Lead-based organic-inorganic hybrid perovskite (OIHP) solar cells can attain efficiencies over 20%. However, the impact of ion mobility and/or organic depletion, structural changes, and segregation ...under operating conditions urge for decisive and more accurate investigations. Hence, the development of analytical tools for accessing the grain-to-grain OIHP chemistry is of great relevance. Here, we used synchrotron infrared nanospectroscopy (nano-FTIR) to map individual nanograins in OIHP films. Our results reveal a spatial heterogeneity of the vibrational activity associated to the nanoscale chemical diversity of isolated grains. It was possible to map the chemistry of individual grains in CsFAMA Cs
FA
MA
Pb(I
Br
)
and FAMA FA
MA
Pb(I
Br
)
films, with information on their local composition. Nanograins with stronger nano-FTIR activity in CsFAMA and FAMA films can be assigned to PbI
and hexagonal polytype phases, respectively. The analysis herein can be extended to any OIHP films where organic cation depletion/accumulation can be used as a chemical label to study composition.
Using machine learning, targets were identified for β-lapachone. Resorting to biochemical assays, β-lapachone was validated as a potent, ligand efficient, allosteric and reversible modulator of ...5-lipoxygenase (5-LO). Moreover, we provide a rationale for 5-LO modulation and show that inhibition of 5-LO is relevant for the anticancer activity of β-lapachone. This work demonstrates the power of machine intelligence to deconvolute complex phenotypes, as an alternative and/or complement to chemoproteomics and as a viable general approach for systems pharmacology studies.
In continuation of our quest for new redox-modulating catalytic antitumor molecules, selenium-containing quinone-based 1,2,3-triazoles were synthesized using rhodium-catalyzed C-H bond activation and ...click reactions. All compounds were evaluated against five types of cancer cell lines: HL-60 (human promyelocytic leukemia cells), HCT-116 (human colon carcinoma cells), SF295 (human glioblastoma cells), NCIH-460 (human lung cells) and PC3 (human prostate cancer cells). Some compounds showed good activity with IC
values below 1 µM. The cytotoxic potential of the naphthoquinoidal derivatives was also evaluated in non-tumor cells, exemplified by L929 cells. Overall, these compounds represent promising new lead derivatives and stand for a new class of chalcogenium-containing derivatives with potential antitumor activity.
The glyoxylate cycle plays an essential role for anaplerosis of oxaloacetate during growth of microorganisms on carbon sources such as acetate or fatty acids and has been shown to contribute to ...virulence of several pathogens. Here, we investigated the transcriptional and post-translational regulation of the glyoxylate cycle key enzyme isocitrate lyase (PbICL) in the human pathogenic fungus Paracoccidioides brasiliensis. Although sequence analyses on fungal isocitrate lyases revealed a high phylogenetic conservation, their regulation seems to differ significantly. Closely related Aspergillus species regulate the glyoxylate cycle at the transcriptional level, whereas Pbicl was constitutively expressed in yeast cells. However, only low PbICL activity was detected when cells were grown in the presence of glucose. Two-dimensional gel analyses with subsequent antibody hybridization revealed constitutive production of PbICL, but low PbICL activity on glucose coincided with extensive protein phosphorylation. Since an in vitro dephosphorylation of PbICL from glucose grown cells strongly increased ICL activity and resembled the phosphorylation pattern of highly active acetate grown cells, post-translational modification seems the main mechanism regulating PbICL activity in yeast cells. In agreement, a transfer of yeast cells from glucose to acetate medium increased PbICL activity without requirement of de novo protein synthesis. Thus, inactivation of PbICL by phosphorylation is reversible, denoting a new strategy for the rapid adaptation to changing environmental conditions.
Selenium-containing quinone-based 1,2,3-triazoles were synthesized using click chemistry, the copper catalyzed azide-alkyne 1,3-dipolar cycloaddition, and evaluated against six types of cancer cell ...lines: HL-60 (human promyelocytic leukemia cells), HCT-116 (human colon carcinoma cells), PC3 (human prostate cells), SF295 (human glioblastoma cells), MDA-MB-435 (melanoma cells) and OVCAR-8 (human ovarian carcinoma cells). Some compounds showed IC50 values < 0.3 μM. The cytotoxic potential of the quinones evaluated was also assayed using non-tumor cells, exemplified by peripheral blood mononuclear (PBMC), V79 and L929 cells. Mechanistic role for NAD(P)H:Quinone Oxidoreductase 1 (NQO1) was also elucidated. These compounds could provide promising new lead derivatives for more potent anticancer drug development and delivery, and represent one of the most active classes of lapachones reported.
Selenium-containing quinones were designed and synthesized by click chemistry reaction and evaluated against several human cancer cell lines showing, in some cases, IC50 values below 0.3 μM. Display omitted
•Selenium-containing quinones were obtained with potent antitumor activity.•Click chemistry was used for the synthesis of selenium-containing quinones.•Mechanistic insights involving NQO1-target were studied.
1,2,3-Triazole-, arylamino- and thio-substituted naphthoquinones (24, 8, and 2 representatives, respectively) were synthesized in moderate yields and evaluated against several human cancer cell lines ...(blood, ovarian, breast, central nervous system, colon, and prostate cancers and melanoma), showing, for some of them, IC50 values below 2μM. The cytotoxic potential of the tested naphthoquinones was also assayed on non-tumor cells such as human peripheral blood mononucluear cells (PBMC) and two murine fibroblast lines (L929 and V79 cells). α-Lapachone- and nor-α-lapachone-based 1,2,3-triazoles and arylamino-substituted naphthoquinones showed potent cytotoxicity against different cancer cell lines. The compounds may represent promising new lead derivatives for anticancer drug development. The electrochemical properties of selected compounds were evaluated in an attempt to correlate them with antitumor activity.
In this article, full quantum mechanical calculations at the DFT‐D level were carried out to study the full catalytic cycle for the hydroformylation of propene, catalyzed by the HRh(CO)(BISBI) ...catalyst. All intermediates and transition states along the elementary steps of the whole catalytic cycle were located and properly characterized. The kinetic constants calculated from transition state theory together with the application of the steady‐state approximation were used to build a kinetic model for the hydroformylation reaction. The calculations show that regioselectivity of the reaction is set at the olefin insertion step, with the H2 oxidative addition being the rate‐determining step of the entire cycle, with an activation energy of 26.0 kcal.mol‐1 for the linear pathway. The kinetic model showed that the CO gas acts as an inhibitor of the reaction at high pressure, and depending on the CO partial pressure, the rate of linear product formation is around 4 to 10 times faster. In line with experimental observations, our computational kinetic model indicated that at high CO partial pressures (> 40 atm), the HRh(CO)(BISBI) catalyst decreases its selectivity. Also was predicted from the computational kinetic model, that the reaction rates for both productions of normal and iso‐butanal are less sensitive to effects of H2 partial pressure concerning the observed with the variation of the partial pressure of CO gas.
This work presents a computational kinetic model for propene hydroformylation catalyzed by HRh(CO)(BISBI). Our model allows determining the reaction rate as a function of the concentrations and the partial pressures of the reactants. Simulating different reaction conditions with our model, we showed that CO acts as an inhibitor and that the oxidative addition of H2 is the rate‐determining step of the cycle.
This research explores the concentration of black carbon (BC) in particulate matter (PM10 and PM2.5) from ten monitoring stations in the Metropolitan Region of Rio de Janeiro (MRRJ), Bonsucesso (BS), ...Botafogo (BOT), Copacabana (COP), Gavea (GAV), Gericino (GER), Lagoa (LAG), Recreio dos Bandeirantes (REC), Santa Cruz (SC), Castelo (CAS) and Urca (URC), covering a range of pollution sources (vehicular, industrial, and residential). PM samples were collected using filter units every week from January 2018 to December 2019. Results revealed high concentrations of PM10 in BS (86 ± 22 µg m-3) and PM2.5 in REC (30 ± 11 µg m-3). Likewise, both monitoring stations exceeded the international limits. In 2019, BC in PM10 decreased in the following order: BS > CAS > GER > BOT > SC > GAV. For 2018, BC in PM2.5 decreased as follows REC > LAG > SC, while 2019 REC > GAV > LAG > COP > URC. REC and BS have industrial and commercial activities and intense vehicular traffic. During the period of study, average BC concentrations in PM10 and PM2.5 were 3.3 ± 1.5 and 1.9 ± 0.70 µg m-3, respectively. These findings indicate that BC concentrations should be monitored and regulated in locations with high levels of traffic-related air pollution for offering new insights and guiding efforts to minimize emissions and enhance public health.
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