I keep hearing about how the rainforests yield so many sources for different medicines, especially cancer. I see provocative statements like these from various sources:
* http://www.physics.org/featuredetail.asp?id=50
And with an estimated 70% of existing cancer drugs derived from rainforest plants, we clearly have much to gain from studying these pristine forests.
*
Just what is the story with the rain forests and medicinal preparations? Do they produce the basis for lots of solid drugs? Are many of the plants used as a basis for cancer drugs in particular?
I think that the issue with rainforests is that they just have so much biodiversity.
More species means you have just that much more chance of finding a species that produces some useful substance.
Also, biologically synthesized molecules have more chance of being medically useful than some random molecule you might synthesize in a lab, because the former have (generally) been evolved to have some useful biological property (useful to the organism that synthesizes it, in the first place, but possibly useful to us too). Unusual molecules synthesized by organisms quite often turn out to have some sort of antibiotic properties, because they are produced as a defense against infection or parasites. Whether they will be useful in humans is another matter, of course. Some of them, for instance, might be more toxic to us than they are to anything likely to infect us, which will not be much use. All the same, a natural antibiotic molecule (or a minor modification of one) that has been evolved under natural selection pressure, is still more likely to turn out to be medically useful than something randomly synthesized.
True, but the sentence you quote, in its context, was talking about antibiotics. Antibiotics are, essentially, poisons, and the medically useful ones are those that are a lot more toxic to things that infect humans than they are to humans themselves. (Pretty much all of them, I believe, are somewhat toxic to humans.)
Not much use as antibiotics. however at least one anti-cancer drug is a failed antibiotic. Antibiotics kill dividing cells, and it was found to kill dividing human cells really well, much better than bacterial cells.
So it was scrapped as an antibiotic, and instead used as an anti-cancer drug for fast growing tumours, where an ability to rapidly dividing human cells is a good thing.
Seventy percent for rainforest plants alone seems a bit high to me. I’d like to see a specific cite. However, a large percentage of anticancer drugs are derived from natural products (that is, compounds originally coming from plants, animals, or microbes). From here:
The reason why tropical forests (and also coral reefs) may be very productive sources of new drugs is because of the highly complex biological interactions that are found in these extremely diverse communities. Many species produce toxins or other biologically active compounds in order to defend themselves against herbivores, predators, competitors, parasites, and diseases. Such compounds are less necessary in temperate and polar communities where there is a smaller array of enemies (although they are found there as well).
If a compound is biologically active against one organism, it often has biological activity against others as well. A toxin a plant uses to defend against caterpillars may affect a specific metabolic pathway, and turn out to be useful in inhibiting the same pathway in cancer cells as well.
Interesting topic-I am a bit skeptical of these claims. In fact, a pharmaceutical firm (Shaman Pharmaceuticals) was set up to develop and market these rain forest 'wonder drugs".
The company went bankrupt-most of the native remedies were eoither not effective, not good enough, or impossible to synthesize.
This is not to say that there are not useful plant compounds out there…its just that searching them all takes time.
What claims, exactly? I’ve already provided a cite for the importance of natural products, some of which are from rainforest organisms, in drug development. This is an area of considerable interest in the pharmaceutical issue; I and some of my colleagues have been involved in several such bioprospecting programs. Pharmaceutical companies wouldn’t be interested unless they were convinced there were possible leads for new drugs there.
I know some of the people who were involved in this enterprise. One of Shaman Pharmaceuticals’ problems was that they were not just trying to develop drugs from rainforest plants, but to discover leads based on indigenous knowledge. That presents a problem in providing on appropriate compensation for intellectual property rights.
Of course, and only a tiny number of the compounds isolated ever advance to become marketable drugs. But that’s true throughout biomedical research.
Well Shaman blew through 18 million $, without discovering a single successful drug.
I’d also wager that temperate plants have given us just as many useful drugs and chemicals-there is nothing special about the rainforest ecology that produces useful drugs.
A trivial amount compared to the usual cost to develop a new drug. From Wiki:
ralph, I am interested to learn of your newfound expertise in this subject.
How much are you wagering? As I have already pointed out, there are special factors in rainforest ecology that make them a particularly favorable place to look for new drug.
Well, digitalis is a drug that was discovered in a temperate-zone plant (foxglove).
There is nothing that says that mutations in temperate zone plants are not as valuable(as in tropical plants).
As for Shaman Pharmaceuticals-they had actual plants identified (by native medicine men) as being effective treatments. When tested (in the USA) most of them turned out to be either useless, or not as good as (available therapies).
I expect that the experience of Shaman would make most investors wary of claims about rainforest-derived drugs.
I would be.
So what? No one is saying that temperate zone plants don’t produce any useful compounds. Anyway, I see you digitalis and raise you quinine, vincristine, vinblastine, physostigmine, and curare, all drugs that come from tropical plants.
All this shows is that you evidently don’t understand my points above. (And “mutations” per se don’t have much to do with it.) There are, first of all, many many more species of plants in rainforests than there are in temperate areas; and second, features of rainforest ecology make them more likely to contain novel bioactive compounds,
Again, so what? This is true of a very high percentage of all drugs, from all sources.
What you “expect,” though, is not based on any actual information. One current program alone, the International Cooperative Biodiversity Groups, includes collaborations with various tropical research groups by Bristol-Myers-Squib, Wyeth Pharmaceuticals, and Esai Pharmaceuticals, as well as Dow Agrosciences.
I guess you must know more about it than Bristol-Myers-Squibb.
