A One-pot Facile Synthesis of 2,3-Dihydroxyquinoxaline and 2,3-Dichloroquinoxaline Derivatives Using Silica Gel as an Efficient Catalyst

Discovery and Characterization of Synthesized and FDA-Approved Inhibitors of Clostridial and Bacillary Collagenases

In view of the worldwide antimicrobial resistance (AMR) threat, new bacterial targets and anti-infective agents are needed. Since important roles in bacterial pathogenesis have been demonstrated for the collagenase H and G (ColH and ColG) from Clostridium histolyticum, collagenase Q1 and A (ColQ1 and ColA) from Bacillus cereus represent attractive antivirulence targets. Furthermore, repurposing FDA-approved drugs may assist to tackle the AMR crisis and was addressed in this work. Here, we report on the discovery of two potent and chemically stable bacterial collagenase inhibitors: synthesized and FDA-approved diphosphonates and hydroxamates. Both classes showed high in vitro activity against the clostridial and bacillary collagenases. The potent diphosphonates reduced B. cereus-mediated detachment and death of cells and Galleria mellonella larvae. The hydroxamates were also tested in a similar manner; they did not have an effect in infection models. This might be due to their fast binding kinetics to bacterial collagenases.

Crystal structure of 9-methoxy-2,3,4,4a,5,6-hexahydro-1H-pyrido [1′,2′:1,6]pyrazino[2,3-b]quinoxaline, C15H18N4O

C15H18N4O, triclinic, P 1 ‾ $P\overline{1}$ (no. 2), a = 6.7562(5) Å, b = 9.5520(6) Å, c = 11.4227(8) Å, α = 97.206(5)°, β = 102.335(6)°, γ = 108.614(7)°, V = 667.39(9) Å3, Z = 2, R gt (F) = 0.0480, wR ref (F 2) = 0.1388, T = 150 K.

Crystal structure of 2-methoxy-4b,5,14,15-tetrahydro-6H-isoquinolino[2′,1′:1,6] pyrazino[2,3-b]quinoxaline, C19H18N4O

C19H18N4O, monoclinic, P21/c (no. 14), a = 11.3744(16) Å, b = 13.7367(15) Å, c = 11.208(2) Å, β = 118.51(2)°, V = 1538.9(5) Å3, Z = 4, R gt (F) = 0.0494, wR ref (F 2) = 0.1327, T = 100(2) K.

Tetrazanbigen Derivatives as Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) Partial Agonists: Design, Synthesis, Structure-Activity Relationship, and Anticancer Activities

Tetrazanbigen (TNBG) is a novel sterol isoquinoline derivative with poor water solubility and moderate inhibitory effects on human cancer cell lines via lipoapoptosis induction. Herein, we developed a series of novel TNBG analogues with improved water solubility and antiproliferative activities. The CCK-8 assay enabled us to identify a novel compound, 14g, which strongly inhibited HepG2 and A549 cell growth with IC₅₀ values of 0.54 and 0.47 μM, respectively. The anticancer effects might be explained by the partial activation and upregulation of PPARγ expression, as indicated by the transactivation assay and western blotting evaluation. Furthermore, the in vitro antiproliferative activity was verified in an in vivo xenograft model in which 14g strongly reduced tumor growth at a dose of 10 mg/kg. In line with these positive observations, 14g exhibited an excellent water solubility of 31.4 mg/mL, which was more than 1000-fold higher than that of TNBG (4 μg/mL). Together, these results suggest that 14g is a promising anticancer therapeutic that deserves further investigation.

Crystal structure of 3-fluoro-9-methoxy-4b,5,14,15-tetrahydro-6H-isoquinolino [2′,1′:1,6]pyrazino[2,3-b]quinoxaline, C19H17FN4O

C19H17FN4O, orthorhombic, Pbca (no. 61), a = 7.0607(2) Å, b = 18.4459(5) Å, c = 23.8955(7) Å, V = 3112.17(15) Å3, Z = 8, Rgt(F) = 0.0543, wRref(F2) = 0.1540, T = 100(2) K.