Vitamin P
Mter pure ascorbic acid became available, it was noticed that in guinea pigs on scorbutic diets this material, in certain instances, was not as effective in alleviating the tendency to hemorrhage as was one of the natural food sources of ascorbic acid, such as citrus fruits. In 1936 Szent-Gyorgyi and co-workers reported the presence of material in red peppers and in citrus fruits which they claimed was beneficial in the control of hemorrhage in man and in guinea pigs and was chemically different from ascorbic acid.
Since the material was thought to be involved in capillary permeability and was first found in paprika, the name "vitamin P" was given the newly discovered factor. It is difficult to demonstrate a vitamin P deficiency state in animals or in man. It was claimed, however, that guinea pigs on a flavone-free diet supplemented with ascorbic acid developed capillary weakness which responded specifically to vitamin P. Many workers feel that the active substances do not warrant the status of a vitamin, since it is possible to produce symptoms only in the scorbutic guinea pig treated with ascorbic acid. Of the several compounds with vitamin P activity the most effective are rutin from buckwheat and esculin from chestnuts. Rutin is 3, 5, 7, 3', 4'-pentahydroxy-flavone-3-rutinoside. Rutinose is a disaccharide containing glucose and rhamnose. Esculin is 6, 7-dihydroxycoumarin-6-glucoside. The active substances are all of plant origin. In citrus fruits the concentration is higher in the rind than in the juice. It is not established that the "vitamin" is required in man. No figures can be given for a requirement that may not exist.
