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A series of isoindolo-benzo-triazines of type 4 was obtained by diazotization of 2-(2-aminoaryl)-1-cyanoisoindoles 3a-j. All the synthesized derivatives were screened by the National Cancer Institute (NCI, Bethesda, USA), for in vitro antitumor activity against a 3-human cancer cell line panel consisting of MCF7 (breast), NCI-H460 (lung), and SF-268 (CNS). Derivatives 4a, f, i, j were selected to be evaluated in the full panel of about 50 human tumor cell lines derived from nine human cancer cell types and showed antiproliferative activity generally in the micromolar range. The most sensitive cell lines were: MOLT-4 and SR of the leukemia subpanel, A549/ATCC and EKVX of the nonsmall cell lung subpanel, COLO-205 of the colon cancer subpanel, LOX IMVI of the Melanoma subpanel, OVCAR-8 of the ovarian cancer subpanel, and MCF7, BT-549 of the breast cancer subpanel.

A new class of compounds, the pyrrolo[2,3-h]quinolin-2-ones, nitrogen isosters of the angular furocoumarin Angelicin, was synthesized with the aim of obtaining new photochemotherapeutic agents with increased antiproliferative activity and lower undesired toxic effects than the lead compound. Two synthetic pathways were approached to allow the isolation both of the dihydroderivatives 10-17 and of the aromatic ring system 23. Compounds 10-17 showed a remarkable phototoxicity and a great UVA dose dependence reaching IC(50) values at submicromolar level. Intracellular localization of these compounds has been evaluated by means of fluorescence microscopy using tetramethylrhodamine methyl ester and acridine orange, which are specific fluorescent probes for mitochondria and lysosomes, respectively. A weak co-staining was observed with mitochondrial stain, whereas a specific localization in lysosomes was observed. Studies directed to elucidate the mode of action of this series of compounds revealed that they do not intercalate with DNA and do not induce photodamage to the macromolecule. On the contrary, they induce significative photodamage to lipids and proteins.

The efficient one-pot synthesis of several new tricyclic systems of type 1 and 2, obtained from the reaction of substituted 2-amino-3-cyanopyrroles and 3-amino-4-cyanopyrroles with BMMAs, is reported. The duration and yields of the reaction strongly depend on the reactivity of the starting pyrrole and on the size of the ring to be formed. Mechanist features of the reaction were investigated and proposed by studying also the reactivity of a 3-aminopyrrole-2,4-dicyano substituted. The method reported represents the first example of the use of BMMA reagents in combination with pyrrole derivatives and allows an easy and versatile entry to a large number of hitherto unknown pyrrolo-pyrimidines further annelated with nitrogen heterocycles of different sizes. These new polycondensed heterocycles possess the requisite to interact with DNA.

Eight derivatives of the new ring system [1,2,3,5]tetrazino[5,4-a]indole-4-one 7, were synthesised in good yields by reaction of 2-diazoindoles with alkyl or aryl isocyanates. Compounds 7 were screened at National Cancer Institute (NCI) for their activity against a panel of approximately 60 human tumour cell lines. Some of them showed antiproliferative activity having generally GI50 in the micromolar range. The most sensitive cell lines were SF-295, SNB-75 and SF-539 of the CNS cancer sub-panel, SR of the leukaemia sub-panel, UACC-62 of the melanoma sub-panel and OVCAR-4 of the ovarian cancer sub-panel.

Pyrrolo[2,1-d][1,2,3,5]tetrazinones 10a-o, compounds that hold the deaza skeleton of the antitumor drug temozolomide, were prepared by reaction of 2-diazopyrroles 9 and isocyanates. Such a synthetic route represents, among those leading to azolotetrazinones reported so far, the only possible one since attempts to cyclize to the title ring system 2-amino-1-carbamoylpyrroles 11 or the mono substituted 2-triazenopyrrole 12 failed. Compounds 10 were screened at the National Cancer Institute (NCI) for their activity against a panel of about 60 human tumor cell lines. Most of them possess remarkable antineoplastic activity having GI(50) values in the low micromolar or sub-micromolar range and reaching, in the case of compound 10d, nanomolar concentrations. The most sensitive cell lines were MDA-N and MDA-MB-435 of the breast sub-panel, and SR, K-562, HL60 (TB) and CCRF-CEM of the leukaemia sub-panel. SAR evaluation and COMPARE computations indicate, for compounds 10, a mechanism of action different from that of temozolomide.