Latest ArticlesFused indolizidines and quinolizidines are important skeletons in a variety of natural products and pharmacologically important compounds. A one-pot tandem route from amide to fused indolizidines and quinolizidines is disclosed. This method is conducted in mild conditions and shows well tolerance of functional groups. It is also easy to be scaled up to gram scale and can be applied smoothly to the total synthesis of alkaloids such as (±)-crispine A, (±)-xylopinine, (±)-desbromoarborescidine A, (±)-harmicine and other bioactive substances.
A Zn-containing graphite carbon (Zn-GC) with uniform Zn metal sites and hierarchical pore structure was obtained by pyrolysis of Zn-based metal organic framework (MOF). Zn-GC exhibited excellent adsorption capacity and reproducibility for formaldehyde. The adsorption capacity of Zn-GC was 736 times that of commercial activated carbon and 5.6 times that of ZSM-5 adsorbents. The characterization and experimental results showed that the surface chemical characteristics of the adsorption material play an important role in the adsorption performance. The superior performance was attributed to Zn metal sites and oxygen-containing functional groups on the MOF derivative as well as hierarchical pore structure. The material showed a great potential in the field of organic pollutant removal.
The stimulator of interferon genes (STING) shows promising clinical activity in infectious diseases and tumors. However, the lack of targeting capability and intracellular stability of STING agonists severely limits the therapeutic efficacy. Recently, drug delivery systems (DDSs) overcome these delivery barriers of STING agonists via passive or active cell targeting, prolonged blood circulation and drug release, and lysosome escape, etc. In this review, we will describe in detail how existing DDSs are designed to overcome delivery barriers and activate the STING pathway, and the current biomedical applications of STING-activating DDSs in the treatments of infectious diseases and tumors. Finally, the prospects and challenges of DDSs in STING activation are discussed.
Autophagy plays a vital role in maintaining the balance of normal physiological state of living cells. In this paper, a polarity-specific two-photon fluorescent probe Lyso-NA based on naphthalimide was synthesized for the purpose of monitoring autophagy during biological research. The results of photophysical properties and theoretical calculation confirmed that different polarities of solvents mainly effected fluorescent intensities of probe. Fluorescent intensity, quantum yield and fluorescence lifetime of probe kept a good linear relationship with polarity respectively. In addition, due to its low toxicity and selective accumulation in lysosomes, Lyso-NA is suitable for detecting changes in lysosomal polarity of living cells. Compare with the imaging results of plasmid transfection, a better performed real-time long-term fluorescent visualization of autophagy in living cells was achieved. Probe Lyso-NA can work as an efficient and cost effective imaging tool for visualizing autophagy in living cells.
A pair of neolignan enantiomers with an unprecedented carbon skeleton, (+)-/(—)-angelignanine [(+)-/(—)-1], was isolated as minor components of an aqueous extract of the Angelica sinensis root heads (guitou). Their structures were determined by spectroscopic data analysis and the absolute configurations were assigned by the circular dichroism (CD) exciton chirality method as well as electronic CD quantum calculations. The enantiomers represent the first 2, 7'-cyclo-8, 9'-neolignans, of which biosynthetic pathways originating from precursors ferulic acid and coniferyl alcohol is proposed. In an in vivo test, both the enantiomers showed significant hypnotic effects at a dose of 10 mg/kg (i.g.).
A green tandem reaction, including insertion/aerobic oxidation/bisindolylation, starting from indoles and diazo compounds has been developed. The combination of water and fluorinated alcohol plays dual roles as solvent and promoter in this chemical transformation. Molecular oxygen in the air acts as an oxidant. 3, 3'-Bis(indolyl)methanes with quaternary carbon were produced under metal-free conditions. No any catalyst and additive were required. N2 and water were released as sole by-products. Absence of water and fluorinated alcohol resulted in Wolff rearrangement product.
Recently, stimuli-responsive DNA nanostructure-based nanodevices have been applied for cancer therapy. In this study, pH-responsive i-motif DNA was modified on gold nanoparticles (AuNPs) via a facile, time-saving freeze-thaw method and utilized to construct stimuli-responsive drug nanocarriers. When the environment pH changes from 7.4 to 5.0, the i-motif DNA would be folded into four-stranded (C-quadruplex) that could be characterized by circular dichroism, and the characteristic of acid stimulate was verified by fluorescence resonance energy transfer (FRET). To enhance specifical cellular uptake, MUC1 aptamer was employed as the targeting moiety. Doxorubicin (Dox) is an anticancer drug that can be efficiently intercalated into GC base pairs of DNA nanostructure to form drug-loaded nanovehicles (Dox@AuNP-MUC1). Additionally, owing to the excellent photothermal conversion efficiency of AuNPs, the synergistic effect between chemotherapy and PTT can be readily achieved by 808 nm near-infrared (NIR) irradiation, which exhibits specifically and efficiently anticancer efficiency. Hence, this multifunctional drug carrier shows the potential for synergistic photothermal-chemotherapy.
Particles administrated intravenously will pass through the pulmonary capillary network before being distributed to the body. Therefore, fabrication of vectors sensitive to blood shear and active with blood components should be a practical approach to develop lung-targeting gene carriers self-regulated by circulatory system. In this work, we designed a series of cationic peptides with the same charge density but varying hydrophobicity and capacity to form hydrogen bonds, and investigated their ability to form complexes with siRNA, the behaviours of peptide/siRNA complexes in the presence of serum under shear, and the lung-targeting efficacy of the complexes regulated by blood. The hydrophobic interaction controls the complexation between peptide and siRNA, while the hydrogen bonds are responsible for the binding of peptides to the serum components in blood. In vivo tests show that all the peptide/siRNA complexes can accumulate in lung. However, only the complexes that exhibit weak interaction with serum components and can be broken down by shear avoid the inflammation and death caused by pulmonary embolism. Moreover, the peptide with strong hydrophobicity can retain siRNA in lung without early release of the cargo. Our study provides a step toward the development of adaptive gene carriers under the regulation of circulatory system.
The reactive oxygen species (ROS) are tightly associated with endoplasmic reticulum (ER) stress. Thus, the deep and visual insight of aberrant ROS fluctuations in the ER can help us better investigate the ER stress-associated pathology. In this work, a fluorescent probe ERC for HOCl detection in the ER based on phenothiazine-derived coumarin platform was developed. In the presence of HOCl, ERC exhibited an emission change from 609 nm to 503 nm within seconds. It also showed high sensitivity (0.44 μmol/L) and superb photostability. Significantly, ERC displayed low cytotoxicity, good cell membrane permeability, and appreciable ER-targetability. Ultimately, the probe was successfully utilized to image exogenous and endogenous HOCl in living cells and reveal the HOCl burst in cisplatin-treated cancer cells.
An unprecedented tunable hydrophobic effect in self-assembly of a small cationic organic fluorophore (NI-TPy+)-based with aggregation-induced emission (AIE) property was realized in aqueous solution. The amplification of hydrophobicity was found to be significantly dependent upon the increasing aggregates of NI-TPy+, which enabled the study of the hydrophobic binding of chaotropic anions with the Hofmeister series.
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