Synthesis and cytostatic activities of didemnin derivatives.

The highly cytostatic didemnins contain a 23-membered cyclopeptolide with a side chain attached to the backbone through the amine group of threonine. Thirty-six derivatives varying the side chain were prepared, but only compounds with D-MeLeu attached to threonine show remarkable biological activities. To protect the macrocycle from degradation by lipases the two ester bonds were replaced successively by amide bonds. Although these variations have a major effect on the conformation and rigidity of the ring, the compound which contains exclusively amide bonds is highly active, equivalent to acetyl-didemnin A.

Synthesis, structure and antitumor activity of new benz[d,e]isoquinoline-1,3-diones.

New benz[d,e]isoquinoline-1,3-diones related to mitonafide (CAS 54824-17-8) and amonafide (CAS 69408-81-7) with double substitution on the chromophore and branched side chains have been synthesized and their biological activity determined. Molecular modeling studies of 3a based on X-ray crystallographic data of mitonafide have shown that the aromatic system intercalates between GC steps of DNA. The in vitro cytotoxic test data using CX-1 and LX-1 cells showed higher cytotoxic activities in disubstituted derivatives compared to both lead compounds. Some of the compounds have been selected for in vivo test using L1210 tumor cells and CX-1 cells. Two of them (3b and 3j) have shown promising activity as good candidates for clinical development.

Synthesis of new derivatives of flavone-8-acetic acid.

The synthesis of new flavone-8-acetic acid derivatives is described. It is studied the influence of a dialkylaminomethyl group in the 3-position on the activity. None of the new compounds showed cytostatic activity.

Bis-naphthalimides: a new class of antitumor agents.

A series of bis-intercalators bearing the 1,8-naphthalimide chromophore has been synthesized and in vitro activities determined. Most compounds have higher activities in HT-29 than the leader compounds Mitonafide and Amonafide. One of them (22) was selected for in vivo studies and presents an interesting activity in MX-1 and OVCAR models. (22) also acts as antitopoisomerase II.

Synthesis and biological activity of new 1,8-diaza-2,9,10-anthracenetrione derivatives.

Diels-Alder heterocycloaddition reactions of 2,5,8-quinolinetriones and 1-azadienes afford 1,8-diaza-2,9,10-anthracenetriones, which are simple analogues of the antitumoral antibiotic diazaquinomicin A. Cytotoxicity in this series and antitumor activity of the lead compound, 6-methyl-1,8-diaza-2,9,10-anthracenetrione, are reported.

Monoclonal antibodies to human tumor necrosis factor alpha: in vitro and in vivo application.

Three stable murine hybridoma cell lines, which secrete monoclonal antibodies (mAb) to human tumor necrosis factor alpha (TNF alpha), were established. None of the monoclonal antibodies cross-reacted with lymphotoxin, interleukin 2 (IL 2) or Interferon gamma (IFN gamma). The highly species-specific monoclonal antibody, designated as mAb 195, neutralizes the cytotoxic activity of human and chimpanzee TNF alpha. This antibody was further used during in vivo studies to neutralize human TNF alpha in a murine animal model. The mAb 114 is a weakly neutralizing antibody that binds to a different epitope of TNF alpha than mAb 195. mAb 114 shows a wide range of cross-reactivity with TNF alpha of the following species: dog, pig, cynomolgus, rhesus, baboon and chimpanzee. The mAb 199 binds to human TNF alpha, but does not neutralize the cytotoxic activity. The epitope recognized by this mAb is in close proximity to mAb 114. A reproducible, sensitive immunoassay for human TNF7 alpha has been developed using the antibodies mAb 199 and mAb 195. The test is performed within 6 hr and detects TNF7 alpha in serum samples, with a limit of detection of 5 to 10 pg/mL.

Autostimulation of dihydrostreptomycin uptake in Bacillus subtilis.

In Bacillus subtilis it was shown that the membrane potential (delta psi) has to reach a threshold value of -180 to -190 mV for efficient uptake of dihydrostreptomycin to occur. The magnitude of delta psi is raised above this threshold, and dihydrostreptomycin uptake greatly enhanced, not only by dihydrostreptomycin itself (autostimulation) and by other miscoding aminoglycoside antibiotics, but also by puromycin, bacitracin and N,N'-dicyclohexylcarbodiimide. Stimulation of uptake by dihydrostreptomycin or puromycin was dependent on a specific interference with ongoing protein synthesis. Thus, chloramphenicol prevented the stimulating effect of puromycin by lowering the magnitude of delta psi. Although normally severely antagonizing streptomycin accumulation, K+, as well as spermidine and putrescine, which are known to stabilize ribosomes, consequently enhanced autostimulation of dihydrostreptomycin uptake in a K+-retention mutant with impaired protein synthesis. It is suggested that miscoding aminoglycosides and puromycin both enhance dihydrostreptomycin uptake by increasing delta psi due to ion fluxes, which are themselves caused by a dramatic stimulation of intracellular proteolysis of faulty proteins.

Variants deficient in phagocytosis of latex beads isolated from the murine macrophagelike cell line J774.

Variants that lack the ability to ingest latex beads were isolated from the mouse macrophagelike cell line J774. Carboxylated latex beads were derivatized with polylysine and then daunomycin by a carbodiimide method. Cells that ingested such beads were killed; variants that survived were isolated. Variants were detected at very low frequency and only after nitrosoguanidine mutagenesis. Of 11 independent isolates, 10 showed a lowered rate of uptake of polystyrene beads (without daunomycin). All of these proved normal in rate and extent of Fc-mediated phagocytosis. There was essentially no change in sensitivity to free daunomycin in the variants compared to the parent. These results support the previous hypothesis that there are differences in the metabolic routes of receptor-mediated and nonspecific phagocytosis.