Standardization of capillary electrophoresis for diagnosis of fragile X syndrome in the Brazilian public health system

Fragile X syndrome (FXS) is the most common cause of inherited intellectual disability. The most common etiology of the syndrome is expansion and methylation of a CGG trinucleotide at chromosome region Xq27.3 involving FMR1 (fragile X mental retardation 1 gene). This disorder is commonly underdiagnosed in children and adolescents, given the high clinical variability. In Brazil, molecular diagnosis of FXS by CE does not exist in the public health system. The current standard for separation and identification of DNA fragment sizes is 50 cm CE, which is uncommon in public genotyping laboratories. This study describes the standardization of 36 cm CE for fragment analysis of samples from patients with intellectual disability suggestive of FXS. Genomic dsDNA was isolated from patients and amplified by PCR using the FMR1 AmplideX^® Kit. It was then possible to detect changes in repeat length of FMR1, such as full mutation and premutation. Thus, the proposed standardization proved to be effective for the diagnosis of FXS, permitting suitable genetic counseling for families. Inclusion of molecular testing such as this in the Brazilian public health service bridges the gap between available technologies and effective diagnosis, universalizing access to genetic testing in central Brazil.     

Intriguing behavior of cinchona alkaloids in the enantioselective organocatalytic hydroxyamination of alpha-substituted-alpha-cyanoacetates

The cinchona alkaloid quinine promotes the enantioselective nitroso-aldol reaction between alpha-aryl-alpha-cyanoacetates and nitrosobenzene to give the hydroxyamination products with total chemoselectivity. Treatment of the reaction mixture with Zn/AcOH affords the corresponding amines in high yield and moderate enantioselectivity. An unusual effect on the enantioselectivity was observed with the catalyst loading and solvent. A reductive protocol allows the construction of an optically active 1,2-diamine moiety bearing a quaternary center.     

Chemical Characterization of Plant Extracts and Evaluation of their Nematicidal and Phytotoxic Potential

Nacobbus aberrans ranks among the “top ten” plant-parasitic nematodes of phytosanitary importance. It causes significant losses in commercial interest crops in America and is a potential risk in the European Union. The nematicidal and phytotoxic activities of seven plant extracts against N. aberrans and Solanum lycopersicum were evaluated in vitro, respectively. The chemical nature of three nematicidal extracts (EC_50,48h ≤ 113 µg mL⁻¹) was studied through NMR analysis. Plant extracts showed nematicidal activity on second-stage juveniles (J2): (≥87%) at 1000 µg mL⁻¹ after 72 h, and their EC₅₀ values were 71.4–468.1 and 31.5–299.8 µg mL⁻¹ after 24 and 48 h, respectively. Extracts with the best nematicidal potential (EC_50,48h < 113 µg mL⁻¹) were those from Adenophyllum aurantium, Alloispermum integrifolium, and Tournefortia densiflora, which inhibited L. esculentum seed growth by 100% at 20 µg mL⁻¹. Stigmasterol (1), β-sitosterol (2), and α-terthienyl (3) were identified from A. aurantium, while 1, 2, lutein (4), centaurin (5), patuletin-7-β-O-glucoside (6), pendulin (7), and penduletin (8) were identified from A. integrifolium. From T. densiflora extract, allantoin (9), 9-O-angeloyl-retronecine (10), and its N-oxide (11) were identified. The present research is the first to report the effect of T. densiflora, A. integrifolium, and A. aurantium against N. aberrans and chemically characterized nematicidal extracts that may provide alternative sources of botanical nematicides.     

A Covalent Organic Helical Cage with Remarkable Chiroptical Amplification

Purely organic shape‐persistent chiral cages are designed through the use of rigid chiral axes. Covalent dimerization of a tripodal fragment bearing chiral allenes forms a molecular twisted prism with loop‐like lateral edges presenting 10‐fold chiroptical amplification compared to its isolated building blocks. The expected geometry of covalent organic helical cage (M,M)₃‐ 1 was confirmed by X‐ray crystal structure analysis. Comparison of the chiroptical responses of this shape‐persistent molecular container with more flexible analogues highlights how the control of the conformational freedom of the molecule can be used to obtain molecular cages with strong chiroptical responses. Selective inclusion‐complex formation with ferrocenium ions [(P,P)₃‐ 1 @Fc⁺] was confirmed and quantified with HR‐ESI‐MS and NMR spectroscopy.     

Synthesis and photophysical properties of fullerene-phthalocyanine-porphyrin triads and pentads

The synthesis and photophysical properties of several fullerene-phthalocyanine-porphyrin triads (1-3) and pentads (4-6) are described. The three photoactive moieties were covalently connected in an one-step synthesis through 1,3-dipolar cycloaddition to C(60) of the corresponding azomethine ylides generated in situ by condensation reaction of a substituted N-porphyrinylmethylglycine derivative and an appropriated formyl phthalocyanine or a diformyl phthalocyanine derivative, respectively. ZnP-C(60)-ZnPc (3), (ZnP)(2)-ZnPc-(C(60))(2) (6), and (H(2)P)(2)-ZnPc-(C(60))(2) (5) give rise upon excitation of their ZnP or H(2)P components to a sequence of energy and charge-transfer reactions with, however, fundamentally different outcomes. With (ZnP)(2)-ZnPc-(C(60))(2) (6) the major pathway is an highly exothermic charge transfer to afford (ZnP)(ZnP(.+))-ZnPc-(C(60)(.-))(C(60)). The lower singlet excited state energy of H(2)P (i.e., ca. 0.2 eV) and likewise its more anodic oxidation (i.e., ca. 0.2 V) renders the direct charge transfer in (H(2)P)(2)-ZnPc-(C(60))(2) (5) not competitive. Instead, a transduction of singlet excited state energy prevails to form the ZnPc singlet excited state. This triggers then an intramolecular charge transfer reaction to form exclusively (H(2)P)(2)-ZnPc(.+)-(C(60)(.-))(C(60)). A similar sequence is found for ZnP-C(60)-ZnPc (3).     

Europium-directed self-assembly of a luminescent supramolecular gel from a tripodal terpyridine-based ligand

Eu(III), the last piece in the puzzle: Europium-induced self-assembly of ligands having a C(3)-symmetrical benzene-1,3,5-tricarboxamide core results in the formation of luminescent gels. Supramolecular polymers are formed through hydrogen bonding between the ligands. The polymers are then brought together into the gel assembly through the coordination of terpyridine ends by Eu(III) ions (blue dashed arrow: distance between two ligands in the strand direction).     

Chiral (2,5)Pyrido[74]allenoacetylenic Cyclophanes: Synthesis and Characterization

Chiral pyridoallenophanes! The synthesis and characterization of chiral acetylenic pyridoallenophanes along with 2,4‐ and 2,5‐pyridyl[Re(CO)₄LBr] complexes are reported. The relative configurations of the four stereoisomers have been unambiguously assigned. Chromatographic resolution of the racemate of the C₄ stereoisomer was accomplished and mirror‐image CD spectra have been obtained (see figure).

     

Periodic solutions for second order differential equations with discontinuous restoring forces

We deal with the existence of periodic solutions for problems with a jump discontinuity. We use an approximation procedure and the method of the lower and upper solutions.