Tongue angioedema in vivo: antagonist response of anti-inflammatory drugs.

BACKGROUND

The toxicity of Dieffenbachia picta, an ornamental plant, arises from its ability to cause painful edema of oral mucous membranes, buccal ulcerations, and tongue hypertrophy after chewing on the stem or contact with the sap.

OBJECTIVE

We compared the anti-inflammatory effect of eugenol (2-methoxy-4-(2-propenyl)phenol) to different drugs, and investigated the role of oxalate crystals in the development of the inflammation reaction.

METHODS

Tongue edema in live mice were measured with a digital tachymeter, 2 h after topical application (0.1 mL) or tissue injection (0.05 mL) of D. picta sap. The mice were treated by intraperitoneal or topical application of drugs, 15 min after edema induction. Vascular permeability was quantified based on abdominal skin plasma extravasation of Evans blue dye in response to intradermal administration of D. picta sap. The proteolytic assay was carried out as previously described (Kunitz M. Crystalline soybean trypsin inhibitor. General properties. J Gen Physiol 1947; 30:291-310.).

RESULTS

Arachidonate cascade antagonists and eugenol showed anti-edematogenic effects. High doses of eugenol (50 μg/kg) and sodium cromoglycate (100 mg/kg), but not a combination of the two, inhibited plasma extravasations. The sap without crystals, its methanol extract, or the ethanol-washed crystals in saline-reconstituted solution did not reproduce the tongue edema seen with the original sap. Topical application of 10% sodium bicarbonate completely abolished the tongue edema.

CONCLUSIONS

The inflammatory response induced by D. picta may be due to mechanical tissue damage resulting from the physical presence of calcium oxalate crystals. We were, however, unable to exclude the possibility of an insoluble toxicity present within the sap as an etiological agent. We realized that emergency treatment should also aim to inhibit antidromic vasodilation and axon reflex flare, reducing mastocyte degranulation and release of tachykinins from nerve endings. We speculate that eugenol showed better antiedematogenic results because it seems to function not only as a classic non-steroidal anti-inflammatory drug, but also as a local anesthetic, blocking neurotransmission in the damaged tissue.