Syntheses, antiviral activities and induced resistance mechanisms of novel quinazoline derivatives containing a dithioacetal moiety

A series of novel quinazoline derivatives containing a dithioacetal moiety were designed and synthesized, and their structures were characterized by 1H nuclear magnetic resonance, 13C nuclear magnetic resonance, and high-resolution mass spectrometry. Bioassay results indicated that compound 4b exhibited remarkable protective activity against cucumber mosaic virus (CMV, EC50 = 248.6 μg/mL) and curative activity against potato virus Y (EC50 = 350.5 μg/mL), which were better than those of ningnanmycin (357.7 μg/mL and 493.7 μg/mL, respectively). Moreover, compound 4b could increase the chlorophyll content in plants, improve photosynthesis, and effectively induce tobacco anti-CMV activity.

Design, Synthesis, Antiviral Bioactivity, and Defense Mechanisms of Novel Dithioacetal Derivatives Bearing a Strobilurin Moiety

A series of dithioacetal derivatives bearing a strobilurin moiety were designed and synthesized on the basis of our previous work. The antiviral activities of these compounds against Potato virus Y (PVY), Cucumber mosaic virus (CMV), and Tobacco mosaic virus (TMV) were systematically evaluated. Bioassay results indicated that C14 elicited excellent curative and protective activities against PVY, CMV, and TMV. The former had 50% effective concentrations (EC50) of 125.3, 108.9, and 181.7 μg/mL, respectively, and the latter had 148.4, 113.2, and 214.6 μg/mL, respectively, which were significantly superior to those of lead compound 6f (297.6, 259.6, and 582.4 μg/mL and 281.5, 244.3, and 546.3 μg/mL, respectively), Ningnanmycin (440.5, 549.1, and 373.8 μg/mL and 425.3, 513.3, and 242.7 μg/mL, respectively), Chitosan oligosaccharide (553.4, 582.8, and 513.8 μg/mL and 547.3, 570.6, and 507.9 μg/mL, respectively), and Ribavirin (677.4, 690.3, and 686.5 μg/mL and 652.7, 665.4, and 653.4 μg/mL, respectively). Moreover, defensive enzyme activities and RT-qPCR analysis demonstrated that the antiviral activity was associated with the changes of SOD, CAT, and POD activities in tobacco, which was proved by the related proteins of abscisic acid signaling pathway. This work provided a basis for further design, structural modification, and development of dithioacetal derivatives as new antiviral agents.

Sporulosol, a New Ketal from the Fungus Paraconiothyrium sporulosum

Sporulosol (1), a new ketal, together with four known compounds, has been isolated from the liquid fermentation cultures of a wetland-soil-derived fungus, Paraconiothyrium sporulosum. Its structure was elucidated primarily by NMR experiments, and was further confirmed by X-ray crystallography. Sporulosol was obtained as a racemic mixture and the resolved two enantiomers racemized immediately after chiral separation. Sporulosol appears to be the first ketal derived from a 6H-benzo[c]chromen-6-one and a benzofuranone unit. The compound showed modest cytotoxicity toward the human tumor cell line T24, with an IC₅₀ value of 18.2 µM.

Lactone Derivatives Produced by a Phaeoacremonium sp., an Endophytic Fungus from Senna spectabilis

Three new isoaigialones, A, B, and C (1-3), along with aigialone (4), were isolated from the crude EtOAc extract of a Phaeoacremonium sp., an endophytic fungus obtained from the leaves of Senna spectabilis. The structures of these compounds were elucidated based on the analysis of spectroscopic data. Compounds 2 and 4 were active against the phytopathogenic fungi Cladosporium cladosporioides and C. sphaerospermum. This is the first report of metabolites produced by an Phaeoacremonium sp., associated with S. spectabilis.

Chewing efficiency and occlusal forces in PMMA, acetal and polyamide removable partial denture wearers

PURPOSE

Thermoplastic materials, such as acetal (AC) and polyamide (PA), constitute an alternative to polymethyl methacrylate (PMMA) based resins as the materials for removable partial dentures. However, none of the previous studies compared chewing efficiency and occlusal forces in the wearers of dentures made of various materials. Therefore, the aim of this study was to determine and compare the chewing efficiency and occlusal forces in PMMA, PA and AC RPDs' wearers. The hypothesis was that the type of denture base material shows a significant effect on chewing efficiency (expressed as a degree of food fragmentation) and occlusal force.

METHODS

The experiment included the group of 30 patients using removable partial dentures. The dentures made of PMMA, acetal and polyamide were tested in each patient. Each denture was worn for 90 days, with a random sequence of the denture manufacturing and insertion. After 7, 30 and 90 days of each denture wear, chewing efficiency coefficient was determined with the aid of a sieving method, and occlusal force was measured with a dynamometer.

RESULTS

The use of dentures made of PMMA or acetal was reflected by a marked increase in chewing efficiency and occlusal force. None of these parameters changed significantly with the time of denture wear. Moreover, no significant correlation was found between chewing efficiency and occlusal forces.

CONCLUSIONS

Denture base material exerts significant effects on the degree of food fragmentation and the level of occlusal forces. The use of dentures and clasps made of materials with lower modulus of elasticity is associated with lower chewing efficiency and lower occlusal forces.

Substituted lactam and cyclic azahemiacetals modulate Pseudomonas aeruginosa quorum sensing

Quorum sensing (QS) is a population-dependent signaling process bacteria use to control multiple processes including virulence that is critical for establishing infection. The most common QS signaling molecule used by Gram-negative bacteria are acylhomoserine lactones. The development of non-native acylhomoserine lactone (AHL) ligands has emerged as a promising new strategy to inhibit QS in Gram-negative bacteria. In this work, we have synthesized a set of optically pure γ-lactams and their reduced cyclic azahemiacetal analogues, bearing the additional alkylthiomethyl substituent, and evaluated their effect on the AHL-dependent Pseudomonas aeruginosa las and rhl QS pathways. The concentration of these ligands and the simple structural modification such as the length of the alkylthio substituent has notable effect on activity. The γ-lactam derivatives with nonylthio or dodecylthio chains acted as inhibitors of las signaling with moderate potency. The cyclic azahemiacetal with shorter propylthio or hexylthio substituent was found to strongly inhibit both las and rhl signaling at higher concentrations while the propylthio analogue strongly stimulated the las QS system at lower concentrations.

A novel hemiacetal from the marine-derived fungus Penicillium citrinum

A novel hemiacetal, citrinacetal (1) was isolated from a marine-derived fungus Penicillium citrinum by column chromatography on silica gel, Sephadex LH-20 and semi-preparative HPLC. Its structure and stereochemistry was established on the basis of HR-ESI-MS, 1D and 2D NMR spectroscopic methods. The NMR spectrum showed this compound exists in solution as a mixture of two stereoisomers. The cytotoxic effect of compound 1 was evaluated in A-549, HL-60, HeLa, and K562 cancer cell lines. However, compound 1 only displayed weak cytotoxic activity on HL-60 cell, with IC50 value 77.4 micromol x L(-1).

Search for antifungal compounds from the wood of durable tropical trees

Research on antifungal compounds from the durable wood from French Guiana Amazonian forest trees highlights the correlation between the activity of their extracts against wood-rotting fungi and human pathogens. The fractionation of an ethyl acetate extract of Sextonia rubra wood led to the isolation of rubrenolide (1) and rubrynolide (2). The potential of compounds 1 and 2 is described through the evaluation of their activity against 16 pathogenic fungi and their cytotoxicity toward NIH-3T3 mammalian fibroblast cells.

Antiprotozoal, anticancer and antimicrobial activities of dihydroartemisinin acetal dimers and monomers

Nine dihydroartemisinin acetal dimers (6-14) with diversely functionalized linker units were synthesized and tested for in vitro antiprotozoal, anticancer and antimicrobial activity. Compounds 6, 7 and 11 [IC(50): 3.0-6.7 nM (D6) and 4.2-5.9 nM (W2)] were appreciably more active than artemisinin (1) [IC(50): 32.9 nM (D6) and 42.5 nM (W2)] against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of the malaria parasite, Plasmodium falciparum. Compounds 10, 13 and 14 displayed enhanced anticancer activity in a number of cell lines compared to the control drug, doxorubicin. The antifungal activity of 7 and 12 against Cryptococcus neoformans (IC(50): 0.16 and 0.55 microM, respectively) was also higher compared to the control drug, amphotericin B. The antileishmanial and antibacterial activities were marginal. A number of dihydroartemisinin acetal monomers (15-17) and a trimer (18) were isolated as byproducts from the dimer synthesis and were also tested for biological activity.

Polyacetal-diethylstilboestrol: A Polymeric Drug Designed for pH-triggered Activation

Those polymer anticancer-drug conjugates currently undergoing clinical evaluation have a tripartite structure; a water-soluble polymer, an anticancer agent and a pendant linker. To simplify the construct it would be attractive to develop anticancer polymer therapeutics that contain the bioactive agent as an integral part of the polymer backbone. The aim of this study was to utilise the reaction between a divinyl ethers and diols, to synthesise polyacetals incorporating a drug with bis-hydroxyl functionality into the polymer backbone. Degradation of the polymer backbone in the acidic environment of the lysosome or the extracellular fluid of some tumours would then trigger drug release eliminating the need for a biodegradable linker. A tert-polymerisation approach was used to incorporate non-steroidal oestrogen diethylstilboestrol (DES) into the mainchain of water-soluble polyacetals synthesised using as co-monomer PEG of Mw 2900 or 3400 g/mol. When PEG2900 was used the resultant polymer had a Mw of 18,900 g/mol, a Mw/Mn of 1.9 and a DES loading 4.3 wt.%. With PEG3400 the polymer Mw was 43,000 g/mol, Mw/Mn=1.8 and it had a DES loading 4.7 wt.%. 1H-NMR confirmed the presence of two distinct sets of acetal peaks, which correspond to the two possible mainchain acetals; from PEG at 1.25-1.3(d) and 4.7-4.8(q) ppm and from DES at 1.55-1.6(d) and 5.4-5.5(q) ppm. These were consistent with the acetal signals observed for the non-water-soluble co-polymer DES: tri(ethylene glycol) divinyl ether (TEGDVE) (1 : 2, Mw=6859 g/mol, Mw/Mn=1.3). When evaluated in vitro, the DES-polyacetal displayed greater cytotoxicity than DES against human and murine tumour cell lines (IC50=48 and 420 microg/ml against MCF-7 human breast cancer cells and IC50=97 and 560 microg/ml against B16F10 murine melanoma cells, respectively). These polymers showed no significant haemolysis at concentrations up to 20 mg/ml confirming suitability for further in vivo evaluation. An enhanced rate of hydrolytic degradation of the polymer backbone was seen at pH 5.5, (65% trans-DES released in 96 h), compared to pH 7.4 (4% trans-DES released in 96 h). These bioresponsive DES-polyacetals tert-polymers are the first water-soluble anticancer polymeric drugs designed for acidic pH-triggered release of a drug incorporated into the polymer mainchain. Their in vitro characteristics suggest further in vivo evaluation is warranted.

Thermal and spectrophotometric studies of new crosslinking method for collagen matrix with glutaraldehyde acetals

Despite the many existing crosslinking procedures, glutaraldehyde (GA) is still the method of choice used in the manufacture of bioprosthesis. The major problems with GA are: (a) uncontrolled reactivity due to the chemical complexity or GA solutions; (b) toxicity due to the release of GA from polymeric crosslinks; and (c) tissue impermeabilization due to polymeric and heterogeneous crosslinks formation, partially responsible for the undesirable calcification of the bioprosthesis. A new method of crosslinking glutaraldehyde acetals has been developed with GA in acid ethanolic solution, and after the distribution inside de matrix, GA is released to crosslinking. Concentrations of hydrochloride acid in ethanolic solutions between 0.1 and 0.001 mol/L with GA concentration between 0.1 and 1.0% were measured in an ultraviolet spectrophotometer to verify the presence of free aldehyde groups and polymeric compounds of GA. After these measurements, the solutions were used to crosslink bovine pericardium. The spectrophotometric results showed that GA was better protected in acetal forms for acid ethanolic solution with HCl at 0.003 mol/L and GA 1.0%(v/v). The shrinkage temperature results of bovine pericardium crosslinked with acetal solutions showed values near 85 degrees C after the exposure to triethylamine vapors.

Insect antifeedant sesquiterpene acetals from the liverwort Lepidolaena clavigera. 2. structures, artifacts, and activity

Clavigerin A ( 1) was isolated from the New Zealand liverwort Lepidolaena clavigera and shown to be a polyoxygenated bergamotane sesquiterpene with an unusual ring system. L. clavigera shows infraspecific variation, since 1 was the only clavigerin detected in a North Island collection, whereas the previously reported clavigerins B ( 2) and C ( 3) were found in South Island collections with no sign of 1. Three new clavigerins, 4- 6, were identified, but these are artifacts formed by alcoholysis of the acetoxy acetal group of the clavigerins 2 and 3, with either the extraction solvent ethanol or the RP column eluent methanol. The insect antifeedant and cytotoxic activities of these compounds are reported, and it is proposed that they act as hidden 1,4-dicarbonyl compounds.

Biological mechanisms of action of novel C-10 non-acetal trioxane dimers in prostate cancer cell lines

The mechanisms of action of three C-10 non-acetal trioxane dimers (TDs) were examined in human (LNCaP) and mouse (TRAMP-C1A and -C2H) prostate cancer cell lines. 1 (AJM3/23), 2 (GHP-TM-III-07w), and 3 (GHP-KB-06) inhibited cell growth with 3 being the most potent in C1A (GI50 = 18.0 nM), C2H (GI50 = 17.0 nM), and LNCaP (GI50 = 17.9 nM) cells. In comparison to a standard cytotoxic agent such as doxorubicin (GI50 = 45.3 nM), 3 (GI50 = 17.9 nM) inhibited LNCaP cell growth more potently. TDs induced G0/G1 cell cycle arrest in LNCaP cells and decreased cells in the S phase. These changes correlated with modulation of G1 phase cell cycle proteins including decreased cyclin D1, cyclin E, and cdk2 and increased p21waf1 and p27Kip1. TDs also promoted apoptosis in LNCaP cells with increased expression of proapoptotic bax. These results demonstrate that TDs are potentially useful agents that warrant further preclinical development for treatment of prostate cancer.

Effect of octadecanoyl acetal sodium sulphite series with different numbers of double bonds on their immunological and surface activities

The relationship between the immunological activities and their surface activities of octadecanoyl acetal sodium sulphite series containing different numbers of double bonds (HOU-C18:n; n = 1, Delta9; n = 2, Delta9,12; n = 3, Delta9,12,15) were studied. The results showed that HOU-C18:n were able to increase the carbon granular clearance rate K, the NK cell activity in spleen and the activity of lysozymes in serum as well as inhibit Staphylococcus aureus and lysozymes in vitro to some degree. As the number of double bonds in HOU-C18:n increased along with the hydrophobic properties and the ability to improve the immune activity, NK cell activity and lysozyme activity decreased, but the bacteriostatic activity increased. It is speculated that HOU-C18:n could improve immunity and bacteriostasis realised by the interaction between the hydrophobic chain and membranes of cells. From the results of the effects of HOU-C18:n on lysozymes in vivo and in vitro, it is speculated that HOU-C18:0 could initiate and greatly enhance lysozyme activity in serum by increasing the amount of lysozymes, while unsaturated HOU-C18:n might do so mainly by increasing the number of lysozymes.

Preparation and biological evaluation of some 1,2-O-isopropylidene-d-hexofuranose esters

The synthesis and biological evaluation of some new glycose esters bearing the 1,2-O-isopropylidene-d-hexofuranose functionality and belonging to the 3-O-acyl-d-allose and 6-O-acyl-d-glucose series are reported. When the results concerning cell growth inhibition are compared, it appears that the 6-O-acyl-d-glucose derivatives are more active than the 3-O-acyl-d-allose compounds. Within both 6-O-acyl-d-glucose and 3-O-acyl-d-allose derivatives, butyric esters displayed the highest inhibitory effects. Inhibition of cell growth is not associated with high induction levels of erythroid differentiation, despite the fact that pivaloates induce erythroid differentiation to an extent similar to that exhibited by previously reported molecules [Bioorg. Med. Chem. Lett.1999, 9, 3153-3158].

Chemotherapy of leishmaniasis part II: synthesis and bioevaluation of substituted arylketene dithioacetals as antileishmanial agents

Some novel aryl substituted ketene dithioacetals have been synthesized using novel synthetic methods. The compounds were screened against Leishmania donovani in hamsters for their activity profile. Some of the compounds inhibited 50-65% parasite growth at 50 mg kg(-1) x 5 days.

New Medium Oxacyclic O,N-Acetals and Related Open Analogues: Biological Activities

Attention is increasingly being focussed on the cell cycle and apoptosis as potential targets for therapeutic intervention in cancer. Taking 1-[(2-oxepanyl)]-5-fluorouracil previously prepared by us, we committed ourselves to increase the lipophilicity of this upper cyclohomologue of Ftorafur and prepared a series of bioisosteric benzannelated seven-membered 5-FU O,N-acetals to test them against the MCF-7 human breast cancer cell line. Benzo-fused seven-membered O,O-acetals or their acyclic analogues led to the expected 5-FU O,N-acetals (or aminals), in addition to six- and to 14-membered aminal structures and acyclic compounds. All the cyclic aminals provoked a G(o)/G(1)-phase cell cycle arrest, whereas Ftorafur, a known prodrug of 5-FU, and 1-[2-(2-hydroxymethyl-4-nitrophenoxy)-1-methoxyethyl]-5-fluorouracil (51) induced an S-phase cell cycle arrest. Although breast cancer is most often treated with conventional cytotoxic agents it has proved difficult to induce apoptosis in breast cancer cells and, consequently, improved clinical responses may be obtained by identifying therapies that are particularly effective in activating apoptosis. 1-(2,3-Dihydrobenzoxepin-2-yl)-5-fluorouracil (26) may be particularly useful in stimulating apoptosis in breast cancer. This compound is more potent as an apoptotic inductor than paclitaxel (Taxol). Finally, a fact that is worth emphasizing is that the cyclic and acyclic 5-FU O,N-acetals induce neither toxicity nor death in mice after one month's treatment when administered intravenously twice a week, with a 50 mg/kg dose each time. Taken together, the experimental findings provide evidence of specific anti-tumour activity of these new substances and warrant further evaluation in in vivo models of breast cancer to future clinical applications.

A New Class of Selective Myocardial Calcium Channel Modulators. 2. Role of the Acetal Chain in Oxadiazol-3-one Derivatives

In the framework of the continuing interest of this research group in the use of 8-aryl-8-hydroxy-8H-[1,4]thiazino[3,4-c][1,2,4]oxadiazol-3-ones (1) as calcium entry blockers, a number of acetals were synthesized and assayed "in vitro". All of them are structurally related to diltiazem and pyrrolobenzothiazines. The effect on the biological profile was measured by functional assays for a wide variety of acetal residues: saturated linear and branched chains, short and long unsaturated E and/or Z chains as well as benzyl and methylcyclohexyl residues. From selective assays on the most active derivative (5b) (EC(50) = 0.04 microM), which is 20 times more active than diltiazem (EC(50) = 0.79 microM), a muscarinic or adenosinic mechanism of action was excluded. A 3D QSAR model was obtained and validated with homologous literature data, and a virtual receptor scheme was derived for the unknown binding site. The following pharmacophoric features favorably affect the potency: one positively charged center, three lipophilic groups, and two hydrogen-bonding acceptor groups.

Hydrophobic Acetal and Ketal Derivatives of Mannopeptimycin-α and Desmethylhexahydromannopeptimycin-α: Semisynthetic Glycopeptides with Potent Activity Against Gram-Positive Bacteria

The effect of introducing hydrophobic groups onto the disaccharide portion of the mannopeptimycins has been examined. Under acid-catalyzed conditions dimethyl acetals and ketals react on the terminal mannose of the disaccharide moiety of mannopeptimycin-alpha and the cyclohexylalanyl analogue 2. The preferentially formed monofunctionalized 4,6-acetals and -ketals display potent antibacterial activities against Gram-positive microorganisms, including MRSA, PRSP, and VRE pathogens.

Ketene acetal and spiroacetal constituents of the marine fungus Aigialus parvus BCC 5311

Aigialone (1) and aigialospirol (2), two structurally unique compounds, were isolated from the mangrove fungus Aigialus parvus BCC 5311. The structure of the new ketene acetal 1 was elucidated by spectral analysis, and its relative stereochemistry was determined by X-ray crystallography. The stereochemistry of aigialospirol (2), elucidated by NMR spectral analysis, suggested that this compound is possibly derived from hypothemycin (3), a metabolite previously isolated from this same fungus.

Antimalarial and Antitumor Evaluation of Novel C-10 Non-Acetal Dimers of 10β-(2-Hydroxyethyl)deoxoartemisinin

Four series of C-10 non-acetal dimers were prepared from key trioxane alcohol 10beta-(2-hydroxyethyl)deoxoartemisinin (9b). All of the dimers prepared displayed potent low nanomolar antimalarial activity versus the K1 and HB3 strains of Plasmodium falciparum. The most potent compound assayed was phosphate dimer 14a, which was greater than 50 times more potent than the parent drug artemisinin and about 15 times more potent than the clinically used acetal artemether. In contrast to their potent activity versus malaria parasites, virtually all of the dimers expressed poor anticancer activity apart from the trioxane phosphate ester dimers 14a and 14b, which expressed nanomolar growth inhibitory (GI50) values versus a range of cancer cell lines in the NCI 60 human cell line screen. Further detailed studies on these dimers in vitro in HL60 cells demonstrate that both phosphate ester dimers (14a and 14b) are more potent than the anticancer agent doxorubicin. Interestingly, phosphate ester monomers 9c and 9d, antimalarially active in the low nanomolar region versus P. falciparum, are inactive as anticancer agents even at concentrations in the millimolar region. This observation emphasizes the importance of two trioxane units for high antiproliferative activity, and we propose that the nature of the linker in dimers of this type plays a crucial role in imparting potent anticancer activity.

Growth inhibition activity of thioacetal artemisinin derivatives against human umbilical vein endothelial cells

Thioacetal artemisinin derivatives, in particular, 10alpha-phenylthiodihydroartemisinins (5), 10beta-benzenesulfonyl-9-epi-dihydroartemisinin (9) and 10alpha-mercaptodihydroartemisinin (11), exhibit good growth inhibition activity against HUVEC proliferation at the concentration level of 1 microM.

New highly active taxoids from 9beta-dihydrobaccatin-9,10-acetals. Part 4

It was shown that a new taxane analogue 3, which exhibited both in vitro antitumor activity and in vivo efficacy by both i.v. and p.o. administration, was prone to be metabolized by human liver microsomes. We identified a major metabolite, M-1, generated by human liver microsomes as 20a, a hydroxylated compound at the pyridine ring of 3. To improve the metabolic stability of 3, we designed and synthesized new taxane analogues based on the structure of M-1, and obtained some compounds that maintained excellent antitumor activity and were scarcely metabolized by human liver microsomes.

Synthesis of the cyclic and acyclic acetal derivatives of 1-(3-C-ethynyl-beta-D-ribo-pentofuranosyl)cytosine, a potent antitumor nucleoside. Design of prodrugs to be selectively activated in tumor tissues via the bio-reduction-hydrolysis mechanism

We have designed and synthesized the acetal derivatives of 1-(3-C-ethynyl-beta-D-ribo-pentofuranosyl)cytosine (ECyd, 1), the 2',3'-O-nitrobenzylidene derivatives 2 and 3 and the 5'-O-(alkoxy)(nitrophenyl)methyl derivatives 6-10 as potential prodrugs of ECyd. These prodrugs can be selectively activated in tumor tissues via a bio-reduction-hydrolysis mechanism owing to the characteristic properties of tumor tissues, such as hypoxia and lower pH. Although the 2',3'-O-(4-nitrobenzylidene) derivatives 2 and 3 were converted bio-reductively into the corresponding 4-aminobenzylidene derivatives by rat S-9 mix, the reduction products, that is, the corresponding amino congeners 4 and 5, proved to be rather stable in an aqueous solution at pH 6.5 used as a pH model for acidic tumor tissues. In contrast, the 5'-O-(alkoxy)(4-nitropheny)methyl derivatives 6-8 were also reduced by rat S-9 mix to the corresponding amino congeners 11-13, which were hydrolyzed to release ECyd more effectively at pH 6.5 than at pH 7.4. Accordingly, the acyclic acetals 6-8 may be efficient prodrugs of ECyd, that are effectively reduced under physiological conditions releasing ECyd in acidic tumor tissues.

Enantiospecific antennal response of bark beetles to spiroacetal (E)-conophthorin

Optically pure synthetic enantiomers of (E)-conophthorin [(E)-7-methyl-1,6-dioxaspiro[4.5]decane], one of the volatiles affecting coniferophagous bark beetles, were tested on antennae of Ips typographus, I. duplicatus, I. subelongatus, Dendroctonus micans, and five Scolytus spp. by using combined gas chromatography-electroantennographic detection (GC-EAD). EAD dose-responses indicated that all three Ips species perceived only the naturally occurring and quantitatively dominant (5S,7S)-enantiomer, while its antipode, (5R,7R)-(E)-conophthorin was antennally inactive. Response thresholds for the Ips species were estimated as between 0.1 ng and 1 ng, or lower. The antennal responses of the Ips species caused by 100 ng of the (5R,7R)-enantiomer might be due to 1% impurity-(the active (5S,7S)-enantiomer) in the (5R,7R)-sample. At the 50-ng level, D. micans and five angiosperm Scolytus species (S. intracatus, S. mali, S. ratzeburgi, S. rugulosus, and S. scolytus) responded strongly to the (5S,7S)-enantiomer, while the (5R,7R)-enantiomer was antennally inactive. Currently updated knowledge on the natural occurrence, and electrophysiological and behavioral activity of (E)-conophthorin is summarized.

New highly active taxoids from 9 beta-dihydrobaccatin-9,10-acetals

To synthesize new highly active taxoids, we designed and synthesized 9 beta-dihydro-9,10-acetal taxoids. In vitro study of these analogues clearly showed them to be more potent than docetaxel.

Effect of surface material on electrostatic charging of houseflies (Musca domestica L)

Houseflies (Musca domestica L) accumulated electrostatic charges when walking over clean, uncharged dielectric surfaces. The charges elicited on a walking housefly by a range of materials were quantified, allowing a triboelectric series to be determined relative to M domestica. This ranged from surfaces that charged individuals positively, e.g. Correx (corrugated polypropylene) [.1 (+/- 4.2)pC], to those that applied a negative charge, e.g. clear cast acrylic [-14.9 (+/- 2.9)pC]. Maximum positive and negative charges accumulated by individual M domestica were +73 and -27 pC. Replicate measurements on the same fly and surface showed little variation. Variation between individuals was not related to sex and was not consistent between surfaces. Different materials charged M domestica significantly differently and individual flies had significantly different charging properties. Variation in temperature between 21.3 degrees C and 24.7 degrees C and humidity between 24% and 41% RH significantly affected charge accumulated by M domestica on some surfaces, although further experimentation is needed to confirm this. The implications of this work are discussed in relation to insect trap design and pollination biology.

Phosphorylated morpholine acetal human neurokinin-1 receptor antagonists as water-soluble prodrugs

The regioselective dibenzylphosphorylation of 2 followed by catalytic reduction in the presence of N-methyl-D-glucamine afforded 2-(S)-(1-(R)-(3, 5-bis(trifluoromethyl)phenyl)ethoxy)-3-(S)-(4-fluoro)phenyl-4-(5-(2- phosphoryl-3-oxo-4H,-1,2,4-triazolo)methylmorpholine, bis(N-methyl-D-glucamine) salt, 11. Incubation of 11 in rat, dog, and human plasma and in human hepatic subcellular fractions in vitro indicated that conversion to 2 would be expected to occur in vivo most readily in humans during hepatic circulation. Conversion of 11 to 2 occurred rapidly in vivo in the rat and dog with the levels of 11 being undetectable within 5 min after 1 and 8 mg/kg doses iv in the rat and within 15 min after 0.5, 2, and 32 mg/kg doses iv in the dog. Compound 11 has a 10-fold lower affinity for the human NK-1 receptor as compared to 2, but it is functionally equivalent to 2 in preclinical models of NK-1-mediated inflammation in the guinea pig and cisplatin-induced emesis in the ferret, indicating that 11 acts as a prodrug of 2. Based in part on these data, 11 was identified as a novel, water-soluble prodrug of the clinical candidate 2 suitable for intravenous administration in humans.

The novel NK1 receptor antagonist MK-0869 (L-754,030) and its water soluble phosphoryl prodrug, L-758,298, inhibit acute and delayed cisplatin-induced emesis in ferrets

The anti-emetic profile of the novel brain penetrant tachykinin NK1 receptor antagonist MK-0869 (L-754,030) 2-(R)-(1-(R)-(3,5-bis(trifluoromethyl)phenylethoxy)-3-(S)-(4-fluor o)phenyl-4-(3-oxo-1,2,4-triazol-5-yl)methylmorpholine and its water soluble prodrug, L-758,298, has been examined against emesis induced by cisplatin in ferrets. In a 4 h observation period, MK-0869 and L-758,298 (3 mg/kg i.v. or p.o.) inhibited the emetic response to cisplatin (10 mg/kg i.v.). The anti-emetic protection afforded by MK-0869 (0.1 mg/kg i.v.) was enhanced by combined treatment with either dexamethasone (20 mg/kg i.v.) or the 5-HT3 receptor antagonist ondansetron (0.1 mg/kg i.v.). In a model of acute and delayed emesis, ferrets were dosed with cisplatin (5 mg/kg i.p.) and the retching and vomiting response recorded for 72 h. Pretreatment with MK-0869 (4-16 mg/kg p.o.) dose-dependently inhibited the emetic response to cisplatin. Once daily treatment with MK-0869 (2 and 4 mg/kg p.o.) completely prevented retching and vomiting in all ferrets tested. Further when daily dosing began at 24 h after cisplatin injection, when the acute phase of emesis had already become established, MK-0869 (4 mg/kg p.o. at 24 and 48 h after cisplatin) prevented retching and vomiting in three out of four ferrets. These data show that MK-0869 and its prodrug, L-758,298, have good activity against cisplatin-induced emesis in ferrets and provided a basis for the clinical testing of these agents for the treatment of emesis associated with cancer chemotherapy.

Substance P-induced vasodilatation is mediated by the neurokinin type 1 receptor but does not contribute to basal vascular tone in man

AIMS

Following intravenous administration of its prodrug, L-758,298, we assessed the pharmacodynamics of L-754,030, a novel and highly selective NK1 receptor antagonist, by examining systemic haemodynamics and the blood flow responses to intra-arterial substance P infusion.

METHODS

Sixteen healthy male volunteers participated in a double-blind, randomised, placebo controlled crossover trial of L-758 298. Forearm blood flow was measured using venous occlusion plethysmography during intrabrachial substance P infusion (0.125-128 pmol min-1 ). In part 1, eight subjects received substance P infusions before and during placebo, 0.25 mg, 1 mg or 5 mg of L-758 298. In part 2, eight subjects received substance P infusions 24 h after placebo or 1.43 mg of L-758 298.

RESULTS

L-758 298 caused dose dependent inhibition of substance P induced vasodilatation (P<0.001). Placebo adjusted differences (95% CI) in baseline forearm blood flow, mean arterial pressure and heart rate showed no relevant changes with 5 mg of L-758 298 (>1400-fold shift in substance P response): 0.00 (-0.49 to +0.49) ml 100 ml-1 min-1, 1. 0 (-3.2 to +5.2) mmHg and 1.9 (-5.9 to +9.7) beats min-1, respectively. Twenty-four hours after 1.43 mg of L-758,298, there was approximately 34-fold shift in response to substance P induced vasodilatation (P<0.008) at plasma L-754 030 concentrations of 2-3 ng ml-1. L-758 298 was generally well tolerated without serious adverse events.

CONCLUSIONS

Substance P induced forearm vasodilatation is mediated by the endothelial cell NK1 receptor in man but endogenous substance P does not appear to contribute to the maintenance of peripheral vascular tone or systemic blood pressure.

Blockage of HIV-1 production through inhibition of proviral DNA synthesis by N,O-didecanoyl serinal dimethylacetal

Six serinal derivatives were synthesized and tested for their anti-human immunodeficiency virus type-1 (HIV-1) activity against HIV-1-infected cells. Of the 6 serinal derivatives tested, only N,O-didecanoyl serinal dimethylacetal (DDSD) was found to strongly suppress progeny virus production from acute HIV-1-infected CEM cells, while not suppressing the HIV-1 p24 production from latent HIV-1-infected ACH-2 cells after stimulation with phorbol 12-myristate 13-acetate. DDSD also inhibited the synthesis of HIV-1 proviral DNA at 20-50 microM, not only 1 h but also 24 h after HIV-1 infection. Taken together, DDSD is a potent inhibitor of HIV-1 production, and may become a unique leading compound for chemotherapy of acquired immunodeficiency syndrome.

Structural optimization affording 2-(R)-(1-(R)-3, 5-bis(trifluoromethyl)phenylethoxy)-3-(S)-(4-fluoro)phenyl-4- (3-oxo-1,2,4-triazol-5-yl)methylmorpholine, a potent, orally active, long-acting morpholine acetal human NK-1 receptor antagonist

Structural modifications requiring novel synthetic chemistry were made to the morpholine acetal human neurokinin-1 (hNK-1) receptor antagonist 4, and this resulted in the discovery of 2-(R)-(1-(R)-3, 5-bis(trifluoromethyl)phenylethoxy)-3-(S)-(4-fluoro)phenyl-4-(3-ox o-1 ,2,4-triazol-5-yl)methyl morpholine (17). This modified compound is a potent, long-acting hNK-1 receptor antagonist as evidenced by its ability to displace [125I]Substance P from hNK-1 receptors stably expressed in CHO cells (IC50 = 0.09 +/- 0.06 nM) and by the measurement of the rates of association (k1 = 2.8 +/- 1.1 x 10(8) M-1 min-1) and dissociation (k-1 = 0.0054 +/- 0.003 min-1) of 17 from hNK-1 expressed in Sf9 membranes which yields Kd = 19 +/- 12 pM and a t1/2 for receptor occupancy equal to 154 +/- 75 min. Inflammation in the guinea pig induced by a resiniferatoxin challenge (with NK-1 receptor activation mediating the subsequent increase in vascular permeability) is inhibited in a dose-dependent manner by the oral preadmininstration of 17 (IC50 (1 h) = 0.008 mg/kg; IC90 (24 h) = 1.8 mg/kg), indicating that this compound has good oral bioavailbility and peripheral duration of action. Central hNK-1 receptor stimulation is also inhibited by the systemic preadministration of 17 as shown by its ability to block an NK-1 agonist-induced foot tapping response in gerbils (IC50 (4 h) = 0.04 +/- 0.006 mg/kg; IC50 (24 h) = 0.33 +/- 0.017 mg/kg) and by its antiemetic actions in the ferret against cisplatin challenge. The activity of 17 at extended time points in these preclinical animal models sets it apart from earlier morpholine antagonists (such as 4), and the piperidine antagonists 2 and 3 and could prove to be an advantage in the treatment of chronic disorders related to the actions of Substance P. In part on the basis of these data, 17 has been identified as a potential clinical candidate for the treatment of peripheral pain, migraine, chemotherapy-induced emesis, and various psychiatric disorders.

Blockage of N-myristoylation of HIV-1 gag induces the production of impotent progeny virus

The role of the N-myristoylation of the human immunodeficiency virus type 1 (HIV-1) gag protein in ACH-2 cells was studied. The infectivity of HIV-1 from the cells stimulated with phorbol 12-myristate 13-acetate (PMA) was suppressed by pretreatment with N-myristoyl glycinal diethylacetal (N-Myr-GOA), a potent N-myristoylation inhibitor, and the blockage of myristoylation resulted in accumulation of immature gag precursors. The viral particles which budded from the non-N-Myr-GOA-treated ACH-2 cells stimulated with PMA exhibited a typical viral phenotype, whereas those which budded from the N-Myr-GOA-treated ACH-2 cells stimulated with PMA were twisted, as observed electron microscopically. In electron microscopic analyses with gold-labeled monoclonal antibodies to gag and env, gag and env were detected adjacent to each other in the PMA-stimulated ACH-2, but no env was detected in the cells treated with N-Myr-GOA. Taken together, the results suggest that the myristoylation of HIV-1 gag seems to be responsible for both maturation of gag and acquisition of HIV-1 infectivity.

Synthesis of N-(6-chloro-7-R-1,1-dioxo-1,4,2-benzodithiazin-3- yl)aminoacetaldehyde dimethyl acetals and their transformations into 8-chloroimidazo [1,2-b][1,4,2]benzodithiazine 5,5-dioxide derivatives with potential anti-HIV or anticancer activity

A series of N-(6-chloro-7-R-1,1-dioxo-1,4,2-benzodithiazin-3- yl)aminoacetaldehyde dimethyl acetals [IIa-IIh] was obtained by the reaction of 6-chloro-7-R-3-methylthio-1,4,2-benzodithiazine 1,1-dioxides [Ia-Ih] with aminoacetaldehyde dimethyl acetal. Cyclization of benzodithiazinylaminoacetaldehyde dimethyl acetals [IIa-IIh] with 98% sulfuric acid gave the appropriate 7-substituted 8-chloroimidazo[1,2-b][1,4,2]benzodithiazine 5,5-dioxides [IIIa-IIIh] in good to high yields. The structures of these compounds were established on the basis of elemental analysis and spectral data (IR, 1H and 13C NMR). Preliminary screening data indicated that compound [IIIa] exhibit moderate anti-HIV activity, and compounds [IIId-IIIg] anticancer activity.

Antibacterial neoclerodane diterpenoids from Ajuga lupulina

The whole plants of Ajuga lupulina afforded five compounds, including three new clerodane diterpenes, lupulins A-C (1-3), whose structures were elucidated by spectral methods. Among these compounds, lupulins A (1) and B (2) as well as the acid hydrolysate (5) of lupulin D (4) showed antibacterial activities against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli.

A synthetic C22 carotenoid inhibits carcinogen-induced neoplastic transformation and enhances gap junctional communication

In 10T1/2 cells several dietary carotenoids have previously been shown to be capable of inhibiting carcinogen-induced neoplastic transformation. Two synthetic novel compounds, a C22 carotenoid, C22-polyene-tetrone-diacetal, and a C28 carotenoid, C28-polyene-tetrone, have now been tested in this system. The C22 compound was active in completely inhibiting 3-methylcholanthrene-induced transformation at 10(-5) M when added during the post-initiation phase of carcinogenesis. Gap junctional intercellular communication was strongly upregulated at this concentration. This activity has previously been shown to be highly correlated with, and has been proposed to be mechanistically linked to, inhibition of transformation by carotenoids in 10T1/2 cells. In contrast, the C28 compound, previously reported to be more active as a singlet oxygen quencher than C22, did not demonstrate activity in 10T1/2 cells in either assay system. This lack of activity was not due to chemical instability or lack of cellular uptake: the C28 compound was more stable in cell culture medium over 7 days and achieved higher cellular levels than the C22 compound (5 x 10(-11) mol/10(6) cells versus 0.5 x 10(-11) mol/10(6) cells). The activity of the C22 compound was not due to toxicity, since transformation occurred in carcinogen-treated cultures after its removal; neither was it due to antiproliferative effects on transformed cells, since the C22 compound did not prevent focus formation by transformed cells in reconstruction experiments. The demonstration that synthetic carotenoids possess biological activities comparable to the most potent naturally occurring compounds suggest that rational synthesis of compounds with improved pharmacological properties should be possible.

Plasmalopsychosine, a novel plasmal (fatty aldehyde) conjugate of psychosine with cyclic acetal linkage. Isolation and characterization from human brain white matter

Through a systematic examination of basic (cationic) lipids separated on Folch's lower phase from extracts of human brain by cation exchange chromatography on carboxymethyl Sephadex in a chloroform/methanol mixture, followed by successive chromatographies on Florisil and Iatrobeads columns, five compounds of basic lipids were separated. Two major unknown compounds A and B and a minor unknown compound C were separated, in addition to minor compounds sphingosine and N,N-dimethylsphingosine. This paper describes the isolation and chemical characterization of major unknown compounds A and B, which were found only in the white matter but not in the gray matter of the human brain. Unmodified psychosine (galactosylsphingosine) was essentially undetectable under the experimental conditions. Unknown compounds A and B were identified as novel plasmal (fatty aldehyde) conjugates of psychosine with cyclic acetal linkage at the galactosyl residue of psychosine. Fatty aldehydes were identified as mainly palmital (16:0) and stearal (18:0). Sphingosine was identified as d18:1 sphingosine. Faster migrating compound A had 3,4-cyclic acetal linkage, and slower migrating compound B had 4,6-cyclic acetal linkage (where m is 14 or 16 and n is 12) as shown below. [formula: see text] Preliminary studies showed that compounds A, B, and C had a weak inhibitory effect on protein kinase C (PKC) and had no cytotoxic effect. In contrast, psychosine displayed a strong cytotoxicity and inhibitory effect on PKC. Therefore, the process controlling the addition or deletion of plasmal cyclic linkage to psychosine could be a crucial step in regulation of PKC, src, or other kinases susceptible to psychosine.

Synthesis and biological activity of galactopyranoside derivatives of 4'-demethylepipodophyllotoxin showing VP-16 (etoposide)-like activity

To investigate the role of the glucoside moiety in the biological activity of VP-16 (etoposide; 4'-demethylepipodophyllotoxin-ethylidene-beta-D-glucoside) and VM-26 (teniposide; 4'-demethyl-epipodophyllotoxin-thenylidene-beta-D-glucoside), a number of acetal and ketal derivatives of 4'-demethylepipodophyllotoxin (DMEP)-beta-D-galactoside were synthesized. The compounds synthesized included acetaldehyde, propionaldehyde, 2-thiophenecarboxaldehyde, phenylacetaldehyde and acetone derivatives. In contrast to the glucose derivatives, where the acetal ring is trans to the pyranose ring, in galactose derivatives it is located in the cis position. The activities of the above compounds have been measured in two different biological assays, based on cross resistance towards mutants exhibiting specific resistance to VP-16/VM-26-like drugs and DNA-strand breaks as measured by the alkaline elution technique. All of the above compounds showed specific cross resistance to VpmR mutants (mutants resistant to VP-16 and VM-26) and caused a dose-dependent enhancement in DNA-strand breakage, providing evidence that they possessed the same kind of biological activity as VP-16 and VM-26. The relative activities of the DMEP-galactose derivatives have been compared with the corresponding DMEP-glucoside compounds. These studies reveal that, for the acetal and ketal derivatives with small R groups (acetaldehyde and acetone derivatives), the activities in the two series are comparable. However, for derivatives with larger, more hydrophobic R groups (2-thiophene or phenylacetaldehyde), the glucoside derivatives showed about 8-10-fold higher activity in comparison with the corresponding galactoside compounds.

Human cellular src gene product: identification of the myristoylated pp60c-src and blockage of its myristoyl acylation with N-fatty acyl compounds resulted in the suppression of colony formation

A p60K protein in human colon adenocarcinoma tumor cell lines was identified as a myristoylated pp60c-src by fluorography and radioimmunoprecipitation analysis. Prevention of the myristoylation of pp60c-src was determined with N-fatty acyl glycinal compounds. Of the compounds tested, N-myristoyl glycinal diethylacetal, N-lauroyl glycinal diethylacetal, N-myristoyl glycyl glycinal diethylacetal, and N-myristoyl-4-aminobutyl-aldehyde diethylacetal strongly blocked the myristoylation, but N-decanoyl glycinal diethylacetal and N-palmitoyl glycinal diethylacetal did not. The myristoyl blocking compounds depressed colony formation, cell proliferation, and specific localization to the plasma membrane of pp60c-src. The results taken together suggest that myristoylation of the c-src oncogene product may be very important for tumorigenicity of c-src gene expressed cells.

2-Chloroacetaldehyde and 2-chloroacetal are potent inhibitors of DNA synthesis in animal cells

The effect of 2-chloroacetaldehyde, CAA, a metabolite of vinyl chloride and 2-chloroacetal, CAC, an ethyl diester of chloroacetaldehyde, on DNA synthesis in animal cells has been investigated. Both compounds drastically inhibited DNA synthesis at 10 to 20 microM. The inhibitory effect of the chemicals appears to be directly on DNA synthesis rather than on the uptake of thymidine or the formation of nucleotides. Residual DNA made in the presence of CAA had an average chain length of 300 nucleotides compared to a length of several thousand nucleotides in the absence of CAA. Synchronization experiments revealed that the inhibitory effect is reversible if 2-chloroacetaldehyde is removed within two hours but not after longer exposures.

Antimyristoylation of the gag proteins in the human immunodeficiency virus-infected cells with N-myristoyl glycinal diethylacetal resulted in inhibition of virus production

The gag proteins of human retroviruses such as human immunodeficiency virus (HIV-1) are specifically myristoylated in their amino termini (1, 2, 3). N-myristoyl glycinal diethylacetal (N-Myr-GOA) and other N-Myr-compounds (N-Myr-Gly-GOA, N-Myr-Gly-Gly-GOA and N-Myr-Gly-Gly-Gly-GOA) were newly synthesized and investigated for activity of antimyristoylation of these gag proteins and for influence on viral replication. Of the N-Myr-compounds tested, N-Myr-GOA most severely inhibited the protein myristoylation; N-Myr-Gly-GOA also inhibited it, but moderately. Furthermore, it was observed that N-Myr-GOA at 20 microM caused noticeable inhibition (about 80%) of the production of mature HIV in the HIV-1-infected MT-4 cells. In this system, N-Myr-GOA substantially inhibited more than 90% of the N-myristoylation of p17 gag protein produced in the HIV-1-infected MT-4 cells. These results suggest that the N-myristoylation of p17 gag protein of HIV-1 may be essential in its structural assembly or maturation.

Blockage of morphological transformation of chick embryo fibroblasts infected with Rous sarcoma virus by N-myristoyl glycinal diethylacetal in vitro

N-Myristoyl glycinal diethylacetal strongly inhibited morphological transformation of chick embryo fibroblasts infected with a temperature-sensitive mutant (tsNY68) of Rous sarcoma virus. Myristoylated or nonmyristoylated pp60v-src, which were expressed in tsNY68-infected cells in the absence or presence of the compound, were identified separately by fluorography or immunoblotting analysis after sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the [3H]myristate-labeled cell lysate. The results taken together suggest that the blockage of morphological transformation was caused by prevention of protein myristoylation of the transforming protein pp60v-src.

Analysis of lyso-platelet activating factor by negative ion gas chromatography/mass spectrometry of the nitrobenzal acetal derivatives

This paper describes the methods that have been employed for the quantification of platelet activating factor (PAF) and its principal metabolite, in biological matrices. In plasma PAF is rapidly hydrolysed to lyso-PAF, which is also the major precursor of PAF. Measurement of lyso-PAF has been accomplished by mass spectrometric methods using cyclic acetal derivatives of the alkyl glycerol produced after removal of the polar head group. We describe the preparation of a novel electron capture derivative for this glycerol and its behaviour under electron impact and negative ion mass spectrometry. High sensitivities have been achieved using the procedures described here.

Antimyristoylation of gag proteins in human T-cell leukemia and human immunodeficiency viruses with N-myristoyl glycinal diethylacetal

N-Myristoyl (N-Myr-) glycinal (aminoacetoaldehyde, GO) diethylacetal (A), which is abbreviated as N-Myr-GOA, and other N-Myr-compounds (N-Myr-Gly-GOA, N-Myr-Gly-Gly-GOA, and N-Myr-Gly-Gly-Gly-GOA) were newly synthesized and then employed for NH2-terminal antimyristoylation of structure proteins in the human T-cell leukemia virus (HTLV-I) and the human immunodeficiency virus (HIV). The protein myristoylation of structure proteins p19gag, of HTLV-I, and p17gag, of HIV, was determined separately, using radiolabeled myristic acid, in vitro. The radiolabeled proteins, after immunoprecipitation with an antiserum to adult T-cell leukemia (ATL) or the anti-p17gag monoclonal antibody of HIV, were identified as p19gag of HTLV-I and p17gag of HIV by fluorography after SDS-polyacrylamide gel electrophoresis (SDS-PAGE). The protein myristoylation was resistant to NH2OH-treatment. Of the N-Myr-compounds tested, N-Myr-GOA remarkably prevented the myristoylation of p19gag and p17gag, but N-Myr-Gly-Gly-GOA and N-Myr-Gly-Gly-Gly-GOA did not.

Preparation and screening of some new thioacetals, sulfones, and derivatives of 4-dichloromethylbenzoyl and 4-trichloromethylbenzoyl chloride as potential antimalarials

The preparation and screening of some potential antimalarials are reported. The new compounds which are inactive as antimalarials are several benzene-, benzyl-, and fluorene thioacetals, beta-disulfones derived from these thioacetals, alpha-chlorobenzyl sulfones, amides, and thioesters derived from 4-dichloromethylbenzoyl chloride and 4-trichloromethylbenzoyl chloride. The known compounds bis(4-aminophenyl)sulfone and 4'-aminophenyl-4-aminobenzene thiolsulfonate also were prepared and showed some antimalarial activity.