Methyl Ester Chloride Research Articles

Study of Antisickling and Vasorelaxant Activities and Acute Toxicity Assessment of Crude Extracts of Leaves of Ficus sycomorus L. (Moraceae)

The leaves of Ficus sycomorus are used in Burkina Faso folk medicine for the treatment of sickle cell disease. The present comparative study of crude extracts of leaves (decoction, macerated extract and a 95% ethanol extract) was performed with the aim to assess the efficiency of this traditional use and to determine the most active of the three extracts. Antisickling activity was assessed by the Emmel's test. Vasorelaxant effect on rat aortic rings precontracted by phenylephrine with and without N-nitro-L-arginine methyl ester chloride (L-NAME) was also evaluated. The 95% ethanol extract (20 mg mL(-1)) showed the most antisickling activity on sickle erythrocytes, by inhibiting completely sickling of double heterozygote SC cells in 60 min and that of homozygote SS cells in 90 min. On the aorta this extract exhibited a significant (p<0.05) vasorelaxant activity, better than that of the other extracts, with an IC50 value of 6.86±0.13 mg mL(-1) against 18.78±0.38 and 28.56±1.27 mg mL(-1), respectively for the macerated extract and the decoction. When the aortic rings were pretreated with L-NAME, only the ethanolic extract conserved its vasorelaxant activity, up to 73% of relaxation. The acute toxicity of the decoction, assessed by intraperitoneal route and using the Litchfield and Wilcoxon method, led to an LD50 value of 1553.61 mg kg(-1) b.wt. This places the drug among those with low toxicity according to the WHO scale. These results confirm those previously obtained and provide a scientific basis supporting the use of this plant in folk medicine against sickle cell disease. They indicate the importance of Ficus sycomorus in the research of new antisickling molecules.

ChemInform Abstract: Synthesis of Squaric Acid Derivatives by Lewis Acid Catalyzed Reaction of Its Dichloride, Methyl Ester Chloride, Diethylamide Chloride, and Ethyl Diester with Unsaturated Organosilanes: New Method for C‐C Bond Formation on Cyclobutenedione.

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Synthesis of squaric acid derivatives by Lewis acid-catalysed reaction of its dichloride, methyl ester chloride, diethylamide chloride, and ethyl diester with unsaturated organosilanes: new method for C–C bond formation on cyclobutenedione

The squaric acid family of derivatives, e.g. dichloride 2, methyl ester chloride 3, diethyl amide chloride 4, and ethyl diester 5, reacted with a variety of unsaturated organosilanes 6 in the presence of a catalyst, typically titanium tetrachloride, at –78 to 0 °C to give addition products (e.g., 7, 9, 11) and/or substitution products (e.g., 8, 10, 12, 13) after dechlorosilylation either via 1,2- or 1,4-addition. The mode of addition depended on the nature of the acid family and on the substitution pattern of the organosilane. The former product predominated in the reaction of the chlorides 2–4 with all silyl ketene ketals used, and with some allylsilanes and silyl enol ethers unless the reactive site (γ to a silyl group) of these silanes was more crowded, whereas the diester 5 gave rise to the latter product 13 irrespective of the substitution pattern. In some cases, catalyst and reaction temperature also affected the mode of addition. The reactivity was found to be in the order 2 > 3 > 4, being reflected in the reaction temperature.

Structure cristalline et conformation moléculaire du chlorure de l'ester méthylique de tosyl-L-arginine

Tosyl-L-arginine methyl ester chloride, a substrate for trypsin, is orthorhombic, space group P2~2121 with a= 8-084, b= 23.579, c= 9.812 ,~. and four molecules in the unit cell. The structure has been solved by direct methods and refined until R=0.05. The conformation of the arginine residue is roughly comparable with one of the two forms in the asymmetric unit of the structure of hydrated L-arginine hydrobromide, but the whole cation is unusually folded: it coils itself in a turn so that the tolyl group is placed above the guanidinium group, with the methyl ester group set outside. The cohesion is achieved by hydrogen bonds between the anion and three out of the four nitrogen atoms of the cations. The hydrophobic methyl ester and tolyl groups are involved in van der Waals bonds.