Synthesis and biological evaluation of thiazolidinedione derivatives with high ligand efficiency to P. aeruginosa PhzS.

The thiazolidinone ring is found in compounds that have widespan biology activity and there is mechanism-based evidence that compounds bearing this moiety inhibit P. aeruginosa PhzS (PaPzhS), a key enzyme in the biosynthesis of the virulence factor named pyocyanin. Ten novel thiazolidinone derivatives were synthesised and screened against PaPhzS, using two orthogonal assays. The biological results provided by these and 28 other compounds, whose synthesis had been described, suggest that the dihydroquinazoline ring, found in the previous hit (A- Kd = 18 µM and LE = 0.20), is not required for PaPzhS inhibition, but unsubstituted nitrogen at the thiazolidinone ring is. The molecular simplification approach, pursued in this work, afforded an optimised lead compound (13- 5-(2,4-dimethoxyphenyl)thiazolidine-2,4-dione) with 10-fold improvement in affinity (Kd= 1.68 µM) and more than 100% increase in LE (0.45), which follows the same inhibition mode as the original hit compound (competitive to NADH).Executive summaryPhzS is a key enzyme in the pyocyanin biosynthesis pathway in P. aeruginosa.Orthogonal assays (TSA and FITC) show that fragment-like thiazolidinedione derivatives bind to PaPhzS with one-digit micromolar affinity.Fragment-like thiazolidinedione derivatives bind to the cofactor (NADH) binding site in PaPhzS.The molecular simplification optimised the ligand efficiency and affinity of the lead compound.

Antinociceptive Effect of the Essential Oil Obtained from the Leaves of Croton cordiifolius Baill. (Euphorbiaceae) in Mice.

Croton cordiifolius Baill. is a shrub known as "quebra-faca" and is used to treat inflammation, pain, wounds, and gastrointestinal disturbances in the semiarid region in the northeast of Brazil. In an ethnobotanical survey in the state of Pernambuco, "quebra-faca" use was cited in 33% of the interviews. Thus, we decided to evaluate the antinociceptive effects of the essential oil from C. cordiifolius (CcEO). Chemical analysis by gas chromatography-mass spectrometry revealed 1,8-cineole (25.09%) and α-phellandrene (15.43%) as major constituents. Antinociceptive activity was evaluated using murine models of chemically induced pain (writhing induced by acetic acid, formalin, capsaicin, and glutamate tests). Opioid and central nervous systems (CNS) involvement were also investigated. Regarding antinociceptive activity, CcEO (50 and 100 mg/kg) reduced the number of writhing responses induced by acetic acid and decreased the licking times in both phases of the formalin test. CcEO also was evaluated in capsaicin- and glutamate-induced nociception. While no effect was observed in the capsaicin test, CcEO (100 mg/kg) was effective in the glutamate test. Naloxone, an opioid antagonist, did not affect the antinociceptive activity of CcEO in writhing test. In conclusion, the antinociceptive effect of CcEO could be explained, at least in part, by inhibition of the glutamatergic system.

Synthesis and antimicrobial activities of 5-Arylidene-thiazolidine-2,4-dione derivatives.

Antibiotic resistance is considered one of the world's major public health concerns. The main cause of bacterial resistance is the improper and repeated use of antibiotics. To alleviate this problem, new chemical substances against microorganisms are being synthesized and tested. Thiazolidines are compounds having many pharmacological activities including antimicrobial activities. For this purpose some thiazolidine derivatives substituted at position 5 in the thiazolidine nucleus were synthesized and tested against several microorganisms. Using a disc diffusion method, antimicrobial activity was verified against Gram-positive, Gram-negative, and alcohol acid resistant bacteria and yeast. The minimum inhibition concentrations (MIC) and minimum bactericidal concentrations (MBC) were determined. All derivatives showed antimicrobial activity mainly against Gram-positive bacteria, with MIC values ranging from 2 to 16 µg/mL.

Antinociceptive and wound healing activities of Croton adamantinus Müll. Arg. essential oil.

Leaves of Croton adamantinus have been used to treat inflammation and skin wounds in the semi-arid area of the Northeast of Brazil. In order to evaluate if the essential oil (EO) was responsible for the claimed activities; antinociceptive, wound healing and antimicrobial tests were carried out. Twenty constituents were identified in C. adamantinus EO by GC-MS, ¹H-NMR and ¹³C-NMR, the major compounds being methyl-eugenol (14.81%) and 1,8-cineol (13.74%). Antinociceptive activity was evaluated by the formalin test and the abdominal contortion assay in mice. The EO (50 and 100 mg/kg) decreased the licking time of both phases of the formalin test when compared to the vehicle, but not to morphine (7.5 mg/kg). In the abdominal contortion assay, the EO (50 and 100 mg/kg) reduced the number of contortions compared to the vehicle and to indometacin (10 mg/kg). The wound healing activity was verified also using two experimental models: excisional wound and dead space. Topical treatment with the EO (1%) increased the wound contraction from the third day of treatment (compared with nitrofurazone 0.2%), while systemic treatment (50 mg/kg/day) increased granulation tissue formation and reduced the water content. C. adamantinus EO also showed antimicrobial activity against Staphylococcus aureus in disk diffusion method. These results corroborate the ethnobotanical use of this specie by Brazilian population.