Synthesis and SAR of tetrahydroisoquinolines as Rev-erbα agonists

The design and synthesis of a novel series of Rev-erbα agonists is described. The development and optimization of the tetrahydroisoquinoline series was carried out from an earlier acyclic series of Rev-erbα agonists. Through the optimization of the scaffold 1, several potent compounds with good in vivo profiles were discovered.     

Pharmacophore-based design and discovery of (−)-meptazinol carbamates as dual modulators of cholinesterase and amyloidogenesis

Multifunctional carbamate-type acetylcholinesterase (AChE) inhibitors with anti-amyloidogenic properties like phenserine are potential therapeutic agents for Alzheimer’s disease (AD). We reported here the design of new carbamates using pharmacophore model strategy to modulate both cholinesterase and amyloidogenesis. A five-feature pharmacophore model was generated based on 25 carbamate-type training set compounds. (?)-Meptazinol carbamates that superimposed well upon the model were designed and synthesized, which exhibited nanomolar AChE inhibitory potency and good anti-amyloidogenic properties in in vitro test. The phenylcarbamate 43 was highly potent (IC₅₀ 31.6?nM) and slightly selective for AChE, and showed low acute toxicity. In enzyme kinetics assay, 43 exhibited uncompetitive inhibition and reacted by pseudo-irreversible mechanism. 43 also showed amyloid-β (Aβ) lowering effects (51.9% decrease of Aβ₄₂) superior to phenserine (31% decrease of total Aβ) in SH-SY5Y-APP₆₉₅ cells at 50?µM. The dual actions of 43 on cholinergic and amyloidogenic pathways indicated potential uses as symptomatic and disease-modifying agents.     

Amino acids and β-aminopropionitrile as inhibitors of seed germination and growth

The germination of lettuce fruits and legume seeds was affected by the imbibition of solutions of certain amino acids. Seedling growth was inhibited more markedly than germination by these compounds. Non-protein amino acids were, as a group, more effective inhibitors of germination and seedling growth than were protein amino acids, with the exception of lysine. Anomalous results were obtained with β-aminopropionitrile.     

Isolation and characterization of brown algal polyphenols as inhibitors of α-amylase,lipase and trypsin

Extracts ofAscophyllum nodosum, Fucus serratus, F. vesiculosus andPelvetia canaliculata contain inhibitors of α-amylase, lipase and trypsin. The inhibitors were isolated and identified by¹H NMR spectroscopy as polyphenols which have apparent molecular weights in the range from 30 000 to 100 000 daltons, as determined by ultra-filtration with Amicon membranes. These polyphenols account for the whole of the inhibitory activity in crude algal extracts. The compounds inhibit α-amylase and trypsin in an apparently non-competitive manner, when preincubated with the enzymes, and the inhibition is directly proportional to the concentration of the inhibitor. Starch protects α-amylase when added to the enzyme together with the inhibitors. Under this condition the effectiveness of the inhibitors is reduced ten-fold.     

Peptides and peptidomimetics as regulators of protein–protein interactions

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The synthesis and evaluation of indolylureas as PKCα inhibitors

PKCα and PKA have crucial but opposing roles in the regulation of calcium handling within myocytes. Identification of compounds that inhibit PKCα, but not PKA, are potential therapeutic targets for the treatment of heart disease. The synthesis of indolylureas are described, and a compound displaying nanomolar inhibition towards PKCα with significant selectivity over PKA has been identified.     

Analysis of saponins and phenolic compounds as inhibitors of α-carbonic anhydrase isoenzymes

A series of phenolic and saponin type natural products such as quercetin, rutin, catechin, epicatechin, silymarin, trojanoside H, astragaloside IV, astragaloside VIII and astrasieversianin X, were investigated for their inhibitory effects against the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). We here report inhibitory effects of these compounds against five α-CA isozymes (hCA I, hCA II, bCA III, hCA IV and hCA VI). Most of the phenolic and saponin type compounds inhibited the isoenzymes quite effectively at low micromolar K_I-s ranging between 0.1 and 4 µM, whereas a few derivatives were ineffective (K_I-s > 100 µM). The results were remarkable which might lead to design of novel CAIs with a diverse inhibition mechanism compared to sulfonamide/sulfamate inhibitors.     

Synthesis and evaluation of β-carboline derivatives as inhibitors of human immunodeficiency virus

A series of β-carboline derivatives were synthesized by utilizing aromatization and chemoselective alkylation method recently reported from our laboratory. Synthesized derivatives were evaluated for anti-HIV activity in human CD4+ T cell line (CEM-GFP) infected with HIV-1 NL_4.3 virus. 1-Formyl-β-carboline-3-carbxylic acid methyl ester (15) showed inhibition of human immunodeficiency virus at IC₅₀ = 2.9 μM.     

Novel diphenyl esters of peptidyl α-aminoalkylphosphonates as inhibitors of chymotrypsin and subtilisin

The activities of novel Cbz-N-protected α-aminophosphonic phenyl esters, analogs of leucine (1–15) and phenylalanine (17–29), which are substituted at the phenyl ester rings, as well as of their peptidic derivatives (31–43), were investigated for their inhibitory effects on chymotrypsin and subtilisin. The chemical nature and position of the examined substituents clearly demonstrated a strong structure–activity relationship. Among all synthesized compounds the most potent phosphonic-type inhibitors of subtilisin and chymotrypsin were identified, with k₂/K_i values 114,380?M^?1s^?1 and 307,380?M^?1s^?1, respectively.     

Acyl derivatives of boswellic acids as inhibitors of NF-κB and STATs

Boswellic acid acylates including their epimers were synthesized and screened against a panel of human cancer cell lines. They exhibited a range of cytotoxicity against various human cancer cell lines thereby leading to the development of a possible SAR. One of the identified lead compounds was found to be an inhibitor of the NF-κB and STAT proteins, warranting further investigations to be developed into a potential anticancer lead.     

Phytoconstituents of Selaginella effusa Alston and Their α-Glucosidase as well as Urease Inhibitory Activities

Three new compounds ( 1 – 2 , 14 ), as well as 22 known compounds ( 3 – 13 , 15 – 25 ), were extracted for the first time from the Selaginella effusa Alston (S. effusa). For the unknown compounds, the planar configurations were determined via NMR and by high-resolution mass spectrometry, while their absolute configurations were determined by calculated electronic circular dichroism (ECD), and the configuration of the stereogenic center of biflavones 4 – 5 were established for the first time. The pure compounds ( 1 – 25 ) were tested in vitro to determine the inhibitory activity of the enzyme-catalyzed reactions. Compounds 1 – 9 inhibited α-glucosidase with IC₅₀ values ranging from 0.30±0.02 to 4.65±0.04 μM and kinetic analysis of enzyme inhibition indicated that biflavones 1 – 3 were mixed-type α-glucosidase inhibitors. Compounds 12 – 13 showed excellent inhibitory activity against urease, with compound 12 (IC₅₀=4.38±0.31 μM) showing better inhibitory activity than the positive control drug AHA (IC₅₀13.52±0.61 μM). In addition, molecular docking techniques were used to simulate inhibitor-enzyme binding and to estimate the binding posture of the α-glucosidase and urease catalytic sites.     

Synthesis of 3′-triazoyl-dinucleotides as precursors of stable Phe-tRNAPhe and Leu-tRNALeu analogues

We report here the synthesis of stable Phe-tRNA^Phe and Leu-tRNA^Leu analogues containing a 1,2,3-triazole ring instead of the ribose-amino acid ester bond. The 1,2,3-triazole ring is generated by dipolar cycloaddition of alkyne Phe and Leu analogues to 3′-azido-3′-deoxyadenosine via the Cu^I-catalysed Huisgen, Meldal, Sharpless 1,3-cycloaddition. The corresponding triazoyl pdCpA dinucleotides, obtained by classical phosphoramidite chemistry, were enzymatically ligated to 22-nt or 74-nt RNA generating stable Phe-tRNA^Phe analogues containing the acceptor stem or full tRNA moieties, respectively. These molecules represent useful tools to study the contribution of the RNA and amino acid moieties in stabilization of aminoacyl-tRNA/protein complexes.     

Kinetics of α-amylase production in a batch and fed-batch culture of Bacillus subtilis with caseinate as nitrogen source and starch as carbon source

Summary Analysis of a large number of experimental data from the cultivation of Bacillus subtilis formed the basis for a kinetic model of the process explaining the effect of composition of the culture medium and of the growth rate on the rate of enzyme production. The resulting rate of formation of -amylase (EC 3.2.1.1) reflects the sum of the rate of enzyme production and the rate of its degradation as affected by the environment. The kinetic dependence confirms the previously described mechanism of regulation of enzyme biosynthesis. The mathematical model of the process served here to determine the optimal conditions for enzyme biosynthesis which were then verified in a fed-batch cultivation. The production of the enzyme in fed-batch culture was found to be twice that found in a batch cultivation.Symbols X biomass concentration, g·l^-1 - t time, h - S ₁ caseinate concentration, g·l^-1 - S ₂ starch concentration, g·l^-1 - P product concentration, U·ml^-1 - r _P specific rate of product formation, U·g^-1·h^-1 - R _P total rate of product formation, U·l^-1·h^-1 - Y yield coefficient - specific growth rate, h^-1     

Glycoforms of serum α1-acid glycoprotein as markers of inflammation and cancer

1-acid glycoprotein (AGP) is a serum acute phase glycoprotein which possesses five N-linked complex type heteroglycan side chains which may be present as bi-, tri- and tetraantennary structures. Depending upon the content of biantennary structure on AGP, up to four glycoforms of AGP are present in serum. These glycoforms can be easily estimated in body fluids by means of crossed affinity-immunoelectrophoresis (CAIE) with the lectin, Concanavalin A (Con A). Con A selectively binds biantennary structures; the more biantennary structures on AGP, the stronger the binding. In acute inflammation, a relative increase of AGP glycoforms with biantennary units is observed - a type I glycosylation change. In some chronic inflammatory states there is an relative decrease of AGP glycoforms with biantennary heteroglycans — a type II glycosylation change. Moreover, in certain other states such as pregnancy, estrogen administration or liver damage, type II glycosylation changes are also seen. A detailed analysis of the clinical applications of the assessment of AGP glycoforms in sera of patients with rheumatic diseases, AIDS and various types of cancers is presented. Accumulated data shows that AGP glycoforms may be very useful in the detection of intercurrent infections in the course of rheumatoid arthritis, systemic lupus erythematosus, or myeloblastic leukaemia, and in the detection of secondary infections in human immunodeficiency virus infected individuals. AGP glycoforms are also very useful in differentiation between various forms of trophoblastic disease and are helpful in monitoring the treatment of these patients. Finally, AGP glycoforms provide valuable information for differentiation between primary and secondary liver cancer.     

The relationship between GPR40 and lipotoxicity of the pancreatic β-cells as well as the effect of pioglitazone

Free fatty acids (FFAs) acutely stimulate insulin secretion from pancreatic β-cells, whereas impair β-cell function following long term exposure. GPR40, a FFAs receptor, has been demonstrated to be activated by both medium and long chain FFAs and played an important role in insulin release. This study was performed to determine the contribution of GPR40 to short- and/or long-term effects of FFAs on glucose-stimulated insulin secretion (GSIS) and the expression of PDX-1 and GLUT2 in pancreatic β-cells, as well as the intervenient effects of pioglitazone on lipotoxicity of β-cells. βTC6 cell line stably expressing GPR40shRNA were established and the intervention of FFAs and pioglitazone on GSIS and expression of PDX-1 and GLUT2 in βTC6 cells was investigated. Results showed that 1-h exposure to FFAs significantly enhanced GSIS and increased expression of PDX-1 and GLUT2 in pSilencer-control transfected cells, but not in cells transfected with GPR40shRNA. While 48-h exposure to FFAs significantly impaired GSIS in pSilencer-control transfected cells as well as cells transfected with GPR40shRNA. Furthermore, pioglitazone enhanced insulin secretion in pSilencer-control transfected cells exposed to FFAs for 48 h, but not in cells transfected with GPR40shRNA. These results indicate that GPR40 mediates the short-term effects of FFAs on GSIS, but does not mediate the chronic lipotoxicity on β-cells. The reverse role of pioglitazone on lipotoxicity of β-cells may be related to GPR40.     

γ-Hydroxyethyl piperidine iminosugar and N-alkylated derivatives: A study of their activity as glycosidase inhibitors and as immunosuppressive agents

An efficient and practical strategy for the synthesis of (3R,4s,5S)-4-(2-hydroxyethyl) piperidine-3,4,5-triol and its N-alkyl derivatives 8a–f, starting from the d-glucose, is reported. The chiral pool methodology involves preparation of the C-3-allyl-α-d-ribofuranodialdose 10, which was converted to the C-5-amino derivative 11 by reductive amination. The presence of C-3-allyl group gives an easy access to the requisite hydroxyethyl substituted compound 13. Intramolecular reductive aminocyclization of C-5 amino group with C-1 aldehyde provided the γ-hydroxyethyl substituted piperidine iminosugar 8a that was N-alkylated to get N-alkyl derivatives 8b–f. Iminosugars 8a–f were screened against glycosidase enzymes. Amongst synthetic N-alkylated iminosugars, 8b and 8c were found to be α-galactosidase inhibitors while 8d and 8e were selective and moderate α-mannosidase inhibitors. In addition, immunomodulatory activity of compounds 8a–f was examined. These results were substantiated by molecular docking studies using AUTODOCK 4.2 programme.     

Relationship Between Ω as well as the Length of 3′poly (dA) and Efficiency of Gene Expression

Three plant high expression vectors harboring 25, 50 and 100 deoxyadenylate (dA) residues respectively in 3' untranslated region (3'-UTR) were constructed by inserting poly(dA) sequence into the primary vector containing CaMV 35S promoter doubled with region B and II which is a leader sequence derived from tobacco mosaic virus, within 5'-UTR. Transient expression of chimeric GUS gene in transgenic tobacco (Nicotiana tabacum L. ) mesophyll protoplasts showed that:doubled enhancer, Ω and poly (dA) increasd GUS expression. When both Ω and poly (dA) were present, the level of expression increased further, compared to that when only Ω was present. Moreover, when Ω was present, doubling the length of poly (dA) resulted in a further increase in GUS expression, which suggested a positive relationship between poly(dA) length and the level of expression.     

Enzymatic synthesis of propyl-α-glycosides and their application as emulsifying and antibacterial agents

Alkyl glycosides have been effectively used in many industries because of their biodegradable, emulsification and antibacterial properties. In this study, the alkyl glycoside of propyl glycosides (PG_n) was synthesized using β-cyclodextrin (β-CD) and 1-propanol through the transglycosylation reaction of recombinant cyclodextrin glycosyltransferase (CGTase) from the Bacillus circulans A11. The optimal condition for the synthesis of propyl glycosides consisted of an incubation of 1.5% (w/v) β-CD and 500 U/mL of CGTase in a water/propanol content containing 10% (v/v) 1-propanol at pH 6.0, 50°C for 96 h. Upon analysis of the product at the optimal condition by TLC, at least three products which move faster than glucose were observed. These transferred products were formed with molecular weights of 222.1, 384.1 and 546.4 daltons as determined by mass spectrometry analysis; these values were in accordance with propyl glucoside (PG₁), propyl maltoside (PG₂) and propyl maltotrioside (PG₃), respectively. PG₁ and PG₂ were produced and prepared on a large scale and subsequently purified by preparative TLC. The combined ¹H- and ¹³C-NMR analysis confirmed that the structures of PG₁ and PG₂ were propyl-α-D-glucopyranoside and propyl-α-D-maltopyranoside, respectively. Both PG₁ and PG₂ showed emulsification activity and stability in their formation in water and n-hexadecane. Furthermore, the antibacterial activity of both products was determined and it was found that PG₂ had a higher antibacterial activity against Staphylococcus aureus and Escherichia coli than that of PG₁.     

Design and characterization of alcalase–chitosan conjugates as potential biocatalysts

Bioprocess and Biosystems Engineering - In this study, alcalase (protease from Bacillus licheniformis) immobilization by adsorption, enzyme crosslinking and covalent enzyme binding to activated...     

Docking and SAR studies of D- and L-isofagomine isomers as human β-glucocerebrosidase inhibitors

We report the structure-activity relationship of a series of D-, and L-isofagomine and fagomine isomers as glycosidase inhibitors. Our study revealed that a positive charge at the anomeric position of d-isofagomines enhanced the potency toward β-glycosidases, while the epimerization at the C3 OH group drastically reduced their inhibitory potency by over three orders of magnitude. Furthermore, d-3,4-di-epi-isofagomine abolished their inhibition activities against all enzymes. L-Isofagomine was also a fairly potent inhibitor of human β-glucocerebrosidase, with an IC?? value of 8.7 μM. A molecular docking study revealed that the positions and orientations of the piperidine ring of D-3-epi-isofagomine in the binding site was similar to that of D-isofagomine, while D-3-epi-isofagomine missed the hydrogen bond interactions between Asp127 and the 3-OH group and between Trp179 and the 3-OH group. Furthermore, the top 10 docking models ranked by IFDscore suggested that D-3,4-di-epi-isofagomine can not bind to β-glucocerebrosidase at a stable interaction mode. These results provide an insight into the structural requirements of isofagomine isomers for developing a new type of pharmacological chaperone for Gaucher disease.