Synthesis of Spiro[5.5]trienones- and Spiro[4.5]trienones-Fused Selenocyanates via Electrophilic Selenocyanogen Cyclization and Dearomative Spirocyclization.

A practical strategy for the synthesis of spiro[5.5]trienones-fused selenocyanates and spiro[4.5]trienones-fused selenocyanates through electrophilic selenocyanogen cyclization and dearomative spirocyclization is reported. This approach was conducted under mild conditions with broad substrate scope and good functional group tolerance. The utility of this procedure is exhibited in the late-stage functionalization of nature product and drug molecules.

N-Trifluoromethylselenophthalimide, an Electrophilic Trifluoromethylselenolation Reagent and Its Application for the Synthesis of 4-Trifluoromethylselenolated Isoxazoles.

A new electrophilic trifluoromethylselenolation reagent, N-trifluoromethylselenophthalimide (Phth-SeCF3), was developed. A strategy for the synthesis of 4-trifluoromethylselenolated isoxazoles through electrophilic trifluoromethylselenolation cyclization has been established by using Phth-SeCF3 as an electrophilic reagent. Moreover, this protocol has the features of broad substrate scope, good functional group tolerance, and high yields.

WhiB4 Regulates the PE/PPE Gene Family and is Essential for Virulence of Mycobacterium marinum.

During the course of infection, pathogenic mycobacteria including Mycobacterium tuberculosis (M. tb) encounter host environments of variable oxygen tension, ranging from the hypoxic center of granulomas to the most oxygenated region in the lung cavities. Mycobacterial responses to changes of oxygen tension are critically related to infection outcomes, such as latency and reactivation. WhiB4 is an iron-sulfur containing transcription factor that is highly sensitive to oxygen exposure. In this study, we found that WhiB4 of Mycobacterium marinum (M. marinum), a pathogenic mycobacterial species that is closely related to M. tb, is required for its virulence. M. marinum ΔwhiB4 exhibited defective intracellular replication in macrophages and diminished virulence in zebrafish. Histology analysis revealed that the host had successfully controlled ΔwhiB4 bacteria, forming well-organized granulomas. RNA-seq analysis identified a large number of pe/ppe genes that were regulated by WhiB4, which provides an explanation for the essential role of WhiB4 in M. marinum virulence. Several antioxidant enzymes were also upregulated in ΔwhiB4, supporting its role in modulation of oxidative stress response. Taken together, we have provided new insight into and proposed a model to explain the physiological role of WhiB4.

Immunogenicity and Protective Efficacy of a Fusion Protein Tuberculosis Vaccine Combining Five Esx Family Proteins.

One strategy to develop the next generation of tuberculosis vaccines is to construct subunit vaccines based on T cell antigens. In this study, we have evaluated the vaccine potential of a fusion protein combining EsxB, EsxD, EsxG, EsxU, and EsxM of Mycobacterium tuberculosis (M. tb). This recombinant protein, named BM, was expressed in and purified from Escherichia coli. Immunization of C57BL/6 mice with purified BM protein formulated in Freund's incomplete adjuvant induced the production of Th1 cytokines (IFN-γ, TNF, and IL-2) and multifunctional CD4+ T cells. Vaccination of BALB/c mice with BM protein followed by intravenous challenge with Mycobacterium bovis BCG resulted in better levels of protection than the two leading antigens, Ag85A and PPE18. Taken together, these results indicate that BM is a protective antigen. Future studies to combine BM with other antigens and evaluate its effectiveness as a booster of BCG or as a therapeutic vaccine are warranted.

Structure characterization of proanthocyanidins from Caryota ochlandra Hance and their bioactivities.

Proanthocyanidins (PAs) from Caryota ochlandra fruit pericarp and fruit flesh were characterized by (13)C nuclear magnetic resonance, high performance liquid chromatography-electrospray ionization mass spectrometry, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry techniques. The fruit pericarp and flesh PAs were complex mixtures of homo- and heteropolymers of B-type procyanidins and prodelphinidins both with degrees of polymerization up to dodecamer. Their antioxidant and antityrosinase activities were investigated. The fruit pericarp PAs exhibited potent antioxidant activity with IC50 values of 142.86 ± 1.53 and 80.51 ± 0.4 µg/ml for DPPH and ABTS free-radical scavenging assays; with FRAP value of 373.09 ± 5.02 mg ascorbic acid equivalent/g dry weight. Furthermore, the fruit pericarp PAs had antityrosinase activity while the fruit flesh PAs could be oxidized by tyrosinase. The structure and antioxidant activities of the C. ochlandra fruit PAs together with their effects on tyrosinase activity would lay scientific foundation for their utilization in food and nutrition industry.

Structure characterization and anti-tyrosinase mechanism of polymeric proanthocyanidins fractionated from kiwifruit pericarp.

To provide information on the structure, activity, and structure-activity relationship of kiwifruit (Actinidia chinensis) pericarp proanthocyanidins (PAs), they were separated into three fractions. These fractions were further identified by MALDI-TOF MS and HPLC-ESI-MS methods. Spectra results revealed that they are complex mixtures of B-type propelargonidins, procyanidins, procyanidins gallate, and prodelphinidins. Enzymatic activity analysis showed that these compounds strongly inhibit the activity of tyrosinase, indicating that they are reversible and mixed-type inhibitors of the enzyme. The results obtained from fluorescence quenching showed PAs inhibit the enzyme activity by interacting with substrate and enzyme. This study confirmed that the mean degree of polymerization (mDP) of PAs produces a positive effect on their anti-tyrosinase activity. In addition, the antioxidant analysis indicated that PAs possess potent antioxidant activity. These conclusions mean kiwifruit pericarp PAs may be explored as insecticides, food preservatives, and cosmetic additives.

Reversible and competitive inhibitory kinetics of amoxicillin on mushroom tyrosinase.

In the present work, we investigated the inhibitory effects of amoxicillin, a bacteriolytic ß-lactam antibiotic drug, on the rate of monophenol hydroxylation and o-diphenol oxidation catalyzed by mushroom tyrosinase. The results showed that amoxicillin could inhibit both monophenolase and diphenolase activities. For monophenolase activity, the inhibition on reaction rate was dose-dependent, while the influence on lag period was not obvious. For diphenolase activity, amoxicillin was found to be a reversible inhibitor, with an IC50 value of 9.0 ± 1.8 mM. Kinetics analysis showed that amoxicillin was a mixed type inhibitor of the enzyme with KI and KIS values of 8.30 mM and 44.79 mM, respectively. Further, the molecular mechanism underlying the inhibition of tyrosinse by amoxicillin was investigated by means of fluorescence quenching and molecular docking techniques. The results showed that amoxicillin could form static interaction with the catalytic pocket of the enzyme through the interaction of amoxicillin with the dicopper irons and amino acid residues in the enzyme active center. Our results contributed to the usage of amoxicillin as a potential tyrosinase inhibitor in the field of medicinal industry and could also provide guidance in the design of novel tyrosinase inhibitors.