Anti-leishmanial activity of Brazilian green, brown, and red algae

Abstract

Leishmaniasis is a disease of public health significance, and the available therapy is unsatisfactory. Studies of marine algae as a source of pharmacologically active compounds have increased worldwide. This study evaluated the activity of algal crude extracts and a purified product against Leishmania amazonensis. Extracts from Caulerpa racemosa, Osmundaria obtusiloba, Stypopodium zonale, Dictyota ciliolata, and Dictyota menstrualis showed EC50/24 h activity with concentrations that ranged from 0.61 to 154.0 μg mL−1. The cytotoxicity of these extracts on macrophages showed CC50/24 h, with a concentration range of 18.2–240.0 μg mL−1. The selectivity index corresponds to values varying from 0.31 to 39.33 for these extracts. A mixture of diterpene isomers isolated from D. menstrualis showed interesting activity against L. amazonensis. In addition, the anti-leishmanial activity of the O. obtusiloba extract showed potential activity that was better than the effect obtained with pentamidine, a reference drug. The alcoholic extract of O. obtusiloba was selected for in vivo tests, and BALB/c mice were infected with L. amazonensis and treated with the O. obtusiloba extract orally for 4 weeks. The treatment showed the ability to control the dissemination of parasites to the draining lymph nodes as well the evolution of cutaneous lesions, indicating a potential therapeutic use of the alcoholic extract of O. obtusiloba. These results provide new perspectives on the development of drugs against leishmaniasis.