Green buckwheat, however, must be processed within 24 hours after harvesting, because it loses its rutin rapidly when cut. It cannot be dried in the field as hay without nearly complete destruction of the rutin. Even Moderately fast drying results in considerable loss of the active constituent. A process for flash drying has been worked out in which, under certain specified conditions of temperature and air flow, the leaves and blossoms may be desiccated in 45 minutes with a minimum loss of rutin. In this process the stems are not dried but are separated from the leaves and blossoms and discarded.

The dried material maybe utilized as a source of rutin. Several solvents will extract the substance. A process has been developed at the Eastern Regional Research Laboratory in which boiling water is used to dissolve out the rutin. Another process, also developed at the laboratory, employs 65 percent alcohol for the purpose. Denatured alcohols or isopropanol can also be used.

When drying is not desirable, the buckwheat can be processed green as soon as it is harvested. The whole plant is submerged in alcohol in a vat and allowed to stand until the next day. The alcoholic solution is drawn off and replaced with fresh alcohol, which is allowed to stand for another day and then drawn off. The alcoholic solutions are distilled to remove the solvent, leaving in the still a mixture of rutin and soluble plant constituents partly dissolved in water derived from the green plant. This is drawn off and cooled. Crude rutin separates out and is collected on a filter. This is now refined by removing the impurities with solvents and recrystallizing until pure rutin remains. The purity of the product is rigorously tested. The over-all yields by this process are somewhat larger than in the procedure that involves drying, because little rutin is lost if the plant is covered with alcohol 3 to 4 hours after harvesting.

Among the other constituents of the plant that are removed from the rutin during refining are some interesting byproducts sugars, lecithin, sitosterol, and others that may find commercial application.

Rutin was on the market in 1947 in somewhat limited quantities and usually druggists dispensed it only on physicians' prescriptions. Several large manufacturing drug companies entered the field, and plentiful supplies of the substance were expected in a short time.

Clinical investigations of the use of rutin in disease were initiated by Dr. J. Q. Griffith, Jr., of the Robinette Foundation, Medical School, University of Pennsylvania, who has studied its medical applications. Rutin for medical study has been furnished to approximately 400 physicians, hospital clinics, and research workers. A summary of their experience follows.

In patients suffering from high blood pressure there often is rupture of weak capillaries, with production of more or less severe hemorrhage. At times these accidents occur in the retina and cause partial or even complete blindness. Several patients suffering from retinal hemorrhage have been treated with rutin. In 83 percent of the cases, no further rupture of the capillaries occurred. Bursting of blood vessels in the brain leads to apoplexy. Rutin cannot cure the apoplexy once it has occurred,

but it may help to prevent future attacks. In 3 years no patient receiving rutin has had an apoplectic stroke, although all were suffering from hypertension and in more or less danger of such an accident.

An interesting development occurred in the treatment of hypertension. One of the best remedies for high blood pressure has an unfortunate tendency to weaken the capillaries of some patients. This fact forces the physician to use this powerful remedy with great caution in such cases. However, if the patient is given rutin, the tendency to weakening of the capillaries is counteracted, and the physician may proceed with his treatment. Similar effects have been noted in connection with the therapeutic use of salicylates and arsenicals, which also tend to weaken the capillary walls.

Although rutin itself is not advocated as a cure for hypertension, a drop in the blood pressure has been noted in 36 percent of the cases under observation. In 6 percent, the decrease was marked; in the remainder, it was moderate. There is a possibility that rutin may be of value in the treatment of diabetic retinitis, a condition that frequently occurs in diabetes and involves bleeding in the retina. Patients with unexplained bleeding from the lungs, not due to tuberculosis, have been relieved by rutin.

Rutin acts like a vitamin in that it restores these conditions to normal, but the affliction may return if rutin is discontinued. Persons who have a natural tendency to increased capillary fragility often relapse some weeks after discontinuing the remedy.

THE AUTHOR

James F. Couch, a native of Massachusetts and a graduate of Harvard University, received a doctor's degree from American University in 1926. In the Bureau of Animal Industry, 1917-40, he did research on the chemistry of poisonous plants, locoweeds, larkspur, lupines, milksickness, and cyanide poisoning. Since 1940 he has been a chemist in charge of the tobacco section in the Bureau of Agricultural and Industrial Chemistry.