Recognition of pharmacophore of ar-turmerone for its anticancer activity

For the analysis of structure activity relationship of ar-turmerone analogues, the compounds containing the various substituents on the phenyl ring and 1(or 2)-naphthyl group in the place of phenyl of ar-turmerone were prepared and tested their cytotoxicity against HL-60, K-562, and L1210 leukemia cellsin vitro. The substituents at para position are methoxy, phenoxy, methyl, trifluoromethyl, fluoro, and chloro. Atmeta position methoxy, methyl, trifluoromethyl, or chloro groups and atortho position methoxy or chloro group were introduced. Against HL-60 and K-562 cells, ED₅₀ values of the analogues are ranged from 0.8 to 30.0 μg/ml. Against L1210 cell, these are located more than 20.0 μg/ml. However, 5-carboethoxy-2-methyl-6-(1-naphthyl)-2-octen-4-one (5n) possesses ED50 valuses 0.8, 2.1, 6.5 μg/ml against HL-60, K-562, L1210 cells, respectively. The electronic nature of the subsituents on phenyl ring of ar-turmerone dose not affect the biological activity. Therefore the flat structure of aromatic portion of ar-turmerone analogues is the more important factor for their activity rather than its electronic nature. The potentiation of the cytotoxicity with the enlargement of aromatic ring region also supports the importance of the plane structure of this area. The restriction of the single bond rotation between C-6 and aromatic ring through the introduction of substituents at theortho position of phenyl ring and the increment of size of alkyl group at C-6 position enhances the activity. Therefore the effective conformation should be the one having the orthogonal arrangement between the aromatic ring and the side chain.     

The role of substituents ofar-turmerone for its anticancer activity

For the evaluation of the role of substituents ofar-turmerone for its anticancer activity, ar-turmerone (1a) and its analogs like 2-methyl-6-(4′-methyphenyl)-2-octen-4-one (1b), 2-methyl-6-phenyl-2-hepten-4-one (1c), 2-methyl-6-phenyl-2-octen-4-one, (1d), and 2-methyl-6-(trans-4′-methylcyclohexyl)-2-hepten-4-one (1e) were prepared and their cytotoxic activities against L₁₂₁₀ cell were determined. Omission of methyl group atpara-position dose not variate the cytotoxicity of ar-turmerone. Elongation of alkyl group at 6-position decreases ED₅₀ value. Saturation of aromatic ring of ar-turmerone markedly decreases the cytotoxicity. Therefore the smaller size of alkyl group at 6-position and aromatic ring of ar-turmerone should be essential for exhibiting its anticancer activity.     

Relationship between structure and antineoplastic activity of arylsulfonylhydrazones of 2-formylprydine N-oxide

The effects of various structural modifications on the antineoplastic activity of the benzenesulfonylhydrazone of 2-formylpyridine N-oxide have been ascertained in mice bearing either Sarcoma 180 or leukemia L1210. To accomplish this a variety of derivatives substituted at the aldehyde proton, the aryl ring, and the 4 position of the pyridine nucleus were synthesized. Antineoplastic activity was retained when nitro, amino, chloro, bromo, fluoro, and methoxy groups were introduced into either the meta or para positions of the phenyl ring of the parent compound. In addition, substitution of the terminal phenyl group by a pyridine ring or by a bulky aromatic ring such as alpha-naphthyl, beta-naphthyl, or fluorenyl did not abolish the marked antitumor activity expressed by this class of agents. Insertion of a nitro function or a morpholino group in the 4 position of the pyridine nucleus of the benzenesulfonylhydrazone of 2-formylpyridine N-oxide resulted in two potent anticancer agents, while the introduction of a chloro function in the 4 position led to a pronounced decrease in biological activity. Furthermore, the essentiality of the aldehydic proton for tumor-inhibitor activity was demonstrated by the inactivity of two derivatives in which the aldehydic proton was replaced by a methyl group or by an oxygen atom.     

Antitumor activity of arylacetylshikonin analogues

Twenty one phenylacetylshikonin analogues were synthesized from various substituted phenyl acetic acids and their cytotoxicity values against A549, K562 and L1210 cell lines and antitumor action in mice bearing S-180 cells were measured. All of phenylacetylshikonin analogues expressed a potent cytotoxicity (ED₅₀, 0.1–1.80 μg/ml) against L1210 and K562 cells. L 1210 cells were the most sensitive to shikonin analogues among these cells. Except 4-methoxyphenylacetylshikonin (0.098μg/ml) and α-acetoxyphenylacetylshikonin (0.10μg/ml), all other shikonin derivatives showed higher ED₅₀ values than phenylacetylshikonin (0.13μg/ml) in L 1210. In K562 cell, α-substitution of phenylacetylshikonin (0.1 μg/ml), while other substitutions increased it slightly; 4-methoxyphenylacetylshikonin (0.033 μg/ml) showed a exceptionally good cytotoxicity against K562 cell. 4-Halogenation tended to decrease the cytotoxic effect on L1210 cells, while it enhanced the effect on K562; 4-bromophenylacetyl [ED₅₀ (L1210)=1.76 μ/ml, ED₅₀ (K 562)=0.32 μg/ml] and 4-chlorophenylacetyl shikonin [ED₅₀ (L 1210)=1.64 μg/ml, ED₅₀ (K562)=0.32 μg/ml]. In contrast, A549 cells were much less sensitive to these shikonin analogues which showed ED₅₀ values of 1.5–13.5 μg/ml. Most of phenylacetylshikonin derivatives showed good antitumor activity in mice bearing S-180 cells. α-A-cetoxyphenylacetylshikonin and 4-dimethylaminophenylacetylshikonin showed highest T/C value (192–195%), implying that introduction of α-acetyl or of 4-dimethyl amino group gave a positive effect on the antitumor activity. Introduction of 4-dimethylamino group enhanced the antitumor activity as shown for 4-dimethylaminophenylacetylshikonin (T/C, 192%). It might be due to improvement of water solubility by dimethylamino group in the molecule.     

Synthesis and biological evaluation of ceramide analogues with substituted aromatic rings or an allylic fluoride in the sphingoid moiety

The biological activity of synthetic ceramide analogues, having modified sphingoid and N-acyl chains, as well as fluorine substituents in the allylic position, was investigated in hippocampal neurons. Their influence on axonal growth was compared to that of C(6)-N-acyl analogues of natural ceramides. D-erythro-Ceramides with a phenyl group in the sphingoid moiety and a short N-acyl chain were able to reverse the inhibitory effect of fumonisin B(1) (FB(1)), but not of D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP), on accelerated axonal growth in hippocampal neurons. Moreover, we demonstrated that a ceramide analogue with an aromatic ring in the sphingoid moiety is recognized as a substrate by glucosylceramide synthase, which suggests that the observed biological effects are mediated by activation of the ceramide analogue via glucosylation. Introduction of a methyl, pentyl, fluoro, or methoxy substituent in the para position of the phenyl ring in the sphingoid moiety yielded partly active compounds. Likewise, substitution of the benzene ring for a thienyl group did not abolish the ability to reverse the inhibition of accelerated axonal growth by FB(1). Both D-erythro- and L-threo-ceramide analogues, having an allylic fluorine substituent, partly reversed the FB(1) inhibition.     

2-Amino-2-oxazolines,VII: Influence of Structural Parameters on the Antidepressant Activity of 5-(1-Aryl-4-piperazino)methyl-2-amino-2-oxazolines

A series of 5-(1-aryl-4-piperazino)methyl-2-amino-2-oxazolines has been prepared and screened for antidepressant activity. Their lipophilic behaviour has been discussed in relation to the nature and the position of substituents on the aromatic ring. The influence of steric effects on the pharmacological activity has been investigated using experimental methods (X-ray diffraction, NMR) and theoretical calculations (semi-empirical quantum mechanics). The ortho-substitution on the phenyl ring or the C-α substitution on the piperazine ring by a methyl group results in the same effects i.e. an increase of the angle between the two rings up to 64° (X-ray and calculation) and a loss of the antidepressant activity. Using NMR, only the influence of the ortho-substitution has been observed.     

Antitumor activity of pedunculagin,one of the ellagitannin

As a part of trials to develop the antitumor agent from tannins isolated from plants, the antitumor activity of pedunculagin, an ellagitannin, isolated fromAlnus hirsuta var.microphylla-was examinedin vitro andin vivo. In vitro, the cytotoxicity was determined by 0.4% trypan blue dye exclusion method. Pedunculagin showed the dose-dependent cytotoxicity against human chronic myelogenous leukemia (K-562), human promyelocytic leukemia (HL-60), mouse lymphoid neoplasm (P388), mouse lymphocytic leukemia (L1210) and mouse sarcoma 180 (S 180) cell lines. ED₅₀ values (ED₅₀) of each cell line were 5.30, 0.92, 2.78, 9.35 and 1.38 μg/ml respectively. The most sensitive cell line was HL-60.In vivo, pedunculagin was administered to ICR mouse with the doses of 50 and 100 μg/kg intraperitoneally once at 20 days before S180 inoculation. Pedunculagin showed the antitumor activity and its T/C ratio (%) was 120.82% in the group of both concentrations.     

New stereocontrolled synthesis and biological evaluation of 5-(1'-hydroxyalkyl)-3-methylidenetetrahydro-2-furanones as potential cytotoxic agents

A series of 3-methylidenetetrahydro-2-furanones 7 bearing various hydroxyalkyl substituents in position 5 were synthesized using novel diastereo- and enantioselective methodology. In vitro cytotoxicity data demonstrated that all prepared compounds were active against L-1210 and HL-60 tissue culture cells with 7e being the most potent (IC(50) = 6.9 microM). Also an increase in activity with an increase in lipophilicity of the substituents in the order H < alkyl < phenyl was observed.     

Inhibition of prostaglandin biosynthesis by 2-aryl-1,3-indandiones

The effect of several 2-aryl-1,3-indandiones on the biosynthesis of prostaglandin E₂ from arachidonic acid by bovine seminal vesicle microsomes was examined. 2-Phenyl-1,3-indandione appeared to be a weak inhibitor but by introducing electron-withdrawing substituents into the phenyl ring and augmenting lipophilicity, very active compounds were obtained. Activity, however, disappeared entirely on substitution in the ortho position. Inhibition was not related to the presence of an acidic group and was irreversible in some cases. The inhibition of prostaglandin biosynthesis by 2-aryl-1,3-indandiones showed no clear relationship with anti-inflammatory action.     

Nicotinic stimulant action of some tolyl and xylyl analogues of 1,1-dimethyl-4-phenylpiperazinium (DMPP)

1. The nicotinic stimulant properties of DMPP have been compared with those of its ortho-, meta- and para-tolyl analogues, and its 2,6- and 3,5-xylyl analogues, on the blood pressure of the cat and on the semispinalis cervicis muscle of the chick.

2. A single ortho-methyl group does not significantly change the nicotinic activity, but two such groups greatly reduce or abolish activity. Meta- or para-methyl substitution reduces activity, but does not abolish it.

3. The effect on nicotinic activity of methyl substitution in the phenyl ring of DMPP closely parallels the effect of ring-methyl substitution in phenyl choline ether.

4. Ortho-methyl substitution has been shown spectroscopically to alter markedly the spatial orientation of the phenyl ring of DMPP relative to the piperazine ring. The effect of these conformational changes on nicotinic activity is discussed in relation to a recent hypothesis concerning the conformation of acetylcholine required for interaction with nicotinic receptors.

5. The compounds tested had no muscarinic activity on the isolated guinea-pig ileum.

     

Synthesis and antimalarial activity of new 3-arylquinoxaline-2-carbonitrile derivatives

New series of 3-arylquinoxaline-carbonitrile derivatives have been synthesized from various 5-substituted or 5,6-disubstituted benzofuroxanes and tested for their in vitro and in vivo activity against the erythrocytic development of Plasmodium falciparum strain with different chloroquine-resistance status. Quinoxaline 1,4-dioxide derivatives showed superior antimalarial activity in respect to reduced quinoxaline analogues. The best activity was observed with nonsubstituted quinoxaline 1,4-dioxides in positions 6 and 7 of the aromatic ring and with a hydrogen or chloro substituent in para position of the phenyl group.     

Studies directed toward ascertaining the active conformation of 1,4-dihydropyridine calcium entry blockers

A series of unsymmetrically substituted 4-phenyl-1,4-dihydropyridine calcium entry blockers were investigated for their ability to relax potassium-contracted rabbit aortic smooth muscle and to competitively displace [3H]nitrendipine from its specific binding sites on guinea pig myocardial membranes in order to delineate the pharmacologically active conformer with respect to the position of the aromatic substituent (synperiplanar or antiperiplanar). The data show that the 1,4-dihydropyridine receptor distinguishes between 2',3'-disubstituted phenyldihydropyridines and 2',5'-disubstituted analogues as measured by changes of vasodilation and receptor affinity in vitro. The IC50 values for vasorelaxation by the analogues presented here correlate best with the Kd values for binding to the predominant receptor of two coexisting dihydropyridine binding sites in the guinea pig myocardium. We report the first observation of an antiperiplanar orientation of an o-phenyl substituent in the X-ray structure of 2-chlorophenyl analogue 3. Using nuclear Overhauser enhancement, we have developed a method that also demonstrates that an ortho (chloro or nitro) substituent on the phenyl ring does not preclude the presence of either synperiplanar or antiperiplanar phenyl rotamer in solution. These experimental findings contrast with the accepted belief that o-phenyl substituents essentially force these 1,4-dihydropyridines into the synperiplanar conformation exclusively.     

Quinoline antifolate thymidylate synthase inhibitors: variation of the C2- and C4-substituents.

Modifications to the bicyclic ring system of the potent thymidylate synthase (TS) inhibitor N-[4-[N-[(2-amino-3,4-dihydro-4-oxo-6- quinazolinyl)methyl]-N-prop-2-ynylamino]benzoyl]-L-glutamic acid (1, CB3717) have led to the synthesis of a series of quinoline antifolates bearing a variety of substituents at the C2 and C4 positions. In general the synthetic route involved the coupling of the appropriate diethyl N-[4-(prop-2-ynylamino)benzoyl]-L-glutamate with a disubstituted 6-(bromomethyl)quinoline followed by deprotection using mild alkali. The compounds were tested as inhibitors of partially purified L1210 TS. As a measure of cytotoxicity, the compounds were tested for their inhibition of the growth of L1210 cells in culture. Good enzyme inhibition and cytotoxicity were found for compounds containing chloro, amino, or methyl substituents at the C2 position with chloro or bromo substituents at C4. The effect on enzyme inhibition of varying the N10 substituent of 2h was similar to that observed in the quinazolinone-containing antifolates, indicating that the quinoline compounds may be interacting with the enzyme in a similar way to the quinazolinones. Also, the introduction of a 2'-fluoro substituent into the benzoyl ring of several of the quinoline antifolates led to an increase in both TS inhibition and the inhibition of L1210 cell growth. These data demonstrate that the N3-H of the pyrimidine ring of the quinazolinone antifolates is not required for binding to TS if appropriate substituents are placed at the C2 and C4 positions of the bicyclic ring system.     

Structure-activity studies of fentanyl

The preparation of analogues of fentanyl with para substituents in the anilino aromatic ring, anilino nitrogen separated from phenyl by methylene or bimethylene, and phenacyl replacing propionyl as the N-acyl substituent is reported. Although all para substituents examined depressed antinociceptive potency in rats, most analogues of this kind were more effective than morphine and the p-F, I, and Me derivatives were only a few-fold less active than fentanyl. Separation of anilino nitrogen from phenyl lowered potency with N-phenethyl analogues retaining reasonable levels of activity (greater than morphine). All the phenacyl analogues were of low potency or inactive. Diagnostic details of the mass spectra of analogues likely to be encountered as "designer drugs' are appended.     

The effects of ortho chloro substituents on the retention of PCB isomers in rat,rabbit, japanese quail,guinea pig and trout

A mixture of 2,2',4,4',6,6'-, 2,2',4,4',5',6-, 2,2',4,4',5,5'-, 2',3,4,4',5,5'- and 3,3',4,4',5,5'-hexachlorobiphenyls (HCBP) was administered by gastric lavage to rats, guinea pigs, rabbits, Japanese quail and trout, and the concentrations in the fat or whole carcass were determined after 29 days. The total HCBP levels in rat, rabbit and guinea pig fatty tissue were 8.27, 6.84 and 4.74 ppm, respectively: whereas 3.02 and 2.15 ppm of the HCBPs were detected in the trout and Japanese quail carcasses. The extent of ortho chloro substitution markedly affected the levels of the individual HCBP isomers retained in the test animals; the rabbit and guinea pig preferentially retained the HCBPs with 0,1 and 2 ortho chloro substituents, the Japanese quail retained only the 3,3',4,4',5,5'-HCBP isomer, whereas no striking preferences in HCBP isomer retention in the rat and trout were observed. The marked differences in the retention of HCBP isomers with 0, 1, 2, 3 and 4 ortho chloro substitution by different animal species should be considered in chronic toxicity studies since the most toxic polychlorinated biphenyls have minimal (1 or 0) ortho chloro substituents.     

Affinity of various ligands for benzodiazepine receptors in rat cerebellum and hippocampus

The structure-affinity relationship of benzodiazepine receptor ligands for binding to their receptors was investigated by measuring the potency of 41 benzodiazepines or benzodiazepine analogues and of 9 non-benzodiazepines for inhibition of [3H]flunitrazepam binding to cerebellar or hippocampal membranes. It was found that a chloro or a fluoro substitutent in position 2' enhanced whereas substituents in position 3 and substituents larger than a methyl group in position 1 of the benzodiazepine ring system reduced the potency of benzodiazepines for inhibition of [3H]flunitrazepam binding in cerebellum or hippocampus. In addition, several benzodiazepines could be identified which have a higher affinity for benzodiazepine receptors in cerebellum than for those in hippocampus. A selectivity of benzodiazepines for their receptors in cerebellum seems to be caused not only by certain substituents in position 1 but also by a chloro group in position 2' and together with this substituent by a hydroxy group in position 3.     

Methylenedioxy-benzopyran analogs of podophyllotoxin, a new synthetic class of antimitotic agents that inhibit tubulin polymerization

A new class of compounds was synthesized and, based on structural analogy to podophyllotoxin, examined as potential microtubule inhibitors and evaluated for in vivo antineoplastic activity. These agents are derivatives of methylenedioxy-benzopyran bearing a phenyl substituent at position 8. The hydrogen atoms at positions 7 and 8 are in a trans configuration, in contrast to the cis configuration of analogous hydrogen atoms at positions 1 and 2 in podophyllotoxin. Compounds with a variety of substituents at positions 6 and 7 were examined, as well as compounds with varying methoxy substituent patterns on the phenyl ring attached at position 8. The most active compounds inhibited tubulin polymerization at concentrations approximately stoichiometric with tubulin, competitively inhibited the binding of colchicine to tubulin, and caused mitotic arrest at cytotoxic drug concentrations. No structure-activity correlations were obvious for the substituents at positions 6 and 7, but optimal activity was only observed when the phenyl substituent at position 8 was a trimethoxybenzene ring identical to the analogous ring in podophyllotoxin (i.e. methoxy groups at positions 3', 4' and 5'). Despite their structural and functional similarities to podophyllotoxin, however, the methylenedioxy-benzopyran derivatives subtly differ from the natural product in their interaction with tubulin, for they stimulated rather than inhibited tubulin-dependent GTP hydrolysis.     

Quinazoline antifolate thymidylate synthase inhibitors: benzoyl ring modifications in the C2-methyl series

The synthesis of nine new 2-methyl-10-propargylquinazoline antifolates with substituents in the p-aminobenzoyl ring is described. In general the synthetic route involved the coupling of the appropriate ring-substituted diethyl N-[4-(prop-2-ynylamino)benzoyl]-L-glutamate with 6-(bromomethyl)-3,4-dihydro-2-methyl-4-oxoquinazoline followed by deprotection using mild alkali. The compounds were tested as inhibitors of partially purified L1210 thymidylate synthase (TS). They were also examined for their inhibition of the growth L1210 cells in culture. Compared to the parent compound 1a the 2'-fluoro analogue 2a exhibited enhanced potency in both systems whereas the 3'-fluoro analogue 3a showed enhanced growth inhibitory properties against L1210 cells despite being a poorer inhibitor of the isolated enzyme. Chloro, hydroxy, methoxy, and nitro substituents in the 2'-position were also well tolerated by the enzyme but failed to give enhanced growth inhibition. The series was extended to cover analogues of the 2'-fluoro, 3'-fluoro, 2'-chloro, 2'-methyl, 2'-amino, 2'-methoxy, and 2'-nitro derivatives with modified alkyl substituents at N10.     

Molecular features of colchicine associated with antimitotic activity and inhibition of tubulin polymerization

Seven selected colchicinc analogs have been studied for their ability to inhibit mitosis in HeLa cell culture and for their ability to inhibit tubulin polymerization in mouse brain supernatants in order to assess the molecular features of colchicine associated with these activities. A good correlation between the systems in vivo and in vitro was found for the compounds tested. It was found that for a substance to exhibit biologic activity it must contain the two aromatic ring systems and the phenyl ring must hear methoxy groups. The tropone ring is not necessary for activity in colchicinc since its conversion to a benzene ring in allocolchicine is accompanied by retention of biologic activity.     

Regioselective synthesis,biological evaluation,and molecular docking of dihydropyrimidin‐4‐ols as acetylcholinesterase inhibitors

A new series of 3,6‐disubstituted 2‐(methylthio)‐4‐(trifluoromethyl)‐3,4‐dihydropyrimidin‐4‐ols displaying methyl, phenyl, aryl, and heteroaryl groups at the 6‐position; and methyl, ethyl, allyl, and phenyl groups at the 3‐position of the dihydropyrimidine ring, were synthesized and evaluated in vitro for acetylcholinesterase inhibitory activity. Seven compounds showed activity with IC₅₀ values in the lower micromolar range. The compound 4‐trifluoromethyl‐6‐(4‐fluorophenyl)‐3‐methyl‐2‐methylthio‐3,4‐dihydropyrimidin‐4‐ol ( 6e ) had the best inhibitory activity (IC₅₀ 2.2 ± 0.9 μm ) and this inhibition was characterized as competitive. The molecular docking study showed that the acetylcholinesterase enzyme accommodates compound 6e in its catalytic site. The enantiomers of compound 6e , present similar interactions: π–π stacking interactions between the aromatic ring of the ligand's 4‐fluorophenyl moiety and the aromatic rings of the electron‐rich Trp84; and H‐bonds between the hydroxyl group of Tyr121 and the hydroxyl moiety from 6e . The antioxidant effect of the dihydropyrimidin‐4‐ols was also investigated.