Allantoin, a Constituent of Maggot Excretions, Stimulates Healing of Chronic Discharging Wounds

Abstract

One of the distinguishing features of the maggot treatment of infected wounds is the rapidity with which the wound usually heals. This has been stressed both in the literature and in statements (7) received from surgeons who have used this treatment. It has already been shown (I, 2, 4, 5, IO) that, in feeding upon necrotic tissue and destroying bacteria, maggots put the wound in a condition more favorable for healing. The rapid rate of healing indicated, however, that maggots are more than merely scavengers and that they excrete something into the wound which directly stimulates the process of healing. An investigation (8) of maggot excretions was begun to determine, if possible, whether any substance with healing properties could be found. Any direct healing effect by maggots would, no doubt, be the result of an involuntary act in connection with their feeding or metabolism. An investigation of the urinary excretions, which contain the products of metabolism, was therefore attempted first. The search was greatly simplified by an analogy as described next. Scattered throughout biological and medical literature are reports that healing of wounds has been stimulated by the application of macerated embryonic tissue or extract. A conspicuous thing about those experiments was that the embryos used typically possessed a well-developed allantois containing allantoin; and in the present investigation it was believed that this might be significant, as most vertebrates and invertebrates, possibly including insects, excrete allantoin as a waste product of metabolism. No mention could be found, however, that the healing effects of embryonic tissues or fluids were due to this substance and, in fact, nothing as to the healing value of allantoin was found at that time in any works on pharmacology, therapeutics, or pathology. Interest was added to the investigation by the finding of an article written by Macalister (3), twenty-three years ago, stating that he had successfully used allantoin obtained from the roots of comfrey in the treatment of chronic ulcers. By the following procedure maggot excretions were readily obtained in sufficient quantity for the separation, purification, and identi-