Structure-based design, optimization of lead, synthesis, and biological evaluation of compounds active against Trypanosoma cruzi.

Chagas' disease affects approximately eight million people throughout the world, especially the poorest individuals. The protozoan that causes this disease-Trypanosoma cruzi-has the enzyme cruzipain, which is the main therapeutic target. As no available medications have satisfactory effectiveness and safety, it is of fundamental importance to design and synthesize novel analogues that are more active and selective. In the present study, molecular docking and the in silico prediction of ADMET properties were used as strategies to optimize the trypanocidal activity of the pyrimidine compound ZN3F based on interactions with the target site in cruzipain. From the computational results, eight 4-amino-5-carbonitrile-pyrimidine analogues were proposed, synthesized (5a-f and 7g-h) and, tested in vitro on the trypomastigote form of the Tulahuen strain of T. cruzi. The in silico study showed that the designed analogues bond favorably to important amino acid residues of the active site in cruzipain. An in vitro evaluation of cytotoxicity was performed on L929 mammal cell lines. All derivatives inhibited the Tulahuen strain of T. cruzi and also exhibited lower toxicity to L929 cells. The 5e product, in particular, proved to be a potent, selective (IC50 = 2.79 ± 0.00 µM, selectivity index = 31.3) inhibitor of T. cruzi. The present results indicated the effectiveness of drugs based on the structure of the receptor, revealing the potential trypanocidal of pyrimidines. This study also provides information on molecular aspects for the inhibition of cruzipain.

Assessment of Cytotoxic/Antitumour Potential and in silico Study of Salazinic Acid Isolated from Parmotrema concurrens.

INTRODUCTION: Despite numerous scientific advances, cancer continues to be one of the main causes of death in the world. This situation has driven the search for promising molecules. Lichen substances have been widely described for their pharmacological potential. OBJECTIVE: The present study evaluated the antitumour potential of a depsidone isolated from Parmotrema concurrens- salazinic acid (SAL) - through in vitro, in vivo and in silico studies. METHODS: The molecule was isolated from the acetonic extract of the lichen and recrystallized in acetone. The macrophage J774, sarcoma-180 and MDA-MB-231 cell lines were used for the MTT cytotoxicity assay. The antitumor assay used a murine model (Swiss albino mice) with sarcoma-180. The animals were treated for seven consecutive days with doses of SAL (25 and 50 mg/kg) and 5-fluorouracil (20 mg/kg). RESULTS: Its purity was determined using high-performance liquid chromatography (94%), and its structure was confirmed by H1 and C13 nuclear magnetic resonance. SAL was not considered toxic to cancer cell lines, showing cell viability rates of 79.49 ± 4.15% and 86.88 ± 1.02% for sarcoma-180 and MDA-MB-231, respectively. The tumour inhibition rate was greater than 80% in the animals treated with SAL and 65% for those that received 5-fluorouracil. Simulations of molecular dynamics to estimate the flexibility of the interactions between human thymidylate synthase and derivatives of SAL and 5-fluorouracil revealed that SAL exhibited greater enzymatic interaction capacity, with highly favourable energy, compared to 5-fluorouracil. CONCLUSION: The present results demonstrate the potential of salazinic acid as a tumour inhibition agent.

Dereplication of Flavonoid Glycoconjugates from Adenocalymma imperatoris-maximilianii by Untargeted Tandem Mass Spectrometry-Based Molecular Networking.

The interpretation of large datasets acquired using high performance liquid chromatography coupled with tandem mass spectrometry represents one of the major challenges in natural products research. Here we propose the use of molecular networking to rapid identify the known secondary metabolites from untargeted MS/MS analysis of Adenocalymma imperatoris-maximilianii plant extracts. The leaves, stems and roots of A. imperatoris-maximilianii were extracted using different solvents according to Snyder selectivity triangle. The samples were analyzed by HPLC coupled with ion trap mass spectrometer in a collision-induced dissociation MS/MS configuration in both positive and negative electrospray ionization modes. Molecular networking simultaneously organized the spectra by cosine similarity. The chemical identification was performed based on the systematic study of the main fragmentation pathways observed for the resulting network. The untargeted tandem mass spectrometry-based molecular networking allowed for the identification of 63 metabolites, mainly mono-, di- and tri-, C- and/or O-glycosyl flavones. Molecular networking was capable not only to dereplicate known flavonoids, but also to point out related prenyl derivatives, described for the first time in Adenocalymma species. The gas-phase reaction route to form the characteristic [M-H2O-(30/60/90)]+ fragments in C-glycosyl flavones was suggested as sequential sugar ring opening followed by retro-aldol elimination involving aldose-ketose isomerization. The use of molecular networking with LC-CID-MS/MS assisted the identification of various isomeric and isobaric flavonoid glycoconjugates by establishing clusters according to the fragmentation similarities. Additionally, the proposed cross-ring sugar cleavages can contribute to the identification of C-glycosides by MS/MS analysis.