What was the name of cartoon that used to air on Teletoon took place in Africa and main female character turned into a gazelle every night as result spell?

The cartoon you're thinking of is called "The Wild Thornberrys".

The main female character, Eliza Thornberry, could talk to animals thanks to a magical amulet. However, her little sister, Debbie, was cursed to transform into a gazelle every night, which led to many hilarious adventures.