CONICET | Buscador de Institutos y Recursos Humanos

Cutaneous leishmaniasis is a clinical form of a parasitic disease characterized by developing skin lesions with raised borders, eventually ulcerated, and limited to a specific area.1 The potential toxicity as well as the increased resistance of standard treatments have led to development of alternative medication. Antimicrobial photodynamic therapy appears as an alternative treatment for localized infections caused by microorganisms.2Our research group has succeeded in the isolation of several anthraquinones (AQs) obtained from H. lycioides with good photosensitizing properties.3 The aim of this work was to study the photoinactivation of Leishmania amazonensis by using soranjidiol (sor) and derivatives structures: 5-chlorosoranjidiol (5-clsor), bisoranjidiol (bis), 7-chlorobisoranjidiol (7-clbis) y lycionine (lyc).AQs were tested at 2.5 μM and photoactivated with blue LED (λ = 410 ± 10 nm and fluence rate=50 mW/cm2). The exposure times corresponded to radiant exposures of 9, 18, 27 and 36 J/cm2. Metacyclic promastigote form of transfected L. amazonensis expressing luciferase enzyme (La-LUC) was used to quantify metabolic activity.4Results showed that sor, 5-clsor and bis produce a decrease above 90% in La-LUC metabolic activity with a radiant exposure of 27 J/cm2, while 7-clbis and lyc exhibited no photoinactivation. Additionally, 5-clsor was tested by using other wavelengths (LEDs emitting at λ= 450 ± 20 nm and λ= 520 ± 20 nm) keeping the same irradiance. This AQ displayed the same reduction in La-LUC metabolic activity when it was photoactivated with the three wavelengths but using a fluence of 36 J/cm2.In conclusion, bis, sor and 5-clsor are natural anthraquinones that exhibited photodynamic inactivation on Leishmania amazonensis, making them potentially attractive for application in cutaneous leishmaniasis treatment.