Definition: In this task, you're given a paragraph from the research paper and your task is to generate a suitable title for the research paper based on the given paper. Under 100 words is a good title length.
Input: A series of the novel C-5 alkynyl pyrimidine nucleoside analogues (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) in which the sugar moiety was replaced by the conformationally restricted Z-and E-2-butenyl spacer between the phthalimido and pyrimidine ring were synthesized by using Sonogashira cross-coupling reaction. Cytostatic activity evaluation of the novel compounds showed that E-isomers exhibited, in general, better cytostatic activities than the corresponding Z-isomers. E-isomer 14 exhibited the best cytostatic effect against all evaluated malignant cell lines, particularly against hepatocellular carcinoma (Hep G2, IC 50 = 4.3 lM). However, this compound was also cytotoxic to human normal fibroblasts (WI 38). Its Z-isomer 7 showed highly specific antiproliferative activity against Hep G2 (IC 50 = 18 lM) and no cytotoxicity to WI 38. Moreover, compounds 3, 4 and 14 expressed some marginal inhibitory activity against HIV-1 and HIV-2.

Synthesis, cytostatic and anti-HIV evaluations of the new unsaturated acyclic C-5 pyrimidine nucleoside analogues