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In this study we report the synthesis of C5/C6-fused uridine phosphonates that are structurally related to earlier reported allosteric P2Y2 receptor ligands. A silyl-Hilbert-Johnson reaction of six quinazoline-2,4-(1H,3H)-dione-like base moieties with a suitable ribofuranosephosphonate afforded the desired analogues after full deprotection. In contrast to the parent 5-(4-fluoropheny)uridine phosphonate, the present extended-base uridine phosphonates essentially failed to modulate the P2Y2 receptor.

In the search for novel cytotoxic agents, sesquiterpenoids and phenylpropanoids have provided interesting lead compounds. From the chloroform extract of the underground parts of Laserpitium latifolium , the daucane sesquiterpenoids laserpitin and acetyldesoxodehydrolaserpitin, and the phenylpropanoids laserin and latifolon were isolated as the major compounds. Acetyldesoxodehydrolaserpitin is identified for the first time in the genus Laserpitium. Using a MTT and a sulforhodamine B (SRB) assay, the cytotoxic and antiproliferative activity of the extract and compounds laserpitin, acetyldesoxodehydrolaserpitin and laserin was tested in two closely related human breast adenocarcinoma cell lines, ie. the invasive MCF 7/6 and the non-invasive MCF 7/AZ. The IC 50 values of the extract were in the range of 184.72 - 397.16 μg/mL, with the most potent effect observed in the MTT test on the MCF 7/6 line. Among the tested compounds, acetyldesoxodehydrolaserpitin exerted a most potent, concentration-dependent effect (IC 50 values of 0.60 and 0.51 m M in the MCF 7/6 cell line, and 2.29 m M and 31.87 m M in the MCF 7/AZ cell line in the MTT and SRB test, respectively). The effect of laserin was more pronounced in the MTT test (IC 50 of 4.57 and 2.46 m M in the MCF 7/6 and MCF 7/AZ, respectively).