IFN‐γ inhibits basal and α‐MSH‐induced melanogenesis

Inflammatory cytokines are closely related to pigmentary changes. In this study, the effects of IFN‐γ on melanogenesis were investigated. IFN‐γ inhibits basal and α‐MSH‐induced melanogenesis in B16 melanoma cells and normal human melanocytes. MITF mRNA and protein expressions were significantly inhibited in response to IFN‐γ. IFN‐γ inhibited CREB binding to the MITF promoter but did not affect CREB phosphorylation. Instead, IFN‐γ inhibited the association of CBP and CREB through the increased association between CREB binding protein (CBP) and STAT1. These findings suggest that IFN‐γ inhibits both basal and α‐MSH‐induced melanogenesis by inhibiting MITF expression. The inhibitory action of IFN‐γ in α‐MSH‐induced melanogenesis is likely to be associated with the sequestration of CBP via the association between CBP and STAT1. These data suggest that IFN‐γ plays a role in controlling inflammation‐ or UV‐induced pigmentary changes.     

The importance of starch and sucrose digestion in nutritive biology of synanthropic acaridid mites: α‐Amylases and α‐glucosidases are suitable targets for inhibitor‐based strategies of mite control

The adaptation of nine species of mites that infest stored products for starch utilization was tested by (1) enzymatic analysis using feces and whole mite extracts, (2) biotests, and (3) inhibition experiments. Acarus siro, Aleuroglyphus ovatus, and Tyroborus lini were associated with the starch‐type substrates and maltose, with higher enzymatic activities observed in whole mite extracts. Lepidoglyphus destructor was associated with the same substrates but had higher activities in feces. Dermatophagoides farinae, Chortoglyphus arcuatus, and Caloglyphus redickorzevi were associated with sucrose. Tyrophagus putrescentiae and Carpoglyphus lactis had low or intermediate enzymatic activity on the tested substrates. Biotests on starch additive diets showed accelerated growth of species associated with the starch‐type substrates. The inhibitor acarbose suppressed starch hydrolysis and growth of the mites. We suggest that the species with higher starch hydrolytic activity in feces were more tolerant to acarbose, and α‐amylase and α‐glucosidase of synanthropic mites are suitable targets for inhibitor‐based strategies of mite control. © 2009 Wiley Periodicals, Inc.     

α1 adrenoceptor activation by norepinephrine inhibits LPS‐induced cardiomyocyte TNF‐α production via modulating ERK1/2 and NF‐κB pathway

Cardiomyocyte tumour necrosis factor α (TNF‐α) production contributes to myocardial depression during sepsis. This study was designed to observe the effect of norepinephrine (NE) on lipopolysaccharide (LPS)‐induced cardiomyocyte TNF‐α expression and to further investigate the underlying mechanisms in neonatal rat cardiomyocytes and endotoxaemic mice. In cultured neonatal rat cardiomyocytes, NE inhibited LPS‐induced TNF‐α production in a dose‐dependent manner. α₁‐ adrenoceptor (AR) antagonist (prazosin), but neither β₁‐ nor β₂‐AR antagonist, abrogated the inhibitory effect of NE on LPS‐stimulated TNF‐α production. Furthermore, phenylephrine (PE), an α₁‐AR agonist, also suppressed LPS‐induced TNF‐α production. NE inhibited p38 phosphorylation and NF‐κB activation, but enhanced extracellular signal‐regulated kinase 1/2 (ERK1/2) phosphorylation and c‐Fos expression in LPS‐treated cardiomyocytes, all of which were reversed by prazosin pre‐treatment. To determine whether ERK1/2 regulates c‐Fos expression, p38 phosphorylation, NF‐κB activation and TNF‐α production, cardiomyocytes were also treated with U0126, a selective ERK1/2 inhibitor. Treatment with U0126 reversed the effects of NE on c‐Fos expression, p38 mitogen‐activated protein kinase (MAPK) phosphorylation and TNF‐α production, but not NF‐κB activation in LPS‐challenged cardiomyocytes. In addition, pre‐treatment with SB202190, a p38 MAPK inhibitor, partly inhibited LPS‐induced TNF‐α production in cardiomyocytes. In endotoxaemic mice, PE promoted myocardial ERK1/2 phosphorylation and c‐Fos expression, inhibited p38 phosphorylation and IκBα degradation, reduced myocardial TNF‐α production and prevented LPS‐provoked cardiac dysfunction. Altogether, these findings indicate that activation of α₁‐AR by NE suppresses LPS‐induced cardiomyocyte TNF‐α expression and improves cardiac dysfunction during endotoxaemia via promoting myocardial ERK phosphorylation and suppressing NF‐κB activation.     

Synthesis of β‐Ketoamide Curcumin Analogs for Anti‐Diabetic and AGEs Inhibitory Activities

Two different series of novel β‐ketoamide curcumin analogs enriched in biological activities have been synthesized. The synthesized compounds were screened for their in vitro anti‐diabetic and AGEs inhibitory activities and exhibited potent to good anti‐diabetic and AGEs inhibitory activities. The molecular docking study was also performed with the α‐amylase enzyme.     

DIGESTION IN ADULT FEMALES OF THE LEAF‐FOOTED BUG Leptoglossus zonatus (HEMIPTERA: COREIDAE) WITH EMPHASIS ON THE GLYCOSIDE HYDROLASES α‐AMYLASE, α‐GALACTOSIDASE,AND α‐GLUCOSIDASE

The leaffooted bug, Leptoglossus zonatus (Hemiptera: Coreidae) is an emerging pest of several crops around the World and up to now very little is known of its digestive system. In this article, glycoside hydrolase (carbohydrase) activities in the adult midgut cells and in the luminal contents of L. zonatus adult females were studied. The results showed the distribution of digestive carbohydrases in adults of this heteropteran species in the different intestinal compartments. Determination of the spatial distribution of α‐glucosidase activity in L. zonatus midgut showed only one major molecular form, which was not equally distributed between soluble and membrane‐bound isoforms, being more abundant as a membrane‐bound enzyme. The majority of digestive carbohydrases were found in the soluble fractions. Activities against starch, maltose and the synthetic substrate NPαGlu were found to show the highest levels of activity, followed by enzymes active against galactosyl oligosaccharides. Based on ion‐exchange chromatography elution profiles and banding patterns in mildly denaturing electrophoresis, both midgut α‐amylases and α‐galactosidases showed at least two isoforms. The data suggested that the majority of carbohydrases involved in initial digestion were present in the midgut lumen, whereas final digestion of starch and of galactosyl oligosaccharides takes place partially within the lumen and partially at the cell surface. The complex of carbohydrases here described was qualitatively appropriate for the digestion of free oligosaccharides and oligomaltodextrins released by α‐amylases acting on maize seed starch granules.     

Prostaglandin I2 upregulates the expression of anterior pharynx‐defective‐1α and anterior pharynx‐defective‐1β in amyloid precursor protein/presenilin 1 transgenic mice

Cyclooxygenase‐2 (COX‐2) has been recently identified to be involved in the pathogenesis of Alzheimer's disease (AD). Yet, the role of an important COX‐2 metabolic product, prostaglandin (PG) I₂, in the pathogenesis of AD remains unknown. Using human‐ and mouse‐derived neuronal cells as well as amyloid precursor protein/presenilin 1 (APP/PS1) transgenic mice as model systems, we elucidated the mechanism of anterior pharynx‐defective (APH)‐1α and pharynx‐defective‐1β induction. In particular, we found that PGI₂ production increased during the course of AD development. Then, PGI₂ accumulation in neuronal cells activates PKA/CREB and JNK/c‐Jun signaling pathways by phosphorylation, which results in APH‐1α/1β expression. As PGI₂ is an important metabolic by‐product of COX‐2, its suppression by NS398 treatment decreases the expression of APH‐1α/1β in neuronal cells and APP/PS1 mice. More importantly, β‐amyloid protein (Aβ) oligomers in the cerebrospinal fluid (CSF) of APP/PS1 mice are critical for stimulating the expression of APH‐1α/1β, which was blocked by NS398 incubation. Finally, the induction of APH‐1α/1β was confirmed in the brains of patients with AD. Thus, these findings not only provide novel insights into the mechanism of PGI₂‐induced AD progression but also are instrumental for improving clinical therapies to combat AD.     

Antidiabetic potential: in vitro inhibition effects of some natural phenolic compounds on α‐glycosidase and α‐amylase enzymes

α‐Glycosidase is a catalytic enzyme and it destroys the complex carbohydrates into simple absorbable sugar units. The natural phenolic compounds were tested for their antidiabetic properties as α‐glycosidase and α‐amylase inhibitors. The phenolic compounds investigated in this study have been used as antidiabetic common medicines. This paper aimed to consider their capability to inhibit α‐amylase and α‐glycosidase, two significant enzymes defined in serum glucose adjustment. These examination recorded impressive inhibition profiles with IC₅₀ values in the range of 137.36–737.23 nM against α‐amylase and 29.01–157.96 nM against α‐glycosidase.     

Pulsatilla decoction and its active ingredients inhibit secretion of NO,ET‐1, TNF‐α, and IL‐1α in LPS‐induced rat intestinal microvascular endothelial cells

To investigate the pharmacological mechanism of the traditional Chinese medicine, Pulsatilla decoction (PD), the levels of nitric oxide (NO), endothelin‐1 (ET‐1), tumor necrosis factor‐α (TNF‐α), and interleukin‐1α (IL‐1α) secreted by cultured rat intestinal microvascular endothelial cells (RIMECs) were determined after treatment with PD and its seven active ingredients, namely anemoside B₄, anemonin, berberine, jatrorrhizine, palmatine, aesculin, and esculetin. RIMECs were challenged with lipopolysaccharide (LPS) at 1 µg ml^?1 for 3 h and then treated with PD at 1, 5, and 10 mg ml^?1 and its seven ingredients at 1, 5, and 10 µg ml^?1 for 21 h, respectively. The results revealed that PD, anemonin, berberine, and esculetin inhibited the production of NO; PD, anemonin, and esculetin inhibited the secretion of ET‐1; PD, anemoside B₄, berberine, jatrorrhizine, and aesculin downregulated TNF‐α expression; PD, anemoside B₄, berberine, and palmatine decreased the content of IL‐1α. It showed that PD and its active ingredients could significantly inhibit the secretion of NO, ET‐1, TNF‐α, and IL‐1α in LPS‐induced RIMECs and suggested they would reduce inflammatory response via these cytokines. Copyright © 2009 John Wiley & Sons, Ltd.     

Aquaporin‐4 deficiency reduces TGF‐β1 in mouse midbrains and exacerbates pathology in experimental Parkinson's disease

Aquaporin‐4 (AQP4), the main water‐selective membrane transport protein in the brain, is localized to the astrocyte plasma membrane. Following the establishment of a 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP)‐induced Parkinson's disease (PD) model, AQP4‐deficient (AQP4^?/?) mice displayed significantly stronger microglial inflammatory responses and remarkably greater losses of tyrosine hydroxylase (TH⁺)‐positive neurons than did wild‐type AQP4 (AQP4^+/+) controls. Microglia are the most important immune cells that mediate immune inflammation in PD. However, recently, few studies have reported why AQP4 deficiency results in more severe hypermicrogliosis and neuronal damage after MPTP treatment. In this study, transforming growth factor‐β1 (TGF‐β1), a key suppressive cytokine in PD onset and development, failed to increase in the midbrain and peripheral blood of AQP4^?/? mice after MPTP treatment. Furthermore, the lower level of TGF‐β1 in AQP4^?/? mice partially resulted from impairment of its generation by astrocytes; reduced TGF‐β1 may partially contribute to the uncontrolled microglial inflammatory responses and subsequent severe loss of TH⁺ neurons in AQP4^?/? mice after MPTP treatment. Our study provides not only a better understanding of both aetiological and pathogenical factors implicated in the neurodegenerative mechanism of PD but also a possible approach to developing new treatments for PD via intervention in AQP4‐mediated immune regulation.     

Enzymatic Resolution of α‐Methyleneparaconic Acids and Evaluation of their Biological Activity

Both enantiomers of three biologically relevant paraconic acids—MB‐3, methylenolactocin, and C75—were obtained with enantioselectivities up to 99% by kinetic enzymatic resolutions. Good enantiomeric excesses were obtained for MB‐3 and methylenolactocin, using α‐chymotrypsin and aminoacylase as enantiocomplementary enzymes, while C75 was resolved with aminoacylase. They all were evaluated for their antiproliferative, antibacterial, and antifungal activities, showing weak effects and practically no difference between enantiomers in each case. At high concentrations (16–64 µg/mL), (–)‐ C75 acted as an antimicrobial agent against Gram‐positive bacteria. Chirality 27:239–246, 2015. © 2015 Wiley Periodicals, Inc.     

Conformations of peptides containing a chiral cyclic α, α‐disubstituted α‐amino acid within the sequence of Aib residues

A single chiral cyclic α,α‐disubstituted amino acid, (3S,4S)‐1‐amino‐(3,4‐dimethoxy)cyclopentanecarboxylic acid [(S,S)‐Ac₅c^dOM], was placed at the N‐terminal or C‐terminal positions of achiral α‐aminoisobutyric acid (Aib) peptide segments. The IR and ¹H NMR spectra indicated that the dominant conformations of two peptides Cbz‐[(S,S)‐Ac₅c^dOM]‐(Aib)₄‐OEt ( 1) and Cbz‐(Aib)₄‐[(S,S)‐Ac₅c^dOM]‐OMe (2) in solution were helical structures. X‐ray crystallographic analysis of 1 and 2 revealed that a left‐handed (M) 3₁₀‐helical structure was present in 1 and that a right‐handed (P) 3₁₀‐helical structure was present in 2 in their crystalline states. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.     

Solution structure of the calmodulin‐like C‐terminal domain of Entamoeba α‐actinin2

Cell motility is dependent on a dynamic meshwork of actin filaments that is remodelled continuously. A large number of associated proteins that are severs, cross‐links, or caps the filament ends have been identified and the actin cross‐linker α‐actinin has been implied in several important cellular processes. In Entamoeba histolytica, the etiological agent of human amoebiasis, α‐actinin is believed to be required for infection. To better understand the role of α‐actinin in the infectious process we have determined the solution structure of the C‐terminal calmodulin‐like domain using NMR. The final structure ensemble of the apo form shows two lobes, that both resemble other pairs of calcium‐binding EF‐hand motifs, connected with a mobile linker. Proteins 2016; 84:461–466. © 2016 Wiley Periodicals, Inc.     

Enantiodifferentiation of α‐hydroxyalkanephosphonic acids in 31P NMR with application of α‐cyclodextrin as chiral discriminating agent

α‐Cyclodextrin was shown to be convenient chemical shift reagent for determination of the enantiomeric composition of α‐hydroxyphosphonic acids by means of ³¹P NMR. The developed methodology appeared to be reliable, repetitive, easy to perform and simple for interpretation. Enantiomeric discrimination in the ³¹P NMR spectra for 12 of 13 studied hydroxyphosphonates was achieved, with baseline separation of resonances obtained for eight compounds. In those cases, the chemical nonequivalence values ranged from 0.069 to 0.313 ppm. The studies showed that enantioselectivity is strongly influenced by the solution pD and the optimal condition was found at pD 2 or 10 depending on the guest structure. On the basis of the ROESY spectra the complexation modes of selected hydroxyphosphonates with α‐cyclodextrin was postulated. Chirality 2010. © 2009 Wiley‐Liss, Inc.     

Novel mechanism of cardiac protection by valsartan: synergetic roles of TGF‐β1 and HIF‐1α in Ang II‐mediated fibrosis after myocardial infarction

Transforming growth factor (TGF)‐β1 is a known factor in angiotensin II (Ang II)‐mediated cardiac fibrosis after myocardial infarction (MI). Hypoxia inducible factor‐1 (Hif‐1α) was recently demonstrated to involve in the tissue fibrosis and influenced by Ang II. However, whether Hif‐1α contributed to the Ang II‐mediated cardiac fibrosis after MI, and whether interaction or synergetic roles between Hif‐1α and TGF‐β pathways existed in the process was unclear. In vitro, cardiac cells were incubated under hypoxia or Ang II to mimic ischaemia. In vivo, valsartan was intravenously injected into Sprague–Dawley rats with MI daily for 1 week; saline and hydralazine (another anti‐hypertensive agent like valsartan) was used as control. The fibrosis‐related proteins were detected by Western blotting. Cardiac structure and function were assessed with multimodality methods. We demonstrated in vitro that hypoxia would induce the up‐regulation of Ang II, TGF‐β/Smad and Hif‐1α, which further induced collagen accumulation. By blocking with valsartan, a blocker of Ang II type I (AT1) receptor, we confirmed that the up‐regulation of TGF‐β/Smad and Hif‐1α was through the Ang II‐mediated pathway. By administering TGF‐β or dimethyloxalylglycine, we determined that both TGF‐β/Smad and Hif‐1α contributed to Ang II‐mediated collagen accumulation and a synergetic effect between them was observed. Consistent with in vitro results, valsartan significantly attenuated the expression of TGF‐β/Smad, Hif‐1α and fibrosis‐related protein in rats after MI. Heart function, infarcted size, wall thickness as well as myocardial vascularization of ischaemic hearts were also significantly improved by valsartan compared with saline and hydralazine. Our study may provide novel insights into the mechanisms of Ang II‐induced cardiac fibrosis as well as into the cardiac protection of valsartan.