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P Lelieveld

Publications and source records attributed to P Lelieveld.

At least 19 recordsLinked to original sources
PubMed1989

Synthesis, mechanism of action, and biological evaluation of mitosenes.

Mitosenes of both the pyrrolo- and pyrido[1,2-a]indole type have been prepared via modification of these heterotricyclic compounds. Several mitosenes have been studied for their reactions with nucleophiles under reductive conditions. The results of these experiments show that the biological activity of mitosenes is based on the mechanism of bioreductive activation. When both leaving groups at C-1 and C-10 in the mitosene are the same, the nucleophile preferably adds to C-10 under reductive conditions. All mitosenes were studied for their biological activities in vitro against L1210, WiDr, and A204. On the basis of these results a selection of three mitosenes was made for a more detailed biological evaluation. Several tumor model systems were used, viz. P388, human tumor xenografts, MAC 13, and MAC 16. The results of these studies show that mitosenes have a more limited range of activities than mitomycin C. Surprisingly, the in vivo activities of mitosene diol 8b and mitosene diacetate 10b against the gastric human tumor xenograft GXF 97 were very high and comparable with that of mitomycin C.

Animals↗
PubMed1989

Lipophilic analogues of sparsomycin as strong inhibitors of protein synthesis and tumor growth: a structure-activity relationship study.

Fourteen derivatives of sparsomycin (1) were synthesized. Six of them were prepared following a novel synthetic route starting from the L-amino acid alanine. Some physicochemical properties, viz. lipophilicity and water solubility, of selected derivatives were measured. The biological activity was tested in vitro in cell-free protein synthesis inhibition assays, in bacterial and tumor cell growth inhibition assays, and in the L1210 leukemia in vivo model in mice. Also for selected drugs the acute toxicity in mice was determined. Ribosomes from both an eukaryotic and a prokaryotic organism were used in the protein synthesis inhibition systems. A linear correlation between the lipophilicity parameters measured was observed. Water solubility and drug toxicity in mice were found to be linearly correlated with lipophilicity. All the derivatives studied are more lipophilic than 1. The deshydroxysparsomycin analogues (30-33) showed an interesting phenomenon: increase in hydrophobicity was accompanied by a considerable increase in water solubility. We found that an increase in hydrophobicity of the drug as a result of replacing the SMe group of 1 with larger alkylthio groups causes an increase in the biological activity of the drug. However, not only the hydrophobicity but also shape and size of the substituent are important; in the homologous series 1-9-10-11-12, 21-22-23-24, and 30-31-32-33, highest protein synthesis inhibitory and in vitro cytostatic activity is found with compounds 11, 23, and 32, respectively, and in comparison with the highly active n-butyl compound 10, the isomeric tert-butyl compound 13 is rather inactive. Polar substituents replacing the SMe group, i.e. Cl in 17 and 35, also render the molecule inactive. Substituting the bivalent sulfur atom for a methylene group decreases the drug's activity. This effect can be compensated for by increasing the length of the alkylsulfinyl side chain. The agreement between the results derived from cell-free and "in vivo" tests is good. The assays using ribosomes of bacterial and eukaryotic organisms give similar results although the latter seem to be more sensitive to changes in hydrophobicity of the drug. Our results confirm the presence of a hydrophobic region at the peptidyl transferase center of the ribosome; the interaction of sparsomycin with this region is more pronounced in the eukaryotic particles. The sparsomycin analogues 11, 23, and 30 show the highest antitumor activity against L1210 leukemia in mice, their median T/C values are 386, 330, and 216%, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

In vivo antitumor activity of sparsomycin and its analogues in eight murine tumor models.

Sparsomycin (Sm) is a known inhibitor of ribosomal protein synthesis with an attractive anticancer potential. Recently, several analogues of Sm which are more active than the parent drug were selected for further study on the basis of in vitro investigations. Six analogues as well as the parent drug were tested for their antitumor activity in eight in vivo murine tumor models: P388 and L1210 leukemias, RC renal cell carcinoma, B16 melanoma, C38 colon carcinoma, LL Lewis lung carcinoma, C22LR osteosarcoma and M5076 sarcoma. Sm itself appeared to have only borderline activity on L1210 leukemia. The analogues that were most active in vitro showed also the highest in vivo activity. The most sensitive tumors were RC, L1210 and P388. Minimal activity was found on B16 and no activity on C22LR, M5076, C38 and LL. The most active compounds are deshydroxy-Sm, ethyl-deshydroxy-Sm and n-pentyl-Sm. There was a considerable loss of activity when L1210 leukemia was implanted sc while the drugs were administered iv. Only one drug, ethyl-deshydroxy-Sm appeared to be active in this assay. No single most effective compound could be found in this study. The overall activity of Sm and its analogues is moderate. The three analogues which show high activity in three ascitic tumors will be further investigated using human tumor xenograft models.

Animals↗
PubMed1988

Pharmacokinetics and toxicity of mitomycin C in rodents, given alone, in combination, or after induction of microsomal drug metabolism.

The pharmacokinetics of mitomycin (MMC) was studied in Wistar rats. Up to five half-lives, the plasma concentration-time curve was biphasic. The AUC changed linearly with increasing doses between 0.5 and 7.5 mg/kg, which corresponds to 0.2 and 3 times the LD50 value in rats. Most of the drug was metabolized, and only 1%-2% and 10%-15% of the dose was eliminated unchanged by biliary and urinary excretion, respectively. The AUC of MMC at the LD50 is slightly less than that reported for the human MTD. Inoculation of MMC together with 5-fluorouracil and doxorubicin did not change the terminal half-life of MMC but decreased the total body clearance and the volume of distribution. The lack of significant influence of phenobarbital and 3-methylcholanthrene pretreatment on the terminal elimination half-life suggests that microsomal drug-metabolizing enzymes inducible by these compounds do not play a decisive role in the in vivo biotransformation of MMC.

Animals↗
PubMed1987

Three tumor sensitivity tests evaluated with mouse tumors.

The predictive value of three types of tumor sensitivity tests was evaluated using mouse tumors. Sensitivities of osteosarcoma C22LR, Lewis lung and M2661 carcinoma were determined for the following drugs: DNA interacting or alkylating agent (doxorubicin, cisplatin, 1,3-bis(2-chloroethyl)-1-nitrosourea, melphalan), antimetabolite (5-fluorouracil, methotrexate) and microtubule inhibitor (vinblastine, vincristine). Volume measurements of the subcutaneously growing tumors after treatment with the same drugs were considered to be the traditional reference system with which the results of the in vitro clonogenic assay, the labeled precursor incorporation assay and the subrenal capsule assay were compared. Results obtained with the in vitro clonogenic assay were highly reproducible. With the 1-h drug exposure technique the predictive accuracy was 71%. This result is in the same range as those found by others for human tumors. Predictive accuracy after continuous drug exposure was only 25%. Vinblastine, vincristine and cisplatin caused no inhibition of labeled precursor incorporation. However, the assay is too unreliable to use, due to the extreme variability when used with the other drugs. From 31 consecutively performed duplicate tests in the subrenal capsule assay, nine showed opposite results. This degree of disagreement between duplicate test results was considered too high to make reliable predictions of tumor sensitivity with this assay.

Animals↗
PubMed1987

Preclinical toxicology of platinum analogues in dogs.

A toxicology study of cis-diamminedichloroplatinum (II) (CDDP), aqua(1,1-bis-(aminomethyl)cyclohexane)sulfatoplatinum(II) (TNO-6), diammine(1,1-cyclobutanedicarboxylato)platinum(II) (CBDCA), cis-dichloro-trans-dihydroxo-cis-bis(isopropylamine)platinum-(IV) (CHIP) and ethylenediaminemalonatoplatinum(II) (JM-40) was carried out in dogs. The main purpose of the study was to compare the results with those obtained earlier in mice and rats and with the toxicology data in humans. Each platinum compound was tested in three dogs. Each dog received three intravenous bolus injections at intervals of 3 weeks. The compounds were administered in dosages of 1.2, 1.0, 12, 10 (or 6) and 10 mg/kg, respectively. Toxic death occurred for two dogs (both on day 54) from haematotoxicity (10 mg/kg CHIP) and renal toxicity (TNO-6), respectively. Serum urea nitrogen and creatinine concentrations were variable after TNO-6 and remained within normal values after treatment with the other compounds. Severe proteinuria was observed in all three dogs treated with TNO-6. Values returned to normal within 16 days. JM-40 did not cause significant proteinuria. CDDP, CBDCA and CHIP caused short-lasting and slight proteinuria. CHIP caused a severe reduction in the number of leukocytes and platelets, while the other drugs caused acceptable reductions. Except after the high dose CHIP regimen, haematotoxicity was of a transient nature. Vomiting in order of severity occurred after TNO-6, CHIP, CDDP and JM-40, while CBDCA did not cause any vomiting. The dogs were sacrificed 6 weeks after the last drug dose. Organs were fixed for histopathology to complete and support clinical-toxicological parameters. On the basis of the results from the single-dose study in dogs and those obtained earlier in mice and rats it can be concluded that the gain from the use of the dog as a prognosticator for organ toxicity in man was disappointing and limited to the prediction of vomiting.

Animals↗
PubMed1987

Structure-activity relationships of sparsomycin: modification at the hydroxyl group.

Ten analogues of the antibiotic sparsomycin were prepared and evaluated in several in vitro tests. Nine of them carry a modification at the hydroxymethylene group of the molecule, two have a disulfide bond instead of the S(O)-CH2-S moiety at the sulfur-containing side chain of the molecule. While the presence of the S-S group decreases the activity of the analogues in all the tests performed, the modification at the OH group has no deleterious effects on the activity when a polyphenylalanine synthesis assay is used in an Escherichia coli extract. The same modifications, however, diminish drastically the activity of the analogues when tested in a similar Saccharomyces cerevisiae extract. A polymerization system in the archaebacterium Halobacterium halobium extract behaves like the eukaryotic preparations. A discrepancy is also found between the results of the polymerization tests and those of the 'puromycin reaction' which is also less sensitive to the modified sparsomycin analogues. The results of cell growth inhibition tests in bacteria as well as in eukaryotic organisms agree only partially with the in vitro data.

Antibiotics, Antineoplastic↗
PubMed1987

Novel bioreductive mitosene and mitosane analogues of mitomycin C.

Mitosenes of both the pyrrolo- and pyrido[1,2-a]indole type have been prepared via a modified Madelung reaction of benzeneacetonitriles ortho-substituted with gamma- and delta-lactam moieties, respectively, followed by modification of the resulting heterotricyclic compounds. Some in vitro anti-tumour activity data of these novel compounds are rearrangement of 2-(1-pyrrolidinyl)-3-vinylquinone derivatives to 5,8-dioxo-1H-pyrrolo[1,2-a]indoles.

Animals↗
PubMed1977

Resolution of small G1 and G2 populations of L1210 leukemia by flow microfluorometric analysis aided by velocity sedimentation.

L1210 leukemic cells grown in vitro were subjected to kinetic analysis using a flow microfluorometer. A single broad peak was found for the DNA content distribution if unfractionated cells were used; prior fractionation using lg velocity sedimentation allowed the separation of small peaks with smaller (G1) and larger (G2) DNA contents from the dominant S phase peak with intermediate DNA content.

Animals↗
PubMed1976

Biologic activity of two derivatives and six possible metabolites of cyclophosphamide (NSC-26271).

The biologic activity in terms of survival of normal hematopoietic stem, osteosarcoma, and L1210 leukemia cells was determined for the following compounds:cyclophosphamide, its derivatives isophosphamide and trophosphamide, its possible metabolites nor-nitrogen mustard, hydroxylamine mustard, 4-ketocyclophosphamide, and and acrolein, and two substitutes for its primary active metabolite 4-hydroxycyclosphamide anhydro-dimer (4-hydroxy-CP-anhydro-dimer) and 4-hydroperoxycyclophosphamide (4-hydroperoxy-CP). On a molar basis none of the compounds shows a better therapeutic ratio between osteosarcoma and bone marrow stem cells than the parent compound. The therapeutic ratio between L1210 leukemia and normal cells is slightly better for 4-hydroperoxy-CP only. It may be concluded that the conversion of 4-hydroxy-CP-anhydro-dimer and 4-hydroperoxy-CP to the primary active metabolite 4-hydroxycyclophosphamide differs quantitatively. Moreover, it appears that by the use of these precursors a better therapeutic ratio might be obtained for some malignancies but not for others.

Acrolein↗