BERKELEY — Annually, Isao Kubo leaves his tiny, crowded laboratory in the basement of Wellman Hall at UC Berkeley and flies to Africa or South America to chat with witch doctors.
Those chats lead Kubo on collection trips up tall trees, through murky waters and into the soil, all for the sake of humankind. Then they lead him back to Berkeley, hauling shrubs, roots, leaves, fruits and oils used in underdeveloped countries to cure ills ranging from headaches to cholera.
At home, the 47-year-old chemist and five assistants employ a jumble of what Kubo calls "very expensive toys" in a lab so jammed with furniture and equipment that you have to turn sideways to get past some of it. The place looks like Frankenstein's laboratory with a little Houston Mission Control thrown in. Seven more assistants work in a less-crowded room across campus.
After sequences of distilling, gurgling, calculating and checking of digital readouts, Kubo finally knows--chemically speaking--exactly what he's brought home. Having broken the folk remedies into their chemical components, the professor goes after the active chemicals, the ones that make the remedies work.
No Takers So Far
Then he synthesizes those active chemicals and, presto, the witch doctors' jungle wisdom has been re-created in a Berkeley laboratory.
When he believes he has successfully synthesized a usable medication, Kubo tries to persuade a pharmaceutical company to manufacture and distribute the drug.
So far, no company has been convinced. But, Kubo said, for five years a major drug company has been testing a potential remedy for cholera. Kubo developed the remedy from maesanin, a chemical he extracted from East African shrubs after watching entire tribes line up to drink tea made from the bush in an effort to ward off cholera. "It takes an average of 10 years for a pharmaceutical company to do the tests," Kubo explained.
Although he has not yet been able to market them, Kubo cited numerous African remedies that may have medical application the world over. He speaks of a headache and memory aid drug taken from the bark of an African tree, a drug from a South American tree used for treating kidney problems and a compound from the bark of a tree in the Amazon that healers prescribe for a disease caused by flukes, a parasitic worm.
The chemist said several companies are considering selling compounds he derived from African plants that "significantly increase the antibiotic effects of certain commercial drugs."
Kubo pointed out that new antibiotics are always needed because organisms become immune to existing medicines. The professor hopes to find some of those needed antibiotics in nature.
Medicine men are psychiatrists as well as internists, so Kubo can't use every treatment they prescribe. "Many times information I get from the witch doctors seems to indicate just psychological effect. I cannot prove any chemical effect," he said.
There is nothing new about deriving drugs from natural sources. Kubo observed that quinine can be made from the bark of the cinchona tree in Asia and Africa, synthetic codeine chemically duplicates the codeine found in opium poppies, ipecac can be made from the root of a Central American plant. And, he adds, 18th-Century English heart patients were apparently the first to be treated with medicine made from the leaves of the foxglove plant, the active ingredient of which is digitalis.
Pesticides the Natural Way
When Kubo is not working on medicine to keep people alive, he is working on pesticides to kill bugs. He has discovered natural pesticides by watching Africans dump certain shrubs into ponds to rid the water of pests, and by noting that locusts in Kenya strip the landscape of vegetation except for a kind of grass that contains a natural insecticide.
Unlike many artificial pesticides, which linger for decades, pesticides developed from nature are biodegradable. Also, Kubo said, most commercial pesticides work by attacking the nervous system, and the poison doesn't care whether that system belongs to a bug or a person. Most natural pesticides are harmless to humans, Kubo added, because natural pesticides tend to interfere with an "insect specific" process, such as the way an insect reproduces, matures or finds food.
For example, Kubo has found that anacardic acid in the root bark of the African msimbwi tree can prevent cricket reproduction. Experiments are under way to see if the acid also will stop reproduction in cockroaches, which are close relatives of crickets. Those experiments began after the professor noticed Africans dumping the fruit of the cashew tree into ponds to kill mosquito larvae and aquatic snails. He later found that the active ingredient in cashew fruit and msimbwi tree root bark was the same.
In East Africa, the chemist found that a mixture of two chemicals from the podocarpus tree (found in many locations, including California) promotes growth in young rice plants but inhibits the growth of lettuce, which is related to many weeds.