Substituted carbamothioic amine-1-carbothioic thioanhydrides as novel trichomonicidal fungicides: Design, synthesis, and biology.

Sexually transmitted diseases like trichomoniasis along with opportunistic fungal infections like candidiasis are major global health burden in female reproductive health. In this context a novel non-nitroimidazole class of substituted carbamothioic amine-1-carbothioic thioanhydride series was designed, synthesized, evaluated for trichomonacidal and fungicidal activities, and was found to be more active than the standard drug Metronidazole (MTZ). Compounds were trichomonicidal in the MIC ranges of 4.77-294.1 µM and 32.46-735.20 µM against MTZ-susceptible and -resistant strains, respectively. Further, compounds inhibited the growth of at least two out of ten fungal strains tested at MIC of 7.50-240.38 µM. The most active compound (20) of this series was 3.8 and 9.5 fold more active than the MTZ against the two Trichomonas strains tested. Compound 20 also significantly inhibited the sulfhydryl groups present over Trichomonas vaginalis and was found to be more active than the MTZ in vivo. Further, a docking analysis carried out with cysteine proteases supported their thiol inhibiting ability and preliminary pharmacokinetic study has shown good distribution and systemic clearance.

Dynamic encapsulation and activation of carbonic anhydrase in multivalent dynameric host matrices.

A straight-forward carbonic anhydrase activation strategy via dynamic encapsulation has been achieved by direct addition of multivalent amide dynamers into enzyme reaction solutions.

Lowering of elevated tissue PCO2 in a hemorrhagic shock rat model after reinfusion of a novel nanobiotechnological polyhemoglobin-superoxide dismutase-catalase-carbonic anhydrase that is an oxygen and a carbon dioxide carrier with enhanced antioxidant properties.

Even though erythrocytes transport both oxygen and carbon dioxide, research on blood substitutes has concentrated on the transport of oxygen and its vasoactivity and oxidative effects. Recent study in a hemorrhagic shock animal model shows that the degree of tissue PCO(2) elevation is directly related to mortality rates. We therefore prepared a novel nanobiotechnological carrier for both O(2) and CO(2) with enhanced antioxidant properties. This is based on the use of glutaraldehyde to crosslink stroma free hemoglobin (SFHb), superoxide dismutase (SOD), catalase (CAT) and carbonic anhydrase (CA) to form a soluble PolySFHb-SOD-CAT-CA. It was compared to blood and different resuscitation fluids on the ability to lower elevated tissue PCO(2) in a 2/3 blood volume loss rat hemorrhagic shock model. Sixty minutes of sustained hemorrhagic shock at 30 mm Hg resulted in the increase of tissue PCO(2) to 95 mm ± 3 mmHg from the control level of 55 mm Hg. Reinfusion of whole blood (Hb 15 g/dL with its RBC enzymes) lowered the tissue PCO2 to 72 ± 4.5 mmHg 60 minutes after reinfusion. PolySFHb-SOD-CAT-CA (SFHb 10 g/dL plus additional enzymes) was more effective than whole blood in lowering PCO(2) lowering this to 66.2 ± 3.5 mmHg. Ringer's Lactated solution or polyhemoglobin lowered the elevated PCO2 only slightly to 87 ± 4.5 mmHg and 84.8 ± 1.5 mmHg, respectively. Moreover, ST-elevation for whole blood (Hb 15 g/dL) and PolySFHb-SOD-CAT-CA (Hb 10 g/dL) was respectively 12.8% ± 4% and 13.0% ± 2% of the control 60 minutes after reinfusion. Both are significantly better than those in the Ringer's lactated group and the PolyHb group. In conclusion, this novel approach for blood substitute design has resulted in a novel nanobiotechnological carrier for both O(2) and CO(2) with enhanced antioxidant properties.

Bioinspired FeIIICdII and FeIIIHgII complexes: synthesis, characterization and promiscuous catalytic activity evaluation.

In this work we report on the synthesis, crystal structure, and physicochemical characterization of the novel dinuclear [Fe(III)Cd(II)(L)(µ-OAc)(2)]ClO(4)·0.5H(2)O (1) complex containing the unsymmetrical ligand H(2)L=2-bis[{(2-pyridyl-methyl)-aminomethyl}-6-{(2-hydroxy-benzyl)-(2-pyridyl-methyl)}-aminomethyl]-4-methylphenol. Also, with this ligand, the tetranuclear [Fe(2)(III)Hg(2)(II)(L)(2)(OH)(2)](ClO(4))(2)·2CH(3)OH (2) and [Fe(III)Hg(II)(L)(µ-CO(3))Fe(III)Hg(II)(L)](ClO(4))(2)·H(2)O (3) complexes were synthesized and fully characterized. It is demonstrated that the precursor [Fe(III)(2)Hg(II)(2)(L)(2)(OH)(2)](ClO(4))(2)·2CH(3)OH (2) can be converted to (3) by the fixation of atmospheric CO(2) since the crystal structure of the tetranuclear organometallic complex [Fe(III)Hg(II)(L)(µ-CO(3))Fe(III)Hg(II)(L)](ClO(4))(2)·H(2)O (3) with an unprecedented {Fe(III)(µ-O(phenoxo))(2)(µ-CO(3))Fe(III)} core was obtained through X-ray crystallography. In the reaction 2→3 a nucleophilic attack of a Fe(III)-bound hydroxo group on the CO(2) molecule is proposed. In addition, it is also demonstrated that complex (3) can regenerate complex (2) in aqueous/MeOH/NaOH solution. Magnetochemical studies reveal that the Fe(III) centers in 3 are antiferromagnetically coupled (J=-7.2cm(-1)) and that the Fe(III)-OR-Fe(III) angle has no noticeable influence in the exchange coupling. Phosphatase-like activity studies in the hydrolysis of the model substrate bis(2,4-dinitrophenyl) phosphate (2,4-bdnpp) by 1 and 2 show Michaelis-Menten behavior with 1 being ~2.5 times more active than 2. In combination with k(H)/k(D) isotope effects, the kinetic studies suggest a mechanism in which a terminal Fe(III)-bound hydroxide is the hydrolysis-initiating nucleophilic catalyst for 1 and 2. Based on the crystal structures of 1 and 3, it is assumed that the relatively long Fe(III···)Hg(II) distance could be responsible for the lower catalytic effectiveness of 2.

Living polypeptides.

Block copolypeptides, which combine the self-assembly of block copolymers and the highly ordered 3D structures of proteins, are potential candidates for novel supramolecular structures and biotech applications, such as biosensors, tissue engineering, and selective drug delivery. The synthesis of model block copolypeptides through living nucleophilic/basic polymerization of alpha-amino acid N-carboxyanhydrides (NCAs) has been a challenge for more than fifty years, most probably due to traces of impurities in the system. This problem has been overcome, using high vacuum techniques in order to create and maintain the conditions necessary for the living polymerization of NCAs with primary amines. This method is a general one and opens avenues leading to novel, well-defined polypeptides with various architectures.

Synthesis and structure of [Zn(OMe)(L)] x [Zn(OH)(L)] x 2(BPh4), L = cis,cis-1,3,5-tris[(E,E)-3-(2-furyl)acrylideneamino]cyclohexane: structural models of carbonic anhydrase and liver alcohol dehydrogenase.

Direct reaction of [Zn(OH)(L)]+, L = cis,cis-1,3,5-tris[(E,E)-3-(2-furyl)acrylideneamino]cyclohexane, with methanol gives a mixture of the starting material and [Zn(OMe)(L)]+; structural analysis of the complexes shows that they are models of reactive intermediates in the catalytic cycles of the zinc enzymes carbonic anhydrase and liver alcohol dehydrogenase.

Scorpion toxins as natural scaffolds for protein engineering.

A compact, well-organized, and natural motif, stabilized by three disulfide bonds, is proposed as a basic scaffold for protein engineering. This motif contains 37 amino acids only and is formed by a short helix on one face and an antiparallel triple-stranded beta-sheet on the opposite face. It has been adopted by scorpions as a unique scaffold to express a wide variety of powerful toxic ligands with tuned specificity for different ion channels. We further tested the potential of this fold by engineering a metal binding site on it, taking the carbonic anhydrase site as a model. By chemical synthesis we introduced nine residues, including three histidines, as compared to the original amino acid sequence of the natural charybdotoxin and found that the new protein maintains the original fold, as revealed by CD and 1H NMR analysis. Cu2+ ions are bound with Kd = 4.2 x 10(-8) M and other metals are bound with affinities in an order mirroring that observed in carbonic anhydrase. The alpha/beta scorpion motif, small in size, easily amenable to chemical synthesis, highly stable, and tolerant for sequence mutations represents, therefore, an appropriate scaffold onto which polypeptide sequences may be introduced in a predetermined conformation, providing an additional means for design and engineering of small proteins.