Many toxic compounds are produced by animals, apparently as chemical protection against predators.
Frogs, especially those that live in the tropics, emit alkaloids, many of which are lethal to mammals in very small amounts.
For example,bufoteninand buphotoxinhave been isolated from toadbufomarinus. Both of these compounds increase the contractile strength of weak heart muscles, and the latter has been reported to cause terrible hallucinations. The dry skin of these animals has been used in zombie powders, leading to the suggestion (unproven) that these and perhaps other compounds present in toad skin are responsible for inducing a translike state associated with zombies.
A related alkaloid, homobatrachotoxin, has been isolated from birds of the genus Pitohui that are endemic to the New Guinea subregion. The same compound (along with batracotoxin) is found in Colombian poison-dart frogs of the genus Phyllobates. Only 2 micrograms of these alkaloids would kill a rat of 1 kg (proportionally less to normal-sized mice). It is possible that frogs and birds synthesize these alkaloids by modification of the closely related substances derived from eating plants.
We have observed several natural products, a large fraction of which appear to be structurally quite complex. For example, carbohydrates such as glucose and nucleic acid bases contain many heteroatom-based functional groups, and, in the former case, also have multiple stereocenters.
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