Cell membranes are fundamental for cellular function as they protect the cell and control passage in and out of the cell. Despite their clear significance, cell membranes are often difficult to study, due to their complexity and the lack of available technologies to interface with them and transduce their functions. Overcoming this complexity by developing simple, reductionist models can facilitate their study. Indeed, lipid layers represent a simplified yet representative model for a cell membrane. Lipid layers are highly insulating, a property that is directly affected by changes in lipid packing or membrane fluidity. Such physical changes in the membrane models can be characterized by coupling them with an electronic transducer. Herein, a lipid monolayer that is stabilized between two immiscible solvents is integrated with an organic electrochemical transistor, which is capable of operating in a biphasic solvent mixture. The platform is used to evaluate how lidocaine, a widely used anesthetic the working mechanism of which is still a matter of debate, interacts with the cell membrane. The present study provides evidence that the anesthetic directly interacts with the lipids in the membrane, affecting their packing and therefore the monolayer permeability. The proposed platform provides an elegant solution for studying compound–membrane interactions.

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 (EC 50 of 35.4 AE 7.7 and 17.6 AE 4.2 lM, respectively) and amastigotes (EC 50 of 20.4 AE 1.9 and 16.0 AE 1.1 lM, respectively), superior to that determined for the positive control miltefosine (EC 50 of 28.7 AE 3.5 lM). 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.

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Background: Chagas disease (American Trypanosomiasis) is classified by the World Health Organization (WHO) as one of the seventeen neglected tropical diseases (NTD), affecting, mainly, several regions of Latin America. Introduction: However, immigration has expanded the range of this disease to other continents. Thousands of patients with Chagas disease die annually, yet no new therapeutics for Chagas disease have been approved, with only nifurtimox and benznidazole available. Treatment with these drugs presents several challenges, including protozoan resistance, toxicity, and low efficacy. Natural products, including the secondary metabolites found in plants, offer a myriad of complex structures that can be sourced directly or optimized for drug discovery. Method: Therefore, this review aims to assess the literature from the last 10 years (2011 – 2021) and present the anti-T. cruzi compounds isolated from plants in this period, as well as briefly discuss computational approaches and challenges in natural product drug discovery. Using this approach, more than 350 different metabolites were divided based on their biosynthetic pathway – alkaloids, terpenoids, flavonoids, polyketides, and phenylpropanoids which displayed activity against different forms of this parasite – epimastigote, trypomastigote and more important, the intracellular form, amastigote. Conclusion: In this aspect, there are several compounds with high potential which could be considered as a scaffold for the development of new drugs for the treatment of Chagas disease – for this, more advanced studies must be performed including pharmacokinetics (PK) and pharmacodynamics (PD) analysis as well as conduction of in vivo assays, these being important limitations in the discovery of new anti-T. cruzi compounds.