Issue Date: May 25, 2009
A LITTLE MORE THAN a year ago, Ilya Raskin, a biochemist and plant biologist at Rutgers University, and Christine Malanga Wilson, a retired Merck & Co. researcher, met in a generic sports bar in a nondescript hotel off the New Jersey Turnpike. They had gathered for some ad hoc knowledge transfer. Raskin was hoping to revive an antimalarial-plant-screening project that Wilson worked on during World War II. Wilson, then 93, spelled out with amazing detail the research environment 60 years earlier.
When the Indonesian island Java fell to Japan in 1942, the U.S. lost access to Cinchona trees, its only source of quinine. With more Allied troops in the South Pacific succumbing to malaria than to enemy fire, government agencies, drug companies, and academic researchers alike scrambled to find new drugs to treat the infection.
As part of that effort, Merck spent millions of dollars to search through hundreds of plant extracts for new treatments. Over the course of seven years, Merck chemists and medical technicians tested more than 600 plants from around the globe for activity against the disease. "We felt very patriotic," Wilson recalls. "Everybody was contributing to the war effort."
Dozens of promising leads were discovered, but after the war, money dried up and the project died out. "Quinine worked so well, there wasn't really any great need for new antimalarials," Raskin explains.
Today, the tenacious Plasmodium falciparum parasite that causes malaria is resistant to quinine and its derivatives. And although combination therapies containing artemisinins, which are extracted from the leaves of the sweet wormwood plant, have become the gold standard of care, their price puts them out of reach for the poor countries most affected by the disease. As a result, upward of a million people die from malaria each year, according to the Swiss public-private partnership Medicines for Malaria Venture (MMV).
Wilson had long thought her wartime research efforts could be of help. She reached out to Raskin after reading an article in the New Jersey Star-Ledger about his natural products research at Rutgers. She explained her role at Merck and offered to give him a copy of a paper detailing the company's results, which had appeared in 1947 in Lloydia, the predecessor to the Journal of Natural Products.
Raskin was intrigued, in particular because the Merck researchers had tested the plant extracts directly in animals, providing a good read on their potential activity in humans. Digging further into the data, scientists in his group discovered that hardly any of the plants had been studied since the war ended.
Thus began an unlikely friendship that both scientists hope will yield new drugs against malaria. Working with partners at the University of Cape Town, in South Africa, and North Carolina State University and armed with funding from MMV, Raskin is reviving the research. The group is systematically retesting the most promising plants for activity and identifying the active compounds. It will eventually use those as the backbone for a medicinal chemistry campaign that could produce cheaper and more effective antimalarials.
As the project has progressed, Raskin has brought his partners and other researchers to meet Wilson. Everyone marvels at Wilson's amazing mind: While most people barely remember what they had for lunch yesterday, she can tick off the names of people she worked with a half-century ago as if they were still close friends.
"I guess that isn't normal. I don't know many 90-year-olds to compare with," Wilson says. But she thinks that the gravity of the project helped keep it fresh in her mind. "Because it was so important to me, I think it stuck," she adds.
Raskin and Wilson have developed something of a routine for these meetings. They meet at the sports bar, in Monroe, N.J., because it's a short drive from Wilson's home. (And if anyone was wondering, Wilson drives herself to the bar.) She arrives, looking a good 20 years younger than her age and dressed in a smart linen blazer and slacks. Then Wilson happily relays her story to whoever has come to listen, even if she finds the attention a bit baffling.
As Wilson tells it, the malaria research began as a modest project in a building called Cottage 3, part of a three-house cluster located near Merck's Rahway, N.J., campus. The two-story private home was converted into a malaria research headquarters, with labs and microscopes on the top floor and research animals below.
The program quickly blossomed into a multi-million-dollar undertaking, Wilson says, involving more than 20 people. The scientists were given more space in a warehouse, where they were careful to create a succession of sealed-off rooms to contain the mosquitoes they were working with. She had "heard through the grapevine" that infected mosquitoes had escaped another company's labs in Colorado, and none of the Merck scientists were interested in unleashing that scourge on muggy New Jersey.
Merck enlisted Boris A. Krukoff, who was a consultant for the New York Botanical Garden, to coordinate a worldwide effort to track down plants. One reason Raskin was keen to revive the project was the "biorational" approach Krukoff took. "They used plants where there was some traditional knowledge associated," Raskin notes. Most commonly, the plants came from tropical locations where they had been used to treat "fevers," a generic term that often meant malaria.
A MODERN CHEMIST accustomed to robotics and advanced chromatography would surely find Merck's testing process daunting. Every step was done by hand, with each plant first handled by chemists, who would extract compounds from the bulb, leaves, or root. Extracts were then sent to Wilson's labs for testing. It was long before in vitro testing requirements existed, and compounds went directly from the plant into an animal.
Wilson would infect seven-day-old chicks and five- or six-day-old ducklings with parasitic cells. The inoculation wasn't pretty: She had to inject the parasite directly into the birds' fragile jugulars. Then, the birds were given either a daily injection or solution of the drug candidate. After five days, technicians would take a blood sample from a bird, stain it, and look for parasites. If no parasitized cells were found after combing through the 10,000 cells on the slide, they knew they had a hit.
A hit would then lead botanists to seek out and test plants related to that species. In all, Krukoff's files suggest nearly 1,000 plants were tested, with more than 600 making it into the Lloydia article that Wilson helped write.
Raskin and his partners at Cape Town and NC State are picking up where Merck left off. In the first stage of the program, Rocky Graziose, an industrious first-year plant biology graduate student at Rutgers, compared the compounds reported in the Lloydia article with subsequent plants studied in connection with malaria. He was able to narrow the list to 60 promising plants by eliminating those that had since shown toxicity or were otherwise ineffective. With the help of Lena Struwe, an ethnobotany expert at Rutgers, Graziose is now confirming the plants' identities. In many cases, the names have changed and, unfortunately, the archives at the botanical garden don't contain vouchers with samples of the source material.
"With such a huge biodiversity that we work with, we will have to use bits and pieces of information, use local experts, and use taxonomic experts from several groups to find the correct name for each plant," Struwe notes.
So far, Graziose has collected samples of 20 out of the 60 promising plants and has developed a process for making extracts. From those extracts, the scientists have identified 10 active species that merit further investigation. Rutgers and NC State will split the work of conducting activity-guided fractionation of those species. Once the pure compounds have been isolated, NC State will be tasked with performing structure characterization of each molecule.
If early studies suggest an active compound is worth pursuing, medicinal chemists at Cape Town will design around its scaffold to improve potency, lengthen half-life, and minimize side effects.
Along every step of the process, the Rutgers scientists keep Wilson up to speed. Graziose sends her reports, and she is officially a consultant on grant applications. "We have an awesome responsibility to really do justice," Raskin says, to the work that Wilson and her colleagues did so long ago.
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