Brasiliensic acid: in vitro cytotoxic and genotoxic, in vivo acute toxicity and in silico pharmacological prediction of a new promising molecule

Brasiliensic acid (Bras) is a chromanone isolated from Calophyllum brasiliense Cambèss. bark extracts with confirmed potential activity on gastric ulcer and Helicobacter pylori infection. This study aimed to investigate the in vitro and in vivo toxicity of Bras and molecular docking studies on its interactions with the H. pylori virulence factors and selected gastric cancer-related proteins. Cytotoxicity was evaluated by alamarBlue© assay, genotoxicity by micronucleus and comet assays, and on cell cycle by flow cytometry, using Chinese hamster epithelial ovary cells. Bras was not cytotoxic to CHO-K1 cells, and caused no chromosomal aberrations, nor altered DNA integrity. Furthermore, Bras inhibited damages to DNA by H2O2 at 1.16 µM. No cell cycle arrest was observed, but apoptosis accounted for 31.2% of the cell death observed in the CHO-K1 at 24 h incubation of the IC50. Oral acute toxicity by Hippocratic screening test in mice showed no relevant behavioral change/mortality seen up to 1,000 mg/kg. The molecular docking approach indicated potential interactions between Bras and the various targets for peptic ulcer and gastric cancer, notably CagA virulence factor of H. pylori and VEGFR-2. In conclusion, Bras is apparently safe and an optimization for Bras can be considered for gastric ulcer and cancer.Communicated by Ramaswamy H. Sarma.

Blue Light-Driven [4+2]-Cycloaddition: Diastereoselective Synthesis of Chromeno[4,3-b]quinoline and Chromeno[4,3-b][1,8]naphthyridine Scaffolds

A one-pot, metal-free, light-driven [4+2]-cycloaddition reaction is described by accessing a diverse collection of chromeno[4,3-b]quinoline and chromeno[4,3-b][1,8]naphthyridine scaffolds in a diastereoselective manner. This process delivered stereoisomers, which were challenging to produce by an inverse-demand Diels-Alder reaction. The tetracyclic products were provided in good yields, promoted by rose bengal and blue light in a single operation. The developed protocol proceeded efficiently without the need for expensive photosensitizers such as Ir or Ru complexes. The cascade is modular and step-economic, and the substrate scope is wide. Polycyclic architectures can be assembled from readily available aniline, aminoazine, indole, and salicylaldehyde derivatives.

1,8-Naphthyridine Derivatives: A Privileged Scaffold for Versatile Biological Activities

1, 8- Naphthyridine nucleus belongs to significant nitrogen-containing heterocyclic compounds which has garnered the interest of researchers due to its versatile biological activities. It is known to be used as an antimicrobial, anti-psychotic, anti-depressant, anti-convulsant, anti- Alzheimer's, anti-cancer, analgesic, anti-inflammatory, antioxidant, anti-viral, anti-hypertensive, antimalarial, pesticides, anti-platelets, and CB2 receptor agonist, etc. The present review highlights the framework of biological properties of synthesized 1, 8-naphthyridine derivatives developed by various research groups across the globe.

Tailor-made amino acid-derived pharmaceuticals approved by the FDA in 2019

Amino acids (AAs) are among a handful of paramount classes of compounds innately involved in the origin and evolution of all known life-forms. Along with basic scientific explorations, the major goal of medicinal chemistry research in the area of tailor-made AAs is the development of more selective and potent pharmaceuticals. The growing acceptance of peptides and peptidomimetics as drugs clearly indicates that AA-based molecules become the most successful structural motif in the modern drug design. In fact, among 24 small-molecule drugs approved by FDA in 2019, 13 of them contain a residue of AA or di-amines or amino-alcohols, which are commonly considered to be derived from the parent AAs. In the present review article, we profile 13 new tailor-made AA-derived pharmaceuticals introduced to the market in 2019. Where it is possible, we will discuss the development form drug-candidates, total synthesis, with emphasis on the core-AA, therapeutic area, and the mode of biological activity.

Multi-parametric analysis of ciprofloxacin toxicity at ecologically relevant levels: Short- and long-term effects on Daphnia magna

The increased presence of emergent compounds, such as pharmaceuticals drugs, in the aquatic compartment has been acknowledged as an evolving environmental issue whose consequences are not yet fully characterized. Specific classes of pharmaceutical drugs, such as fluoroquinolone antibiotics, can exert toxic effects to non-target species with ecological significance, since these compounds are environmentally stable and persistent, and may interact with some of the key physiologic processes of organisms. Despite such characteristics, knowledge about the effects of these drugs is still scarce, especially to non-target organisms. The present study aimed to evaluate the effects of chronic and acute exposures of the cladoceran Daphnia magna to the fluoroquinolone antibiotic ciprofloxacin. Putative toxic effects were assessed, following acute and chronic exposures to ecologically relevant concentrations of ciprofloxacin, through enzymatic (cholinesterase - ChEs, catalase - CAT, glutathione S-transferases - GSTs) and non-enzymatic (thiobarbituric acid reactive substances - TBARS, glycogen - Gly) biomarkers. In addition, we also determined behavioural (swimming distance - SD) and morphological (body length of the first brood - BL1B) endpoints in animals exposed to this drug. Ciprofloxacin acute exposure resulted in increased CAT and ChEs activities, and inhibited GSTs activity. After chronic exposure, ChEs activity was significantly inhibited, while GSTs activity was significantly enhanced. TBARS levels were only increased at higher concentrations of ciprofloxacin. CAT activity and Gly content did not evidence a clear and significant pattern of variation. SD was slightly inhibited during dark cycles. BL1B presented a significant decrease for animals subjected to an intermediate concentration. Results showed that even ecologically relevant concentrations of ciprofloxacin may cause oxidative stress in individuals of D. magna. The present study showed important data that corroborate the occurrence of significant biochemical alterations in key features of an aquatic organism when exposed to relevant levels of a widely used antibiotic, establishing essential links between environmental exposure to this specific drug and putative toxic challenges that may result in irreversible changes and damages, especially at the individual level. However, changes in the size of neonates suggest that population alterations are likely to occur under real scenarios of chronic contamination by this drug.

In vitro toxic evaluation of two gliptins and their main impurities of synthesis

Background

The presence of impurities in some drugs may compromise the safety and efficacy of the patient’s treatment. Therefore, establishing of the biological safety of the impurities is essential. Diabetic patients are predisposed to tissue damage due to an increased oxidative stress process; and drug impurities may contribute to these toxic effects. In this context, the aim of this work was to study the toxicity, in 3 T3 cells, of the antidiabetic agents sitagliptin, vildagliptin, and their two main impurities of synthesis (S1 and S2; V1 and V2, respectively).

Methods

MTT reduction and neutral red uptake assays were performed in cytotoxicity tests. In addition, DNA damage (measured by comet assay), intracellular free radicals (by DCF), NO production, and mitochondrial membrane potential (ΔψM) were evaluated.

Results

Cytotoxicity was observed for impurity V2. Free radicals generation was found at 1000 μM of sitagliptin and 10 μM of both vildagliptin impurities (V1 and V2). A decrease in NO production was observed for all vildagliptin concentrations. No alterations were observed in ΔψM or DNA damage at the tested concentrations.

Conclusions

This study demonstrated that the presence of impurities might increase the cytotoxicity and oxidative stress of the pharmaceutical formulations at the concentrations studied.

In vitro toxicity assessment of rivaroxaban degradation products and kinetic evaluation to decay process

Degradation kinetics of oral anticoagulant rivaroxaban (RIV) was assessed in acid and alkaline media and while exposed to UVC radiation. Among all stress conditions tested, kinetic degradation process was better described by a zero-order model. A stability indicating method was validated for the analysis of the anticoagulant RIV in tablets by high-performance liquid chromatography. Robustness was evaluated with a two-level Plackett-Burman experimental design. The effect of acute exposition of the human hepatoblastoma HepG2 cell line to RIV stressed samples (100 and 500 µM) was assessed through in vitro toxicity tests. MTT reduction, neutral red uptake, mitochondrial membrane potential, and low molecular weight DNA diffusion assays were employed for cytotoxicity evaluation (5×10⁴ cells/well). The genotoxic potential was assessed by comet assay (2×10⁴ cells/well). Acute toxicity to HepG2 cells was assessed after 24 h incubation with sample solutions, for each test. A direct relationship between the increased amount of alkaline degradation products and higher cytotoxic potential was found. Results obtained by viability assay investigations support the concerns on risks associated with acute toxicity and genotoxicity of pharmaceutical samples containing degradation products as impurities.

²⁰¹Tl⁺-labelled Prussian blue nanoparticles as contrast agents for SPECT scintigraphy

Prussian blue (PB) and its analogues on the nanometric scale are exciting nano-objects that combine the advantages of molecular-based materials and nanochemistry. Herein, we demonstrate that ultra-small PB nanoparticles of 2-3 nm can be easily labelled with radioactive (201)Tl(+) to obtain new nanoprobes as radiotracers for 201-thallium-based imaging.