Joshua Katzhendler

Relacin, a novel antibacterial agent targeting the Stringent Response.

Finding bacterial cellular targets for developing novel antibiotics has become a major challenge in fighting resistant pathogenic bacteria. We present a novel compound, Relacin, designed to inhibit (p)ppGpp production by the ubiquitous bacterial enzyme RelA that triggers the Stringent Response. Relacin inhibits RelA in vitro and reduces (p)ppGpp production in vivo. Moreover, Relacin affects entry into stationary phase in Gram positive bacteria, leading to a dramatic reduction in cell viability. When Relacin is added to sporulating Bacillus subtilis cells, it strongly perturbs spore formation regardless of the time of addition. Spore formation is also impeded in the pathogenic bacterium Bacillus anthracis that causes the acute anthrax disease. Finally, the formation of multicellular biofilms is markedly disrupted by Relacin. Thus, we establish that Relacin, a novel ppGpp analogue, interferes with bacterial long term survival strategies, placing it as an attractive new antibacterial agent.

Anthraquinone intercalators as carrier molecules for second-generation platinum anticancer drugs

Summary A series of complexes PtAm2L [where Am2 = (NH3)2, ethylenediamine(en), 1,2-diaminocyclohexane (DACH) or (NH3)(c-C6H11NH2) and where L is a bidentate 1,1-dicarboxylate ligand tethered to 1-aminoanthraquinone by various spacers] was prepared and screened in vitro against P388 leukemia cells. The free ligands displayed moderate activity and the corresponding platinum complexes were tenfold more active. The nature of the linker chain does not seem to affect the potency of the complexes. The potency depends on the nature of the inert amine ligand [NH3 > DACH > en]. The low aqueous solubility of these complexes prevented any in vivo studies and the preparation of water soluble analogs is currently under way.

Design, synthesis and structure–activity relationship of novel Relacin analogs as inhibitors of Rel proteins

Rel proteins in bacteria synthesize the signal molecules (p)ppGpp that trigger the Stringent Response, responsible for bacterial survival. Inhibiting the activity of such enzymes prevents the Stringent Response, resulting in the inactivation of long-term bacterial survival strategies, leading to bacterial cell death. Herein, we describe a series of deoxyguanosine-based analogs of the Relacin molecule that inhibit in vitro the synthetic activity of Rel proteins from Gram positive and Gram negative bacteria, providing a deeper insight on the SAR for a better understanding of their potential interactions and inhibitory activity. Among the inhibitors evaluated, compound 2d was found to be more effective and potent than our previously reported Relacin.

Preparation, characterization and the anticancer activity of a novel series of triaminemonochloroplatinum(II) cations linked to anthraquinone intercalators

Abstract A new series of complexes of the type [PtAm2LCl]+ (where Am = NH3 or Am2 = ethylenediamine and L is a monodentate AQ-Y-(CH2)n-NH2, AQ = anthraquinone, Y = NH, O) was prepared and screened in vitro against P388 leukemia. These complexes displayed higher activities than the corresponding neutral PtAm2L2 1:2 Pt:anthraquinone complexes but lower than the neutral diaminedichloro 1:1 complexes. The [Pt(en)LCl]+ complexes were significantly less active than the cis- and trans-[Pt(NH3)2LCl]+ complexes. The cis and trans isomers displayed similar activities. The complexes bearing the shorter linker chains were more active than those with longer chains. In vivo toxicity studies indicate that they are significantly less toxic than cis-DDP.

Poly(α-hydroxy acid)s and poly(α-hydroxy acid-co-α-amino acid)s derived from amino acid.

Polyesters derived from the α-hydroxy acids, lactic acid, and glycolic acid, are the most common biodegradable polymers in clinical use. These polymers have been tailored for a range of applications that require a physical material possessing. The physical and mechanical properties of these polymers fit the specific application and also safely biodegrade. These polymers are hydrophobic and do not possess functional side groups. This does not allow hydrophilic or hydrophobic manipulation, conjugation of active agents along the polymer chain, etc. These manipulations have partly been achieved by block copolymerization with, for example, poly(ethylene glycol), to obtain an amphiphilic copolymer. The objective of this review is to survey PLA functional copolymers in which functional α-hydroxy acids derived from amino acids are introduced along the polymer chain, allowing endless manipulation of PLA. Biodegradable functional polyesters are one of the most versatile biomaterials available to biomedical scientists. Amino acids with their variable side chains are ideal candidates for synthesizing such structural as well as stereochemically diverse polymers. They render control over functionalization, conjugation, crosslinking, stimulus responsiveness, and tunable mechanical/thermal properties. Functionalized amino acid derived polyesters are widely used, mainly due to advancement in ring opening polymerization (primarily O-carboxyanhydride mediated). The reaction proceeds under milder conditions and yields high molecular weight polymers. We reviewed on advances in the synthetic methodologies for poly-α-hydroxy esters derived from amino acids with appropriate recent examples.

The effect of diaminoalkyl-anthraquinone derivatives on the growth of the promastigotes of Leishmania tropica minor, L. T. major, L. donovani and L. aethiopica

By combining knowledge of polyamine biosynthesis and its inhibition by various analogues with that on the activity of synthetic anthraquinones, a series of six anthraquinone derivatives were synthesized. Their ability to inhibit the growth of leishmanial promastigotes in vitro was used as a preliminary screen to check their potential as new antileishmanial chemotherapeutics. They were tested against four strains, representing four different species; Leishmania tropica major, L. tropica minor, L. aethiopica and L. donovani, associated with four separate disease syndromes. All six derivatives exhibited a fair degree of antileishmanial activity, some being more effective than others. They all inactivated cultures at 100 micrograms/ml and some did so at 10 micrograms/ml and even 1 microgram/ml; but taking different lengths of time to achieve this. Antileishmanial activity associated with anthraquinone derivatives might provide a new approach to the chemotherapy of leishmaniasis.

Poly(α-hydroxy alkanoic acid)s Derived From α-Amino Acids†

Biodegradable polyesters derived from hydrophobic amino acids are synthesized by various techniques, resulting in a wide range of molecular weights. The polymers are prepared via a) direct condensation with p-toluenesulfonic acid (PTSA) as catalyst, b) ring-opening polymerization (ROP) of O-carboxyanhydrides, and c) ROP of cyclic dilactones. The polymers obtained by the first method reach a molecular weight ranging from 1000 to 3000 Da, whereas those formed by the second and third method yield extended molecular weights of 15000-30000 Da. The purity of the monomers as well as their steric bulkiness are key factors affecting the polymerizability of cyclic monomers by ROP. Other parameters such as spatial ring alignment and proximity organization may also play a role.

Detection of Specific Bglobin Mutations in Kurdish Jews with β-Thalassmia

Patients with β-thalassemia, of Kurdish extraction, were screened for the presence of two mutations, in the TATA box and in codon 44, previously discovered in this ethnic isolate. Of the 56 chromosomes analyzed, 13 were found to carry the TATA box mutation and 17 the codon 44 mutation. The result of this work provides a basis for a more efficient prenatal diagnosis program for this community.

An Improved Method for the Preparation of Methyl dichlorophosphite. A Key Reagent In the Phosphite Method of Oligonucleotide Synthesis

Abstract The reaction between phosphorus trichloride (PCl3) and trimethyl phosphite (CH3O)3p, has been examined by 31Pnmr, in order to achieve a simple and efficient procedure for the formation of methyl dichlorophosphite (CH3OPCl2), which is a key intermediate in the synthesis of oligonucleotides. The yield of the reaction was also studied on a preparative scale and it was found that the optimal condition is obtained when the reactants molar ratio is 1:1.

Oleylamine-carbonyl-valinol inhibits auto-phosphorylation activity of native and T315I mutated Bcr-Abl, and exhibits selectivity towards oncogenic Bcr-Abl in SupB15 ALL cell lines

Chronic myeloid leukemia (CML) is characterized by the presence of p210Bcr-Abl which exhibits an abnormal kinase activity. Selective Abl kinase inhibitors have been successfully established for the treatment of CML. Despite high rates of clinical response, CML patients can develop resistance against these kinase inhibitors mainly due to point mutations within the Abl protein kinase domain. Previously, we have identified oleic acid as the active component in the mushroom Daedalea gibbosa that inhibited the kinase activity of Bcr-Abl. Here, we report that the oleyl amine derivatives, S-1-(1-Hydroxymethyl-2-methyl-propyl)-3-octadec-9-enyl-urea [oleylaminocarbonyl-L-N-valinol,oroleylaminocarbonyl-S-2-isopropyl-N-ethanolamine,oleylamine-carbonyl-L-valinol] (cpd 6) and R-1-(1-Hydroxymethyl-2-methyl-propyl)-3-octadec-9-enyl-urea [oleylamineocarbonyl-D-N-valinol, oleylaminocarbonyl-R-2-isopropyl-N-ethanolamine, or oleylamine-carbonyl-D-valinol] (cpd 7), inhibited the activity of the native and T315I mutated Bcr-Abl. Furthermore, cpd 6 and 7 exhibited higher activity towards the oncogenic Bcr-Abl in comparison to native c-Abl in SupB15 Ph-positive ALL cell line.