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.

Pufferfish: Canceling chemo pain

Experienced chefs know how to slice into the pufferfish to avoid the deadly tetrodotoxin, which disrupts the nervous system and can cause fatal paralysis of important muscles that control breathing and heart rate.

But the toxin of the spiky fish may also treat chronic pain, such as that related to chemotherapy. Researchers at the John Theurer Cancer Center have found that the toxin is 3,000 times more potent than the pain-killer morphine, without the crippling side-effects of addiction and nausea.

So they are testing the tetrodotoxin-based pain reliever in a small group of cancer patients to ensure its safety and effectiveness. They will have to compare its efficacy against that of existing drugs used to treat chemotherapy pain before the U.S. Food and Drug Administration will consider it for approval.

Shark: Making bacteria feel unwelcome

The skin of a shark might appear as smooth as rubber, but up close it's so rough that some cultures used the skin like sandpaper. Sharklet Technologies, however, is pioneering a new use for the fearsome fish's skin, which is constructed of sharp, interlaced ridges that together make an inhospitable environment for microbes.

The company is developing medical devices such as urinary catheters that mimic the texture of shark skin to ward off common infections from staphylococcus aureus, methicillin-resistant staphylococcus aureus (MRSA) and pseudomonas aeruginosa.

The catheters could help to reduce the tide of urinary tract infections that plague around a quarter of all patients who use the devices for a week or more.

King cobra: Taking the bite out of morphine

One bite of a King Cobra could kill a human, but that fatal venom could also hold the key to relieving chronic pain and pain during surgery.

Professor Manjunatha Kini of the National University of Singapore, who is developing the compound, says that it could be 20 to 200 times more potent than morphine. Like the pufferfish toxin, though, King Cobra poison lacks the addictive properties of that painkiller and others like it currently on the market.

Within a year, Kini hopes to test the drug in patients. In recent animal tests, mice receiving the agent were able to withstand almost twice the thermal pain of animals that did not take the compound.

See Part 2 here.