Cordia americana: Evaluation of in vitro anti-herpes simplex virus activity and in vivo toxicity of leaf extracts

Herpes simplex virus (HSV) type 1 and type 2 are responsible for causing infections whose symptoms can vary from subclinical to severe manifestations. Cordia americana is a plant used by traditional communities for the treatment of wounds and diarrhoea, as well as infections like flu and syphilis. Scientific evidence has shown that, among other biological activities, the plant possesses antiviral properties; however, the evaluation of the in vivo toxicity of preparations of this plant is still lacking. This study assessed the in vitro anti-HSV-1 and anti-HSV-2 activity of a crude extract (CE) obtained from the leaves of C. americana, as well as its aqueous (FAq) and ethyl-acetate fractions (FAc). In addition, the in vivo toxicity of the FAq was assessed. The sulforhodamine B method was performed to determine the antiviral activity and the in vivo toxicity was evaluated according to Brazilian federal regulations. The CE, FAq, and FAc demonstrated antiviral activity against HSV-1 in vitro, presenting EC50 values of 7.0±1.4, 1.5±0.35, and 7.5±3.8, respectively. The FAq also had activity against HSV-2 with an EC50 of 11.8±1.02. The toxicological study of FAq in animals showed that it had very low toxicity. No death occurred during acute or subchronic experiments, where up to 5000 mg/kg and 150 mg/kg FAq were tested respectively; and there were no signs of toxicity in the subchronic test. The results of this study, in conjunction with further studies, pave the way for a potential topical treatment for skin and mucosal diseases, such as HSV-1 and HSV-2 infections.