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Biofilms are three-dimensional structures formed as a result of microorganism's adhesion on a biotic or abiotic surface. Once a biofilm is established, it is onerous to eradicate it or kill the pathogens therein. Thus, targeting the microbial adhesion process, the initial stage of biofilm formation, is a reasonable approach to avoid challenges associated with subsequently formed biofilms. While many properties of interacting material that play significant roles in initial bacterial adhesion have been widely studied, the effect of surface stiffness on bacterial adhesion was relatively underexplored. In this study, we aimed to investigate the effect of surface stiffness on the adhesion of microbial species found in the oral cavity by employing representative oral bacteria, Streptococcus mutans and Streptococcus oralis, and the fungus, Candida albicans. We compared the adhesion behavior of these species alone or in combination toward various surface stiffness (0.06 - 3.01 MPa) by assessing the adhered and planktonic cell numbers at an early (4 h) adhesion stage under various carbon sources and the presence of conditioning film. Our data revealed that in general, a higher amount of microbial cells adhered to softer PDMS surfaces than stiffer ones, which indicates that surface stiffness plays a role in the adhesion of tested species (either single or co-cultured). This pattern was more obvious under sucrose conditions than glucose + fructose conditions. Interestingly, in monospecies, saliva coating did not alter the effect of surface stiffness on S. mutans adhesion while it diminished S. oralis and C. albicans adhesion. However, in the multispecies model, saliva coating rendered the percentage of all adhered microbes to varied PDMS not distinct. The data provide new insights into the role of surface stiffness on microbial mechanosensing and their initial adhesion behavior which may set a scientific foundation for future anti-adhesion strategies.

The toxic pyroglutamate form of amyloid-β (pE-Aβ) is important for the pathogenesis of early Alzheimer's disease (AD); therefore, reducing pE-Aβ by inhibiting glutaminyl cyclase (QC) provides a promising strategy for developing disease-modifying AD drugs. In this study, potent and selective QC inhibitors with desirable drug-like properties were discovered by replacing the 3,4-dimethoxyphenyl group in a QC inhibitor with a bioisosteric indazole surrogate. Among them, 3-methylindazole-6-yl and 3-methylindazole-5-yl derivatives with an N-cyclohexylurea were identified as highly potent inhibitors with IC

Triple-negative breast cancer (TNBC) is an aggressive heterogeneous disease with a divergent profile. It has an earlier tendency to form metastases and is associated with poor clinical outcomes due to the limited treatment options available. Heat-shock protein (HSP90) represents a potential treatment target as it promotes tumor progression and metastasis by modulating the maturation and stabilization of signal transduction proteins. We sought to investigate the efficacy of the C-terminal HSP90 inhibitor L80 on cell proliferation, breast cancer stem cell (BCSC)-like properties, tumor growth and metastasis. L80 suppressed cell viability and concomitantly inhibited AKT/MEK/ERK/JAK2/STAT3 signaling in TNBC cells but did not induce cytotoxicity in normal cells. L80 effectively targeted BCSC-like traits, together with significant reductions in the CD44high/CD24low-population, ALDH1 activity and mammosphere forming-ability. In support of the in vitro observations, L80 administration caused significant impairment in tumor growth, angiogenesis and distant metastases in an orthotopic allograft model with BCSC-enriched cells in vivo. These phenomena were associated with the suppression of BCSC-like characteristics and STAT3 dysfunction. Our findings highlight properties of the L80 compound that may be useful in suppressing metastatic TNBC.

On the basis of deguelin, a series of the B,C-ring truncated surrogates with N-substituted amide linkers were investigated as HSP90 inhibitors. The structure activity relationship of the template was studied by incorporating various substitutions on the nitrogen of the amide linker and examining their HIF-1α inhibition. Among them, compound 57 showed potent HIF-1α inhibition and cytotoxicity in triple-negative breast cancer lines in a dose-dependent manner. Compound 57 downregulated expression and phosphorylation of major client proteins of HSP90 including AKT, ERK and STAT3, indicating that its antitumor activity was derived from the inhibition of HSP90 function. The molecular modeling of 57 demonstrated that 57 bound well to the C-terminal ATP-binding pocket in the open conformation of the hHSP90 homodimer with hydrogen bonding and pi-cation interactions. Overall, compound 57 is a potential antitumor agent for triple-negative breast cancer as a HSP90 C-terminal inhibitor.

Leucyl-tRNA synthetase (LRS) plays an important role in amino acid-dependent mTORC1 signaling, which is known to be associated with cellular metabolism and proliferation. Therefore, LRS-targeting small molecules that can suppress mTORC1 activation may provide an alternative strategy to current anticancer therapy. In this work, we developed a library of leucyladenylate sulfate analogues by extensively modifying three different pharmacophoric regions comprising adenine, ribose and leucine. Several effective compounds were identified by cell-based mTORC1 activation assays and further tested for anticancer activity. The selected compounds mostly exhibited selective cytotoxicity toward five different cancer cell lines, supporting the hypothesis that the LRS-mediated mTORC1 pathway is a promising alternative target to current therapeutic approaches.

A series of N-benzyl 5-(4-sulfamoylbenzylidene-2-thioxothiazolidin-4-one analogs, designed as hybrids of CY09 and JC121, were investigated as inhibitors of NLRP3 inflammasome activation. Among them, compounds 34 and 36 were identified as promising NLRP3 inhibitors by measuring the amount of active caspase-1 p20 and IL-1β produced by NLRP3 inflammasome activation. Further studies indicated that both compounds inhibited NLRP3 inflammasome assembly by reducing the formation of NLRP3 and ASC oligomer specks and selectively inhibited only NLRP3 inflammasome activation and not other inflammasomes such as NLRC4 and AIM2.

A series of 2-(3,5-substituted 4-aminophenyl)acetamide and propanamide derivatives were investigated as human TRPV1 antagonists. The analysis of the structure-activity relationship indicated that 2-(3,5-dihalo 4-aminophenyl)acetamide analogues displayed excellent antagonism of hTRPV1 activation by capsaicin and showed improved potency compared to the corresponding propanamides. The most potent antagonist (36) exhibited potent and selective antagonism for hTRPV1 not only to capsaicin but also to NADA and elevated temperature; however, it only displayed weak antagonism to low pH. Further studies indicated that oral administration of antagonist 36 blocked the hypothermic effect of capsaicin in vivo but demonstrated hyperthermia at that dose. A docking study of 36 was performed in our established hTRPV1 homology model to understand its binding interactions with the receptor and to compare with that of previous antagonist 1.

According to recent studies, leucyl-tRNA synthetase (LRS) acts as a leucine sensor and modulates the activation of the mammalian target of rapamycin complex 1 (mTORC1) activation. Because overactive mTORC1 is associated with several diseases, including colon cancer, LRS-targeted mTORC1 inhibitors represent a potential option for anti-cancer therapy. In this work, we developed a series of simplified leucyladenylate sulfamate analogues that contain the N-(3-chloro-4-fluorophenyl)quinazolin-4-amine moiety to replace the adenine group. We identified several compounds with comparable activity to previously reported inhibitors and exhibited selective mTORC1 inhibition and anti-cancer activity. This study further supports the hypothesis that LRS is a promising target to modulate the mTORC1 pathway.

A series of A-region analogues of 2-(3-fluoro-4-methylsufonamidophenyl) propanamide 1 were investigated as TRPV1 antagonists. The analysis of structure-activity relationship indicated that a fluoro group at the 3- (or/and) 5-position and a methylsulfonamido group at the 4-position were optimal for antagonism of TRPV1 activation by capsaicin. The most potent antagonist 6 not only exhibited potent antagonism of activation of hTRPV1 by capsaicin, low pH and elevated temperature but also displayed highly potent antagonism of activation of rTRPV1 by capsaicin. Further studies demonstrated that antagonist 6 blocked the hypothermic effect of capsaicin in vivo, consistent with its in vitro mechanism, and it showed promising analgesic activity in the formalin animal model.

Diacylglycerol (DAG) is a key lipid second messenger downstream of cellular receptors that binds to the C1 domain in many regulatory proteins. Protein kinase C (PKC) isoforms constitute the most prominent family of signaling proteins with DAG-responsive C1 domains, but six other families of proteins, including the chimaerins, Ras-guanyl nucleotide–releasing proteins (RasGRPs), and Munc13 isoforms, also play important roles. Their significant involvement in cancer, immunology, and neurobiology has driven intense interest in the C1 domain as a therapeutic target. As with other classes of targets, however, a key issue is the establishment of selectivity. Here, using [(3)H]phorbol 12,13-dibutyrate ([(3)H]PDBu) competition binding assays, we found that a synthetic DAG-lactone, AJH-836, preferentially binds to the novel PKC isoforms PKCδ and PKCϵ relative to classical PKCα and PKCβII. Assessment of intracellular translocation, a hallmark for PKC activation, revealed that AJH-836 treatment stimulated a striking preferential redistribution of PKCϵ to the plasma membrane relative to PKCα. Moreover, unlike with the prototypical phorbol ester phorbol 12-myristate 13-acetate (PMA), prolonged exposure of cells to AJH-836 selectively down-regulated PKCδ and PKCϵ without affecting PKCα expression levels. Biologically, AJH-836 induced major changes in cytoskeletal reorganization in lung cancer cells, as determined by the formation of membrane ruffles, via activation of novel PKCs. We conclude that AJH-836 represents a C1 domain ligand with PKC-activating properties distinct from those of natural DAGs and phorbol esters. Our study supports the feasibility of generating selective C1 domain ligands that promote novel biological response patterns.

A series consisting of 117 2-(halogenated phenyl) acetamide and propanamide analogs were investigated as TRPV1 antagonists. The structure–activity analysis targeting their three pharmacophoric regions indicated that halogenated phenyl A-region analogs exhibited a broad functional profile ranging from agonism to antagonism. Among the compounds, antagonists 28 and 92 exhibited potent antagonism toward capsaicin for hTRPV1 with Ki[CAP] = 2.6 and 6.9 nM, respectively. Further, antagonist 92 displayed promising analgesic activity in vivo in both phases of the formalin mouse pain model. A molecular modeling study of 92 indicated that the two fluoro groups in the A-region made hydrophobic interactions with the receptor.

A series of O-substituted analogs of the C-ring-truncated scaffold of deguelin designed as heat shock protein 90 (HSP90) C-terminal inhibitors were investigated as novel antitumor agents against human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Among the synthesized compounds, compound 37 displayed significant inhibition in both trastuzumab-sensitive and trastuzumab-resistant breast cancer cells with little cytotoxicity to normal cells. Mechanistic studies of compound 37 carried out by HSP90α C-terminal inhibitor screening, the induction of the heat shock response and downregulation of HSP90 client proteins indicated that the antitumor activity of 37 in breast cancer cells could be attributed to the destabilization and inactivation of HSP90 client proteins by the binding of 37 to the C-terminal domain of HSP90. A molecular docking study of compound 37 with a HSP90 homology model indicated that its S-isomer fit well in the ATP binding site of the C-terminal domain, forming key interactions.

Leucyl-tRNA synthetase (LRS) has been reported to be a possible mediator of intracellular amino acids signaling to mTORC1. Given that mTORC1 is associated with cell proliferation and tumorigenesis, the LRS-mediated mTORC1 pathway may offer an alternative strategy in anticancer therapy. In this study, we developed a series of simplified analogues of leucyladenylate sulfamate (1) as LRS-targeted mTORC1 inhibitors. We replaced the adenylate group with a N-(3,4-dimethoxybenzyl)benzenesulfonamide (2a) or a N-(2-phenoxyethyl)benzenesulfonamide groups (2b) that can maintain specific binding, but has more favorable physicochemical properties such as reduced polarity and asymmetric centers. Among these simplified analogues, compound 16 and its constrained analogue 22 effectively inhibited S6K phosphorylation in a dose-dependent manner and exhibited cancer cell specific cytotoxicity against six different types of cancer cells. This result supports that LRS is a viable target for novel anticancer therapy.

A series of 2-substituted 6-t-butylpyridine and 4-t-butylphenyl C-region analogues of 2-(3-fluoro-4-methylsulfonamidophenyl)propanamides were investigated for hTRPV1 antagonism. The analysis of structure activity relationships indicated that the pyridine derivatives generally exhibited a little better antagonism than did the corresponding phenyl surrogates for most of the series. Among the compounds, compound 7 showed excellent antagonism toward capsaicin activation with K(i) = 0.1 nM and compound 60S demonstrated a strong antiallodynic effect with 83% MPE at 10 mg/kg in the neuropathic pain model. The docking study of 7S in our hTRPV1 homology model indicated that the interactions between the A/B-regions of 7S with Tyr511 and the interactions between the t-butyl and ethyl groups in the C-region of 7S with the two hydrophobic binding pockets of hTRPV1 contributed to the high potency.

Human indoleamine 2,3-dioxygenase 1 (hIDO1) and tryptophan dioxygenase (hTDO) are rate-limiting enzymes in the kynurenine pathway (KP) of l -tryptophan ( l -Trp) metabolism and are becoming key drug targets in the combination therapy of checkpoint inhibitors in immunoncology. To discover a selective and potent IDO1 inhibitor, a structure–activity relationship (SAR) study of N-hydroxybenzofuran-5-carboximidamide as a novel scaffold was investigated in a systematic manner. Among the synthesized compounds, the N-3-bromophenyl derivative 19 showed the most potent inhibition, with an IC50 value of 0.44 μM for the enzyme and 1.1 μM in HeLa cells. The molecular modeling of 19 with the X-ray crystal structure of IDO1 indicated that dipole-ionic interactions with heme iron, halogen bonding with Cys129 and the two hydrophobic interactions were important for the high potency of 19.

A series of 1-indazol-3-(1-phenylpyrazol-5-yl)methyl ureas were investigated as hTRPV1 antagonists. The structure–activity relationship study was conducted systematically for both the indazole A-region and the 3-trifluoromethyl/t-butyl pyrazole C-region to optimize the antagonism toward the activation by capsaicin. Among them, the antagonists 26, 50 and 51 displayed highly potent antagonism with Ki(CAP) = 0.4–0.5 nM. Further, in vivo studies in mice indicated that these derivatives both antagonized capsaicin induced hypothermia, consistent with their in vitro activity, and themselves did not induce hyperthermia. In the formalin model, 51 showed anti-nociceptive activity in a dose-dependent manner.

Based on the lead compound L-80 (compound 2), a potent heat shock protein 90 (HSP90) inhibitor, a series of C-ring truncated deguelin analogs were designed, synthesized and evaluated for Hypoxia Inducible Factor-1α (HIF-1α) inhibition as a primary screening method. Their structure-activity relationship was investigated in a systematic manner by varying the A/B ring, linker and D/E ring, respectively. Among the synthesized inhibitors, compound 5 exhibited potent HIF-1α inhibition in a dose-dependent manner and significant antitumor activity in human non-small cell lung carcinoma (H1299), with better activities than L-80. It also inhibited in vitro hypoxia-mediated angiogenic processes in human retinal microvascular endothelial cells (HRMEC). The docking study of 5 showed a similar binding mode as L-80: it occupied the C-terminal ATP-binding pocket of HSP90, indicating that the anticancer and antiangiogenic activities of 5 were derived from HIF-1α destabilization by inhibiting the C-terminal ATP-binding site of hHSP90.

A series of indane-type acetamide and propanamide analogues were investigated as TRPV1 antagonists. The analysis of structure–activity relationship indicated that indane A-region analogues exhibited better antagonism than did the corresponding 2,3-dihydrobenzofuran and 1,3-benzodioxole surrogates. Among them, antagonist 36 exhibited potent and selective antagonism toward capsaicin for hTRPV1 and mTRPV1. Further, in vivo studies indicated that antagonist 36 showed excellent analgesic activity in both phases of the formalin mouse pain model and inhibited the pain behavior completely at a dose of 1 mg/kg in the 2nd phase.

A series of fluorophenyl and pyridine analogues of 1 and 2 were synthesized as ring-truncated deguelin surrogates and evaluated for their HIF-1α inhibition. Their structure-activity relationship was systematically investigated based on the variation of the linker B-region moiety. Among the inhibitors, compound 25 exhibited potent HIF-1α inhibition in a dose-dependent manner and significant antitumor activity in H1299 with less toxicity than deguelin. It also inhibited in vitro hypoxia-mediated angiogenic processes in HRMECs. The docking study indicates that 25 occupied the C-terminal ATP-binding pocket of HSP90 in a similar mode as 1, which implies that the anticancer and antiangiogenic activities of 25 are derived from HIF-1α destabilization by binding to the C-terminal ATP-binding site of hHSP90.

A series of α-substituted acetamide derivatives of previously reported 2-(3-fluoro-4-methylsulfonamidophenyl)propanamide leads (1, 2) were investigated for antagonism of hTRPV1 activation by capsaicin. Compound 34, which possesses an α-m-tolyl substituent, showed highly potent and selective antagonism of capsaicin with Ki(CAP) = 0.1 nM. It thus reflected a 3-fold improvement in potency over parent 1. Docking analysis using our homology model indicated that the high potency of 34 might be attributed to a specific hydrophobic interaction of the m-tolyl group with the receptor.

Through the fine tuning of the activity-sensitive aminoalkoxy moiety of 4,6-bisphenyl-2-(3-alkoxyanilino)pyrimidine as a novel inhibitor of the receptor for advanced glycation end products (RAGE), the tertiary amine was elucidated as an essential part associated with RAGE inhibition. On the basis of this finding, a 3-(N,N-dimethylamino)pyrrolidine analog 12o was identified as a therapeutically useful RAGE inhibitor with improved activity and solubility. Molecular modeling studies predicted that the improved inhibitory activity is induced by additional hydrogen bonds between the nitrogen atom of the pyrrolidine ring and Arg48 and by an interaction between the dimethylamino-substituent of the pyrrolidine moiety and a relatively hydrophobic groove in the RAGE binding site.

A series of N -[{2-(4-methylpiperidin-1-yl)-6-(trifluoromethyl)-pyridin-3-yl}methyl] N ′-(6,6-fused heterocyclic) ureas have been investigated as h TRPV1 antagonists. Among them, compound 15 showed highly potent TRPV1 antagonism to capsaicin, with K i(ant) = 0.2 nM, as well as antagonism to other activators, and it was efficacious in a pain model. A docking study of 15 with our h TRPV1 homology model indicates that there is crucial hydrogen bonding between the ring nitrogen and the receptor, contributing to its potency.

DAG-lactones afford a synthetically accessible, high affinity platform for probing structure activity relationships at the C1 regulatory domain of protein kinase C (PKC). Given the central role of PKC isoforms in cellular signaling, along with their differential biological activities, a critical objective is the design of isoform selective ligands. Here, we report the synthesis of a series of DAG-lactones varying in their side chains, with a particular focus on linoleic acid derivatives. We evaluated their selectivity for PKC epsilon versus PKC alpha both under standard lipid conditions (100% phosphatidylserine, PS) as well as in the presence of a nuclear membrane mimetic lipid mixture (NML). We find that selectivity for PKC epsilon versus PKC alpha tended to be enhanced in the presence of the nuclear membrane mimetic lipid mixture and, for our lead compound, report a selectivity of 32-fold.

A series of 2-alkyl/alkenyl pyridine C-region derivatives of 2-(3-fluoro-4-methylsulfonylaminophenyl)propanamides were investigated as hTRPV1 antagonists. Multiple compounds showed excellent and stereospecific TRPV1 antagonism with better potency than previous lead 2. Among them, compound 15f demonstrated a strong analgesic profile in a rat neuropathic pain model and blocked capsaicin-induced hypothermia in a dose-dependent manner. Docking analysis of (S)-15f with our hTRPV1 homology model provided insight into its specific binding mode.

A series of α-methylated analogues of the potent sRTX thiourea antagonists were investigated as rTRPV1 ligands in order to examine the effect of α-methylation on receptor activity. The SAR analysis indicated that activity was stereospecific with the (R)-configuration of the newly formed chiral center providing high binding affinity and potent antagonism while the configuration of the C-region was not significant.

Neural stem cells (NSCs) proliferate and differentiate into neurons and glia depending on the culture environment. However, the underlying mechanisms determining the fate of NSCs are not fully understood. Growth factors facilitate NSC proliferation through mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) kinase (MEK) and MAPK activation, and NSCs differentiate into neurons, astrocytes, or oligodendrocytes when mitogens are withdrawn from the culture media. Here, we aimed to identify the effects and roles of MEK signaling on the determination of NSC fate. MEK inhibitors, U0126, SL327, and PD98059, had differential effects on NSC differentiation. U0126 and SL327, which are known to inhibit MEK1 and MEK2, induced neuronal differentiation, whereas PD98059, which is reported to preferentially inhibit MEK1 at higher concentrations, increased astrocytogenesis. Knockdown of MEK2 using small interfering RNA increased neurogenesis and over-expression of wild type (WT) MEK2 inhibited neurogenesis, suggesting a repressive role of MEK2 in neuronal differentiation. The chemical structure of PD98059 appears to be important for induction of astrocytogenesis because not only PD98059 (2'-amino-3'-methoxyflavone) but also its chemical structural mimetic, 3'-methoxyflavone, enhanced astrocytogenesis. Therefore, in our study, we suggest that MEK inhibitors have distinct functions in determining NSC fate. Inhibition of MEK2 is important for induction of neurogenesis in NSCs. U0126 and SL327 increase neurogenesis through MEK2 inhibition, whereas PD98059 induced astrocytogenesis in NSCs, which is mediated by the chemical structure, particularly the 3'-methoxy group rather than its renowned MEK1 inhibition.

In order to discover a novel type of analgesic, we investigated dual activity ligands with TRPV1 antagonism and mu-opioid receptor affinity with the goal of eliciting synergistic analgesia while avoiding the side effects associated with single targeting. Based on a combination approach, a series of 4-benzyl-4-(dimethylamino)piperidinyl analogues were designed, synthesized and evaluated for their receptor activities. Among them, compound 49 exhibited the most promising dual-acting activity toward TRPV1 and the mu-opioid receptor in vitro. In vivo, 49 displayed potent, dose-dependent antinociceptive activity in both the 1st and 2nd phases in the formalin assay. Consistent with its postulated mechanism, we confirmed that in vivo, as in vitro, compound 49 both antagonized TRPV1 and functioned as a mu-opioid agonist. This result indicates that dual-acting TRPV1 antagonist/mu-opioid ligands can be made and represent a new and promising class of analgesic.

Neural stem cells are multipotent and self-renewing cells that can differentiate into new neurons and hold great promise for treating various neurological disorders including multiple sclerosis, Parkinson’s disease, and Alzheimer’s disease. Small molecules that can trigger neurogenesis and neuroprotection are particularly useful not only because of their therapeutic implications but also because they can provide an invaluable tool to study the mechanisms of neurogenesis. In this report, we have developed and screened 25 aminopropyl carbazole derivatives that can enhance neurogenesis of cultured neural stem cells. Among these analogues, compound 9 demonstrated an excellent proneurogenic and neuroprotective activity with no apparent toxicity. We believe that compound 9 can serve as an excellent lead to develop various analogues and to study the underlying mechanisms of neurogenesis.

A series of carbonate analogues of 5′-halogenated RTX have been investigated in order to examine the effect of the carbonate group as a linker and the role of halogens in the reversal of activity from agonism to antagonism for rat and human TRPV1 heterologously expressed in Chinese hamster ovary cells. The carbonate analogues showed similar activities to the corresponding RTX derivatives in rat TRPV1 but lower potency in human TRPV1. 5-Halogenation converted the agonists to partial agonists or full antagonists and the extent of antagonism reflected the order of I > Br > Cl > F, with a somewhat greater extent of antagonism for the derivatives of the 4-amino RTX surrogates compared to the corresponding derivatives of RTX itself. The carbonate analogues of I-RTX (60) and 5-bromo-4-amino-RTX (66) were potent and full antagonists with K(i(ant)) = 2.23 and 2.46 nM, respectively, for rat TRPV1, which were ca. 5-fold more potent than I-RTX (2) under our conditions. The conformational analysis of the I-RTX-carbonate (60) indicated that its bent conformation was similar to that of I-RTX, consistent with compound 60 and I-RTX showing comparable potent antagonism.

The structure activity relationships of 2-oxy pyridine derivatives in the C-region of N-(6-trifluoromethyl- pyridin-3-ylmethyl) 2-(3-fluoro-4-methylsulfonylaminophenyl)propanamides as hTRPVl antagonists were investigated. The analysis indicated that the lipophilicity of the 2-oxy substituents was critical for potent antagonism and 4 or 5 carbons appeared to be optimal for activity. Multiple compounds proved to have comparable activity to 1, which had been reported as the most potent antagonist for capsaicin activity among the previous series of compounds. Further analysis of compounds 22 (2-isobutyloxy) and 53 (2-benzyloxy) in the formalin test in mice demonstrated strong analgesic activity with full efficacy. Docking analysis of 53S using our hTRPVl homology model indicated that the A- and B-region 2-(3-fluoro-4-methylsulfonylaminophenyl)propanamide made important hydrophobic and hydrogen bonding interactions with Tyr511 and that the C-region 6-trifluoromethyl and 2-benzyloxy groups of pyridine occupied the two hydrophobic binding pockets, respectively.

The structure–activity relationships of N-(3-acyloxy-2-benzylpropyl)-N′-4-[(methylsulfonylamino)benzyl] thioureas, which represent simplified RTX-based vanilloids, were investigated by varying the distances between the four principal pharmacophores and assessing binding and antagonistic activity on rTRPV1. The analysis indicated that a 3-pivaloyloxy-2-benzylpropyl C-region conferred the best potency in binding affinity and antagonism. The molecular modeling of this best template with the tetrameric homology model of rTRPV1 was performed to identify its binding interactions with the receptor.

Structure–activity relationships for the A-region in a series of N-4-t-butylbenzyl 2-(4-methylsulfonylaminophenyl) propanamides as TRPV1 antagonists have been investigated. Among them, the 3-fluoro analogue 54 showed high binding affinity and potent antagonism for both rTRPV1 and hTRPV1 in CHO cells. Its stereospecific activity was demonstrated with marked selectivity for the (S)-configuration (54S versus 54R). A docking study of 54S with our hTRPV1 homology model highlighted crucial hydrogen bonds between the ligand and the receptor contributing to its potency.

A series of DAG-lactones with polar 3-alkylidene substituents have been investigated as PKC-α ligands and antitumor agents. Extensive analysis of structure–activity relationships for the 3-alkylidene chain revealed that polar groups such as ether, hydroxyl, aldehyde, ester, acyloxy, and amido were tolerated with similar binding affinities and reduced lipophilicities compared to the corresponding unsubstituted alkylidene chain. Among the derivatives, compounds 5, 6 and 8 with an ether type of side chain showed high binding affinities in range of Ki = 3–5 nM and excellent antitumor profiles, particularly against the colo205 colon cancer and the K562 leukemia cell lines.

A series of bicyclic analogues having indan and tetrahydronaphthalene templates in the A-region were designed as conformationally constrained analogues of our previously reported potent TRPV1 antagonists (1, 3). The activities for rat TRPV1 of the conformationally restricted analogues were moderately or markedly diminished, particularly in the case of the tetrahydronaphthalene analogues. The analysis indicated that steric constraints at the benzylic position in the bicyclic analogues may be an important factor for their unfavorable interaction with the receptor.

Five new structural analogues of substituted-1H-quinolinones (19, 20, 23, 24, and 26) have been synthesized and evaluated for Staphylococcus aureus methionyl-tRNA synthetase enzyme inhibitory activity. These compounds were also tested against pathogens of six S. aureus, two Enterococcus faecalis, and one Enterococcus faecium. Among all the synthesized quinolinones, compound 20 displayed significant inhibitory activities in the strains of E. faecalis and E. faecium.

A series of 2-benzyl and 2-phenyl-3-hydroxypropyl pivalates designed to incorporate the principal pharmacophores of phorbol esters have been synthesized and tested as PKC-α ligands. Among the analogues, 13c exhibited the most potent binding affinity with a K i = 0.7 μM. The synthesized analogues were subjected to molecular modeling analysis based on two alternative models of the phorbol pharmacophore and a docking study of 13c was carried out.

The structure-activity relationships for the 'B-region' of N-(4-t-butylbenzyl)-N'-[4-(methylsulfonylamino)benzyl]thiourea analogues have been investigated as TRPV1 receptor antagonists. A docking model of potent antagonist 2 with the sensor region of TRPV1 is proposed.

The three-dimensional quantitative structure–activity relationships of 57 2-[(aminopropyl)amino]-4(1H)-quinolinone analogues as Staphylococcus aureus methionyl-tRNA synthetase (MetRS) inhibitors with excellent antibacterial profile were investigated and docking studies were performed. The CoMFA analysis provided a model with a q 2 value of 0.579 and an r 2 value of 0.970, in which the good correlation between the MetRS inhibitory activities (IC 50 ) and the steric and electrostatic molecular fields around the analogues was examined. Two inhibitors ( 1 and 17 ) were docked into the binding pocket of Escherichia coli MetRS imported from the X-ray crystal structure of the MetRS-methionine complex, and the details of their interaction with the amino acids of the active site are discussed.

A recent clinical study showed that statins, which are inhibitors of cholesterol biosynthesis pathway, reduced the prevalence of Alzheimer's disease (AD). Animal studies that have employed high cholesterol diet indicate significant relationship between cholesterol level and senile plaque deposition. Here, we investigated the effects of lovastatin on beta-amyloid production and senile plaque deposition in an animal model of AD (Tg2576 mice). As expected, lovastatin treatment reduced plasma cholesterol level in both male and female mice. However, lovastatin enhanced the amounts of beta-amyloid and other beta-secretase derived peptides in females, but not in males. Likewise, lovastatin increased the number of plaques in the hippocampus and cortex of females, but not in males. Lovastatin did not change the amounts of full-length or alpha-secretase processed amyloid precursor protein (APP), or presenilin 1 (PS1) in either sex. Thus, lovastatin lowers cholesterol level in both genders, but enhances beta-amyloid production and senile plaque deposition only in brains of female Tg2576 mice. Our results suggest that low plasma cholesterol levels might be a risk factor for AD in females.

In order to determine the importance of the two ester pharmacophores in high affinity, conformationally constrained DAG-lactones ( Lac-1 – 5 ) as PK-C ligands, we have independently replaced the sn-1 and sn-2 carbonyl esters in these compounds by ketone ( 2 , 10 , 11 ), amide ( 3 , 25 – 28 ), and hydroxyl ( 12 , 13 ) isosteres. Although the ketone analogue of the sn-1 ester ( 2 ) exhibited comparable activity to the parent Lac-1 when taking into account the difference in lipophilicities, the other isosteres were significantly poorer PK-Cα ligands compared to the parent DAG-lactones. This study demonstrates that the ester functionality in DAG-lactone plays an important role in the ligand's capacity to form a strong hydrogen bond with Gly253 at the active site. The discrete K i analysis from the sn-1 and sn-2 isosteres further confirms that the DAG-lactones bind preferentially to the C1-domain in the sn-2 binding mode, as previously suggested.

A series of sulfamate surrogates of methionyl and isoleucyl adenylate have been investigated as MetRS and IleRS inhibitors by modifications of the sulfamate linker and adenine moieties. The discovery of 2-iodo Ile-NHSO(2)-AMP (58) as a potent Escherichia coli IleRS inhibitor revealed that a significant hydrophobic interaction between the 2-substituent of Ile-NHSO(2)-AMP and the adenine binding site of IleRS provided its high potency to the enzyme.

Four pyrrolidine derivatives were prepared by the formation of a 5-membered ring based on capsazepine. Among them, the two carbon extended derivatives, 4a (IC(50)=55 microM) and 4b (IC(50)=3 microM), both showed different levels of antagonist activity against the vanilloid receptor in a (45)Ca(2+)-influx assay.

The stereospecific introduction of ( R )- and ( S )-OH groups at position C-3 of two diacylglycerol γ-lactones (DAG-lactones) previously identified as strong protein kinase C (PK-C) ligands is presented. The compounds were designed to investigate whether the extra OH group in a specific orientation could establish an additional hydrogen bond with the C1 domain of PK-C, thus providing a DAG analogue with reduced lipophilicity. The OH groups were introduced following two different diastereoselective multistep syntheses starting from diacetone- d -glucose. The PK-C binding affinities for the new compounds were weaker in comparison to those of the parent compounds, suggesting that the extra OH does not engage efficiently in hydrogen bonding at the receptor.

In vitro metabolism of acetylcholinesterase inhibitors containing 3-[ 18 F]fluoromethylbenzyl- ([ 18 F] 1 ) and 4-[ 18 F]fluorobenzyl-piperidine moieties ([ 18 F] 2 ) was studied and compared with the in vivo metabolism. Defluorination of the [ 18 F] 1 mainly occurred to generate [ 18 F]fluoride ion both in vitro and in vivo. In contrast, the [ 18 F] 2 was converted into an unknown polar metabolite in both metabolism methods and another metabolite, 4-[ 18 F]fluorobenzoic acid in vitro. These results demonstrated that the in vitro method can be used to predict the in vivo metabolism of both radiotracers.

As aminoacyl adenylate surrogates, a series of methionyl and isoleucyl phenolic analogues containing bioisosteric linkers mimicking ribose have been investigated. Inhibition of synthesized compounds to the aminoacylation reaction by the corresponding Escherichia coli methionyl-tRNA and isoleucyl-tRNA synthetases indicated that 18 was found to be a potent inhibitor of isoleucyl-tRNA synthetase. A molecular modeling study demonstrated that in 18, isovanillate and hydroxamate served as proper surrogates for adenine and ribose in isoleucyl adenylate, respectively.

Four stable analogues of methionyl adenylate (3-6) were designed as inhibitors of methionyl-tRNA synthetase and synthesized from 2',3'-isopropylideneadenosine. They strongly inhibited aminoacylation activity of methionyl-tRNA synthetases isolated from Escherichia coli, Mycobacterium tuberculosis, Saccharomyces cerevisiae and human. Among the microorganisms tested, however, these chemicals showed the growth inhibition effect only on E. coli.

The pharmacophore-guided approach used in the first phase of the design of novel protein kinase C (PKC) ligands was based on the study of the geometry of bioequivalent pharmacophores present in diacylglycerol (DAG) and in the more potent phorbol ester tumor promoters. A number of potent DAG lactones were generated by this approach, in which the glycerol backbone was constrained into various heterocyclic rings to reduce the entropic penalty associated with DAG binding. Based on the information provided by X-ray and NMR structures of the cysteine-rich, C1 phorbol ester/DAG binding domain, the DAG lactones were further modified to optimize their interaction with a group of highly conserved hydrophobic amino acids along the rim of the C1 domain. This receptor-guided approach culminated with the synthesis of a series of “super DAG” molecules that can bind to PKC with low nanomolar affinities. These compounds provide insight into the basis for PKC ligand specificity. Moreover, some of the compounds reviewed herein show potential utility as antitumor agents.

A series of methionine analogues have been synthesized as inhibitors of methionyl-tRNA synthetase and evaluated for their inhibitory activities of E. coli methionyl-tRNA synthetase and bacterial growth. Among them, L -methionine hydroxamate 20 has proved to be the best inhibitor of the enzyme with K i = 19 μM and showed a growth inhibition against E.coli JM 109, P. vulganis 6059 and C. freundii 8090.

The replacement of the sn-1 and sn-2 carbonyl esters in DAG-surrogate lactones by sulfonate esters showed that their isosteric properties in protein kinase C binding are controlled by the location of the hydrophobic alkyl chain on the molecule. The CO and SO2 groups appear to be true isosteres only when they are adjacent to the alkyl chain, which is presumed to insert normal to the lipid bilayer.