A pre-targeting strategy for imaging glucose metabolism using technetium-99m labelled dibenzocyclooctyne derivative

During the last four decades, nuclear medicine has undergone enormous growth, and positron emission tomography (PET) has been in the driving seat for most of the time. ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) is the most widely used agent for the detection of hibernating myocardium and metabolically active cancer tissue. But its cost and limited availability are the main limitations. For a long time different researchers and groups of pharmacists have tried to label glucose with a cheaper and long-acting radionuclide like ^99mTc. However, they failed to achieve this goal owing to the chemical complexity of ^99mTc and the lack of maintaining the physiological activity of diagnostic compounds. A pre-targeting strategy based on strain-promoted [3 + 2] azide-alkyne cycloaddition (SPAAC) reaction was applied to solve this problem. Functional click synthons were synthesized: 2-azido-2-deoxy-d-glucose (GlucN₃) as a glucose analogue, and N- (2- (2- (2- (bis (pyridin-2-ylmethyl) amino) ethoxy) ethoxy) ethyl-2- (6H-11,12-didehydrodibenzo [a,e] cycloocten-5-ylideneaminooxy) acetamide (C7) as a ^99mTc(CO)₃ labeling and azido-binding group. The results of biodistribution experiments in mice bearing S180 tumor show the relatively high tumor/blood ratio (up to 2.95) and tumor/muscle ratio (up to 6.37), and both of them decreases significantly in the glucose blocking experiment. It indicates that GlucN₃ behaves similarly to glucose and that in vivo SPAAC reactions can occur effectively. It is supposed that this pre-targeting strategy can indeed enhance target specificity and may be used for glucose metabolism imaging in tumor diagnosis.     

Synthesis and characterization of a photoresponsive doxorubicin/combretastatin A4 hybrid prodrug

To explore the application of photoremovable protecting groups (PPGs) in the field of combination chemotherapy, we designed and synthesized a photoresponsive hybrid prodrug 4 that bearing both doxorubicin (DOX) and combretastatin A4 (CA4). Light triggered drug release investigation found that DOX release was mainly accomplished by 405?nm light while CA4 release was mainly triggered by 365?nm light, i.e., prodrug 4 exhibited a quasi-sequential release behavior when a sequential light irradiation strategy was applied. Cell viability evaluation confirmed the increased cytotoxicity of prodrug 4 compared with individual drugs towards MDA-MB-231cells, indicating that a synergistic effect was achieved.     

Synthesis of novel dihydrotriazine derivatives bearing 1,3-diaryl pyrazole moieties as potential antibacterial agents

Three novel series of dihydrotriazine derivatives bearing 1,3-diaryl pyrazole moieties were designed, synthesized and evaluated in terms of their antibacterial and antifungal activities. Most of the synthesized compounds showed potent inhibition of several Gram-positive bacterial strains (including multidrug-resistant clinical isolates) and Gram-negative bacterial strains with minimum inhibitory concentration values in the range of 1–64?µg/mL. Compounds 4b and 4c presented the most potent inhibitory activity against Gram-positive bacteria (S. aureus 4220, MRSA 3167, QRSA 3519) and Gram-negative bacteria (E. coli 1924), with minimum inhibitory concentration values of 1 or 2?µg/mL. Compared with previous studies, these compounds exhibited a broad spectrum of inhibitory activity. The cytotoxic activity of the compounds 4a, 4b, 4c and 11n were assessed in L02 cells. In vitro enzyme study implied that compound 4c exerted its antibacterial activity through DHFR inhibition.     

Design and synthesis of novel 1-phenyl-3-(5-(pyrimidin-4-ylthio)-1,3,4-thiadiazol- 2-yl)urea derivatives with potent anti-CML activity throughout PI3K/AKT signaling pathway

In this investigation, a series of 1-phenyl-3-(5-(pyrimidin-4-ylthio)-1,3,4- thiadiazol-2-yl)urea receptor tyrosine kinase inhibitors were synthesized by a simple and efficient structure-based design. Structure-activity relationship (SAR) analysis of these compounds based on cellular assays led to the discovery of a number of compounds that showed potent activity against human chronic myeloid leukemia (CML) cell line K562, but very weak or no cellular toxicity through monitoring the growth kinetics of K562 cell during a period of 72 h using the real-time live-cell imaging. Among these compounds, 1-(5-((6-((3-morpholinopropyl) amino)pyrimidin-4-yl)thio)-1,3,4-thiadiazol-2-yl)-3-(4-(trifluoromethyl)phenyl)urea (7) exhibited the least cellular toxicity and better biological activity in cellular assays (K562, IC₅₀: 0.038 μM). Compound 7 also displayed very good induced-apoptosis effect for human CML cell line K562 and exerted its effect via a significantly reduced protein phosphorylation of PI3K/Akt signal pathway by Human phospho-kinase array analysis. In vitro results indicate that 1-phenyl-3-(5-(pyrimidin-4-ylthio)-1,3,4- thiadiazol-2-yl)urea derivatives are lead molecules for further development as treatment of chronic myeloid leukemia and cancer.