RESUMO
OBJECTIVE: This work describes the isolation of anti-Leishmania amazonensis metabolites from Saururus cernuus (Saururaceae). Additionally, ultrastructural changes in promastigotes were evidenced by electron microscopy. METHODS: The MeOH extract from the leaves of S. cernuus was subjected to bioactivity-guided fractionation. Anti-L. amazonensis activity of purified compounds was performed in vitro against promastigote and amastigote forms. KEY FINDINGS: Bioactivity-guided fractionation of the MeOH extract from the leaves of S. cernuus afforded two related tetrahydrofuran dineolignans: threo,threo-manassantin A (1) and threo,erythro-manassantin A (2). Compounds 1 and 2 displayed activity against promastigotes (EC50 of 35.4 ± 7.7 and 17.6 ± 4.2 µm, respectively) and amastigotes (EC50 of 20.4 ± 1.9 and 16.0 ± 1.1 µm, respectively), superior to that determined for the positive control miltefosine (EC50 of 28.7 ± 3.5 µm). Reduced cytotoxicity for host cells was observed for both compounds. Additionally, ultrastructural changes in promastigotes leading to an alteration of structural morphology were observed, as evidenced by electron microscopy. Furthermore, these compounds altered the morphology and physiology of the plasmatic membrane of L. amazonensis. CONCLUSIONS: The obtained results indicated that dineolignans 1 and 2 could be considered as a scaffold for the design of novel and selective drug candidates for the treatment of leishmaniasis.
Assuntos
Antiprotozoários/farmacologia , Leishmania/efeitos dos fármacos , Leishmaniose/tratamento farmacológico , Lignanas/farmacologia , Saururaceae/química , Animais , Antiprotozoários/química , Antiprotozoários/isolamento & purificação , Furanos/química , Furanos/isolamento & purificação , Furanos/farmacologia , Leishmaniose/parasitologia , Lignanas/química , Lignanas/isolamento & purificação , Camundongos , Camundongos Endogâmicos BALB C , Microscopia Eletrônica , Fosforilcolina/análogos & derivados , Fosforilcolina/farmacologia , Folhas de PlantaRESUMO
The MeOH extract from leaves of Saururus cernuus L. (Saururaceae) displayed in vitro activity against trypomastigote forms of T. cruzi (100% of parasite death at 200⯵g/mL), suggesting the presence of bioactive compounds. Thus, the bioactivity-guided fractionation was carried out, leading to the isolation of three related neolignan derivatives, identified as threo-austrobailignan-5 (1), threo-austrobailignan-6 (2), and threo-dihydroguaiaretic acid (3). Anti-T. cruzi activity of compounds 1-3 was performed against cell-derived trypomastigotes and intracellular amastigotes. Additionally, the mammalian cytotoxicity was investigated using NCTC cells. Compound 2 was the most effective against extracellular trypomastigotes with IC50 of 3.7⯵M, while compound 3 showed activity in both clinically relevant forms of the parasite, trypomastigotes and amastigotes, with IC50 values of 7.0 and 16.2⯵M, respectively. However, the structurally related compound 1 was inactive. Based on these results, compounds 2 and 3 were selected to evaluate the mechanism of cellular death. Compound 2 induced alteration in the plasma membrane permeability and consequently in the ROS levels after 120â¯min of incubation. By using flow cytometry and fluorescence microscopy, compound 3 showed alterations in the mitochondrial membrane potential (ΔΨm) of trypomastigotes. Considering the promising chemical and biological properties of neolignans 2 and 3, these compounds could be used as starting points to develop new lead compounds for Chagas disease.