Decolorization of acid and basic dyes: understanding the metabolic degradation and cell-induced adsorption/precipitation by Escherichia coli.

Escherichia coli strain DH5α was successfully employed in the decolorization of commercial anthraquinone and azo dyes, belonging to the general classes of acid or basic dyes. The bacteria showed an aptitude to survive at different pH values on any dye solution tested, and a rapid decolorization was obtained under aerobic conditions for the whole collection of dyes. A deep investigation about the mode of action of E. coli was carried out to demonstrate that dye decolorization mainly occurred via three different pathways, specifically bacterial induced precipitation, cell wall adsorption, and metabolism, whose weight was correlated with the chemical nature of the dye. In the case of basic azo dyes, an unexpected fast decolorization was observed after just 2-h postinoculation under aerobic conditions, suggesting that metabolism was the main mechanism involved in basic azo dye degradation, as unequivocally demonstrated by mass spectrometric analysis. The reductive cleavage of the azo group by E. coli on basic azo dyes was also further demonstrated by the inhibition of decolorization occurring when glucose was added to the dye solution. Moreover, no residual toxicity was found in the E. coli-treated basic azo dye solutions by performing Daphnia magna acute toxicity assays. The results of the present study demonstrated that E. coli can be simply exploited for its natural metabolic pathways, without applying any recombinant technology. The high versatility and adaptability of this bacterium could encourage its involvement in industrial bioremediation of textile and leather dyeing wastewaters.

Water recycle as a must: decolorization of textile wastewaters by plant-associated fungi.

Textile dye effluents are among the most problematic pollutants because of their toxicity on several organisms and ecosystems. Low cost and ecocompatible bioremediation processes offer a promising alternative to the conventional and aspecific physico-chemical procedures adopted so far. Here, microorganisms resident on three real textile dyeing effluent were isolated, characterized, and tested for their decolorizing performances. Although able to survive on these real textile-dyeing wastewaters, they always showed a very low decolorizing activity. On the contrary, several plant-associated fungi (Bjerkandera adusta, Funalia trogii, Irpex lacteus, Pleurotus ostreatus, Trametes hirsuta, Trichoderma viride, and Aspergillus nidulans) were also assayed and demonstrated to be able both to survive and to decolorize to various extents the three effluents, used as such in liquid cultures. The decolorizing potential of these fungi was demonstrated to be influenced by nutrient availability and pH. Best performances were constantly obtained using B. adusta and A. nidulans, relying on two strongly different mechanisms for their decolorizing activities: degradation for B. adusta and biosorption for A. nidulans. Acute toxicity tests using Daphnia magna showed a substantial reduction in toxicity of the three textile dyeing effluents when treated with B. adusta and A. nidulans, as suggested by mass spectrometric analysis as well.

Discovery of substituted benzyl tetrazoles as histamine H3 receptor antagonists.

A series of potent and subtype selective H3 receptor antagonists containing a novel tetrazole core and diamine motif is reported. A one-pot multi-component Ugi reaction was utilised to rapidly develop the structure-activity relationships (SAR) of these compounds. Optimisation for liver microsome stability (t(1/2)>60 min), minimal CYP inhibition (IC(50)>50 microM) and high cell permeability (Caco-2 P(app) >20x10(-6) cm/s) identified several compounds with drug-like properties.

Different effects of microbubble destruction and translation in Doppler measurements.

In flow measurements in which microbubbles are involved, the amplitude and phase of the received echo signal are noticeably influenced by the transmitted ultrasound intensity. Previous studies have shown that, when such intensity is progressively increased, the Doppler spectrum is accordingly distorted, i.e., it is asymmetrically broadened toward the negative frequency side. Such deformation has been attributed to radiation force, which pushes the microbubbles into the sound propagation direction, thus yielding additional phase delays in the received echoes. However, the possible contribution of microbubble destruction to this spectral deformation has not been considered yet. In this paper, this issue is investigated by analyzing the experimental spectra produced by two different types of microbubbles suspended in a moving fluid and insonified in pulsed wave (PW) mode at programmable pulse repetition frequency (PRF) and pressure. Conditions are created in which either the radiation force or the destruction mechanism is expected to be dominant. Effects produced by the two phenomena on the Doppler spectrum are shown to be different. When the PRF is low (2 kHz), so that, according to theoretical simulations, the radiation force effect is negligible, a 26 dB noise floor increase is observed for a 13 dB pressure increment. For a higher PRF (16 kHz), the same pressure increase not only affects the noise floor, but also causes the bubbles to deviate from their original streamlines, yielding a Doppler bandwidth increase by a factor of 5. It is concluded that asymmetrical spectral broadening is mainly due to radiation force, and microbubble destruction mainly results in an increased noise floor without affecting the spectral shape.

Synthesis and evaluation of new Hsp90 inhibitors based on a 1,4,5-trisubstituted 1,2,3-triazole scaffold.

Ruthenium catalyzed 1,3-cycloaddition (click chemistry) of an azido moiety installed on dihydroxycumene scaffold with differently substituted aryl propiolates gave a new family of 1,4,5-trisubstituted triazole carboxylic acid derivatives that showed high affinity toward Hsp90 associated with cell proliferation inhibition, both in nanomolar range. The 1,5 arrangement of the resorcinol, the aryl moieties, and the presence of an alkyl (secondary) amide in position 4 of the triazole ring were essential to get high activity. Docking simulations suggested that the triazoles penetrate the Hsp90 ATP binding site. Some 1,4,5-trisubstituted triazole carboxamides induced dramatic depletion of the examined client proteins and a very strong increase in the expression levels of the chaperone Hsp70. In vitro metabolic stability and in vivo preliminary studies on selected compounds have shown promising results comparable to the potent Hsp90 inhibitor NVP-AUY922. One of them, (compound 18, SST0287CL1) was selected for further investigation as the most promising drug candidate.

Efficient double glycoconjugation to naturalize high molecular weight disperse dyes.

Commercially available Disperse Orange 29 (1a) and Disperse Red 1 (2a) were elaborated to glycoconjugated species, following a new version of a previously-described 'naturalisation' procedure. Glutamic acid was chosen to achieve a double glycoconjugation, which is essential to give to the original disperse dye a water solubility suitable for reaching optimal dyeing conditions. UV-vis plot of the 'naturalised' species showed negligible differences when compared to those of the commercial dyes.

Straightforward synthesis of enantiomerically pure (3S,4R)- and (3R,4S)-3,4-isopropylidenedioxypyrroline 1-oxide, precursors of functionalized cis-dihydroxy azaheterocycles, by a novel "one-pot" procedure.

The enantiomerically pure nitrone 3, a valuable precursor of mono- and bicyclic azaheterocycles, has been synthesized in 57% yield by a novel "one-pot" process starting from lactol 1, in turn readily available from D-arabinose. The same process, consisting of reaction with a O-silyl-protected hydroxylamine followed by mesylation in pyridine, furnished ent-3 in 55% yield when applied to L-arabinose.