strange behaviors

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Looking for the next Viagra (Save the Planet–5)

Posted by Richard Conniff on February 10, 2012

In Durban's Berea Herbal Market

One standard shortcut, for instance, is to look for remedies from traditional medicine.  That’s how researchers found metformin, and the drugs derived from the rosy periwinkle, among many others.  Even so, I didn’t expect much, as an outsider and a product of the technological world, when I visited one such traditional medicine market not long ago in downtown Durban, South Africa.  To be honest, I was imagining a single dusty shop with an aging witch doctor gathering cobwebs behind the counter.  Instead, I found myself wandering through a vast sprawl of vendors’ booths, extending down rows the length of a football field.  Plump women in kerchiefs, some of them with their faces painted clay-colored against sunburn, sat behind bin after bin of woody and leafy products, all labeled with Zulu names that meant nothing to me.

But my guide, a traditional medicine practitioner named Jabu Ndholovu, once showed up at the University of KwaZulu-Natal with a bag of woody chips from the roots of a flowering grassland plant said to cure male impotence.  The plant’s scientific name is Eriosema kraussianum, but the Zulu name has more poetry:  bangalala University chemists duly extracted 50 compounds from the plant and put four of them through the standard laboratory test, using rabbit penile tissue.   One turned out to be 85 percent as effective as Viagra.  And unlike Viagra, bangalala is a product local people can afford.  Biodiversity might thus, in fact, be a means of having better sex.  For that matter, Viagra itself is a naturally-derived product, a close chemical variant on a substance, theophylline, originally found in tea.  So the future of life on earth and the possibility of sex tonight might, in truth, be closely related propositions.

Researchers who seek clues in traditional medicine markets like the one in Durban mostly run into dead ends.  That’s the nature of such research.  But they persist because local knowledge accumulated over hundreds of years now and then tips the odds in favor of finding something useful.   The hitch is that the only people paying attention these days are underfunded government and academic researchers.

Most big pharmaceutical companies don’t bother much with drug discoveries from the natural world any more.  Instead, beginning in the 1980s, they bought into the myth of humans as a technological super-species.  So they now rely mostly on computers and combinatorial chemistry to spin out thousands of closely-related variants on a given molecule.   The idea is that they can then browse through this library of synthetic compounds to find substances effective for almost any condition.  But so far, critics say, this has turned out to be roughly as effective as working your way through the Manhattan phone directory asking strangers if they happen to have a cure for the common cold.  After 25 years of work, and tens of billions of dollars invested, says David Newman, D. Phil., of the National Cancer Institute (NCI), combinatorial chemistry has so far produced only a single new FDA-approved drug.

Natural pharmacy

Newman,who heads the NCI’s natural products branch, isn’t suggesting that drug companies should give up on the technology.  But a better way to make it work, he argues, is by starting with compounds known to be biologically active—that is, the ones found in the natural world.  Then you use combinatorial chemistry to add or subtract traits until you arrive at a drug that meets human needs.   “As a discovery tool, combinatorial chemistry is terrible,” he says, but as “an optimization tool it is magnificent.”   We just need to acknowledge at the outset that the basic playbook still comes from Mother Nature.

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