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In Their Quest For Cures, Medical Researchers Take Cues From Mother Nature

Scientists are looking at nature’s myriad molecules -- studying substances like tree bark and fungi -- in hopes of coming up with cures for cancer and other maladies.

Yew tree bark contains an anti-tumor agent
Yew tree bark contains an anti-tumor agent
Cédric Duval

Always a source of scientific inspiration, Mother Nature is now playing a key role in combinatorial chemistry, explained researchers involved in last week's "Chemistry and Health: from molecules to medicines' conference, hosted by France's Université Paris-Sud. An important line of study in the pharmaceutical industry, combinatorial chemistry involves rapid synthesis or the computer simulation of a large number of different but structurally related molecules or materials.

Two decades ago, combinatorial chemistry caught the imagination of researchers. "Back then, we thought that we could rapidly create a library of several thousand molecules, but that idea was too simplistic so it did not work," says Fanny Roussin of France's National Center for Scientific Research (CNRS). "What we must do is combine several approaches including the study of natural substances, which has already proved its worth."

A study published earlier this year in The Journal of Natural Products confirms that natural molecules, also called "bio-sourced" molecules, have made a phenomenal contribution to human health. From 1981 to 2006, about 50% of new molecules have been extracted from plants, fungus and microorganisms. For instance, almost 60% of anti-tumor agents are extracted from nature. Perhaps the best example is Taxotere, a blockbuster drug marketed worldwide by Sanofi-Aventis. Taxotere is in fact an analogue of taxol which is an extract from the bark of yew trees.

"Studying natural substances makes us discover complex and original molecules that we haven't thought of before," says Roussi. Her research took her to Malaysia, a country that has rich endemic biodiversity. Several plant extracts have already been taken there. The screening of those plant extracts has led to the identification of a new compound called Meiogynine A, isolated from the bark of Meiogyne cylindrocarpa, and capable of restoring apoptosis. This process of programmed cell death that may occur in multi-cellular organisms is inhibited in more than 50% of cancers, resulting in the uncontrolled growth of tumors. Meiogynine A acts on some anti-apoptotic proteins and might have the ability to restart the process of programmed cell death. Bio-sourced molecules are also interesting because of their unique active modes.

For instance, the discovery of a fungal toxin called Brefeldin A (BFA) foresees new ways to inhibit G proteins. "In many diseases including cancer, the role of these proteins has been recognized for a long time, but inhibiting them causes potentially dangerous side-effects because G proteins communicate signals from many hormones and neurotransmitters," says Mahel Zeghouf, a CNRS researcher at the Laboratory of Structural Enzymology and Biochemistry.

Even if researchers are interested in natural molecules, it is still very difficult to put them to use medically. Most of the time, they cannot be found everywhere, and the quantity of active agents that can be extracted from them is too small. The natural places where they grow are also fragile. For instance, the Meiogyne cylindrocarpa forest in Malaysia was destroyed to make room for oil palm plantations. Synthesis can be helpful in that case because it allows researchers to produce larger, exploitable quantities. "The problem is that it is difficult to synthesize these molecules (or analogues) quickly and at a reasonable price," says Laurent Schio, a medical manager in medicinal chemistry and oncology at Sanofi.

One solution is hemisynthesis. A relatively simple natural molecule biologically close to the active principle, which can be found quite easily, has to be identified. Then, "missing parts' are introduced by chemical means. Meiogynine A and analogues were created like this, because other more traditional methods had failed," says Roussi.

Read the original article in French.

Photo – Neosnaps

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Society

In Northern Kenya, Where Climate Change Is Measured In Starving Children

The worst drought in 40 years, which has deepened from the effects of climate change, is hitting the young the hardest around the Horn of Africa. A close-up look at the victims, and attempts to save lives and limit lasting effects on an already fragile region in Kenya.

Photo of five mothers holding their malnourished children

At feeding time, nurses and aides encourage mothers to socialize their children and stimulate them to eat.

Georgina Gustin

KAKUMA — The words "Stabilization Ward" are painted in uneven black letters above the entrance, but everyone in this massive refugee camp in Kakuma, Kenya, calls it ya maziwa: The place of milk.

Rescue workers and doctors, mothers and fathers, have carried hundreds of starving children through the doors of this one-room hospital wing, which is sometimes so crowded that babies and toddlers have to share beds. A pediatric unit is only a few steps away, but malnourished children don’t go there. They need special care, and even that doesn’t always save them.

In an office of the International Rescue Committee nearby, Vincent Opinya sits behind a desk with figures on dry-erase boards and a map of the camp on the walls around him. “We’ve lost 45 children this year due to malnutrition,” he says, juggling emergencies, phone calls, and texts. “We’re seeing a significant increase in malnutrition cases as a result of the drought — the worst we’ve faced in 40 years.”

From January to June, the ward experienced an 800 percent rise in admissions of children under 5 who needed treatment for malnourishment — a surge that aid groups blame mostly on a climate change-fueled drought that has turned the region into a parched barren.

Opinya, the nutrition manager for the IRC here, has had to rattle off these statistics many times, but the reality of the numbers is starting to crack his professional armor. “It’s a very sad situation,” he says, wearily. And he believes it will only get worse. A third year of drought is likely on the way.

More children may die. But millions will survive malnutrition and hunger only to live through a compromised future, researchers say. The longer-term health effects of this drought — weakened immune systems, developmental problems — will persist for a generation or more, with consequences that will cascade into communities and societies for decades.

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