Protective Effects of Mangosteen Extract on H2O2-Induced Cytotoxicity in SK-N-SH Cells and Scopolamine-Induced Memory Impairment in Mice

Mangosteen extracts (ME) contain high levels of polyphenolic compounds and antioxidant activity. Protective effects of ME against β-amyloid peptide (Aβ), induced cytotoxicity have been reported. Here, we further studied the protective effects of ME against oxidative stress induced by hydrogen peroxide (H₂O₂) and polychlorinated biphenyls (PCBs), and demonstrated the protection against memory impairment in mice. The cytoprotective effects of ME were measured as cell viability and the reduction in ROS activity. In SK-N-SH cell cultures, 200 μg/ml ME could partially antagonize the effects of 150 or 300 µM H₂O₂ on cell viability, ROS level and caspase-3 activity. At 200, 400 or 800 µg/ml, ME reduced AChE activity of SK-N-SH cells to about 60% of the control. In vivo study, Morris water maze and passive avoidance tests were used to assess the memory of the animals. ME, especially at 100 mg/kg body weight, could improve the animal’s memory and also antagonize the effect of scopolamine on memory. The increase in ROS level and caspase-3 activity in the brain of scopolamine-treated mice were antagonized by the ME treatment. The study demonstrated cytoprotective effects of ME against H₂O₂ and PCB-52 toxicity and having AChE inhibitory effect in cell culture. ME treatment in mice could attenuate scopolamine-induced memory deficit and oxidative stress in brain.     

Hepatocyte nuclear factor 4α regulates the expression of the murine pyruvate carboxylase gene through the HNF4-specific binding motif in its proximal promoter

Pyruvate carboxylase (PC) is the first regulatory enzyme of gluconeogenesis. Here we report that the proximal promoter of the murine PC gene contains three binding sites for hepatocyte nuclear factor 4α (HNF4α). These sites include the classical direct repeat 1 (DR1) (− 386/− 374), non-perfect DR1 (− 118/− 106) and HNF4α-specific binding motif (H4-SBM) (− 26/− 14). Under basal conditions, mutation of the non-perfect DR1 decreased promoter activity by 50%, whereas mutation of neither the DR1 nor the H4-SBM had any effect. In marked contrast, only mutation of the H4-SBM decreased HNF4α-transactivation of the promoter activity by 65%. EMSA revealed that HNF4α binds to the DR1site and H4-SBM with similar affinity while it binds poorly to the non-perfect DR1. Interestingly, this non-perfect DR1 also coincides with two E-boxes. Mutation of the non-perfect DR1 together with the nearby E-box reduced USF1- but not USF2-transactivation of promoter activity, suggesting that USF1 partly contributes to the basal activity of the promoter. Substitution of the H4-SBM with the DR1 marginally reduced the basal promoter activity but did not eliminate HNF4α-transactivation, suggesting that HNF4α can exert its effect via DR1 within this promoter context. ChIP-assay confirmed that HNF4α is associated with the H4-SBM. Suppression of HNF4α expression in AML12 cells down-regulated PC mRNA and PC protein by 60% and 50%, respectively, confirming that PC is a target of HNF4α. We also propose a model for differential regulation of P1 promoter of PC gene in adipose tissue and liver.     

Karyotypic study of five Lutjanid species using conventional and Ag-NORs banding techniques

The first cytogenetic comparisons of five snapper species from Thailand were presented here. Renal cell samples were taken from blacktail snapper (Lutjanus fulvus), five lined snapper (L. quinquelineatus), dory snapper (L. fulviflamma), brownstripe red snapper (L. vitta), and mangrove red snapper (L. argentimaculatus). The mitotic chromosome preparation was prepared directly from kidney cells. Conventional staining and Ag-NOR banding techniques were applied to stain the chromosomes. The results exhibited that all five snapper species have the diploid chromosome numbers of 2n = 48 and the fundamental numbers (NF) of 48. The presences of large, medium, and small telocentric chromosomes were 22-24-2, 24-20-4, 36-10-2, 28-16-4 and 36-10-2, respectively. The Ag- NORs banding technique provides the pair of nucleolar organizer regions (NORs) at subcentromeric region of the long arm of the respective telocentric chromosome pairs 9, 1, 3, 4 and 9. Their karyotype formulas is as follows: L. fulvus (2n = 48): L ₂₂ ^t + M ₂₄ ^t + S ₂ ^t , L. quinquelineatus (2n = 48): L ₂₄ ^t + M ₂₀ ^t + S ₄ ^t , L. fulviflamma (2n = 48): Lt36 + Mt10 + St2, L. vitta (2n = 48): L ₂₈ ^t + M ₁₆ ^t + S ₄ ^t , and L. argentimaculatus (2n = 48): L ₃₆ ^t + M ₁₀ ^t + S ₂ ^t .     

Molecular Cloning and Expression of α-Globin and β-Globin Genes from Crocodile (Crocodylus siamensis)

The first report of complete nucleotide sequences for α- and β-globin chains from the Siamese hemoglobin (Crocodylus siamensis) is given in this study. The cDNAs encoding α- and β-globins were cloned by RT-PCR using the degenerate primers and by the rapid amplification of cDNA ends method. The full-length α-globin cDNA contains an open reading frame of 423 nucleotides encoding 141 amino acid residues, whereas the β-globin cDNA contains an open reading frame of 438 nucleotides encoding 146 amino acid residues. The authenticity of both α- and β-globin cDNA clones were also confirmed by the heterologous expression in Escherichia coli (E. coli). This is the first time that the recombinant C. siamensis globins were produced in prokaryotic system. Additionally, the heme group was inserted into the recombinant proteins and purified heme-bound proteins were performed by affinity chromatography using Co²⁺-charged Talon resins. The heme-bound proteins appeared to have a maximum absorbance at 415 nm, indicated that the recombinant proteins bound to oxygen and formed active oxyhemoglobin (HbO₂). The results indicated that recombinant C. siamensis globins were successfully expressed in prokaryotic system and possessed an activity as ligand binding protein.     

DFT and TDDFT study on the electronic structure and photoelectrochemical properties of dyes derived from cochineal and lac insects as photosensitizer for dye-sensitized solar cells

Essential parameters related to the photoelectrochemical properties, such as ground state geometries, electronic structures, oxidation potential and electron driving force, of cochineal insect dyes were investigated by DFT and TDDFT at the B3LYP/6-31+G(d,p) level of the theory. The results show that the major charge flow dynamic for all dyes is the HOMO→LUMO transition. The bi-coordinated binding mode, in which the dye uses one carboxyl- and hydroxyl oxygen bound to Ti(IV), is found for all dye-TiO₂ systems. Additionally, the doubly bi-coordinated binding mode in which the dye used both carboxyl groups bound to two Ti(IV) is also possible due to high energy distribution occupied at anchoring groups. This study highlights that most of these insect dyes can be good photosensitizers in dye-sensitized solar cells based on their strong binding to the TiO₂ surface, good computed excited state oxidation potential and thermodynamically favored electron driving force.     

Hopane triterpenes as chemotaxonomic markers for the scale insect pathogens Hypocrella s. lat. and Aschersonia

The scale insect pathogens Hypocrella s. lat. and their Aschersonia anamorphs, collected at various locations in Thailand, were surveyed for their productivity of three hopane triterpenes, zeorin (6α,22-dihydroxyhopane), dustanin (15α,22-dihydroxyhopane), and 3β-acetoxy-15α,22-dihydroxyhopane, when cultured in a liquid medium (potato-dextrose broth) under static conditions. Among 53 strains of Aschersonia species, 48 strains (91 %) produced at least one of these compounds. Hypocrella and Moelleriella species (43 strains) also frequently produced these triterpenoids; only two strains lacked all of these triterpenes. The results demonstrate that hopane triterpenes may be suitable for use as chemotaxonomic markers for Hypocrella and Moelleriella species and their Aschersonia anamorphs.