Antileishmania and immunomodulatory potential of cashew nut shell liquid and cardanol.

Conventional treatments for leishmaniasis have caused serious adverse effects, poor tolerance, development of resistant strains. Natural products have been investigated as potential therapeutic alternatives. The cashew nut shell liquid (CNSL) is a natural source of phenolic compounds with several biological activities, where cardanol (CN) is considered one of the most important and promising compounds. This study aimed to evaluate antileishmanial, cytotoxic and immunomodulatory activities of CNSL and CN. Both showed antileishmanial potential, with IC50 for CNSL and CN against Leishmania infantum: 148.12 and 56.74 µg/mL; against Leishmania braziliensis: 85.71 and 64.28 µg/mL; against Leishmania major: 153.56 and 122.31 µg/mL, respectively. The mean cytotoxic concentrations (CC50) of CNSL and CN were 37.51 and 31.44 µg/mL, respectively. CNSL and CN significantly reduced the percentage of infected macrophages, with a selectivity index (SI) >20 for CN. CNSL and cardanol caused an increase in phagocytic capacity and lysosomal volume. Survival rates of Zophobas morio larvae at doses of 3; 30 and 300 mg/kg were: 85%, 75% and 60% in contact with CNSL and 85%, 60% and 40% in contact with CN, respectively. There was a significant difference between the survival curves of larvae when treated with CN, demonstrating a significant acute toxicity for this substance. Additional investigations are needed to evaluate these substances in the in vivo experimental infection model.

Limonene-carvacrol: A combination of monoterpenes with enhanced antileishmanial activity.

BACKGROUND: Leishmaniasis is a parasitosis with a wide incidence in developing countries. The drugs which are indicated for the treatment of this infection usually are able to promote high toxicity. PURPOSE: A combination of limonene and carvacrol, monoterpenes present in plants with antiparasitic activity may constitute an alternative for the treatment of these diseases. METHODS: In this study, the antileishmania activity against Leishmania major, cytotoxicity tests, assessment of synergism, parasite membrane damage tests as well as molecular docking and immunomodulatory activity of limonene-carvacrol (Lim-Car) combination were evaluated. RESULTS: The Lim-Car combination (5:0; 1:1; 1:4; 2:3; 3:2; 4:1 and 0:5) showed potential antileishmania activity, with mean inhibitory concentration (IC50) ranging from 5.8 to 19.0 µg.mL-1. They demonstrated mean cytotoxic concentration (CC50) ranging from 94.1 to 176.0 µg.mL-1, and did not show significant hemolytic effect. In the investigation of synergistic interaction, the 4:1 Lim-Car combination showed better fractional inhibitory concentration (FIC) index as well as better activity on amastigotes and IS. The samples caused considerable damage to the parasite membrane this monoterpene activity seems to be more related to Trypanothione Reductase (TryR) enzyme interaction, demonstrated in the molecular docking assay. In addition, the 4:1 Lim-Car combination stimulated macrophage activation, and showed at was the best association, with reduction of infection and infectivity of parasitized macrophages. CONCLUSION: The 4:1 Lim-Car combination appears to be a promising candidate as a monotherapeutic antileishmania agent.