Field of Science

Praise the warts please

The most important biodiversity we will destroy will be that which we will never know about. One of the telling signs of this trend is the decline in frogs round the world. Croaks and warts apart, frogs and toads are some of the most important animals not only in the ecological chain, but also as the source of potent drugs for human beings. In order to save ourselves by clearing away more forests and making space, we are actually sealing our fate forever. This is not apparent or obvious, but then, most of the important things in life never are, or become so when it's too late. The problem is that when we are dealing with such complex systems, they are very prone to what in technical fields is called 'normal error', error introduced simply by our inability to grasp the fine points of a complicated system, error introduced because of the inherent complexity of the system. We may think frogs are yet another species jumping around, but it's becoming apparent- and only after we have done irreversible damage- that they form a crucial link, a hub between different parts of the entire biosphere, whose importance tragically would manifest itself only after it has been destroyed, and by then it would have been characteristically too late.

The colourful little cute red frog above is also one of the most poisonous species on the planet- nature alluring, but red in tooth and claw. It produces a poison, a grain of which smaller than one of salt can kill a human being. South American natives coated their arow-tips with this poison from the Arrow-poison frog to deadly effect. But it was another cousin of this frog, shown to the right, that led to the discovery of Epibatidine, an alkaloid that turned out to be a potent non-addictive analgesic, whose derivatives would replace addictive drugs like morphine and lead to better painkillers. The alkaloid was extracted from the frog's skin after making painfully difficult efforts to breed it in captivity. Literally hundreds of alkaloids with diverse pharmacological actions have been isolated from just the skin of amphibians in the last thirty years. This is just one among countless examples. Sponges from the ocean, for instance, have been the source of some of the most important anti-cancer drug candidates discovered in the last twenty years. According to a recent report in Nature, around half of the drugs currently in use have originated from nature. The importance of preserving natural sources for new life-saving agents can hardly be overemphasized.
Yesterday, I was reading the reminiscences of Jerrold Meinwald, the pioneering organic chemist at Cornell University, who turned his chemical talents towards uncovering the extraordinary chemical diversity in nature, thus becoming one of the pathfinders of the science of chemical ecology. Among Meinwald's string of papers, one of the latest ones deals with the extraction of novel compounds (sulfated nucleosides) from the dreaded funnel-web spider shown below, one of the most poisonous species of spiders on the planet.

These compounds promise new leads for stroke and other neurological disorders. This is again, just one example. How much remains to be discovered? Meinwald says,

"What might one anticipate to be the future of natural products chemistry and chemical ecology in this post-genomic, post-9/11 age? Is there anything left to discover? The answer to this question is certainly a resounding "yes". To begin with a small example, there are roughly 40,000 described species of spider, all capable of paralyzing their prey, but less than 1% of their venoms have been subjected to careful analysis. Surely there are great opportunities here for the discovery of novel neuropharmacological agents. There are about a million described insect species, and a conservative estimate of three million species of insect on earth all together. We can estimate, then, that 99.9% remain as potential targets for chemical study. Among soil bacteria, something like 99% are presently unculturable. Nevertheless, these organisms are known to be genetically extremely diverse, and it appears highly likely that a knowledge of their secondary metabolites would be not only chemically fascinating but also of great value to medicine and agriculture. It is certain that the study of extremophiles will greatly broaden our understanding of what kinds of chemistry can support life. We can conclude that most of nature remains to be explored at the molecular level."

It is mind-blowingly wonderful to imagine then, given the wealth of new and useful drug leads that we have already isolated from so small a section of the biodiversity of our planet, what potentialities lie for us in the future. But then, wonder turns to woe when we realise how much of this biodiversity we are destroying on a per day basis- the loss of species that one day would have supplied us with life saving drugs, with the cure for AIDS perhaps, is heartbreakingly incomprehensible. Most of them will silently die away, and already have, and left behind will be human beings, for whom the bell ominously tolls...Is this the true face of capitalism? The destruction of the future of our race for petty, short term gains in the present and 'near' future?

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  1. Almost makes me appreciate natural products, wait, nevermind. ;)

  2. Well, you better stick to buckyballs and nanotubes...there's too many natural product/synthetic/med chem guys and girls around, but not enough "material girls" :D

  3. nice post Ashutosh.

    Interesting you start your post off with frogs. A friend of mine (who is a grad student in conservation/ecology/forestry, who studied frogs (and other amphibia) before getting on to his present research. He studied them in the silent valley (in the Western Ghats in India). That region alone has well over 150 species of amphibia (a conservative estimate).

    And most of us don't even know how rich in biodiversity most regions are.

  4. thanks! it's amazing how many species were in that single region...really painful how many are being destroyed.


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