Contact dermatitis associated with Astronium urundeuva (allemão) Engl., a traditional medicinal plant from Brazil

Abstract

Astronium urundeuva (allemão) Engl. (Anacardiaceae) is used in northeastern Brazilian folk medicine largely for the treatment of gynaecological and dermatological problems (1). Previous studies of this plant have shown antiulcerogenic (2), analgesic and anti-inflammatory (3, 4) effects. In clinical practice, there is anecdotal evidence that the use of A. urundeuva in topical preparations may cause, maintain or worsen cutaneous lesions, such as acute, subacute and chronic dermatitis. The present study deals with the preparation of extracts of A. urundeuva to be used in patch tests to determine prevalence of sensitivity and the dominant allergens involved with sensitization.

It was accomplished in a transverse study of cases of contact dermatitis and sensitization to A. urundeuva in 137 patients attended at Dermatology Center of Walter Cantídio University Hospital/Federal University of Ceará, Brazil. The patients were submitted to patch test using hexane and ethanol extract of A. urundeuva and derived fractions. The plant was collected in Meruoca Hill, situated in Ceará State, and identified by Dr Afrânio Fernandes from the Prisco Bezerra Herbarium of Federal University of Ceará, where a voucher specimen is deposited under number 29851. The patch testing was preceded by anamnese and physical examination then applied using: Standard series (PATCHKIT STANDARD®– FDA Allergenic), hexane and ethanol extracts in 2.5%, 5% and 10%; fractions of the hexane (Aur1, Aur2) and ethanol extracts (Aur3, Aur4) in 1% and 2% and cardol in 1% concentrations. All the samples and the constituents of the complementary series were diluted in ethyl alcohol (92.8 °) that was used as negative control. 3 of 137 (2%) patients showed 1 or more positive reactions to the hexane and ethanol extracts and fractions of A. urundeuva in the patch tests.

Patient 1 had a positive test to 5% and 10% EtOH extract. He reported using topical preparation of A. urundeuva to treat a cutaneous rash, but instead of improvement, had accentuation of the lesions. Lesions resolved once treatment with the A. urundeuva preparation was stopped. Patient 2 showed positive results for the hexane extract, fraction Aur4 (2%) and cardol (1%). The patient also reported an improvement of the dermatitis, after suspension of topical use of A. urundeuva. Patient 3 had positive results with the fractions Aur3 (1%) and Aur4 (2%). Phytochemical tests (5) were performed with the fractions Aur1 and Aur2 which were classified as triterpenes; Aur3 showed to contain flavonoids and Aur4 contains pyrogallic tannins. In conclusion, ethanol soluble extractives and to a lesser extent hexane soluble extractives from the bark of A. urundeuva are capable of eliciting positive patch test reactions in persons who have apparently become sensitized to the plant material following its topical use.