Venom from the skin of certain arrow – poison tree frogs of tropical America has long been used by natives to anoint dart tips (As we can see in the movie Apocalypto)
The most powerful known frog venom is Batrachotoxin from the kokoi frog of Columbia which can kill a person.
Structure of batrachotoxin
Batrachotoxin is nothing but a steroid-alkaloid which does not exist in nature. It is found only in three frogs and two birds all over the world.
Interestingly, an average P. Terribilis, a tiny frog of size about 1.5 inches contains adequate toxin to kill over a 10000 mice-perhaps enough to kill 10 to 20 humans.
P. Terribilis
There is no evidence that the P. Terribilis was poisonous when evolved. The scientists believe that its diet must contain poisonous insects by which they became poisonous.