Highlights • Acinetobacter baumannii is one of the main emergent pathogens owing to the high frequency of infections and its multidrug resistance. • The anticancer drug mitomycin C (MMC) is able to ...kill A. baumannii exponential-phase, stationary-phase and biofilm cells. • MMC is able to rescue Galleria mellonella larvae against otherwise lethal doses of reference and clinical A. baumannii strains, even those with multidrug resistance sensitive only to the highly nephrotoxic antibiotic colistin.
Mitochondrial aldehyde dehydrogenase (ALDH2) has been proposed as a key enzyme in cardioprotection during ischemia–reperfusion processes. This proposal led to the search for activators of ALDH2 with ...the aim to develop cardioprotective drugs. Alda‐1 was the first activator of ALDH2 identified and its cardioprotective effect has been extensively proven in vivo; however, the mechanism of activation is not fully understood. A crystallographic study showed that Alda‐1 binds to the entrance of the aldehyde‐binding site; therefore, Alda‐1 should in essence be an inhibitor. In the present study, kinetic experiments were performed to characterize the effect of Alda‐1 on the properties of ALDH2 (kinetic parameters, determination of the rate‐limiting step, reactivity of the catalytic cysteine) and on the kinetic mechanism (type of kinetics, sequence of substrates entering, and products release). The results showed that Alda‐1 dramatically modifies the properties of ALDH2, the Km for NAD+ decreased by 2.4‐fold, and the catalytic efficiency increased 4.4‐fold; however, the Km for the aldehyde increased 8.6‐fold, thus, diminishing the catalytic efficiency. The alterations in these parameters resulted in a complex behavior, where Alda‐1 acts as inhibitor at low concentrations of aldehyde and as an activator at high concentrations. Additionally, the binding of Alda‐1 to ALDH2 made the deacylation less limiting and diminished the pKa of the catalytic cysteine. Finally, NADH inhibition patterns indicated that Alda‐1 induced a change in the sequence of substrates entry and products release, in agreement with the proposal of both substrates entering ALDH2 by the NAD+ entrance site.
Activator of human ALDH2 Alda‐1 protects cell integrity from diverse stress conditions; however, the activation mechanism is not fully understood. Kinetic characterization showed that binding of Alda‐1 to ALDH2 activates the catalytic cysteine reducing its pKa, which induces the switching of order of substrates binding and products release, additionally, Alda‐1 increases the rate of the limiting step of the reaction.
To develop novel chemotherapeutic alternatives for the treatment of Chagas disease, in this study, a set of new amino naphthoquinone derivatives were synthesised and evaluated in vitro on the ...epimastigote and trypomastigote forms of Trypanosoma cruzi strains (NINOA and INC-5) and on J774 murine macrophages. The design of the new naphthoquinone derivatives considered the incorporation of nitrogenous fragments with different substitution patterns present in compounds with activity on T. cruzi, and, thus, 19 compounds were synthesised in a simple manner. Compounds 2e and 7j showed the lowest IC50 values (0.43 µM against both strains for 2e and 0.19 µM and 0.92 µM for 7j). Likewise, 7j was more potent than the reference drug, benznidazole, and was more selective on epimastigotes. To postulate a possible mechanism of action, molecular docking studies were performed on T. cruzi trypanothione reductase (TcTR), specifically at a site in the dimer interface, which is a binding site for this type of naphthoquinone. Interestingly, 7j was one of the compounds that showed the best interaction profile on the enzyme; therefore, 7j was evaluated on TR, which behaved as a non-competitive inhibitor. Finally, 7j was predicted to have a good pharmacokinetic profile for oral administration. Thus, the naphthoquinone nucleus should be considered in the search for new trypanocidal agents based on our hit 7j.
Quorum sensing (QS) in
coordinates the expression of virulence factors, some of which are used as public goods. Since their production is a cooperative behavior, it is susceptible to social cheating ...in which non-cooperative QS deficient mutants use the resources without investing in their production. Nevertheless, functional QS systems are abundant; hence, mechanisms regulating the amount of cheating should exist. Evidence that demonstrates a tight relationship between QS and the susceptibility of bacteria against the attack of lytic phages is increasing; nevertheless, the relationship between temperate phages and QS has been much less explored. Therefore, in this work, we studied the effects of having a functional QS system on the susceptibility to temperate bacteriophages and how this affects the bacterial and phage dynamics. We find that both experimentally and using mathematical models, that the lysogenic bacteriophages D3112 and JBD30 select QS-proficient
phenotypes as compared to the QS-deficient mutants during competition experiments with mixed strain populations
and
in
, in spite of the fact that both phages replicate better in the wild-type background. We show that this phenomenon restricts social cheating, and we propose that temperate phages may constitute an important selective pressure toward the conservation of bacterial QS.
The resveratrol (RSV) efficacy to affect the proliferation of several cancer cell lines was initially examined. RSV showed higher potency to decrease growth of metastatic HeLa and MDA-MB-231 ...(IC50 = 200–250 μM) cells than of low metastatic MCF-7, SiHa and A549 (IC50 = 400–500 μM) and non-cancer HUVEC and 3T3 (IC50≥600 μM) cells after 48 h exposure. In order to elucidate the biochemical mechanisms underlying RSV anti-cancer effects, the energy metabolic pathways and the oxidative stress metabolism were analyzed in HeLa cells as metastatic-type cell model. RSV (200 μM/48 h) significantly decreased both glycolysis and oxidative phosphorylation (OxPhos) protein contents (30–90%) and fluxes (40–70%) vs. non-treated cells. RSV (100 μM/1–5 min) also decreased at a greater extent OxPhos flux (net ADP-stimulated respiration) of isolated tumor mitochondria (> 50%) than of non-tumor mitochondria (< 50%), particularly with succinate as oxidizable substrate. In addition, RSV promoted an excessive cellular ROS (2–3 times) production corresponding with a significant decrement in the SOD activity (but not in its content) and GSH levels; whereas the catalase, glutahione reductase, glutathione peroxidase and glutathione-S-transferase activities (but not their contents) remained unchanged. RSV (200 μM/48 h) also induced cellular death although not by apoptosis but rather by promoting a strong mitophagy activation (65%). In conclusion, RSV impaired OxPhos by inducing mitophagy and ROS over-production, which in turn halted metastatic HeLa cancer cell growth.
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•RSV preferentially blocks metastatic cancer cell growth.•RSV deters cancer cell growth by impairing cellular respiration and glycolysis.•RSV also promotes ROS over-production and mitophagy activation.
This study shows that the non-steroidal anti-inflammatory drug (NSAID) celecoxib and its non-cyclooxygenase-2 (COX2) analogue dimethylcelecoxib (DMC) exert a potent inhibitory effect on the growth of ...human cervix HeLa multi-cellular tumor spheroids (MCTS) when added either at the beginning ("preventive protocol"; IC
= 1 ± 0.3 nM for celecoxib and 10 ± 2 nM for DMC) or after spheroid formation ("curative protocol"; IC
= 7.5 ± 2 µM for celecoxib and 32 ± 10 µM for DMC). These NSAID IC
values were significantly lower than those attained in bidimensional HeLa cells (IC
= 55 ± 9 µM celecoxib and 48 ± 2 µM DMC) and bidimensional non-cancer cell cultures (3T3 fibroblasts and MCF-10A mammary gland cells with IC
from 69 to >100 µM, after 24 h). The copper-based drug casiopeina II-gly showed similar potency against HeLa MCTS. Synergism analysis showed that celecoxib, DMC, and casiopeinaII-gly at sub-IC
doses increased the potency of cisplatin, paclitaxel, and doxorubicin to hinder HeLa cell proliferation through a significant abolishment of oxidative phosphorylation in bidimensional cultures, with no apparent effect on non-cancer cells (therapeutic index >3.6). Similar results were attained with bidimensional human cervix cancer SiHa and human glioblastoma U373 cell cultures. In HeLa MCTS, celecoxib, DMC and casiopeina II-gly increased cisplatin toxicity by 41-85%. These observations indicated that celecoxib and DMC used as adjuvant therapy in combination with canonical anti-cancer drugs may provide more effective alternatives for cancer treatment.
Methanosarcina acetivorans, considered a strict anaerobic archaeon, was cultured in the presence of 0.4-1% O2 (atmospheric) for at least 6 months to generate air-adapted cells; further, the ...biochemical mechanisms developed to deal with O2 were characterized. Methane production and protein content, as indicators of cell growth, did not change in air-adapted cells respect to cells cultured under anoxia (control cells). In contrast, growth and methane production significantly decreased in control cells exposed for the first time to O2. Production of reactive oxygen species was 50 times lower in air-adapted cells versus control cells, suggesting enhanced anti-oxidant mechanisms that attenuated the O2 toxicity. In this regard, (i) the transcripts and activities of superoxide dismutase, catalase and peroxidase significantly increased; and (ii) the thiol-molecules (cysteine + coenzyme M-SH + sulfide) and polyphosphate contents were respectively 2 and 5 times higher in air-adapted cells versus anaerobic-control cells. Long-term cultures (18 days) of air-adapted cells exposed to 2% O2 exhibited the ability to form biofilms. These data indicate that M. acetivorans develops multiple mechanisms to contend with O2 and the associated oxidative stress, as also suggested by genome analyses for some methanogens.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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