Structural Properties of Covalently Crosslinked Gels as Probed by Scattering Techniques

This paper reviews some characteristic results obtained by scattering techniques in two sorts of swollen covalently crosslinked networks : neutral networks swollen by a good solvent and weakly ionized gels. For neutral networks swollen at saturation, the local conformation of the chains was found to be the same as in semi-dilute solutions, whereas some concentration inhomogeneities are observed at larger scale. Ionized gels are characterized by a peak of the structure factor and the absence of long range stationary concentration fluctuations at the concentration of preparation of the gels.

Synthesis and characterization of the antitumor activities of analogues of meridine, a marine pyridoacridine alkaloid

Marine compounds with pyridoacridine skeletons are known to exhibit interesting antitumor activities. Among these compounds, meridine has already been reported as having significant antitumor activities in vitro. We synthesized 24 analogues of meridine substituted on ring A with the aim of obtaining compounds that display significantly higher in vitro antitumor activities than meridine. The 24 compounds and meridine used as a control compound were tested at 6 different concentrations on 12 different human cancer cell lines including various histopathological types (glioblastomas and breast, colon, lung, prostate, and bladder cancers). The IC(50) value (i.e., the drug concentration inhibiting the mean growth value of the 12 cell lines by 50%) of these 25 compounds ranged over 5 log concentrations, i.e., between 10 and 0.0001 microM, with four of the compounds exhibiting a significantly higher in vitro antitumor activity than meridine. These compounds will now be subjected to further pharmacological investigation including in vivo testing on both conventional murine tumors and human tumors grafted onto nude mice.

The first synthesis of the pentacyclic pyridoacridine marine alkaloids: arnoamines A and B

The synthesis of the marine pyridoacridine alkaloids arnoamines A and B has been accomplished in six and seven steps from 4-chloro-8-methoxy-5-nitroquinoline in 13% and 4% overall yield, respectively.

Triflusulfuron-methyl dissipation in water and soil

This paper reports laboratory studies of the behavior and fate of triflusulfuron-methyl in aqueous buffer and soils. Aqueous hydrolysis was pH-dependent and fast in acidic buffer solutions. In basic buffers, the hydrolysis rate variation was low between pH 7 and pH 10. The degradation pathway in the range of pH 4-10 was via cleavage of the sulfonylurea bridge to form two transformation products: 2-amino-4-(dimethylamino)-6-(2,2,2-trifluoroethoxy)-1,3, 5-triazine (2) and 6-methyl-2-methylcarboxylate benzene sulfonamide (3). Comparison of transformation rates in sterile and nonsterile soils indicates that chemical and microbial processes are important in soil degradation. The former is more important in acidic soils, and the latter is more important in basic soils. A biphasic model fits well with dissipation of triflusulfuron-methyl in soil. The triazine formed during the first step of transformation was degraded more rapidly in basic soils than in acidic soils.

Degradation of iprodione by a soil Arthrobacter-like strain

A bacterial strain able to transform iprodione was isolated from a fast iprodione-degrading soil by enrichment procedures. Transformation was detected through 3,5-dichloroaniline production as measured by a rapid colorimetric method. The strain, MA6, was tentatively identified as an Arthrobacter sp. When it was incubated with MA6 in a minimum mineral medium (pH 6.5), iprodione (8.8 mumol/liter) was transformed into two major metabolites that were identified by high-performance liquid chromatography analysis: 3,5-dichlorophenylcarboximide (metabolite 1) and (3,5-dichlorophenylurea) acetic acid (metabolite 2), which was produced after ring cleavage of the former product. These products were synthesized in the laboratory and compared with metabolites 1 and 2 which were formed during iprodione degradation. Small quantities of 3,5-dichloroaniline also appeared in the bacterial culture but did not substantially increase between the first and second days of incubation. In contrast, in the sterile control medium, iprodione was spontaneously transformed into hydantoic acid and an iprodione isomer. Chemical and biological transformations of iprodione seem to occur through two different pathways. One biological degradation pathway is proposed.

Synthesis of Mannich bases of arylidenepyridazinones as analgesic agents

A series of 5-arylidenepyridazin-3-ones substituted in the 2-position by an arylpiperazinoalkyl moiety (2-16) was synthesized and evaluated for analgesic activity. In the phenylbenzoquinone-induced writhing test, Mannich bases 2-14 were the most active compounds (6.1 < or = ED50 < or = 43.0 mg/kg, orally; ED50 is the half-maximal effective dose). Pyridazinones 8 and 9, with a 3-chlorophenylpiperazinomethyl substituent, also exhibited significant anti-inflammatory and antipyretic effects. The activities in the phenylbenzoquinone-induced writhing test were subjected to a Hansch analysis, and a significant correlation with lipophilicity and Hammett's constants was obtained.

Anticonvulsant activity of 3-oxo-5-substituted benzylidene-6-methyl-(4H)-2-pyridazinylacetamides and 2-pyridazinylacetylhydrazides

A series of 3-oxo-5-substituted-benzylidene-6-methyl-(4H)-2- pyridazinylacetamides and 2-pyridazinylacetylhydrazides were synthesized and evaluated for anticonvulsant activity against electrically and chemically induced seizures. In the maximal electroshock-induced seizures test, most of the derivatives showed an anticonvulsant effect better than that of sodium valproate, a commonly used anticonvulsant drug. At 100 mg/kg orally, compounds 5a and 5b respectively protected 50 and 60% of the mice against pentylentetrazole-induced seizures. In addition, these two derivatives showed significant anticonvulsant properties at doses that did not produce ataxia or sedation. The title compounds were also tested for their ability to antagonize convulsions induced by bicuculline and strychnine. Their effect on tremors induced by oxotremorine in mice was also evaluated.

Uptake and phytotoxicity of the herbicide metsulfuron methyl in corn root tissue in the presence of the safener 1,8-naphthalic anhydride

Growth of Zea mays L. cv Potro roots was inhibited by the herbicide metsulfuron methyl (MSM) at the lowest concentration tested: 5 nanomoles per liter. Pretreatment of corn seeds with commercial 1,8-naphthalic anhydride (NA) at 1% (w/w) partially reversed MSM-induced root growth inhibition. MSM at a concentration of 52 nanomoles per liter was taken up rapidly by roots and accumulated in the corn tissue to concentrations three times those in the external medium; the safener NA increased MSM uptake up to 48 hours. The protective effect of NA was related to the ability of the safener to increase the metabolism of MSM; tenfold increases in the metabolic rates of MSM were observed in NA-pretreated corn seedlings grown for 48 hours on 52 nanomolar [(14)C]MSM solution. DNA synthesis determined by measurement of [(3)H]thymidine incorporation into DNA was inhibited by root MSM applications; after a 6-hour application period, 13 nanomolar MSM solution reduced DNA synthesis by 64%, and the same reduction was also observed with NA-pretreated seedlings. Pretreatment of corn seeds with safener NA did not increase the acetolactate synthase activity in the roots and did not change, up to 13 micromoles per liter, the in vitro sensitivity of roots to MSM.

[In vitro enzyme inhibitory and in vivo cardioprotective activities of hibiscus (Hibiscus sabdariffa L.)]

A crude hydroalcoholic extract from Hibiscus sabdariffa L. calyces showed in vitro an appreciable enzyme-inhibiting activity towards the Angiotensin I Converting Enzyme (ACE), attributable to flavones, but weak inhibiting activities towards elastase, trypsin and alpha-chymotrypsin. The angioprotective activity in vivo, also important, was due to flavones and anthocyanins.

Synthesis and pharmacological evaluation of N-substituted 4,6-diaryl-3-pyridazinones as analgesic, antiinflammatory and antipyretic agents

The synthesis and the pharmacological evaluation of 19 new 4,6-diaryl-3-pyridazinones are reported. All compounds were screened for analgesic, antiinflammatory and antipyretic activities. Introduction of an arylpiperazinomethyl moiety in the 2-position of the pyridazinone ring resulted in the most potent activities. Compounds 2a, 2b, 2h and 2i exhibited a higher analgesic activity than did aspirin or noramidopyrine in the hot plate test.

[Synthesis, antisecretory, and anti-ulcer activity of new 5-arylidene-2-ureidoalkyl-3-pyridazinones]

By addition of methylisocyanate to 5-arylidene 2-aminoalkyl 3-pyridazinones a series of derivatives substituted in the 2-position by an ureidoalkyl moiety was obtained in good yields. Gastric antisecretory and anti-ulcer activities of these new compounds were evaluated. The influence of the substituents attached to the pyridazine ring was discussed.

[Synthesis and antidepressive effects of diaryl-4,6-amino-3-pyridazine analogs of minaprine]

The reaction of 3-chloro pyridazines with various amines led to a series of minaprine analogues. Most of them exhibited significant antidepressant activity. The influence of the substituents attached to the pyridazine ring was discussed.

[Effect of application of a herbicide propyzamide into the soil by study of mineralization of glucose 14C(U) and distribution of radioactivity in various fractions of the soil (laboratory and open field tests)]

The effects of the herbicide PROPYZAMIDE are studied in laboratory and field conditions. The modifications involved are characterized by measurement of 14C-glucose mineralization and radioactivity incorporation into the soil fractions. In laboratory conditions, temperature and moisture are kept stable and the experiment is performed during less than 24 hours. In these conditions, Kerb 50 (commercial formulation of propyzamide) and the emulsifier (material used in propyzamide formulation) exert little effect on 14CO2 evolution. In field conditions, propyzamide andKerb 50 are applied once at two different doses: at field rate (1,5 kg/ha) and twentyfold this rate. Essays are duplicated. The herbicide (propyzamide in Celanol and Kerb 50) and the emulsifiers alone (Celanol and the material used in propyzamide formulation) are applied on the soil surface (application date: 3.02.81). Two weeks later and then every month during four months, samples are taken to the depth of about 5 cm (Propyzamide migrates very slowly in the first centimeters of the soil). The characterization experiment is performed on 10 g soil samples by 14C-glucose incubation at 28 degrees C during two hours. 14CO2 evolved is measured after incubation and acidification with HCl. Then radioactivity distribution in the soil is counted after chemical fractionation of soil. This distribution is about 10-16.5% as 14CO2, 22-37% in the acid-soluble fraction, 10-25% in the alkali-soluble fraction and 15-45% in the human fraction (measured as 14CO2 evolved after combustion). This distribution is little modified by the herbicides or the emulsifiers but its evolution is significantly related to environmental conditions (temperature). Nevertheless a few modifications are observed. They can be due to the herbicide propyzamide itself but the emulsifiers and the degradation products of propyzamide can also influence the measurement (After forty days in the soil, 70-95% of the starting active ingredient have disappeared). They can also be a result of the initial effects of the products (modification of the microflora and of the environment).

[Degradation reactions of a carbamate herbicide, chlorbufam: effect of soil factors]

Kinetics of degradation of chlorbufam is determined in aqueous solution, in aqueous solution with humic acids, argilo-humic complexes, soil and sterile soil. The adsorption is also evaluated in this different fractions. The adsorption process has a protecting effect and the chlorbufam is not chemically degraded when it is adsorbed on organic matter. The biodisponibility is also decreased by adsorption.

Etude de l'équilibre tautomère des pyrazolinones-4

The keto–enol equilibria in variously substituted 4-pyrazolinones were studied in several solvents; these compounds exist in the enol form only. An MO theoretical study of these compounds in comparison to the 5-pyrazolinones is reported.