A near-infrared fluorescent probe for monitoring leucine aminopeptidase in living cells.

Leucine aminopeptidase (LAP), one of the important cancer-related biomarkers, is significantly over-expressed in many malignant tumor cells. Developing an effective fluorescent probe for high-specificity and in situ trapping of endogenous LAP in living samples is still challenging. In this project, we report a water-soluble near-infrared (NIR) fluorescent probe (CHMC-M-Leu) for specific monitoring of LAP in vitro and in vivo. The novel fluorescent probe (CHMC-M-Leu) contains a NIR-emitting fluorophore (CHMC-M) as the reporter and l-leucine as the enzyme-active trigger moiety which are linked together by a p-aminobenzyl alcohol (PABA) section. Upon exposure to LAP, the fluorescence at 625 nm gets impressively enhanced, which belongs to the near-infrared region and is beneficial for imaging in vivo. Furthermore, the novel fluorescent probe exhibits fast response and highly chemoselective detection of LAP in various bio-related species. In addition, CHMC-M-Leu shows favourable cellular uptake and was successfully used to monitor endogenous LAP in living cells.

Highly Sensitive Ratiometric Self-Assembled Micellar Nanoprobe for Nitroxyl and Its Application In Vivo.

Nitroxyl (HNO) is a derivative of nitric oxide (NO) that plays an essential role in various biological and pharmacological events. Until now, the in situ trapping and specific detection of HNO in living samples is still challenging. In this project, we fabricated a novel BODIPY-based micellar nanoprobe for monitoring nitroxyl in vitro and in vivo in ratiometric mode in aqueous solution. The probe (P-BODIPY-N) contains an asymmetrical BODIPY dye for fluorescent signaling and a diphenylphosphinobenzoyl as the trigger moiety; then we encapsulated P-BODIPY-N into the hydrophobic interior of an amphiphilic copolymer (mPEG-DSPE) and prepared a novel BODIPY-based micellar nanoprobe: NP-BODIPY-N. As far as we know, this probe is the first reported ratiometric fluorescent nanoprobe for HNO, which exhibits ultrasensitivity, high selectivity, and good biocompatibility. Above all, this nanoprobe shows favorable cellular uptaken and was successfully used to detect intracellular HNO released by Angeli's salt in living cells and zebrafish larvae. These results indicate that our newly designed nanoprobe will provide a promising tool for the studies of HNO in living system.

A Ratiometric Fluorescent Probe for Monitoring Leucine Aminopeptidase in Living Cells and Zebrafish Model.

Leucine aminopeptidase (LAP) is an important cancer-related biomarker, which shows significant overexpression in malignant tumor cells like liver cancer. Developing an effective method to monitor LAP in tumor cells holds great potential for cancer diagnosis, treatment, and management. In this work, we report a novel BODIPY-based fluorescent probe (BODIPY-C-Leu) capable of monitoring LAP in vitro and in vivo in both ratiometric and turn-on model. BODIPY-C-Leu contains an asymmetrical BODIPY dye for fluorescent signaling and a dipeptide (Cys-Leu) as the triggered moiety. Activation occurs by cleavage of the amide bond in dipeptides and subsequently an intramolecular S → N conversion to convert sulfur-substituted BODIPY to amino-substituted BODIPY, resulting in a dramatic fluorescence variation to realize the detection of LAP. Furthermore, we have successfully employed BODIPY-C-Leu to monitor LAP activity in different cancer cells, indicating that HeLa cells have a higher level of LAP activity than A549 cells. Importantly, we demonstrated the capability of the probe for real-time monitoring the drug-induced LAP level changes in zebrafish.

Clinical trials of stem cell-based therapies for pediatric diseases: a comprehensive analysis of trials registered on ClinicalTrials.gov and the ICTRP portal site.

BACKGROUND: Research on clinical trials that employ stem cells to treat children's diseases is limited. The clinical trial registry database provides a unique window to us to get known about clinical trial researches with different statuses. However, few studies aimed to perform a comprehensive and thorough analysis of those registered trials in the aforementioned field based on ClinicalTrials.gov and the ICTRP portal site. METHODS: Our study covered the clinical researches about stem cell therapy enrolling subjects aged under 18 years old registered on ClinicalTrials.gov and WHO ICTRP before May 18, 2021. A cross-sectional study was implemented to comprehensively describe and analyze the included trials that met the criteria. Results were available on ClinicalTrials.gov, and publications related to the included trials were identified. All analyses were performed utilizing the SPSS 25.0 software. RESULTS: Eventually, 202 clinical trials were included and evaluated. The participant number of trials tended to be small; 71.3% were enrolled < 50. And 93.5% of the subjects were without gender restrictions. Till May 2020, 112 trials had been preliminary completed, of which only 39 trials had published papers or uploaded results. Most (73.6%) of 186 interventional trials were in phase 1 and phase 2, where 131 (70.4%) trials were conducted without masking, and 26.3% trials were randomized; 55.4% trials were performed single group assignment. Of 16 observational trials, case-only/series took up 37.5%. Hematopoietic stem cells (37.1%) and mesenchymal stem cells (36.1%) were mostly employed, while umbilical cord blood (UCB)-derived cells (24.3%) and bone marrow (BM)-derived cells (20.8%) were the major sources. CONCLUSIONS: This study provided an overall picture of utilizing stem cells for treatment and management of childhood diseases. Since clinical trials in this area are insufficient in quantity and quality, there is an urgent need of larger, better-designed trials. Increased investment in clinical research of stem cell treatment products should be carried out to achieve the transformation of results as soon as possible. Moreover, it is important to optimize the management of the registration platform and shorten the time it takes for research results to be published.

Borane-catalyzed cascade Friedel-Crafts alkylation/[1,5]-hydride transfer/Mannich cyclization to afford tetrahydroquinolines.

An unprecedented redox-neutral annulation reaction of tertiary anilines with electron-deficient alkynes was developed that proceeds through a cascade Friedel-Crafts alkylation/[1,5]-hydride transfer/Mannich cyclization sequence. Under B(C6F5)3 catalysis, a range of functionalized 1,2,3,4-tetrahydroquinolines were facilely constructed in moderate to good yields with exclusive 3,4-anti-stereochemistry. The commercial availability of the catalyst and the high atom and step economy of the procedure, together with metal-free and external oxidant-free conditions, make this an attractive method in organic synthesis.

Zircon record of an Archaean crustal fragment and supercontinent amalgamation in quaternary back-arc volcanic rocks.

Magmatism has profoundly influenced the evolution of the geosphere, hydrosphere, atmosphere, and biosphere in back-arc basins. However, the timing of the magmatism in the Okinawa Trough (OT) is not well constrained by the age spectra of zircons. Here, for the first time, we carry out an integrated study combining in situ analysis of zircon U-Th-Pb and Hf-O isotopes, and trace element compositions of zircons from the volcanic rocks from the southernmost part of the OT. We found that the young (< 100 ka) zircons in these volcanic rocks have old (108 Ma to 2.7 Ga) inherited cores, which were captured as the magma ascended through the rifting continental crust. In particular, the inherited Archean zircons strongly suggest that remnants of the old East Asian continental blocks underlie the embryonic crustal rifting zone. Moreover, the ages of most of the inherited zircons correspond to five supercontinent amalgamation events. Specifically, the Archaean inherited zircons, which have positive εHf(t) and low δ18O values, correspond to the formation of juvenile continental crust. In contrast, the negative εHf(t) and high δ18O values of the post-Archaean inherited zircons indicate that their parental magma contained recycled older crust due to the enhanced crust-mantle interactions during the evolution of the early continental crust. Therefore, the inherited zircons in the back-arc volcanic rocks not only reflect the evolution of the local magmatism, but they also contain a record of the Archaean crustal fragment and of several global continental amalgamation events.

B(C6F5)3-Catalyzed ß-Functionalization of Pyrrolidines Using Isatins via Borrowing Hydrogen: Divergent Access to Substituted Pyrrolidines and Pyrroles.

We report herein a B(C6F5)3-catalyzed redox-neutral ß-functionalization of pyrrolidines with isatins. Under transition-metal- and oxidant-free conditions at ambient temperature, a series of pyrrolidines bearing a functionalized exocyclic alkene are accessed in high efficiency through a borrowing hydrogen process. A simple switch to higher reaction temperature in a one-pot procedure also provides access to a diverse array of C(3)-functionalized pyrroles while liberating water and hydrogen gas as the only byproducts.

A Leucine Aminopeptidase-Activated Theranostic Prodrug for Cancer Diagnosis and Chemotherapy.

Currently, chemotherapy is a widely used and important treatment for cancer. However, almost all of the treatments have shortcomings associated with poor specificity and high toxicity, which results in severe side effects to normal cells and tissue. This is a very important problem, and yet, it currently remains unanswered. Therefore, the development of the method for the more effective delivery of anticancer drugs to their targets and real-time monitoring of the localization of the drugs are very important. Herein, we designed a theranostic prodrug: CPT-p-Leu, which was constructed using fluorescent camptothecin (CPT), a self-immolative linker and leucine (Leu) residue. Upon exposure to LAP (leucine aminopeptidase: LAP), the amide bond in CPT-p-Leu will be cleaved, followed by an intramolecular 1,6-elimination, which triggers the active anticancer drug (CPT) release and recovers the fluorescence of CPT. With our design, the anticancer drug, CPT, can be used as both a drug and a fluorescence reporter, making our system suitable to accurately and effectively track the released CPT distribution. Based on this strategy, CPT-p-Leu could achieve the chemoselective detection of LAP and monitoring of the anticancer drug release. Furthermore, it also provides a very convenient way to accurately determine the location of the released drug in living samples. In addition, CPT-p-Leu shows a good cell membrane permeability and enhanced cytotoxicity toward LAP overexpressing cancer cells. We anticipate that our research will facilitate the development of improved theranostic systems for cancer therapy.

B(C6F5)3-Catalyzed redox-neutral ß-alkylation of tertiary amines using p-quinone methides via borrowing hydrogen.

Herein, we present the first example of catalytic redox-neutral ß-functionalization of tertiary amines through a borrowing hydrogen process. This B(C6F5)3-catalyzed procedure utilizes commercially or readily available catalysts and substrates and promotes a direct functionalization of the C(sp3)-H bond at the ß-position of acyclic tertiary amines through conjugate addition to para-quinone methides. Compared to previous work on direct ß-functionalization of tertiary amines under oxidative conditions, besides being metal-free, the significant advantage of this method is that neither stoichiometric oxidants nor reductants are needed which may otherwise generate unnecessary waste.

Traceless synthesis of 3-N-substituted-2-thioxoquinazoline-4-ones on a soluble polymeric support.

The synthesis of 3-N-substituted-2-thioxoquinazoline-4-ones is described with a traceless linker strategy using poly(ethylene glycol) (PEG) as a soluble polymeric support. Staudinger-Aza-Wittig reaction of PEG-supported azide with Ph(3)P and CS(2) gave the corresponding PEG-supported phenyl isothiocyanate. Treatment of the phenyl isothiocyanate with different primary amines led, via intramolecular cyclization and simultaneous cleavage from PEG, to 2-thioxoquinazoline-4-ones with of moderate to excellent yields.

(S)-1-[(S)-4-Benzyl-2-thioxothia-zolidin-3-yl]-3-hydroxy-butan-1-one.

The title compound, C(14)H(17)NO(2)S(2), was synthesized by asymmetric aldol condensation of N-acyl-thia-zolidinethione with acetaldehyde. In the mol-ecule, the thia-zolidine five-membered ring assumes an envelope conformation. Inter-molecular C-H⋯O and intra-molecular O-H⋯O and C-H⋯S hydrogen bonding helps to stabilize the structure.

Novel synthesis of N(4)-substituted 1,4-benzodiazepine-2,5-diones using poly(ethylene glycol) as soluble polymer support.

An efficient method for the liquid-phase combinatorial synthesis of N4-substituted 1,4-benzodiazepine-2,5-diones has been developed. Poly(ethylene glycol) (PEG) stepwise reacted with bromoacetyl bromide, a primary amine and 2-azidobenzoic acid to give a potential PEG-bound dipeptide, which was reduced by NaI / acetic acid, along with concurrent cyclization and cleavage of the seven-membered heterocycle from the PEG support.

Green synthesis of tetrahydrobenzo[b]Pyrans by microwave assisted multi-component one-pot reactions in PEG-400.

Polyethylene glycol is found to be a nontoxic and recyclable reaction medium for the microwave-assisted, multi-component one-pot reactions of aromatic aldehydes with ethyl-2-cyanoacetate and 1,3-cyclohexanedione or 5,5- dimethyl-1,3-cyclohexanedione in the presence of piperidine. This environmentally friendly microwave protocol offers ease of operation and enables recyclability of reaction medium and synthesis of a variety of substituted tetrahydrobenzo[b]pyran derivatives. It is an efficient, promising, and green synthetic strategy to construct tetrahydrobenzo[b]pyran skeleton.

Synthesis of a library of benzoindolizines using poly(ethylene glycol) as soluble support.

A library of benzoindolizines (pyrrolo [1,5-a] quinolines 10 and pyrrolo [1,5-a] quinolines 9) has been synthesized using poly(ethylene glycol) (PEG) as soluble polymer support. The PEG-supported isoquinolinium salt 4 reacted, respectively, with active alkenes 11 using tetrakispyridinecobalt(II) dichromate (TPCD) as oxidant or alkynes 12 to give 10, of which yields were from moderate to high. By analogy, the reaction of PEG-supported quinolinium salt 3 with 12 was to produce 9. However, in the presence of TPCD the reaction of 3 with 11 afforded indolizines 8, which was discovered firstly.