Shotgun Kinetic Target-Guided Synthesis Approach Enables the Discovery of Small-Molecule Inhibitors against Pathogenic Free-Living Amoeba Glucokinases.

Pathogenic free-living amoebae (pFLA) can cause life-threatening central nervous system (CNS) infections and warrant the investigation of new chemical agents to combat the rise of infection from these pathogens. Naegleria fowleri glucokinase (NfGlck), a key metabolic enzyme involved in generating glucose-6-phosphate, was previously identified as a potential target due to its limited sequence similarity with human Glck (HsGlck). Herein, we used our previously demonstrated multifragment kinetic target-guided synthesis (KTGS) screening strategy to identify inhibitors against pFLA glucokinases. Unlike the majority of previous KTGS reports, our current study implements a "shotgun" approach, where fragments were not biased by predetermined binding potentials. The study resulted in the identification of 12 inhibitors against 3 pFLA glucokinase enzymes─NfGlck, Balamuthia mandrillaris Glck (BmGlck), and Acanthamoeba castellanii Glck (AcGlck). This work demonstrates the utility of KTGS to identify small-molecule binders for biological targets where resolved X-ray crystal structures are not readily accessible.

Pyrazole-Thiazole Core-Containing Analogs Exhibit Adjunctive Activity with Meropenem against Carbapenem-Resistant Enterobacteriaceae (CRE).

Pyrazole-thiazole core-containing compound KP-40 and 20 novel derivatives were designed and synthesized through traditional SAR analysis. These molecules displayed adjunctive activity with meropenem against Gram-negative bacteria evidenced by a range of fractional inhibitory concentration (FIC=0.5-0.25) and minimum adjunctive concentration (MAC=128-32 µM) values. Of this series of molecules, four compounds displayed notable adjunctive potential, with FIC and MAC values of 0.25 and 32 µM, respectively. Moreover, the solubility of these compounds was improved to an acceptable range. Further analysis using our "in house" permeation and efflux multi parameter optimization (PEMPO) algorithm revealed key physicochemical properties that may be critical for the development of active Gram-negative antibacterials. Taking PEMPO scores into consideration prior to executing synthesis of analogs may be a simple, yet rapid and effective strategy that can be used in conjunction with traditional SAR approaches to aid in the design of potent Gram-negative antibacterials.

Ruthenium-Catalyzed Cross-Selective Asymmetric Oxidative Coupling of Arenols.

(Aqua)ruthenium(salen) complex 1c achieved good to high chemo- and enantioselective oxidative cross-coupling of arenols. The catalytic system can be used to selectively produce C1-symmetric bis(arenol)s from the combination of C3- and C7-substituted 2-naphthols or phenols even when there is no significant difference in oxidation potential between the cross-coupling partners. This unique cross-selectivity is dominated by steric rather than electronic effects of the arenols and can be controlled by chemoselective single-electron oxidation and oxidative carbon-carbon bond formation.

A Whole-Cell Screen for Adjunctive and Direct Antimicrobials Active against Carbapenem-Resistant Enterobacteriaceae.

Carbapenem-resistant Enterobacteriaceae (CRE) are an emerging antimicrobial resistance threat for which few if any therapeutic options remain. Identification of new agents that either inhibit CRE or restore activity of existing antimicrobials is highly desirable. Therefore, a high-throughput screen of 182,427 commercially available compounds was used to identify small molecules which either enhanced activity of meropenem against a carbapenem-resistant Klebsiella pneumoniae ST258 screening strain and/or directly inhibited its growth. The primary screening methodology was a whole-cell screen/counterscreen combination assay that tested for reduction of microbial growth in the presence or absence of meropenem, respectively. Screening hits demonstrating eukaryotic cell toxicity based on an orthogonal screening effort or identified as pan-assay interference compounds (PAINS) by computational methods were triaged. Primary screening hits were then clustered and ranked according to favorable physicochemical properties. Among remaining hits, we found 10 compounds that enhanced activity of carbapenems against a subset of CRE. Direct antimicrobials that passed toxicity and PAINS filters were not, however, identified in this relatively large screening effort. It was previously shown that the same screening strategy was productive for identifying candidates for further development when screening known bioactive libraries inclusive of natural products. Our findings therefore further highlight liabilities of commercially available small-molecule screening libraries in the Gram-negative antimicrobial space. In particular, there was especially low yield in identifying compelling activity against a representative, highly multidrug-resistant, carbapenemase-producing K. pneumoniae strain.

Spectroscopic investigation of the noncovalent association of the nerve agent simulant diisopropyl methylphosphonate (DIMP) with zinc(II) porphyrins.

Organophosphonates pose a significant threat as chemical warfare agents, as well as environmental toxins in the form of pesticides. Thus, methodologies to sense and decontaminate these agents are of significant interest. Porphyrins and metalloporphyrins offer an excellent platform to develop chemical threat sensors and photochemical degradation systems. These highly conjugated planar molecules exhibit relatively long-lived singlet and triplet states with high quantum yields and also form self-associated complexes with a wide variety of molecules. A significant aspect of porphyrins is the ability to functionalize the peripheral ring system either directly to the pyrrole rings or to the bridging methine carbons. In this report, steady-state absorption and fluorescence are utilized to probe binding affinities of a series of symmetric and asymmetric zinc(II) metalloporphyrins for the nerve agent simulant diisopropyl methylphosphonate (DIMP) in hexane. The red shifts in the absorption and emission spectra observed for all of the metalloporphyrins probed are discussed in the frame of Gouterman's four orbital model and a common binding motif involving coordination between the metalloporphyrin and DIMP via interaction between the zinc metal center of the porphyrin and phosphoryl oxygen of DIMP (Zn-O═P) is proposed.

Asymmetric olefin aziridination using a newly designed Ru(CO)(salen) complex as the catalyst.

Highly enantioselective and good to high-yielding aziridination of conjugated and non-conjugated terminal olefins and cyclic olefins was achieved using a newly designed Ru(CO)(salen) complex as the catalyst in the presence of SESN(3) under mild conditions.

Quest for highly porous metal-metalloporphyrin framework based upon a custom-designed octatopic porphyrin ligand.

A porous metal-metalloporphyrin framework, MMPF-2, has been constructed from a custom-designed octatopic porphyrin ligand, tetrakis(3,5-dicarboxyphenyl)porphine, that links a distorted cobalt trigonal prism secondary building unit. MMPF-2 possesses permanent microporosity with the highest surface area of 2037 m(2) g(-1) among reported porphyrin-based MOFs, and demonstrates a high uptake capacity of 170 cm(3) g(-1) CO(2) at 273 K and 1 bar.

Three-dimensional porous metal-metalloporphyrin framework consisting of nanoscopic polyhedral cages.

An unprecedented nanoscopic polyhedral cage-containing metal-metalloporphyrin framework, MMPF-1, has been constructed from a custom-designed porphyrin ligand, 5,15-bis(3,5-dicarboxyphenyl)porphine, that links Cu(2)(carboxylate)(4) moieties. A high density of 16 open copper sites confined within a nanoscopic polyhedral cage has been achieved, and the packing of the porphyrin cages via an "ABAB" pattern affords MMPF-1 ultramicropores which render it selective toward adsorption of H(2) and O(2) over N(2), and CO(2) over CH(4).

Cobalt carbaporphyrin-catalyzed cyclopropanation.

Cobalt complexes of N-confused porphyrins and benziphthalocyanine, which both feature organometallic bonds at the macrocycle cores, catalyze the cyclopropanation of styrene with a higher trans-selectivity than the corresponding porphyrin and phthalocyanine complexes.

Photocurrent generation from porphyrin/fullerene complexes assembled in a tethered lipid bilayer.

A modular photocurrent generation system, based on amphiphilic porphyrin and fullerene species assembled in a tethered lipid bilayer matrix, is reported here. The key findings are (1) the amount of photoactive species can be quantitatively controlled in each leaflet of the bilayer and (2) the sequential formation of the bilayer allows a directional organization of these agents on electrodes. Photocurrent generation from seven differently configured photoactive bilayers is studied, which reveals several critical factors in achieving efficient photoinduced electron transfer across lipid membranes. Detailed fluorescence characterization is performed on porphyrin samples either in liposomes or surface-tethered bilayers; and the observed fluorescence quenching is correlated with photocurrents generated from the electrode-immobilized lipid films. The potential usefulness of this lipid-based approach is discussed in connection to several existing molecular photovoltaic systems.

Premenopausal factors influencing premature ovarian failure and early menopause.

OBJECTIVES: We conducted this study to examine premenopausal risk factors associated with premature ovarian failure (POF) and early menopause (EM) among Korean women. METHODS: A 73% of total women aged 30-69 at four districts in the KMCC (Korean Multi-center Cancer Cohort) was participated in this study during 2002-2003. We selected 137 POF and 281 EM cases who had menopause before age 40 and at age 40-44, respectively, and 1318 normal menopause (NM) controls that experienced menopause at age 45-60, and among them, selected idiopathic POF (n=84) and EM (n=261) after excluding surgical/medical menopause. We collected the information of premenopausal lifestyle and reproductive risk factors. Multivariate and polytomous logistic regression were used to estimate POF and EM risk and to differentiate POF and EM risk using ordinal and nominal scale. RESULTS: Cigarette smoking was associated with an increased risk of idiopathic POF (OR=1.82 [1.03-3.23]), whereas oral contraceptive use was associated with a reduced risk of natural EM (OR=0.62 [0.43-0.90]). Idiopathic POF risk by both factors differed from idiopathic EM risk (p-nominal<0.05). Factors related to ovulation, such as later menarche, irregular menstruation and longer breast feeding cumulatively reduced the risk of natural EM and POF (p-ordinal<0.05). In analysis including medical and surgical menopause, lung tuberculosis, hysterectomy, past cancers, and lower number of deliveries before menopause were associated with POF. CONCLUSIONS: Our findings indicate that etiology in POF development may partly differ from that in EM.