10.22376/ijpbs.2019.10.1.p1-12 Volume 5 Issue 4 2014 (October - December) We have designed and synthesized a new symmetrical porphyrins 3a-d and their nanoparticles based on extended lessThan i greaterThan π lessThan /i greaterThan -conjugation concept. The new sensitizers were fully characterized by CHN analysis, UV-Vis., lessThan sup greaterThan 1 lessThan /sup greaterThan H-NMR, TEM and Mass spectroscopy. The new sensitizers and their nanoparticles were evaluated as antitumor activity against HepG2, WI-38, VERO and MCF-7 cell lines. It was found that porphyrin nanoparticles have the most potent activity. RASHA E. EL-MEKAWY AND SRAA ABU-MELHA Pyrrole, Porphyrin, porphyrin nanoparticles, Antitumor activity 501-515