Naphthalene combretastatin analogues: synthesis, cytotoxicity and antitubulin activity

Conformationally restricted macrocyclic analogues of combretastatins

New analogues of combretastatins have been evaluated as inhibitors of tubulin polymerization. These compounds present a macrocyclic structure, in which the para positions of the aromatic moieties have been linked by a 5- or 6-atoms chain, in order to produce a conformational restriction. This could contribute to determine the active conformation for these ligands. Such a conformational restriction and/or the steric hindrance makes them less potent inhibitors than the model compound CA-4.

Naphthylnitrobutadienes as pharmacologically active molecules: evaluation of the in vivo antitumour activity

On the basis of our previous interesting results in vitro on the antiproliferative activity of (1E,3E)-1,4-bis(1-naphthyl)-2,3-dinitro-1,3-butadiene (1-Naph-DNB) we have designed and synthesized the new molecule methyl (2Z,4E)-2-methylsulphanyl-5-(1-naphthyl)-4-nitro-2,4-pentadienoate (1-Naph-NMCB) characterized by the same naphthylnitrobutadiene array but with a different functional group at one end of the diene system. This new molecule showed an in vitro antiproliferative activity more significant than that found for the original 1-Naph-DNB. In order to verify in vivo our in vitro results we have tested the antitumour activity of 1-Naph-DNB and 1-Naph-NMCB in several murine tumour models, namely the myelomonocytic P388 and the Lewis lung carcinoma 3LL in BDF1 mice, the melanoma B16 in C57Bl mice, the fibrosarcoma WEHI 164 in nude mice and, finally, the C51 colon cancer in Balb/c mice. In the case of 1-Naph-NMCB the analysis of the antitumour activity has been preceded by toxicological experiments on CD-1 mice, in order to determine the lethal (LD) and the maximal tolerated (MTD) doses together with the spectrum of histological alterations caused by its iv administration. The results obtained show that the modification of the original structure of 1-Naph-DNB according to the molecular-simplification strategy has led to an asymmetric nitrobutadiene array, i.e. that of 1-Naph-NMCB, endowed with an antitumour activity which is in some cases even better than that showed by the parental compound itself, together with differences in tumour selectivity and negligible histological toxic effects.A promising, versatile route to new, more active and/or safe nitrobutadiene derivatives has thus been positively tested.

Synthesis and biological activity of naphthalene analogues of phenstatins: Naphthylphenstatins

Novel phenstatin analogues with a 2-naphthyl moiety combined with either a 2,3,4- or a 3,4,5-trimethoxyphenyl ring have been synthesized, and their tubulin polymerization inhibiting and cytotoxic activities have been evaluated. The 2-naphthyl ring is a better replacement for the 3-hydroxy-4-methoxyphenyl ring in the phenstatin series than in the combretastatin series. For the naphthylphenstatins, the carbonyl is required, and the preferred orientation of the trimethoxyphenyl ring is the one found in combretastatins.

Cytotoxic 5-aryl-1-(4-nitrophenyl)-3-oxo-1,4-pentadienes mounted on alicyclic scaffolds

The 5-aryl-1-(4-nitrophenyl)-3-oxo-1,4-pentadienyl pharmacophore was incorporated into four series of compounds 1-4. Compounds 1a-g comprised a cluster of 3-arylidene-1-(4-nitrophenylmethylene)-2-oxo-3,4-dihydro-1H-naphthalenes while the analogues 2a-g consisted of a group of 6-arylidene-2-(4-nitrophenylmethylene)cyclohexanones. Three other compounds prepared in this study were 1-(4-nitrophenylmethylene)-3-(3,4,5-trimethoxyphenylmethylene)-2-oxo-2,3-dihydro-1H-indene 3a as well as two 5-arylidene-2-(4-nitrophenylmethylene)cyclopentanones 4a,b. The compounds were evaluated against human Molt 4/C8 and CEM T-lymphocytes as well as murine L1210 cells. In general, the compounds in series 1 displayed marked cytotoxicity having IC50 values in the 1-5 microM range while the related cyclohexyl analogues in series 2 were slightly less potent (IC50 figures were mainly 5-10 microM). The relative locations of two aryl rings present in all four series were considered to contribute significantly to bioactivity and may have accounted for the virtual absence of cytotoxic properties in series 3 and 4. Most of the compounds were administered intraperitoneally to mice using doses up to and including 300 mg/kg. No mortalities were noted. The inhibiting effect of most of the compounds towards Helicobacter pylori is noteworthy. The modes of action of representative compounds include the induction of apoptosis while some compounds weakly inhibited tubulin polymerisation and human N-myristoyltransferase.