Nature, it turns out, is one big medicine cabinet. We can thank the willow plant for the salicin that turned into aspirin, and the poppy for the pain-killing powers of morphine. Even poison can become potions — a viper’s venom, for instance, is part of a powerful anti-clotting drug that can keep blood flowing instead of clumping up.

Increasingly, such toxins are proving to be attractive sources of potentially life-saving drugs. About half of existing medications emerge from the flora and fauna that surround us, which hints that potentially thousands of additional drugs are yet to be discovered, albeit protected by the vicious bite of a poisonous snake or the harmful blood-sucking of a tick.

From cancer treatment to painkillers, here are the agents that may be hazardous materials today but could evolve into powerful medications tomorrow.

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