Design, combinatorial chemical synthesis and in vitro characterization of novel urea based gelatinase inhibitors.

A novel series of hydroxamate/urea-based inhibitors of gelatinases has been discovered via solid-phase combinatorial chemistry. SAR of P1', P2', and P3' has been exploited and structures different from traditional succinate-based MMP inhibitors have been found.

Design, synthesis, and biological evaluation of conformationally constrained aci-reductone mimics of arachidonic acid.

An efficient and convergent synthesis has been developed for the production of 3,4-dihydroxy-5-[4-(2-((2Z)-hexenyl)phenyl)-3-(1Z)-but enyl]-2 (5H)-furanone (12d). This hydrophobic antioxidant is a stable conformationally constrained mimic of arachidonic acid (AA) (1) and its respective aci-reductone analogue (2). Pd(0)-catalyzed cross-coupling of 5-(3-butynyl)-3,4-dihydroxy-2(5H)-furanone (7) with 2-((2Z)-hexenyl)iodobenzene (8d) followed by Lindlar catalyzed hydrogenation produces 12d. Butynyl intermediate 7 is prepared from 2-(benzyloxy)-5-deoxyascorbic acid (15) by iodination (I2, PPh3, Imd), iodo substitution with lithium acetylide ethylenediamine complex (LiAEDA, HMPA, -5 degrees C), and benzyl group cleavage (Ac2O, Pyr, BCl3). The utility of this synthetic method was demonstrated by the synthesis of analogues 10e-k. Biological testing revealed that certain of these antioxidants inhibit both cyclooxygenase (COX) and 5-lipoxygenase (5-LO) with comparable efficacy as reported for aspirin and zileuton, respectively. The antioxidant activity of these aci-reductones, measured as a function of their inhibitory effect on CCl4-induced lipid peroxidation of hepatic microsomes, exceeds that produced by alpha-tocopherol. Synthetic routes and initial structure-activity relationships (SAR) for these novel mixed functioning antioxidants are presented.

Induction of DNA topoisomerase II-mediated DNA cleavage by beta-lapachone and related naphthoquinones.

Recent studies have suggested that 3,4-dihydro-2,2-dimethyl-2H-naphtho[1,2-b]pyran-5,6-dione (beta-lapachone) inhibits DNA topoisomerase I by a mechanism distinct from that of camptothecin. To study the mechanism of action of beta-lapachone, a series of beta-lapachone and related naphthoquinones were synthesized, and their activity against drug-sensitive and -resistant cell lines and purified human DNA topoisomerases as evaluated. Consistent with the previous report, beta-lapachone does not induce topoisomerase I-mediated DNA breaks. However, beta-lapachone and related naphthoquinones, like menadione, induce protein-linked DNA breaks in the presence of purified human DNA topoisomerase IIalpha. Poisoning of topoisomerase IIalpha by beta-lapachone and related naphthoquinones is independent of ATP and involves the formation of reversible cleavable complexes. The structural similarity between menadione, a para-quinone, and beta-lapachone, an ortho-quinone, together with their similar activity in poisoning topoisomerase IIalpha, suggests a common mechanism of action involving chemical reactivity of these quinones. Indeed, both quinones form adducts with mercaptoethanol, and beta-lapachone is 10-fold more reactive. There is an apparent correlation between the rates of the adduct formation with thiols and of the topoisomerase II-poisoning activity of the aforementioned quinones. In preliminary studies, beta-lapachone and related naphthoquinones are found to be cytotoxic against a panel of drug-sensitive and drug-resistant tumor cell lines, including MDR1-overexpressing cell lines, camptothecin-resistant cell lines, and the atypical multidrug-resistant CEM/V-1 cell line.

Inhibition of topoisomerase II by ICRF-193, the meso isomer of 2,3-bis(2,6-dioxopiperazin-4-yl)butane. Critical dependence on 2,3-butanediyl linker absolute configuration.

The bis(2,6-dioxopiperazine)s are a structurally and mechanistically unique class of topoisomerase II inhibitors that do not bind DNA and that do not stabilize topoisomerase II-DNA strand passing intermediates ("cleavable complexes"). The most effective topoisomerase II inhibitor in the bis(2,6-dioxopiperazine) series is ICRF-193 (meso or S*, R* isomer), with a meso 2,3-butanediyl linker connecting the dioxopiperazine rings. The two enantiomeric diastereomers, (R,R) and (S,S), of ICRF-193 possessing the two optically active 2,3-butanediyl linkers have been prepared from their respective optically pure 2,4-diaminobutanes via 2,3-diaminobutane-N,N,N',N'-tetraacetic acid, esterification, and imide formation. Both in vivo and in vitro assays for catalytic inhibition of topoisomerase II were employed to show that the (S,S)- and (R,R)-isomers are almost inactive as topoisomerase II inhibitors. The data indicate that the meso stereochemistry of the alkanediyl linker is crucial for activity and provides additional evidence that the cytotoxicity of the bis(2,6-dioxopiperazine)s is due to their ability to inhibit topoisomerase II.

Differential eudismic ratios in the antagonism of human platelet function by phenoxy- and thiophenoxyacetic acids.

The antilipidemic drug clofibric acid (CPIB) exhibits antiplatelet effects. In order to examine the role of enantioselectivity and hydrophobicity, the mono(desmethyl) enantiomers of 2-(4-chlorophenoxy)propanoic acid (CPPA), related butanoate homologs, 2-(4-chlorophenoxy)butanoic acid (CPBA), thioether relatives, 2-(4-chlorothiophenoxy)propanoic acid (CTPA) and corresponding butanoate homologs, 2-(4-chlorothiophenoxy)butanoic acid (CTBA) were studied. All compounds inhibit prostaglandin-dependent human platelet aggregation and serotonin secretion induced by ADP. For the phenoxy acid series, (+)-(R)-CPPA is 5-fold more potent than either (-)-(S)-CPPA or CPIB giving a rank order potency of (+)-(R)-CPPA > (+)-(R)-CPBA > (-)-(S)-CPPA > (-)-(S)-CPBA. With the exception of (-)-(S)-CTPA, all thiophenoxy acid enantiomers are less potent than their respective phenoxy acid isomers [(+)-(R)-CTPA > (-)-(S)-CTPA > (+)-(R)-CTBA > (-)-(S)-CTBA]. The same rank order of potencies are observed against responses induced by arachidonic acid (AA) with the exception of CPIB which is inactive. However, inhibition of thrombin-induced [3H]-AA release by phenoxyacetic acids is not stereoselective but correlates with hydrophobicity.

Beta-lapachone-mediated apoptosis in human promyelocytic leukemia (HL-60) and human prostate cancer cells: a p53-independent response.

beta-Lapachone and certain of its derivatives directly bind and inhibit topoisomerase I (Topo I) DNA unwinding activity and form DNA-Topo I complexes, which are not resolvable by SDS-K+ assays. We show that beta-lapachone can induce apoptosis in certain cells, such as in human promyelocytic leukemia (HL-60) and human prostate cancer (DU-145, PC-3, and LNCaP) cells, as also described by Li et al. (Cancer Res., 55: 0000-0000, 1995). Characteristic 180-200-bp oligonucleosome DNA laddering and fragmented DNA-containing apoptotic cells via flow cytometry and morphological examinations were observed in 4 h in HL-60 cells after a 4-h, > or = 0.5 microM beta-lapachone exposure. HL-60 cells treated with camptothecin or topotecan resulted in greater apoptotic DNA laddering and apoptotic cell populations than comparable equitoxic concentrations of beta-lapachone, although beta-lapachone was a more effective Topo I inhibitor. beta-Lapachone treatment (4 h, 1-5 microM) resulted in a block at G0/G1, with decreases in S and G2/M phases and increases in apoptotic cell populations over time in HL-60 and three separate human prostate cancer (DU-145, PC-3, and LNCaP) cells. Similar treatments with topotecan or camptothecin (4 h, 1-5 microM) resulted in blockage of cells in S and apoptosis. Thus, beta-lapachone causes a block in G0/G1 of the cell cycle and induces apoptosis in cells before, or at early times during, DNA synthesis. These events are p53 independent, since PC-3 and HL-60 cells are null cells, LNCaP are wild-type, and DU-145 contain mutant p53, yet all undergo apoptosis after beta-lapachone treatment. Interestingly, beta-lapachone treatment of p53 wild type-containing prostate cancer cells (i.e., LNCaP) did not result in the induction of nuclear levels of p53 protein, as did camptothecin-treated cells. Like other Topo I inhibitors, beta-lapachone may induce apoptosis by locking Topo I onto DNA, blocking replication fork movement, and inducing apoptosis in a p53-independent fashion. beta-Lapachone and its derivatives, as well as other Topo I inhibitors, have potential clinical utility alone against human leukemia and prostate cancers.

Structure of 6-fluoro-1,2,3,4,7,12-hexahydro-7-methyl-12-methylene- benz[a]anthracene.

The X-ray analysis confirms the structure of the 12-methylene tautomer formed by the acid catalysis of 6-fluoro-1,2,3,4-tetrahydro-7,12-dimethylbenz[a]anthracene. The central C ring is in a boat conformation, with the result that the molecule is bent about a line through atoms C(7) and C(12) with a dihedral angle of 32.5 degrees. The cyclohexene A ring is in a half-chair conformation.

Inhibition of low density lipoprotein oxidation by thyronines and probucol.

Oxidation of low density lipoproteins (LDL) results in increased macrophage uptake of LDL which may contribute to the formation of macrophage-derived foam cells in the early atherosclerotic lesion. In this study we show that thyroxine (T4), its optical antipodes, certain desiodo analogs and probucol inhibited cupric sulfate-catalyzed oxidation of human LDL in a concentration-dependent manner as assessed by measuring the electrophoretic mobility, thiobarbituric acid reactive substances (TBARS) and LDL degradation in mouse macrophages. In Cu(2+)-catalyzed LDL oxidation at 24 hr, the TBARS level was 80 nmol/mg LDL protein/24-hr incubation. The concentrations (microM) of each agent producing 50% inhibition in the formation of oxidized LDL (IC50) for TBARS, electrophoretic mobility and macrophage degradation, respectively, were 1.13, 1.27 and 1.30 for reversed triiodothyronine; 1.33, 1.80 and 1.27 for triiodothyronine; 1.33, 1.37 and 1.37 for racemic thyroxine, DL-T4; 1.10, 1.40 and 1.50 for L-T4; 1.13, 1.33 and 1.23 for D-T4; and 1.47, 1.63 and 1.37 for probucol. No differences in inhibitory potency were observed when rT3, T3, the optical antipodes of T4 and the hydrophobic antioxidant drug probucol were compared. In air-induced LDL oxidation, TBARS was 16.1 nmol/mg LDL protein/6-hr incubation. The IC50 concentrations (microM) for TBARS and diene conjugation, respectively, were 0.187 and 0.336 for D-T4; 0.205 and 0.243 for L-T4 and 1.30 and 3.02 for probucol. With air-induced LDL oxidation conditions, the L-T4 concentrations included the physiological range, and thyroid-binding globulin did not modify the inhibitory effect of the endogenous enantiomer, L-T4. Putative uptake of this stereoisomer into LDL inhibited oxidation of these lipoproteins. Since concentrations of these thyronines which blocked air-induced LDL oxidation were in the physiological range, we conclude that thyronines, like the pharmacological agent probucol, limit the oxidative modification of LDL and thus may serve as natural inhibitors of atherogenesis.

Aci-reductones enhance interleukin-2-induced lymphocyte cytotoxicity.

Arachidonic acid (AA) metabolites and reactive oxygen species (ROS) are implicated in the suppression of interleukin-2 (IL-2) activity. We investigated the effects of aci-reductones, compounds that function both as inhibitors of AA metabolism and as scavengers of ROS, on the generation of IL-2-induced, lymphokine activated killer (LAK) activity. Aci-reductones belonging to the 4-aryl-2-hydroxytetronic acid system improved the in vitro generation of LAK activity from IL-2-treated human peripheral blood mononuclear cells (PBMC) approximately 4-fold. Those aci-reductones belonging to the 3,4-dihydroxyhenzofuranone class were less effective. LAK activity improvement was comparable to that produced by indomethacin with superoxide dismutase plus catalase and comparable to the improvement produced by depleting PBMC of monocytes. Aci-reductones completely suppressed the production of prostaglandin E2 from PBMC in response to IL-2 and partially suppressed superoxide anion production. Daudi cell and lymphocyte subset proliferation and monocyte viability were not affected. Less improvement in LAK activation was observed when PBMC depleted of monocytes were exposed to IL-2 and aci-reductones. We conclude that aci-reductones improve LAK generation from PBMC in vitro. This property may be mediated via effects on monocyte AA and ROS metabolism.

Modulation of carcinogenicity in 1,2,3,4-tetrahydro-7,12- dimethylbenz[a]anthracene (THDMBA) by fluorine substitution: crystal structures of the 5- and 6-fluoro regioisomers.

1,2,3,4-Tetrahydro-7,12-dimethylbenz[a]anthracene (THDMBA) is an animal carcinogen which lacks an aromatic bay-region and shows promise as a model to investigate non-classical mechanisms of carcinogenesis. The fluorine-substituted derivatives at positions 5 and 6 on the B-ring exhibit a striking range of oncogenic potential wherein the 6F-THDMBA is twice as potent as the parent carcinogen, but the 5F-THDMBA is virtually inactive. To study structure-reactivity relationships for these fluorine regioisomers, we have determined the three-dimensional structures of the compounds by single-crystal X-ray diffraction. These crystal structures are the first such to be reported for any monofluoro anthracene (or pyrene) derivative. The partially-reduced A-ring exists in both enantiomeric half-chair conformers in the crystalline state, and the compounds have quasi-planar anthracene ring systems which exhibit a right-handed twist in the 'beta'-conformer, with the expected opposite twist in the other. A complete analysis of bond lengths, bond angles and torsion angles is presented. Preliminary electrostatic potentials have been derived from the X-ray data sets, and the results indicate significant differences in potential between 5F- and 6F-THDMBA at positions near the partially reduced bay region. Such results are likely to be of importance in the understanding of metabolic activation to reactive intermediates capable of bonding covalently to DNA.

Comparative metabolism in vitro of a novel carcinogenic polycyclic aromatic hydrocarbon, 1,2,3,4-tetrahydro-7,12-dimethylbenz[a]anthracene, and its two regioisomeric B-ring fluoro analogues.

A novel biotransformation pathway likely exists for carcinogenic 1,2,3,4-tetrahydro-7,12-dimethylbenz[a]anthracene (THDMBA), since this A-ring-reduced polycyclic aromatic hydrocarbon does not have an aromatic bay-region. The comparative metabolism of THDMBA, a non-carcinogenic 5F analogue, and a more carcinogenic 6F-THDMBA species was examined to determine potential DNA-bonding metabolites. Rat liver microsomes from phenobarbital-treated animals were incubated in the presence of THDMBA (or fluoro-THDMBA), NADPH, and O2. Metabolic products and the parent compound were extracted into organic solvent and analyzed/purified using reversed-phase high-performance liquid chromatography. Structure identification of metabolites using proton nuclear magnetic resonance, mass spectroscopy, and ultraviolet/visible spectroscopy indicated that hydroxylations at benzylic C1 and at the C7- and C12-CH3 functions are major oxidation products of THDMBA. Major metabolites for the noncarcinogenic 5F-THDMBA are the C4-hydroxy, C7-hydroxymethyl, and C12-hydroxymethyl derivatives. However, the potent carcinogen 6F-THDMBA only yielded major hydroxylation products at C1 and C12-CH3. These results together with a consideration of the electronic and steric effects of fluorine and the biological activities of these polycyclic aromatic hydrocarbons suggest that hydroxylation at the hindered benzylic C1 position or the C12-CH3 group of THDMBA is important for the biotransformation of such polycyclic aromatic hydrocarbons to DNA-bonding species.

In vivo and in vitro peroxisome proliferation properties of selected clofibrate analogues in the rat. Structure-activity relationships.

We have examined, relative to clofibric acid (CPIB), the effects of a chemical series of phenoxyacetic acids and of two asymmetric CPIB analogues, the R(+)- and S(-)-enantiomers of 2-(4-chlorophenoxy)propionic acid (4-CPPA) and 2-(4-chlorophenoxy)butyric acid (4-CPBA), on hepatic peroxisome proliferation both in vivo and in vitro utilizing cholesterol-fed rats and primary cultured rat hepatocytes respectively. Peroxisome proliferation was assessed by measuring changes in peroxisomal fatty acyl-CoA oxidase (FACO) and microsomal laurate hydroxylase (LH) activities as well as by electron microscopic examination of 3,3'-diaminobenzidine-stained liver slices. CPIB and enantiomers of 4-CPPA and 4-CPBA (0.6 mmol/kg/day for 7 days) produced hepatomegaly, lowered serum cholesterol levels, and caused 4.7- to 12.9-fold and 2.9- to 6.1-fold increases in hepatic FACO and LH activities, respectively, in cholesterol-fed rats. Electron micrographs of liver cells showed an increased number of peroxisomes from cholesterol-fed rats given S(-)-4-CPBA and CPIB. Likewise, these compounds (0.03 to 1.0 mM) induced FACO and LH in primary rat hepatocyte cultures after 72 hr. R(+)- and S(-)-Enantiomers of 4-CPPA produced similar concentration-dependent and maximal increases in both FACO and LH activities, whereas enantiomeric selectivity [S(-) greater than R(+)] for the induction of these two enzymes was observed with the isomers of 4-CPBA. The increases in the activities of FACO and LH caused by S(-)-4-CPBA were similar to those elicited by 1.0 mM CPIB (58.6- and 9.8-fold respectively). These results show that the enantiomers of 4-CPPA and 4-CPBA induce the peroxisome proliferation-associated enzymes FACO and LH in vivo and in vitro, and that the S(-)-isomer of 4-CPBA causes a greater induction of FACO and LH in vitro than its corresponding R(+)-isomer, indicating that these two enzymes are induced in an enantioselective manner. Optimal induction of the peroxisome proliferation-associated enzymes FACO and LH in rat hepatocyte cultures was produced by phenoxyacetic acids possessing (1) a chlorine atom at the 4-position of the phenyl ring, (2) a dimethyl or mono-ethyl substitution at the alpha-carbon atom of the carboxylic acid side chain; and (3) an S(-)-orientation for chiral analogues possessing a mono-ethyl group at the alpha-carbon atom of the carboxylic acid side chain.(ABSTRACT TRUNCATED AT 400 WORDS)

Cytotoxicity, anchorage-independent growth, and DNA adduct formation in human neonatal fibroblasts by 1,2,3,4-tetrahydro-7,12-dimethylbenz(a)-anthracene (TH-DMBA), its six aryl fluoro regioisomers, and an exo methylene tautomer.

1,2,3,4-Tetrahydro-7,12-dimethylbenz(a)anthracene (TH-DMBA), its six possible fluorosubstituted regioisomers, and the C-7 exo methylene tautomer of the 11F derivative have been investigated for their cytotoxicity and for their ability to induce anchorage-independent growth and to form adducts in human neonatal foreskin fibroblasts. All compounds tested exhibited a low level of cytotoxicity, determined as percent cloning efficiency, up to a final concentration of 30 micrograms/ml. Except for 5F-TH-DMBA and the C-7 exo methylene tautomer, all compounds induced anchorage-independent growth of neonatal foreskin fibroblasts in soft agar at all concentrations tested (1, 3, 10 and 30 micrograms/ml). The C-7 exo methylene tautomer induced anchorage-independent growth only at a concentration of 10 micrograms/ml. Among the compounds tested the 6F derivative was the most effective compound at 1 microgram/ml. The D-ring fluoro isomers induced anchorage-independent growth at a frequency comparable to TH-DMBA itself, with the 11F derivative being the least effective of the four D-ring regioisomers. All compounds except 5F-TH-DMBA formed detectable adducts with cellular DNA as determined by 32P postlabeling procedures, when the cells were treated at 1 microgram/ml. Two adducts were detected in cells treated with TH-DMBA and four adducts were detected in DNA obtained from cells treated with 6F-TH-DMBA. The level of bonding for the D-ring fluoro isomers was quantitatively less and sometimes qualitatively different than that for TH-DMBA. For the D-ring compounds, the ability to induce anchorage-independent growth frequency correlated with the total quantity of adduct formed. The C-7 exo methylene tautomer formed a single adduct and the level of bonding was less than one adduct per 10(9) nucleotides. Analysis of these results led to the proposal that the planar anthracene ring structure (rings B, C, and D) of TH-DMBA and possibly oxidative metabolism at benzylic carbon 4 of the A-ring are important to DNA bonding and initiation of induction of anchorage-independent growth.

Mono and bis(bioreductive) alkylating agents: synthesis and antitumor activities in a B16 melanoma model.

Several potentially bis(alkylating) bis(quinones) (3-5) and 1,4- and 1,3-bis(alkylating) monoquinones (6-13) belonging to general structure 2,2'-ethylenebis[5-[(leaving group)methyl]-1,4-benzoquinone] (3-5) and 2,5- and 2,6-bis[(leaving group)methyl]-1,4-benzoquinone water-soluble and -insoluble classes were prepared by oxidative demethylation of the corresponding tetramethoxydiphenylethanes (17-19) and dimethoxybenzenes (24, 27, 36-39), respectively. Methods employed for the preparation of tetramethoxydiphenylethane intermediates involved (1) arylmethyl bromide coupling and (2) catalytic hydrogenation of stilbene intermediates derived via Wittig reaction of (arylmethyl)phosphonium salts with aryl aldehydes. However, in biological investigations using a subcutaneous B16 (hypoxic) melanoma tumor in BDF1 hybrid mice with cyclophosphamide as positive control the most interesting series of structurally related analogues were the potentially monoalkylating monoquinones of the 2-[(leaving group)methyl]-1,4-benzoquinone type (i.e., 14 and 15) having water-insoluble (acetoxy) and water-solubilizing (succinate) groups. Serial measurements of tumor size, and evaluation of increased life span, in response to drug treatment also revealed potentially 1,4-bis(alkylating) (bromomethyl)-1,4-quinone 7 and 1,3-bis(alkylating) (hydroxymethyl)-1,4-quinone 10 to have variable activity, but none of the potentially bis(alkylating) bis(quinones) showed antitumor properties in this model.

Pharmacologic effects of 4-chlorophenol in rats: comparison to clofibrate.

4-Chlorophenol (4-CP) is an identified trace contaminant in commercial clofibrate preparations and the pharmacologic effects of 4-CP have not yet been widely established. We have examined the dose-dependent effects of oral 4-CP and clofibrate administration on selected hepatic parameters and on serum glucose, cholesterol, and triglyceride concentrations in male rats. 4-CP treatment (0.00125-0.08 mmol/kg, twice a day) of rats for 2 weeks increased hepatic microsomal protein (20-30%) and cytochrome P-450 (20-190%) contents without changing liver/body weight ratios. Both 4-CP (0.0025 mmol/kg body wt, twice a day) and CPIB (0.4 mmol/kg body wt, twice a day) treatment to rats for 2 weeks caused significant elevations in microsomal cytochrome P-450 content and in the maximal activities of ethylmorphine, aminopyrine, and benzphetamine N-demethylase, but not in the activity of zoxazolamine 6-hydroxylase. With the same dose of 4-CP, time-dependent increases in hepatic microsomal protein, cytochrome P-450, and the activity of benzphetamine N-demethylase were observed for a 4-week period, and the induction of hepatic microsomal benzphetamine N-demethylase activity by 4-CP was associated with an increased enzyme synthesis. 4-CP treatment produced a marked morphologic change in liver cell ultrastructure, including a proliferation of mitochondria and endoplasmic reticulum at lower 4-CP doses. A clustering of intracellular organelles (mitochondria and endoplasmic reticulum) and a foamy cytoplasm were seen at doses greater than 0.01 mmol/kg, twice a day for 2 weeks, and at 0.0025 mmol/kg, twice a day for greater than 4 weeks. The effects of 4-CP and clofibrate on fasting blood glucose and fasting serum lipid levels were also monitored throughout an 8-week period. Both 4-CP (0.005 mmol/kg body wt, twice a day) and clofibrate (0.2 mmol/kg body wt, twice a day) produced significant elevations in fasting serum glucose levels, but this dosage of 4-CP did not alter serum lipid and lipoprotein parameters, whereas clofibrate significantly reduced serum total cholesterol and high density lipoprotein cholesterol levels. These results lead us to conclude that 4-CP does not contribute to the antilipidemic effects of clofibrate.

Potent antiplatelet effects of cyclic clofibric acid (CPIB) analogs on human platelets.

CPIB possesses antiplatelet as well as hypolipidemic activities. Two cyclic CPIB analogs, 6-phenylchroman-2-carboxylic acid (PCCA) and 6-cyclohexylchroman-2-carboxylic acid (CHCCA) were also found to be antagonists of the prostaglandin (PG)-dependent pathway of human platelet activation. PCCA and CHCCA were inhibitors of aggregation (AGG) and secretion (SEC) induced by ADP or epinephrine (E) [second waves only] and arachidonic acid (AA) with IC50 values ranging from 2.3-8.7 microM for PCCA and 3.7-12.1 microM for CHCCA. Neither compound antagonized the proaggregatory effects of the thromboxane A2 (TXA2) receptor agonist, U46619. CPIB blocked ADP and E-induced AGG and SEC (IC50's greater than 1200 microM) but not AA- or U46619-induced responses. Only CPIB blocked thrombin-induced AA release. Data showed that PCCA and CHCCA inhibited AA-induced malondialdehyde formation (IC50's = 9.3 and 11.3 microM, respectively) and thrombin-induced production of prostaglandin E2, prostaglandin F2 alpha, and TXB2 with IC50's ranging from 2.9 to 13.4 microM. PCCA and CHCCA were at least 200- to 500-fold more potent than CPIB as inhibitors of the PG-dependent pathway of human platelet activation. We conclude that PCCA and CHCCA act by inhibiting platelet cyclooxygenase activity whereas CPIB blocks the activity of phospholipase A2. Hypolipidemic PCCA and CHCCA represent a potent class of cyclooxygenase inhibitors which may be more useful than CPIB for treatment of atherosclerotic and thrombotic disorders.

Serum lipoprotein and apoprotein concentrations in 4-(4-chlorophenyl)-2-hydroxytetronic acid and clofibrate-treated cholesterol and cholic acid-fed rats.

Influence of clofibrate and an aci-reductone, 4-(4-chlorophenyl)-2-hydroxytetronic acid (CHTA) on lipoproteins and apoproteins was studied in cholesterol- plus cholic acid-fed rats. CHTA (0.4 mmol/kg body wt, twice daily) significantly lowered serum total cholesterol and triglyceride concentrations at both 10 and 16 days, whereas clofibrate at the same dose did not alter serum cholesterol levels, but elevated serum triglyceride concentrations at 16 days. The abnormal cholesterol-rich very low density lipoproteins (VLDL), intermediate density lipoproteins (IDL) and low density lipoproteins (LDL) produced by cholesterol plus cholic acid were significantly reduced in their cholesterol content by treatment with CHTA, a compound having an oxidation reduction potential. Conversely, clofibrate administration increased VLDL-cholesterol with concomitant decreases in IDL- and LDL-cholesterol concentrations. Administration of CHTA to cholesterol- plus cholic acid-fed rats significantly increased concentrations of VLDL and IDL, but had no effect on HDL protein. Both CHTA and clofibrate administration to cholesterol- plus cholic acid-fed rats significantly lowered IDL protein concentrations. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) studies of apoproteins revealed that clofibrate treatment significantly reduced apoC-III and C-II in VLDL, C-II in IDL, and apoA-IV and A-I in HDL. Rats treated with CHTA significantly raised apoC-II and C-III in HDL.(ABSTRACT TRUNCATED AT 250 WORDS)

Synthesis and P-388 antitumor properties of the four diastereomeric 1-hydroxy-3,4-diaminocyclohexane-Cl2PtII complexes.

Synthesis and antileukemic activity in vivo of the four diastereomeric 1-hydroxy-3,4-diaminocyclohexane-Cl2PtII complexes (Cl2PtII-3a-d) are described. Respective bis(phenylmethyl) (1 alpha,2 alpha,4 beta)-, (1 alpha,2 alpha,4 alpha)-, (1 alpha,2 beta,4 beta)-, and (1 alpha,2 beta,4 alpha)-(4-hydroxy-1,2-cyclohexanediyl)bis(carbamates) (5a, 5b, 7a, 7b) were prepared by hydroboration-oxidation of the bis(carbobenzoxyamino) derivatives (4,5) of cis- and trans-4,5-diaminocyclohexene. The relative stereochemistry of intermediates 5a and 5b was established by correlation with the alcohol obtained by NaBH4 reduction of bis(phenylmethyl) (1 alpha,2 alpha,3 alpha,4 alpha)-(3,4-epoxy-1,2-cyclohexanediyl)bis(carbamate) (8), the all-cis stereochemistry of which was unambiguously determined by X-ray crystallographic analysis. In the P-388 murine leukemia model these monohydroxycyclohexanediamine-PtII complexes were more effective than the PtII complexes of the related diol diamines 1a-e but were less active than the cisplatin positive control.