Electrochemical-induced solvent-tuned selective C(sp3)-H bond activation towards the synthesis of C3-functionalized chromone derivatives.

An unprecedented solvent-tuned electrochemical method for selective C(sp3)-H bond activation towards the synthesis of C3 functionalized chromone derivatives has been developed. This electrosynthesis protocol provides an efficient and green way to access various C3-functionalized chromones by avoiding traditionally employed transition metals and high temperatures. The swappable chemoselectivity was controlled mainly by altering the solvent and the current. A plausible reaction mechanism has been proposed with the help of radical capture and cyclic voltammetry experiments.

B(C6F5)3/CPA-Catalyzed Aza-Diels-Alder Reaction of 3,3-Difluoro-2-Aryl-3H-indoles and Unactivated Dienes.

Here we report B(C6F5)3/CPA-catalyzed enantioselective aza-Diels-Alder reaction of 3,3-difluoro-2-Aryl-3H-indoles with unactivated dienes to access chiral 10,10-difluoro-tetrahydropyrido[1,2-a]indoles. This protocol allows the formation of pyrazole-based C2-quaternary indolin-3-ones with high enantioselectivities and regioselectivities. Moreover, gram-scale synthesis of the 10,10-difluoro-tetrahydropyrido[1,2-a]indole skeleton was successfully achieved without any reduction in both yield and enantioselectivity.

Effects of dietary supplementation of glycerol monolaurate on laying performance, egg quality, antioxidant capacity, intestinal morphology and immune function in late-phase laying hens.

The objective of this study was to evaluate the effects of different levels of glycerol monolaurate (GML) on laying performance, egg quality, antioxidant capacity, intestinal morphology and immune function in late-phase laying hens. A total of 480 Hy-Line Variety Brown hens (age 54 wk) were randomly assigned to 5 treatments: the control group (basal diet) and 4 GML groups (basal diet supplemented with 100, 200, 300, and 400 mg/kg GML). Each treatment consisted of 8 replicates with 12 hens each and the trial lasted for 8 wk. The results showed that dietary inclusion of GML increased the ADFI in the entire experimental period and the average egg weight in wk 5 to 8 and wk 1 to 8 of the experiment (linear, P < 0.05). Dietary GML addition linearly increased albumen height, Haugh unit and yolk color, and quadratically increased eggshell thickness (P < 0.05). The serum SOD activity, T-AOC and IgG concentrations in the 200 mg/kg GML group, and GSH-Px activity in 200 and 300 mg/kg GML groups were increased, while the MDA concentration in 200 and 300 mg/kg GML groups was decreased than those in the control group (P < 0.05). The jejunal villus height and villus height: crypt depth in 300 mg/kg GML group were higher than that in the control group (P < 0.05). The mRNA expression of TLR4, IL-1ß and TNF-α in spleen and jejunum decreased with the increase of dietary GML concentration (linear, P < 0.05). In conclusion, dietary GML supplementation could improve egg quality, antioxidant capacity, intestinal morphology and immune function in late-phase laying hens, and dietary 300 mg/kg GML inclusion is suggested.

Asymmetric Organocatalyzed Cyclization Cascade Reactions of 3,3-Difluoro-2-aryl-3H-indoles and Enamides.

The direct functionalization of ß-C(sp2)-H bonds in enamides has garnered increasing attention within the realm of organic synthesis. However, these remarkable advancements are predominantly dependent on transition metals; limited success has been achieved via organocatalytic catalysis. Herein, we report a CPA-catalyzed ß-C(sp2)-H functionalization of enamides cascade intramolecular cyclization to synthesize the chiral dihydropyrimido[1,6-a]indoles bearing gem-difluoromethylene. Moreover, this methodology enables the synthesis of diverse chiral dihydropyrimido[1,6-a]indoles with outstanding enantioselectivities in moderate to high yields.

Electrochemical-Induced C-N Bond Formation: A New Method to Synthesis (Z)-Quinazolinone Oximes Using Primary Amines and Quinazolin-4(3H)-one.

A novel and highly selective electrochemical method for the synthesis of diverse quinazolinone oximes via direct electrooxidation of primary amines/C(sp2)-H functionalization of oximes has been developed. The reaction is conducted in an undivided cell under constant current conditions and is oxidant-free, open-air, and eco-friendly. Notably, the protocol shows good functional group tolerance, providing versatile quinazolinone oximes in good yields. Moreover, the mechanism is investigated through control experiments and cyclic voltammogram (CV) experiments.

NADH dehydrogenase-like complex L subunit improves salt tolerance by enhancing photosynthetic electron transport.

Cyclic electron transport (CET) around photosystem I (PSI) mediated by the NADH dehydrogenase-like (NDH) complex is closely related to plant salt tolerance. However, whether overexpression of a core subunit of the NDH complex affects the photosynthetic electron transport under salt stress is currently unclear. Here, we expressed the NDH complex L subunit (Ndhl) genes ZmNdhl1 and ZmNdhl2 from C4 plant maize (Zea mays) or OsNdhl from C3 plant rice (Oryza sativa) using a constitutive promoter in rice. Transgenic rice lines expressing ZmNdhl1, ZmNdhl2, or OsNdhl displayed enhanced salt tolerance, as indicated by greater plant height, dry weight, and leaf relative water content, as well as lower malondialdehyde content compared to wild-type plants under salt stress. Fluorescence parameters such as post-illumination rise (PIR), the prompt chlorophyll a fluorescence transient (OJIP), modulated 820-nm reflection (MR), and delayed chlorophyll a fluorescence (DF) remained relatively normal in transgenic plants during salt stress. These results indicate that expression of ZmNdhl1, ZmNdhl2, or OsNdhl increases cyclic electron transport activity, slows down damage to linear electron transport, alleviates oxidative damage to the PSI reaction center and plastocyanin, and reduces damage to electron transport on the receptor side of PSI in rice leaves under salt stress. Thus, expression of Ndhl genes from maize or rice improves salt tolerance by enhancing photosynthetic electron transport in rice. Maize and rice Ndhl genes played a similar role in enhancing salinity tolerance and avoiding photosynthetic damage.

Electrochemical multicomponent [2+2+1] cascade cyclization of enaminones and primary amines towards the synthesis of 4-acylimidazoles.

An electrochemical multicomponent [2+2+1] cascade cyclization of enaminones and primary amines towards the synthesis of 4-acylimidazoles has been developed. In an undivided cell, enaminones and primary amines can smoothly participate in this reaction to provide a series of 1,2-disubstituted 4-acylimidazoles at room temperature. The reaction avoids the use of both transition-metal catalysts and oxidation reagents, which makes it more sustainable and renewable.

Highly Enantioselective Synthesis of 3a-Fluorofuro[3,2-b]indolines via Organocatalytic Aza-Friedel-Crafts Reaction/Selective C-F Bond Activation.

Fluoroalkylated compounds are of high interest in drug discovery and have inspired the evolution of diverse C-F bond activation methodologies. However, the selective activation of polyfluorinated compounds remains challenging. Herein, we describe an unprecedented strategy for synthesizing enantioenriched fluorofuro[3,2-b]indolines through the organocatalytic aza-Friedel-Crafts reaction coupled with selective C-F bond activation. These reactions feature excellent enantioselectivities (≤96% ee) and yields (≤96%) as well as good functional group compatibility. Mechanistic investigations by means of 19F nuclear magnetic resonance experiments provided sufficient support for silica gel as the key medium in this transformation.

Isolation and Identification of the Causal Agent of Top Rot and the Genetic Architecture of Resistance in Maize.

In maize (Zea mays), the disease known as "top rot" causes necrosis of the upper plant, disrupts tassel formation and pollen dispersal, and decreases yield. However, the causal agent, mode of pathogen infestation, and genetic architecture of resistance in maize remain to be explored. Here, to identify the causal agent, we isolated 41 fungal strains from maize plants infected with top rot. We classified these strains into six groups based on their morphological and molecular characteristics. Four species of Fusarium (F. fujikuroi, F. equiseti, F. proliferatum, and F. verticillioides) were able to cause top rot, with F. fujikuroi and F. equiseti being the main causal agents. Microscopic observations of a F. fujikuroi strain labeled with enhanced green fluorescent protein revealed that this pathogen first colonizes the stomata of leaves and then spreads through intercellular spaces, creating an expanding lesion. To dissect the genetic basis of maize resistance to top rot, we performed quantitative trait locus (QTL) mapping using a recombinant inbred line population constructed from the resistant parent LDC-1 and the susceptible parent YS501. Under natural conditions in Yangzhou and Hainan, we detected three and five QTLs, respectively, with qRtr7-1, located on chromosome 7, detected in both environments. Using inoculated seedlings, we detected three QTLs for resistance on chromosomes 1, 5, and 8. These results improve our understanding of maize top rot and provide a theoretical basis for its control.

Enantioselective Alkynylation of 2-Aryl-3H-indol-3-ones via Cooperative Catalysis of Copper/Chiral Phosphoric Acid.

A facile enantioselective alkynylation of cyclic ketimines attached to a neutral functional group utilizing the dual Cu(I)-CPA catalysis is described. The strategy of the alkynylation of 2-aryl-3H-indol-3-one directly to chiral propargylic amines containing indolin-3-one moiety in good yields and enantioselectivities. Moreover, gram-scale synthesis of chiral propargylamines based C2-quaternary indolin-3-ones was performed. The synthetic applications were confirmed by transformations of the products with no decrease in the yield and enantioselectivity.

A borate-based peroxynitrite fluorescent probe and its application in fluorescence imaging of living cells.

As a bioactive species with high oxidation capacity, peroxynitrite (ONOO-) plays a crucial role in the regulation of diverse pathophysiological processes, and the overproduction of ONOO- is closely associated with various physiological diseases such as liver injury, pulmonary fibrosis and so on. Herein, two borate-based fluorescent probes 3a and 3b were synthesized for monitoring ONOO- by a simple substitution reaction. The experimental results showed that 3a and 3b had high selectivity and sensitivity for ONOO-. The detection limits of 3a and 3b were 79.46 nM and 32.12 nM, respectively. Moreover, the recognition was not disturbed by other active oxygen groups and common ions. More importantly, the probes 3a and 3b had low cytotoxicity and were successfully used to detect endogenous and exogenous ONOO-. They would provide an efficient detection method for further exploring the physiological and pathological role of ONOO- in complex biological systems and related diseases.

B(C6F5)3-catalyzed ß-C(sp3)-H alkylation of tertiary amines with 2-aryl-3H-indol-3-ones.

The ß-C-H functionalization of amines is one of the most powerful tools for the synthesis of saturated nitrogen-containing heterocycles in organic synthesis. However, the ß-C-H functionalization of amines via redox-neutral addition with cyclic-ketimines is still unprecedented. Herein, the ß-C-H functionalization of tertiary amines is described, providing the corresponding 1,3-diamines containing the indolin-3-one moiety in high yields via the B(C6F5)3-catalyzed borrowing hydrogen strategy. According to the experimental results, a possible catalytic cycle has been proposed to rationalize the process of this reaction. Notably, the ß-C-H alkylation of amines is external oxidant- and transition-metal-free, which makes a significant contribution to promoting economical chemical synthesis.

Organocatalyzed Enantioselective Aza-Morita-Baylis-Hillman Reaction of Cyclic Ketimine with α,ß-Unsaturated γ-Butyrolactam.

The enantioselective aza-MBH reaction is an efficient strategy for constructing novel carbon-carbon bonds, providing access to multitudinous chiral densely functionalized MBH products. However, the enantioselective aza-MBH reaction of cyclic-ketimines that would generate a versatile synthon is still missing and challenging. Herein, we developed a challenging direct organocatalytic asymmetric aza-MBH reaction involving cyclic ketimines attached to a neutral functional group. Moreover, the α,ß-unsaturated γ-butyrolactam was utilized as a rare nucleophile alkene in this work. The reactions provide enantiomerically enriched 2-alkenyl-2-phenyl-1,2-dihydro-3H-indol-3-ones, bearing with a tetra-substituted stereogenic center. Moreover, this reaction features high α-selectivities, high enantioselectivities (up to 99% ee), and good yields (up to 80%).

A graphitic-C3N4 derivative containing heptazines merged with phenyls: synthesis, purification and application as a high-efficiency metal-free quasi-green phosphor for white LEDs.

Because rare-earth elements are scarce, expensive, and unsustainable, it is of great significance to develop rare-earth-free (even metal-free) luminescent materials as phosphors for LEDs. Here, a graphitic-C3N4 (g-C3N4) derivative containing some heptazines merged with phenyls has been synthesized via thermal polymerization of melamine and quinazoline-2,4(1H,3H)-dione at an optimal mole ratio of 18 : 1. In comparison with g-C3N4 synthesized from melamine only, the photoluminescent (PL) emission colour changed from blue to green, the maximum emission wavelength (λ em,max) changed from 467 nm to 508 nm, and the PL quantum yield (PLQY) increased from 8.0% to 24.0%. It was further purified via vacuum sublimation, and a product with yellowish green emission (λ em,max = 517 nm) and PLQY up to 45.5% was obtained. This sublimated product had high thermal stability and low thermal quenching; its thermal decomposition temperature was as high as 527 °C, and its relative PL emission intensity at 100 °C was 90.8% of that at 20 °C. Excited by blue light chips (λ em,max ≈ 460 nm), cold, neutral and warm white LEDs can be fabricated using the sublimated product and orange-emitting (Sr,Ba)3SiO5:Eu2+ as phosphors. The good performances of these white LEDs (for example, the CIE coordinates, color rendering index and correlated color temperature were (0.31, 0.33), 84.4 and 6577 K, respectively) suggest that the low-efficiency blue-emitting g-C3N4 had been successfully converted into a high-efficiency metal-free quasi-green phosphor.

Effects of OsRCA Overexpression on Rubisco Activation State and Photosynthesis in Maize.

Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the rate-limiting enzyme for photosynthesis. Rubisco activase (RCA) can regulate the Rubisco activation state, influencing Rubisco activity and photosynthetic rate. We obtained transgenic maize plants that overproduced rice RCA (OsRCAOE) and evaluated photosynthesis in these plants by measuring gas exchange, energy conversion efficiencies in photosystem (PS) I and PSII, and Rubisco activity and activation state. The OsRCAOE lines showed significantly higher initial Rubisco activity and activation state, net photosynthetic rate, and PSII photochemical quantum yield than wild-type plants. These results suggest that OsRCA overexpression can promote maize photosynthesis by increasing the Rubisco activation state.

A human antibody potently neutralizes RSV by targeting the conserved hydrophobic region of prefusion F.

Respiratory syncytial virus (RSV) continues to pose serious threats to pediatric populations due to the lack of a vaccine and effective antiviral drugs. RSV fusion (F) glycoprotein mediates viral-host membrane fusion and is a key target for neutralizing antibodies. We generated 23 full-human monoclonal antibodies (hmAbs) against prefusion F protein (pre-F) from a healthy adult with natural RSV infection by single B cell cloning technique. A highly potent RSV-neutralizing hmAb, named as 25-20, is selected, which targets a new site Ø-specific epitope. Site-directed mutagenesis and structural modelling analysis demonstrated that 25-20 mainly targets a highly conserved hydrophobic region located at the a4 helix and a1 helix of pre-F, indicating a site of vulnerability for drug and vaccine design. It is worth noting that 25-20 uses an unreported inferred germline (iGL) that binds very poorly to pre-F, thus high levels of somatic mutations are needed to gain high binding affinity with pre-F. Our observation helps to understand the evolution of RSV antibody during natural infection. Furthermore, by in silico prediction and experimental verification, we optimized 25-20 with KD values as low as picomolar range. Therefore, the optimized 25-20 represents an excellent candidate for passive protection against RSV infection.

Asymmetric aza-Friedel-Crafts Reaction of Cyclic Ketimines with 5-Aminopyrazole Derivatives: Expedient Access to Pyrazole-Based C2-quaternary Indolin-3-Ones.

A chiral phosphoric acid-catalyzed enantioselective aza-Friedel-Crafts reaction of 5-aminopyrazole derivatives with cyclic ketimines attached to a neutral functional group is reported. This protocol allows the formation of pyrazole-based C2-quaternary indolin-3-ones with high enantioselectivities and regioselectivities. Moreover, gram-scale synthesis of the 5-aminopyrazole-based C2-quaternary indolin-3-ones was performed, with no decrease in the yield and enantioselectivity.

Chiral phosphoric acid-catalyzed enantioselective aza-Friedel-Crafts reaction of naphthols and electron-rich phenols with 2-aryl-3H-indol-3-ones.

The enantioselective aza-Friedel-Crafts reaction is one of the most straightforward and efficient strategies for constructing a new carbon-carbon bond bearing quaternary stereocenter in organic synthesis, but the catalytic asymmetric aza-Friedel-Crafts reaction of naphthols/phenols with cyclic-ketimines attached to a neutral functional group remains still relatively unexplored. Herein, a highly enantioselective aza-Friedel-Crafts reaction of cyclic-ketimines and naphthols/phenols has been realized using a chiral phosphoric acid catalyst. A variety of chiral aminonaphthols (chiral indolin-3-ones) containing a quaternary stereocenter at the C2 position were obtained with excellent outcomes (up to 97% yield, 98% ee). Moreover, the synthetic utility of the enantiomerically enriched chiral aminonaphthols was demonstrated in some efficient transformations. According to the experimental results, a possible transition state model has been proposed to rationalize the origin of asymmetric induction.

Design of Near-Infrared-Triggered Cellulose Nanocrystal-Based In Situ Intelligent Wound Dressings for Drug-Resistant Bacteria-Infected Wound Healing.

Postoperative infected wound complications caused by residual tumor cells, bacterial biofilms, and drug-resistant bacteria have become the main challenge in postsurgical skin regeneration. Herein, a bionic cellulose nanocrystal (CNC)-based in situ intelligent wound dressing with near-infrared (NIR)-, temperature-, and pH-responsive functions was designed by using NIR-responsive CNC as the network skeleton, dynamic imine bonds between dialdehyde cellulose nanocrystals and doxorubicin, chitosan oligosaccharide as the pH-responsive switch, and temperature-sensitive poly(N-isopropyl acrylamide) as the temperature-responsive in situ formation switch. The as-prepared wound dressing with the intertwining three-dimensional (3D) network structure possessed high drug loadability of indocyanine green (30 mg/g) and doxorubicin (420 mg/g) simultaneously. The temperature-, NIR-, and pH-responsive switches endowed the wound dressing with controllable on-demand drug release behavior. In particular, the temperature switch endowed the dressing with a shape-adaptable ability on irregularly infected wounds. Interestingly, the wound dressing showed excellent antitumor activity for A375 tumor cells, antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and bacterial biofilm removal ability. Therefore, the developed wound dressing can provide an ideal synergistic treatment strategy combined with chemotherapy and photodynamic and photothermal therapy for postoperative drug-resistant bacteria-infected wound healing.

Dual light-responsive cellulose nanofibril-based in situ hydrogel for drug-resistant bacteria infected wound healing.

In situ hydrogels with rapid hemostasis and antibacterial activity have received considerable attention in the field of wound healing. Herein, a white light and NIR dual light-responsive cellulose nanofibril (CNF)-based in situ hydrogel wound dressing is tailored by using white light-responsive CNF and endogenous antibacterial CNF as the skeleton, Prussian blue nanoparticles, Pluronic® F127 and hydroxypropyl methyl cellulose as the NIR, temperature-responsive switch and binder, respectively. The dressing exhibits rapid hemostasis properties in rat liver injury model with low blood loss of 286.4 mg and short hemostasis time of 63 s. Meanwhile, the antibacterial activity of the dressing with white and NIR irradiation against Escherichia coli, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) is higher than 99.9 %. Interestingly, the dressing with biocompatibility can promote MRSA infection wound healing and can be removed on demand without secondary injury to skin. Therefore, it has promising applications for first-aid hemostasis and wound healing.