Biomedical subjects

Roberta Loddo

Publications and source records attributed to Roberta Loddo.

24 records · Page 2Linked to original sources

PubMed2002

Antitumor agents. 1. Synthesis, biological evaluation, and molecular modeling of 5H-pyrido[3,2-a]phenoxazin-5-one, a compound with potent antiproliferative activity.

The iminoquinone is an important moiety of a large number of antineoplastic drugs and plays a significant role in the nucleus of actinomycins, powerful, highly toxic, natural antibiotics that target DNA as intercalating agents. A series of polycyclic iminoquinonic compounds, 2-amino-3H-phenoxazin-3-one (1), 2-amino-1,9-diacetyl-3H-phenoxazin-3-one (2), 2-acetylamino-3H-phenoxazin-3-one (3), 3H-phenoxazin-3-one (4), 5H-pyrido[3,2-a]phenoxazin-5-one (5), and 5H-pyrido[3,2-a]phenothiazin-5-one (6), strictly related to the actinomycin chromophore, were synthesized for developing new anticancer intercalating drugs. The antiproliferative activity of these compounds, evaluated against representative human liquid and solid neoplastic cell lines, showed that 5 and its isoster 6 were the most active compounds inhibiting cell proliferation in a submicromolar range. Compound 5 was also evaluated against KB subclones (KBMDR, KB7D, and KBV20C), which overexpress the MDR1/P-glycoprotein drug efflux pump responsible for drug resistance. All the above KB subclones did not show altered sensitivity to the antiproliferative activity of 5. UV-vis and (1)H NMR spectroscopy experiments support the phenoxazinone 5/DNA binding. Molecular mechanics methods were used to build a three-dimensional model of the 5/[d(GAAGCTTC)]2 complex. Electrostatic interactions between the hydrogen of the positively charged pyridine nitrogen of 5 and the negatively charged oxygen atoms (O4' and O5') of the cytosine C5 residue together with stacking forces contribute to the high antiproliferative activity. The metal(II)-assisted synthesis procedure of 5 is described, and the formation mechanism is proposed.

Antineoplastic Agents↗

PubMed2002

Antitumor agents. 2. Synthesis, structure-activity relationships, and biological evaluation of substituted 5H-pyridophenoxazin-5-ones with potent antiproliferative activity.

New antiproliferative compounds, 5H-pyrido[3,2-a]phenoxazin-5-ones (1-10), 5H-benzophenoxazin-5-one (11), 5H-pyrido[2,3-a]phenoxazin-5-one (12), 5H-pyrido[3,4-a]phenoxazin-5-one (13), and 5H-pyrido[4,3-a]phenoxazin-5-one (14), were synthesized and evaluated against representative human neoplastic cell lines. The excellent cytotoxic activity of these polycyclic phenoxazinones, structurally related to the actinomycin chromophore, is discussed in terms of structural changes made to rings A and D (Chart 1). Electron-withdrawing or electron-donating substituents were introduced at different positions of ring A to probe the electronic and positional effects of the substitution. A nitro group in R(2) or in R(1) increases the cytotoxic activity, whereas electron-donating methyl groups in any position lead to 10- to 100-fold decreasing of the activity. The low antiproliferative activity of benzophenoxazinone 11 and pyridophenoxazinones 13 and 14 confirms the crucial role of pyridine nitrogen in the W position of ring D in DNA binding. The unexpected high activity exhibited by 12, which has the nitrogen in the X position, could be ascribed to a different mechanism of action, which needs further investigation.

Antineoplastic Agents↗

PubMed2002

Synthesis, biological evaluation, and binding mode of novel 1-[2-(diarylmethoxy)ethyl]-2-methyl-5-nitroimidazoles targeted at the HIV-1 reverse transcriptase.

A novel series of 1-[2-(diarylmethoxy)ethyl]-2-methyl-5-nitroimidazole (DAMNI) analogues were synthesized and tested in cell-based assays and in enzyme assays against HIV-1 recombinant reverse transcriptase (RT). Preparation of the new derivatives was performed by reacting the appropriate benzhydrols or the corresponding bromides with 1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole or the 3-hydroxypropyl homologue. Several compounds showed anti-HIV-1 activity in the submicromolar range. Structure-activity relationship studies suggested that meta substitution at one phenyl ring of the diarylmethane moiety strongly influences the antiviral activity. The 3,5-disubstitution at the same phenyl ring led to less potent derivatives. Molecular modeling and docking studies within the RT non-nucleoside binding site confirmed that DAMNIs, similar to other NNRTIs such as TNK-651 and delavirdine (BHAP U90152), assume a butterfly-like conformation that appears to be halfway between that of classical NNRTIs, such as nevirapine, HEPT, TBZ, TIBO, and DABOs, and the conformation of BHAPs. In particular, the diphenylmethane moiety mimics the wings whereas the 1-(2-methyl-5-nitroimidazolyl)ethane portion resembles the BHAP 5-methanesulfonamidoindole-2-carbonylpiperazine portion.

Animals↗

PubMed2002

Synthesis and evaluation for biological activity of 3-alkyl and 3-halogenoalkyl-quinoxalin-2-ones variously substituted. Part 4.

A new series of 3-isopropyl-, 3-trifluoromethyl- and 3-bromomethylquinoxaline-2-ones variously substituted on the benzo-moiety were synthesized and submitted to a preliminary in vitro evaluation for antibacterial, antifungal and anti-HIV activities. Furthermore, all compounds were also tested for cytotoxicity. Results of the screening showed that compound 10 exhibits moderate antimicrobial activity against Staphylococcus aureus (MIC = 33 microM), and that 25 and 26 showed interesting cytotoxicity versus mock-infected MT-4 cells. All the other compounds were inactive.

Anti-Infective Agents↗

PubMed2002

Pyrrolo[1,2-f]phenanthridines and related non-rigid analogues as antiviral agents.

The pyrrolo[1,2-f]phenanthridines 8-22 and the corresponding non-rigid analogues 23-41 were synthesised and their ability to inhibit the replication of HIV-1 was tested. Only the polycyclic derivatives 10, 11, and 13 showed a weak anti-HIV activity, whereas several pyrrolo-phenanthridines (8, 10, 16-18) were found to stimulate the multiplication of MT-4 cells at low concentrations. Derivative 10 demonstrated to possess the unique property of stimulating the multiplication of lymphocytes joined to HIV inhibition.

Anti-HIV Agents↗

PubMed2002

Synthesis and antiproliferative activity of 3-aryl-2-(1H-benzotriazol-1-yl)acrylonitriles. Part III.

A new series of 30 3-aryl-2-(1H-benzotriazol-1-yl)acrylonitriles were synthesized and tested for biological activity as part of our research in the antimicrobial and antitumor fields. In particular, title compounds were evaluated in vitro against representative strains of Gram-positive and Gram-negative bacteria (S. aureus, Salmonella spp), mycobacteria (M. fortuitum, M. smegmatis ATCC 19420 and M. tuberculosis ATCC 27294), yeast and mould (C. albicans ATCC 10231 and A. fumigatus). Furthermore, their antiretroviral activity against HIV-1 was determined in MT-4 cells together with cytotoxicity. In these assays title compounds and 47 additional derivatives described previously (P. Sanna, A. Carta, M.E. Rahbar Nikookar, Eur. J. Med. Chem. 35 (2000) 535-543; P. Sanna, A. Carta, L. Gherardini, M.E. Rahbar Nikookar, Farmaco 57 (2002) 79-87) were tested for their capability to prevent MT-4 cell growth. All compounds resulted devoid of antibacterial, antifungal and anti-HIV-1 activity. In anti-mycobacterial assays several compounds resulted active (MIC(50)=6.0-70 microM) against M. tuberculosis. However, since they showed cytotoxicity against MT-4 cells at lower concentrations (CC(50)=0.05-25 microM), their anti-mycobacterial activity was not selective. For this reason, the most cytotoxic compounds were also evaluated for antiproliferative activity against a panel of human cell lines derived from both hematological and solid tumors. Compound 34 resulted the most potent compound against the above human tumor-derived cell lines.

Acrylonitrile↗