Synthesis of uracil–coumarin conjugates as potential inhibitors of virus replication

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Synthesis of 4′-substituted 2′-deoxy-4′-thiocytidines and its evaluation for antineoplastic and antiviral activities

4′-Azido- (7), 4′-C-fluoromethyl- (8) 4′-C-ethynyl- (9) and 4′-C-cyano- (10) 2′-deoxy-4′-thiocytidines have been synthesized. In this study, it was found that the isolated yield of 4′-thiouracil nucleoside 13 in a Lewis acid-promoted Vorbrüggen-type glycosidation utilizing 12 was better than that of the electrophilic glycosidation reaction between silylated uracil and 11. This improved result prompted us to perform the glycosidation utilizing 36 and 43 for the synthesis of 37 and 44. Introduction of the azido group was carried out by nucleophilic substitution in the 4′-benzoyloxy derivative 22a. On the other hand, 9 and 10 were synthesized by way of the chemical manipulation of the hydroxymethyl group at the 4′-position of 46.Evaluation of the antineoplastic activity of 2 and 7–10 against human B-cell (CCRF-SB) and T-cell leukemia (Molt-4) cell lines revealed that 4′-azido- (7) and 4′-C-fluoromethyl- (8) derivatives exhibited cytotoxic activity whereas no cytotoxicity was observed in the 4′-C-ethynyl- (9) and 4′-C-cyano- (10) derivatives as well as the parent compound 2. Compound 7 was also found to possess promising antiviral activity against VZV and HSV-1 without any cytotoxity against HEL host cells. It is noteworthy that 7 exhibited potent inhibitory activities against the thymidine kinase-deficient (TK^?) mutant of VZV and HSV-1.     

Dissolving pulp from eucalyptus sawdust for regenerated cellulose products

Cellulose - This study assesses the possibility of obtaining regenerated cellulose products (beads and films) from eucalyptus sawdust dissolving pulps produced by non-conventional processes,...     

Testing equality between several populations covariance operators

In many situations, when dealing with several populations, equality of the covariance operators is assumed. An important issue is to study whether this assumption holds before making other inferences. In this paper, we develop a test for comparing covariance operators of several functional data samples. The proposed test is based on the Hilbert–Schmidt norm of the difference between estimated covariance operators. In particular, when dealing with two populations, the test statistic is just the squared norm of the difference between the two covariance operators estimators. The asymptotic behaviour of the test statistic under both the null hypothesis and local alternatives is obtained. The computation of the quantiles of the null asymptotic distribution is not feasible in practice. To overcome this problem, a bootstrap procedure is considered. The performance of the test statistic for small sample sizes is illustrated through a Monte Carlo study and on a real data set.     

Inference under functional proportional and common principal component models

In many situations, when dealing with several populations with different covariance operators, equality of the operators is assumed. Usually, if this assumption does not hold, one estimates the covariance operator of each group separately, which leads to a large number of parameters. As in the multivariate setting, this is not satisfactory since the covariance operators may exhibit some common structure. In this paper, we discuss the extension to the functional setting of the common principal component model that has been widely studied when dealing with multivariate observations. Moreover, we also consider a proportional model in which the covariance operators are assumed to be equal up to a multiplicative constant. For both models, we present estimators of the unknown parameters and we obtain their asymptotic distribution. A test for equality against proportionality is also considered.     

Thermal Analysis,Quantum Chemical Calculations,and Structural Characterization by Single Crystal Synchrotron Radiation of a Monoclinic Polymorph of Citraconic acid

Abstract  

The crystal structure of a monoclinic polymorph of methyl maleic acid (citraconic acid, polymorph II) was determined using single crystal synchrotron data from a small fragment extracted from the reagent bottle. The material crystallizes in space group P2₁/c with unit cell parameters a = 8.109(2), b = 7.090(2), c = 10.709(3) ?, β = 114.148(16)°, V = 561.8(3) ?³, Z = 4, d _c = 1.538 g cm⁻³. In this polymorph, the carboxylic group with the α-methyl group participates in cyclic hydrogen bonds with graph set symbol R₂² (8) R_{2}^{2} (8) , while the other carboxylic group participates in a hydrogen bonding pattern represented by the C(4) graph set symbol. In contrast, in a previously reported polymorph (polymorph I) obtained by slow evaporation from ethyl acetate, both carboxylic groups participate in cyclic hydrogen bonding motifs. Thermal analysis suggests that the transformation of polymorph II into polymorph I is monotropic.     

Absolute Configuration of Two Eudesmane Derivatives from <Emphasis Type="Italic">Verbesina turbacensis</Emphasis> H.B.K.

Abstract  

Two compounds isolated from the aerial parts of Verbesina turbacensis H.B.K, are reported in this work. Both compounds crystallize in the orthorhombic system, space group P2₁2₁2₁. Compound (1), 6β-[cinnamoyloxy]-3β,4α-dihydroxyeudesmane, formula C₂₄H₃₄O_4, has unit cell parameters a = 9.6234(2), b = 12.3137(3) and c = 18.6277(5) Å, V = 2207.38(9) Å³, Z = 4. On the other hand, 6β-[cinnamoyloxy]-eudesman-15-oic acid (2), formula C₂₄H₃₂O_4, has cell parameters a = 8.7035(3), b = 14.2020(4), c = 17.1590(5) Å, V = 2120.97(11) Å³, Z = 4.