Synthesis of chalcones and their antimicrobial and drug potentiating activities.

The increased resistance of microorganisms to antimicrobial drugs makes it necessary to search for new active compounds, such as chalcones. Their simple chemical structure makes them molecules easy to synthesize. Therefore, the aim of this study was to evaluate the antimicrobial and potentiating activity of antibiotics and antifungals by synthetic chalcones against strains of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Candida tropicalis. The synthesis of chalcones was carried out by Claisen-Schimidt aldol condensation. Nuclear Magnetic Resonance (NMR) and Gas Chromatography Coupled to Mass Spectrometry (GC/MS) were also performed. Microbiological tests were performed by the broth microdilution method, using gentamicin, norfloxacin and penicillin as standard drugs for the antibacterial assay, and fluconazole for the antifungal assay. Three chalcones were obtained (1E,4E)-1,5-diphenylpenta-1,4-dien-3-one (DB-Acetone), (1E,3E,6E,8E)-1,9-diphenylnone-1,3,6,8-tetraen-5-one (DB-CNM), (1E,4E)-1,5-bis (4-methoxyphenyl) penta-1,4-dien-3-one (DB-Anisal). The compound DB-Acetone was able to inhibit P. aeruginosa ATCC 9027 at a concentration of 1.4 × 102 µM (32 µg/mL), while DB-CNM and DB-Anisal inhibited the growth of S. aureus ATCC 25923 at 17.88 × 102 µM and 2.71 × 101 µM (512 µg/mL and 8 µg/mL) respectively. In the combined activity, DB-Anisal was able to potentiate the effect of the three antibacterial drugs tested against E. coli 06, norfloxacin (128 for 4 µg/mL ±1) against P. aeruginosa 24 and penicillin (1,024 for 16 µg/mL ±1) against S. aureus 10. In antifungal assays, chalcones were not able to inhibit the growth of fungal strains tested. However, both showed potentiating activity with fluconazole, ranging from 8.17 x 10-1 µM (0.4909 µg/mL) to 2.35 µM (13.96 µg/mL). It is concluded that synthetic chalcones have antimicrobial potential, demonstrating good intrinsic activity against fungi and bacteria, in addition to potentiating the antibiotics and antifungal tested. Further studies are needed addressing the mechanisms of action responsible for the results found in this work.

Orofacial antinociceptive effect of sulphated polysaccharide from the marine algae Hypnea pseudomusciformis in rodents.

This study aimed to evaluate the antinociceptive effect of sulphated polysaccharide from the marine algae Hypnea pseudomusciformis (PLS) using rodent models of orofacial pain. Acute pain was induced by formalin, capsaicin, cinnamaldehyde, acidified saline or glutamate (cutaneous modes) and hypertonic saline (corneal model). In one experiment, animals were pretreated with ruthenium red, glibenclamide, naloxone, L-NAME, methylene blue or ketamine to investigate the mechanism of antinociception. In another experiment, animals pretreated with PLS or saline were submitted to the temporomandibular joint formalin test. In yet another, animals were submitted to craniofacial pain induced by mustard oil. Motor activity was evaluated with the open-field test. Cytotoxicity and antioxidant activities were also assessed. Pre-treatment with PLS significantly reduced nociceptive behavior associated with acute pain. Antinociception was effectively reduced, but not inhibited, by ruthenium red and ketamine. L-NAME and glibenclamide enhanced the PLS effect. PLS antinociception was resistant to methylene blue, naloxone and heating. PLS presented no cytotoxicity or antioxidant properties. Our results confirm the potential pharmacological relevance of PLS as an inhibitor of orofacial nociception in acute pain probably mediated by glutamatergic, nitrergic, TRPs and K + ATP pathways.

Heterocyclic chalcone (E)-1-(2-hydroxy-3,4,6-trimethoxyphenyl)-3-(thiophen-2-yl) prop-2-en-1-one derived from a natural product with antinociceptive, anti-inflammatory, and hypoglycemic effect in adult zebrafish.

Diabetes is a disease linked to pathologies, such as chronic inflammation, neuropathy, and pain. The synthesis by the Claisen-Schmidt condensation reaction aims to obtain medium to high yield chalconic derivatives. Studies for the synthesis of new chalcone molecules aim at the structural manipulation of aromatic rings, as well as the replacement of rings by heterocycles, and combination through chemical reactions of synthesized structures with other molecules, in order to enhance biological activity. A chalcone was synthesized and evaluated for its antinociceptive, anti-inflammatory and hypoglycemic effect in adult zebrafish. In addition to reducing nociceptive behavior, chalcone (40 mg/kg) reversed post-treatment-induced acute and chronic hyperglycemia and reduced carrageenan-induced abdominal edema in zebrafish. It also showed an inhibitory effect on NO production in J774A.1 cells. When compared with the control groups, the oxidative stress generated after chronic hyperglycemia and after induction of abdominal edema was significantly reduced by chalcone. Molecular docking simulations of chalcone with Cox -1, Cox-2, and TRPA1 channel enzymes were performed and indicated that chalcone has a higher affinity for the COX-1 enzyme and 4 interactions with the TRPA1 channel. Chalcone also showed good pharmacokinetic properties as assessed by ADMET. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03696-8.

GABAA receptor participation in anxiolytic and anticonvulsant effects of (E)-3-(furan-2-yl)-1-(2hydroxy-3,4,6-trimethoxyphenyl)prop-2-en-1-one in adult zebrafish.

Anxiety is a mental disorder that affects 25% of patients with epilepsy, and treatments for anxiety and seizures involve the use of benzodiazepines, a class of drugs that have many adverse effects such as decreased motor coordination, drowsiness, and sedation. Thus, new types of drugs with minimal side effects are of immediate requirement. Chalcones comprise a class of compounds with important therapeutic potential and have recently been investigated for their potential as anxiolytic and anticonvulsant agents. Therefore, this study aimed to evaluate the anxiolytic and anticonvulsant effects of the synthetic chalcone (E)-3-(furan-2-yl)-1-(2hydroxy-3,4,6-trimethoxyphenyl)prop-2-en-1-one (FURCHAL) using adult zebrafish as an animal model. Anxiolytic potential was assessed using the light/dark test and the anticonvulsant effect in 3-stage pentylenetetrazol (PTZ)-induced seizure tests. The mechanisms of the anxiolytic effect were analyzed using γ-aminobutyric acid (GABA) and the serotoninergic system. The anxiolytic effect of FURCHAL was verified by a reduction in fish locomotion, similar to diazepam (DZP), which may involve the GABAA receptor, as there was no reversal in the anxiolytic behavior of animals treated with FURCHAL by serotonergic antagonists. In addition, pretreatment with flumazenil blocked the anticonvulsant effect of FURCHAL and DZP at all three stages, indicating that FURCHAL also has anticonvulsant effects and that the presence of the α,ß unsaturated aromatic system and heterocyclic moiety in FURCHAL provided greater affinity for the GABAA receptors. Molecular docking revealed that the interactions involved in the formation of the protein-binding complex FURCHAL-GABAA are formed by three H-bonds involving the oxygen atoms of FURCHAL, and notably, complexes operated in the same region of the DZP site. Thus, this study adds new evidence and highlights that FURCHAL can potentially be used to develop compounds with anxiolytic and anticonvulsant properties.

Computational approach towards the design of artemisinin-thymoquinone hybrids against main protease of SARS-COV-2.

BACKGROUND: The sanitary emergency installed in the world, generated by the pandemic of COVID-19, instigates the search for scientific strategies to mitigate the damage caused by the disease to different sectors of society. The disease caused by the coronavirus, SARS-CoV-2, reached 216 countries/territories, where about 199 million people were reported with the infection. Of these, more than 4 million died. In this sense, strategies involving the development of new antiviral molecules are extremely important. The main protease (Mpro) from SARS-CoV-2 is an important target, which has been widely studied for antiviral treatment. This work aims to perform a screening of pharmacodynamics and pharmacokinetics of synthetic hybrids from thymoquinone and artemisin (THY-ART) against COVID-19. RESULTS: Molecular docking studies indicated that hybrids of artemisinin and thymoquinone showed a relevant interaction with the active fraction of the enzyme Mpro, when compared to the reference drugs. Furthermore, hybrids show an improvement in the interaction of substances with the enzyme, mainly due to the higher frequency of interactions with the Thr199 residue. ADMET studies indicated that hybrids tend to permeate biological membranes, allowing good human intestinal absorption, with low partition to the central nervous system, potentiation for CYP-450 enzyme inhibitors, low risk of toxicity compared to commercially available drugs, considering mainly mutagenicity and cardiotoxicity, low capacity of hybrids to permeate the blood-brain barrier, high absorption and moderate permeability in Caco-2 cells. In addition, T1-T7 tend to have a better distribution of their available fractions to carry out diffusion and transport across cell membranes, as well as increase the energy of interaction with the SARS-CoV-2 target. CONCLUSIONS: Hybrid products of artemisinin and thymoquinone have the potential to inhibit Mpro, with desirable pharmacokinetic and toxicity characteristics compared to commercially available drugs, being indicated for preclinical and subsequent clinical studies against SARS-CoV-2. Emphasizing the possibility of synergistic use with currently used drugs in order to increase half-life and generate a possible synergistic effect. This work represents an important step for the development of specific drugs against COVID-19.