Laccase-catalyzed oxidation of phenolic compounds in organic media

Rhus vernificera laccase-catalyzed oxidation of phenolic compounds, i.e., (+)-catechin, (−)-epicatechin and catechol, was carried out in selected organic solvents to search for the favorable reaction medium. The investigation on reaction parameters showed that optimal laccase activity was obtained in hexane at 30 °C, pH 7.75 for the oxidation of (+)-catechin as well as for (−)-epicatechin, and in toluene at 35 °C, pH 7.25 for the oxidation of catechol. E_a and Q₁₀ values of the biocatalysis in the reaction media of the larger log p solvents like isooctane and hexane were relatively higher than those in the reaction media of lower log p solvents like toluene and dichloromethane. Maximum laccase activity in the organic media was found with 6.5% of buffer as co-solvent. A wider range of 0–28 μg protein/ml in hexane than that of 0–16.7 μg protein/ml in aqueous medium was observed for the linear increasing conversion of (+)-catechin. The kinetic studies revealed that in the presence of isooctane, hexane, toluene and dichloromethane, the K_m values were 0.77, 0.97, 0.53 and 2.9 mmol/L for the substrate of (+)-catechin; 0.43, 0.34, 0.14 and 3.4 mmol/L for (−)-epicatechin; 2.9, 1.8, 0.61 and 1.1 mmol/L for catechol, respectively, while the corresponding V_max values were 2.1 × 10⁻², 2.3 × 10⁻², 0.65 × 10⁻² and 0.71 × 10⁻² δA/μg protein min); 1.8 × 10⁻², 0.88 × 10⁻², 0.19 × 10⁻² and 1.0 × 10⁻² δA/μg protein min); 0.48 × 10⁻², 0.59 × 10⁻², 0.67 × 10⁻² and 0.54 × 10⁻² δA/μg protein min), respectively. FT-IR indicated the formation of probable dimer from (+)-catechin in organic solvent. These results suggest that this laccase has higher catalytic oxidation capacity of phenolic compounds in suitable organic media and favorite oligomers could be obtained.     

Efficient expression of gene variants that harbour AGA codons next to the initiation codon

In an effort to improve the knowledge about the rules which direct the effect of the early ORF sequences on translation efficiency, we have analyzed the effect of pairs of the six arginine codons at the second and third positions on the expression of lacZ variants. Whereas the pairs of identical AGA or AGG codons were favorable for the gene expression, identical pairs of each of the four CGN codons were very inefficient. This result was unexpected because tandems of AGA or AGG codons located in more internal gene positions provoke deficient expression whilst internally located CGU and CGC are the most abundant and efficiently translated arginine codons. The mixed combinations of AGA and each of the CGN codons usually resulted in efficient rates of lacZ expression independently of the peptidyl-tRNA propensity to dissociate from the ribosome. Thus, the variant harboring the pair of AGA codons was expressed as efficiently as the variant carrying a pair of AAA codons in the same positions, a configuration reported as one of the most common and efficient for gene expression. We explain these results assuming that the presence of adenines in these early positions enhance gene expression. As expected, specific mRNA levels correlated with the intensity of lacZ expression for each variant. However, the induction of lacZ AGA AGA gene in pth cells accumulated peptidyl-tRNA^Arg4 as well as a short 5′-proximal lacZ mRNA fragment suggesting ribosome stalling due to depletion of aminoacylated-tRNA^Arg4.     

Synthesis, cytotoxic evaluation, and DNA binding of novel thiazolo[5,4-b]quinoline derivatives

A series of novel alkylamino and 9-anilinothiazolo[5,4-b]quinolines were synthesized as potential antitumoral agents. The in vitro cytotoxicity of these compounds was evaluated on several cell lines. The inclusion of electron-withdrawn/acceptor hydrogen-bond groups at position 3' of the anilino ring and the presence of an alkylamino chain on the tricyclic framework (regardless of its position) seem to be structural features relevant to cytotoxic activity.     

S-allylmercaptocysteine scavenges hydroxyl radical and singlet oxygen <Emphasis Type="Italic">in vitro</Emphasis> and attenuates gentamicin-induced oxidative and nitrosative stress and renal damage <Emphasis Type="Italic">in vivo</Emphasis>

Background  

Oxidative and nitrosative stress have been involved in gentamicin-induced nephrotoxicity. The purpose of this work was to study the effect of S-allylmercaptocysteine, a garlic derived compound, on gentamicin-induced oxidative and nitrosative stress and nephrotoxicity. In addition, the in vitro reactive oxygen species scavenging properties of S-allylmercaptocysteine were studied.     

Decline of neural tube defects cases after a folic acid campaign in Nuevo León,México

BACKGROUND: Nuevo León is a state in northeastern Mexico, near the border of Texas. Mean mortality rate from 1996-98 due to anencephaly cases was 0.6/1,000. In 1999 a surveillance program for the registry and prevention of neural tube defects (NTD) cases was initiated. METHODS: Cases were obtained from hospitals and OB-GYN clinics by immediate notification, death certificates, or fetal death registries. Only isolated cases of NTD were included. In August 1999 a folic acid campaign was initiated with the free distribution of the vitamin to low-income women with a recommendation to take a 5.0-mg pill once a week. Number of cases and rates from 1999 to 2001 were compared (chi(2) test). RESULTS: After 2 years there has been a significant reduction in the number of cases and rates. In 1999 there were 95 NTD cases and in the years 2000 and 2001 there were only 59 and 55 respectively (P < 0.001). NTD rate decreased from 1.04/1,000 in 1999 to 0.58/1,000 in 2001. Anencephaly and spina bifida rates decreased from 0.55/1,000 to 0.29/1,000 and from 0.47/1,000 to 0.22/1,000 respectively, from 1999-2001. Decrease of female cases was higher than male cases for both phenotypes. CONCLUSION: After 2 years there was a 50% decrease in the incidence of anencephaly and spina bifida cases with a significant reduction of infant mortality and disability. These results encourage us to propose the use of a single tablet of 5.0-mg of folic acid per week as an alternative to supplementation on a daily basis.     

Serum Lipid Levels and Dyslipidaemia Prevalence among 2–10 Year-Old Northern Mexican Children

Background and Aims

The increase in overweight and obese children may be linked to increased rates of dyslipidaemia. The aim was to assess the prevalence of dyslipidaemia and associated risk factors among the Northern Mexican child population.

Methods and Results

Four hundred and fifty-one subjects aged between 2 and 10 (47.5% girls) took part in the Nuevo León State Survey of Nutrition and Health 2011–2012. According to the 2011 Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents, serum lipid levels (mg/dL) were categorized into three subgroups (acceptable, borderline-high/low or high/low) as follows: TChol: acceptable <170, borderline-high 170–199, high ≥200; LDL-chol: acceptable <110, borderline-high 110–129, high ≥130; non-HDL-chol: acceptable <120, borderline-high 120–144, high ≥145; HDL-chol: acceptable >45, borderline-low 40–45, low <40; and TG: acceptable <75, borderline-high 75–99, high ≥100 in ≤9 year-old children, and acceptable <90, borderline-high 90–129, and high ≥130 in 10 year-old children. The overall prevalence of borderline-high + high TG, non-HDL-chol, TChol, and LDL-chol was 63.0%, 44.1%, 43.5%, and 29.9%, respectively. The overall prevalence of borderline-low + low HDL-chol was 46.3%. The overall frequency of dyslipidaemia was 54.3%. Thirteen children (2.9%) had all five symptoms of dyslipidaemia. The most common dyslipidaemia was high TG in combination (26.2%) and in isolation (10.6%).

Conclusions

Half of the children had at least one abnormal lipid concentration. A high TG level was the most frequent dyslipidaemia. Obesity was associated with the occurrence of at least one abnormal lipid level. These findings emphasize the need to pay further attention to the prevention of cardiovascular disease and obesity from an early age.     

Surface Plasmon Resonances of Metallic Nanostars/Nanoflowers for Surface-Enhanced Raman Scattering

We investigate theoretically the optical properties associated to plasmon resonances of metal nanowires with cross section given by low-order Chebyshev nanoparticles (like rounded-tip nanostars or nanoflowers). The impact of the nanoflower shape is analyzed for varying symmetry and deformation parameter through the spectral dependence of resonances and their corresponding near field distributions. Large field intensity enhancements are obtained at the gaps between petals, apart from the tips themselves, which make these nanostars/nanoflowers specially suitable to host molecules for surface-enhanced Raman scattering sensing applications.     

Proteomic analysis identifies in vivo candidate matrix metalloproteinase‐9 substrates in the left ventricle post‐myocardial infarction

Matrix metalloproteinase‐9 (MMP‐9) deletion has been shown to improve remodeling of the left ventricle post‐myocardial infarction (MI), but the mechanisms to explain this improvement have not been fully elucidated. MMP‐9 has a broad range of in vitro substrates, but relevant in vivo substrates are incompletely defined. Accordingly, we evaluated the infarct regions of wild‐type (wt) and MMP‐9 null (null) mice using a proteomic strategy. Wt and null groups showed similar infarct sizes (48±3 in wt and 45±3% in null), indicating that both groups received an equal injury stimulus. Left ventricle infarct tissue was homogenized and analyzed by 2‐DE and MS. Of 31 spot intensity differences, the intensities of 9 spots were higher and 22 spots were lower in null mice compared to wt (all p<0.05). Several extracellular matrix proteins were identified in these spots by MS, including fibronectin, tenascin‐C, thrombospondin‐1, and laminin. Fibronectin was observed on the gels at a lower than expected molecular weight in the wt group, which suggested substrate cleavage, and the lower molecular weight spot was observed at lower intensity in the MMP‐9 null group, which suggested cleavage by MMP‐9. Immunoblotting confirmed the presence of fibronectin cleavage products in the wt samples and lower levels in the absence of MMP‐9. In conclusion, examining infarct tissue from wt and MMP‐9 null mice by proteomic analysis provides a powerful and unique method to identify in vivo candidate MMP substrates.     

Tricolorin A, a potent natural uncoupler and inhibitor of photosystem II acceptor side of spinach chloroplasts

Tricolorin A, (11 S )-11-hydroxyhexadecanoic acid 11- O - α - l - rhamnopyranosyl-(1↠3)- O - α - l -{2- O -(2 S -methylbutanoyl)-4- O -(2 S -methylbutanoyl)}-rhamnopyranosil-(1↠2)- O - β - d -glucopyranosil-(1↠2)- β -fucopyranoside-(1,3'-lactone), the major phytogrowth inhibitor isolated from Ipomoea tricolor Cav. (Convolvulaceae) was found to be a potent uncoupler (U₅₀=0.33 μ M ) of photophosphorylation in spinach chloroplasts. Tricolorin A inhibited H⁺-uptake and adenosine 5'-triphosphate (ATP) synthesis, and stimulated basal and phosphorylating electron flows. Using a combination of two well-known fluorescent ΔpH probes, 9-aminoacridine and 9-amino-6-chloro-2-methoxyacridine, the uncoupling behavior of tricolorin A was also demonstrated for submitochondrial particles. Polarographic data showed that high concentrations (20 μ M ) of tricolorin A inhibited photosystem II (PSII) electron flow at the level of plastoquinone B (Q_B). Chlorophyll (Chl) a fluorescence analysis showed that tricolorin A induced accumulation of Q_A⁻ and strongly decreased the electron transport capacity, suggesting that the target of this molecule was located at the Q_B level. The macrocyclic lactone-type structure of this allelopathic agent proved to be an important structural requirement for uncoupling activity since its hydrolysis caused loss of the inhibitory potential.