Inhibitory action of vitamin P compounds on hyaluronidase.

In 1936 Szent-Gybrgyi and coworkers (1) described the isolation of a material which was capable of increasing capillary resistance in man, and which they called citrin or vitamin P. Subsequent work has shown that many substances have this property, and vitamin P activity has been attributed variously to flavones, flavanones, and flavonols. Higby (2) found that crude hesperidin possessed vitamin P activity, but that upon purification it became inactive. He attributed the activity of the crude preparations to the presence of hesperidin in soluble form, as the chalcone. Majovski et al. (3) postulated that pure hesperidin was inactive because of its relative insolubility. Scarborough (4), however, found that hesperidin, as well as its aglycone hesperetin, was active in pure form. Rutin has been reported to increase capillary resistance in man (5), as have esculin and its aglycone esculetin (6). The mechanism by which these and the other known vitamin P substances act to increase capillary resistance is unknown, although Lavollay (7) has postulated that they function as inhibitors of adrenalin oxidation, and that adrenalin itself or its first oxidation product is the true vitamin P. It has been suggested that hyaluronidase plays a role in the maintenance of capillary strength. Duran-Reynals (8) reported that the permeability of the vascular system could be increased by preparations rich in hyaluronidase. More recently hyaluronidase has been considered as a factor “in accentuating capillary fragility rather than in inducing direct changes in capillary permeability” (9). The possibility is thus raised that the effect of vitamin P substances in increasing capillary resistance is due to an inhibition of the action of hyaluronidase. It appeared that an investigation of this point might bear fruitful results.