Isolation and Biological Evaluation of Alfa-Mangostin as Potential Therapeutic Agents against Liver Fibrosis.

The increased proliferation and activation of hepatic stellate cells (HSCs) are associated with liver fibrosis development. To date, there are no FDA-approved drugs for the treatment of liver cirrhosis. Augmentation of HSCs apoptosis is one of the resolutions for liver fibrosis. In this study, we extracted α-mangostin (1,3,6-trihydroxy-7-methoxy-2,8-bis(3-methyl-2-butenyl)-9H-xanthen-9-one) from the fruit waste components of mangosteen pericarp. The isolated α-mangostin structure was determined and characterized with nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS) and compared with those known compounds. The intracellular signaling pathway activities of α-mangostin on Transforming growth factors-beta 1 (TGF-ß1) or Platelet-derived growth factor subunit B (PDGF-BB) induced HSCs activation and were analyzed via Western blot and Real-time Quantitative Polymerase Chain Reaction (Q-PCR). α-Mangostin-induced mitochondrial dysfunction and apoptosis in HSCs were measured by seahorse assay and caspase-dependent cleavage. The in vivo anti-fibrotic effect of α-mangostin was assessed by carbon tetrachloride (CCl4) treatment mouse model. The data showed that α-mangostin treatment inhibited TGF-ß1-induced Smad2/3 phosphorylation and alpha-smooth muscle actin (α-SMA) expression in HSCs in a dose-dependent manner. Regarding the PDGF-BB-induced HSCs proliferation signaling pathways, α-mangostin pretreatment suppressed the phosphorylation of extracellular-signal-regulated kinase (ERK) and p38. The activation of caspase-dependent apoptosis and dysfunction of mitochondrial respiration (such as oxygen consumption rate, ATP production, and maximal respiratory capacity) were observed in α-mangostin-treated HSCs. The CCl4-induced liver fibrosis mouse model showed that the administration of α-mangostin significantly decreased the expression of the fibrosis markers (α-SMA, collagen-a2 (col1a2), desmin and matrix metalloproteinase-2 (MMP-2)) as well as attenuated hepatic collagen deposition and liver damage. In conclusion, this study demonstrates that α-mangostin attenuates the progression of liver fibrosis through inhibiting the proliferation of HSCs and triggering apoptosis signals. Thus, α-mangostin may be used as a potential novel therapeutic agent against liver fibrosis.

Infrared Spectra of (Z)- and (E)-•C2H3C(CH3)I Radicals Produced upon Photodissociation of (Z)- and (E)-(CH2I)HC═C(CH3)I in Solid para-Hydrogen.

Ozonolysis of isoprene to produce Criegee intermediates such as methyl vinyl ketone oxide (MVKO), C2H3C(CH3)OO, is an important process in atmospheric chemistry. MVKO was recently produced and identified in laboratories after photolysis of a gaseous mixture of 1,3-diiodo-but-2-ene, (CH2I)HC═C(CH3)I, and O2, but the mechanism of its formation remains unexplored. We synthesized pure (Z)- and (E)-1,3-diiodo-but-2-ene and measured their distinct IR spectra. Upon irradiation at 280 nm of (Z)- and (E)-1,3-diiodo-but-2-ene in solid p-H2 at 3.3 K, the fission of the terminal C-I bond yields (Z)- and (E)-3-iodo-but-2-en-1-yl [•C2H3C(CH3)I] radicals, respectively. These radicals were characterized with infrared absorption lines at 2962.4, 1423.8, 1265.3, 1120.9/1127.0, 921.4/922.3, and 792.5/791.7 cm-1, and 16 additional weaker lines for (Z)-•C2H3C(CH3)I and 1405.2, 1208.2, 1106.0/1103.9, 934.2/933.4, and 785.1/784.9 cm-1 and five additional weaker ones for (E)-•C2H3C(CH3)I. The assignments were derived according to behavior on secondary photolysis and comparison of the vibrational wavenumbers and the IR intensities of observed lines with those calculated with the B2PLYP-D3/aug-cc-pVTZ-pp method. These observations confirmed that only the terminal I atom, not the central one, was photodissociated at 280 nm and, in solid p-H2, the excess energy after photodissociation induced no change in conformation. These new spectra of •C2H3C(CH3)I radicals can provide valuable information for the understanding of the mechanism of formation of Criegee intermediate MVKO from the source reaction of photolysis of (CH2I)HC═C(CH3)I in O2 in the laboratory.

Linker and N-Terminal Domain Engineering of Pyrrolysyl-tRNA Synthetase for Substrate Range Shifting and Activity Enhancement.

The Methanosarcina mazei pyrrolysyl-tRNA synthetase (PylRS)⋅tRNAPyl pair can be used to incorporate non-canonical amino acids (ncAAs) into proteins at installed amber stop codons. Although engineering of the PylRS active site generates diverse binding pockets, the substrate ranges are found similar in charging lysine and phenylalanine analogs. To expand the diversity of the ncAA side chains that can be incorporated via the PylRS⋅tRNAPyl pair, exploring remote interactions beyond the active site is an emerging approach in expanding the genetic code research. In this work, remote interactions between tRNAPyl, the tRNA binding domain of PylRS, and/or an introduced non-structured linker between the N- and C-terminus of PylRS were studied. The substrate range of the PylRS⋅tRNAPyl pair was visualized by producing sfGFP-UAG gene products, which also indicated amber suppression efficiencies and substrate specificity. The unstructured loop linking the N-terminal and C-terminal domains (CTDs) of PylRS has been suggested to regulate the interaction between PylRS and tRNAPyl. In exploring the detailed role of the loop region, different lengths of the linker were inserted into the junction between the N-terminal and the C-terminal domains of PylRS to unearth the impact on remote effects. Our findings suggest that the insertion of a moderate-length linker tunes the interface between PylRS and tRNAPyl and subsequently leads to improved suppression efficiencies. The suppression activity and the substrate specificity of PylRS were altered by introducing three mutations at or near the N-terminal domain of PylRS (N-PylRS). Using a N-PylRS⋅tRNAPyl pair, three ncAA substrates, two S-benzyl cysteine and a histidine analog, were incorporated into the protein site specifically.

Effective Construction of a High-Capacity Boronic Acid Layer on a Quartz Crystal Microbalance Chip for High-Density Antibody Immobilization.

Boronic acids (BAs) provide strong potential in orientation immobilization of antibody and the modification method is crucial for efficiency optimization. A highly effective method has been developed for rapid antibody immobilization on gold electrodes through the electrodeposition of a BA⁻containing linker in this study. Aniline-based BA forms a condense layer while antibody could automatically immobilize on the surface of the electrode. Compare to traditional self-assembled monolayer method, the electrodeposition process dramatically reduces the modification time from days to seconds. It also enhances the immobilized efficiency from 95 to 408 (ng/cm²) with a strong preference being exhibited for shorter aniline-based linkers.

Silicon Quantum Dot Nanoparticles with Antifouling Coatings for Immunostaining on Live Cancer Cells.

Fluorescent silicon quantum dots (SiQDs) have shown a great potential as antiphotobleaching, nontoxic and biodegradable labels for various in vitro and in vivo applications. However, fabricating SiQDs with high water-solubility and high photoluminescence quantum yield (PLQY) remains a challenge. Furthermore, for targeted imaging, their surface chemistry has to be capable of conjugating to antibodies, as well as sufficiently antifouling. Herein, antibody-conjugated SiQD nanoparticles (SiQD-NPs) with antifouling coatings composed of bovine serum albumin (BSA) and polyethylene glycol (PEG) are demonstrated for immunostaining on live cancer cells. The monodisperse SiQD-NPs of diameter about 130 nm are synthesized by a novel top-down method, including electrochemical etching, photochemical hydrosilylation, high energy ball milling, and "selective-etching" in HNO3 and HF. Subsequently, the BSA and PEG are covalently grafted on to the SiQD-NP surface through presynthesized chemical linkers, resulting in a stable, hydrophilic, and antifouling organic capping layer with isothiocyanates as the terminal functional groups for facile conjugation to the antibodies. The in vitro cell viability assay reveals that the BSA-coated SiQD-NPs had exceptional biocompatibility, with minimal cytotoxicity at concentration up to 1600 µg mL(-1). Under 365 nm excitation, the SiQD-NP colloid emits bright reddish photoluminescence with PLQY = 45-55% in organic solvent and 5-10% in aqueous buffer. Finally, through confocal fluorescent imaging and flow cytometry analysis, the anti-HER2 conjugated SiQD-NPs show obvious specific binding to the HER2-overexpressing SKOV3 cells and negligible nonspecific binding to the HER2-nonexpressing CHO cells. Under similar experimental conditions, the immunofluorescence results obtained with the SiQD-NPs are comparable to those using conventional fluorescein isothiocyanate (FITC).

Free radical reaction between 2-benzoyl-1,4-benzoquinones and 1,3-dicarbonyl compounds.

A manganese(III)-mediated reaction between 2-benzoyl-1,4-benzoquinones and 1,3-dicarbonyl compounds that produces benzo[c]furan-4,7-diones and anthracene-1,4-diones with high chemoselectivity is described. With ethyl butyrylacetate, by changing the solvent, benzo[c]furan-4,7-diones and anthracene-1,4-diones can be generated in high chemoselectivities. With ethyl benzoylacetate, N ,N-dimethyl acetoacetamide and 1,3-diones, benzo[c]furan-4,7-diones were produced effectively with high selectivity. With 2-alkyl-5-benzoyl-1,4-benzoquinones, the regioselectivity of this reaction was also studied and the corresponding benzo[c]furan-4,7-dione and anthracene-1,4-dione derivatives were obtained in high regioselectivity.