For centuries Chinese medicine has seen restorative properties in an Asian fungus that invades and destroys insects. Now a drug drawing on that age-old lore is poised to become an important new treatment for multiple sclerosis.

A Food and Drug Administration panel unanimously recommended this month that the drug called fingolimod be approved as the first oral medicine for MS, an often-debilitating disease in which the body's own immune system attacks a fatty substance protecting nerve fibers. The drug, assuming it gets final FDA approval, would significantly expand the treatment options for the hundreds of thousands of Americans with MS.

Nature was the first source of medicines to treat human disease and remains an important one. The Japanese scientists who discovered fingolimod added their names to a list that goes back to the European chemists who derived aspirin from a substance in willow bark and Alexander Fleming, who found that a fungus produced a bacteria-killing substance called penicillin.

Fingolimod comes from an idea hatched a quarter-century ago by Tetsuro Fujita, a Kyoto University pharmacology professor who had investigated bitter plants used in traditional Asian medicine. A wonder drug at the time was cyclosporin, which helps tamp down the immune system in transplant patients to reduce the risk of organ rejection. The chemical cyclosporin is derived from a fungus, first isolated from soil samples, that uses the substance to attack other fungi.

Dr. Fujita says he reasoned that an even more powerful immunosuppressant chemical ought to be present in a group of Asian fungi known in Chinese and Japanese as "winter-insect-summer-plants." These fungi attack insects in the winter with their chemical arsenal. By summertime, the insect is dead and its corpse has been transformed into a vessel for the blooming fungus. Ironically, the same properties that make the chemical deadly in the insect world may also have a helpful side for people suffering from certain autoimmune diseases, in which an overactive immune-system response causes the body to attack its own cells.