cats LOVE meat!
A lot of enzyme supplements are made with papaya enzymes (it's called papain. And bromelain is from pineapples). But I don't think you could get a cat to eat fresh papaya!
And some cats do need help, if they have a digestive disorder. But normal cats shouldn't need digestive enzyme supplements.