A novel ratiometric fluorescent probe for the detection of uric acid in human blood based on H2O2-mediated fluorescence quenching of gold/silver nanoclusters.

In this work, a ratiometric fluorescent probe (RF-probe) for highly sensitive and selective detection of uric acid was reported for the first time toward H2O2 based on inner filter effect (IFE) between bimetallic gold/silver nanoclusters (Au/Ag NCs) and 2,3-diaminophenazine (DAP). For this RF-probe, uric acid was degraded to allantoin and H2O2. Upon the addition of HRP, o-phenylenediamine (OPD) could be catalytically oxidized to DAP in the presence of H2O2, then the fluorescence intensity corresponding to DAP at 580 nm increased dramatically with a fluorescence quenching of BSA-Au/Ag NCs at 690 nm, resulting in a RF-probe toward uric acid. This RF-probe allowed for the sensitive detection of uric acid in range of 5.0 × 10-6 M to 5.0 × 10-5 M with a detection limit (S/N = 3) as low as 5.1 × 10-6 M. At the same time, it has been successfully used for uric acid levels detection in human serum, and the results are consistent with those of the hospital. RF-probe built may provide a ratiometric fluorescence universal platform for detection of various species involving in the production of H2O2 in other biological systems.

Photocatalytic properties of zinc sulfide nanocrystals biofabricated by metal-reducing bacterium Shewanella oneidensis MR-1.

Accumulation and utilization of heavy metals from wastewater by biological treatment system has aroused great interest. In the present study, a metal-reducing bacterium Shewanella oneidensis MR-1 was used to explore the biofabrication of ZnS nanocrystals from the artificial wastewater. The biogenic H2S produced via the reduction of thiosulfate precipitated the Zn(II) as sulfide extracellularly. Characterization by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and field emission scanning electron microscope (FESEM) confirmed the precipitates as ZnS nanocrystals. The biogenic ZnS nanocrystals appeared spherical in shape with an average diameter of 5 nm and mainly aggregated in the medium and cell surface of S. oneidensis MR-1. UV-vis DRS spectra showed ZnS nanoparticles appeared a strong absorption below 360 nm. Thus, the photocatalytic activity of ZnS was evaluated by the photodegradation of rhodamine B (RhB) under UV irradiation. The biogenic ZnS nanocrystals showed a high level of photodegradation efficiency to RhB coupled with a significant blue-shift of maximum adsorption peak. A detailed analysis indicated the photogenerated holes, rather than hydroxyl radicals, contributed to the photocatalytic decolorization of RhB. This approach of coupling biosynthesis of nanoparticles with heavy metal removal may offer a potential avenue for efficient bioremediation of heavy metal wastewater.

A new briarane-type diterpenoid from the South China Sea Gorgonian Dichotella gemmacea.

One new briarane-type diterpenoid, dichotellide V (1), along with four known analogues, gemmacolide N (2), dichotellide J (3), junceelin A (4) and junceellolide A (5), was isolated from the South China Sea gorgonian Dichotella gemmacea. All of the isolated compounds (1-5) were established by comprehensive analysis of the spectral data, especially 1D and 2D NMR (HMQC and HMBC) spectra. The cytotoxic activities of these compounds were evaluated.

Pestalols A-E, new alkenyl phenol and benzaldehyde derivatives from endophytic fungus Pestalotiopsis sp. AcBC2 isolated from the Chinese mangrove plant Aegiceras corniculatum.

Five alkenyl phenol and benzaldehyde derivatives, pestalols A-E (1-5), as well as seven known compounds (6-12), were isolated from endophytic fungus Pestalotiopsis sp. AcBC2 derived from the Chinese mangrove plant Aegiceras corniculatum. Their structures were determined by spectroscopic analyses. Compounds 2 and 3 showed cytotoxicity against a panel of 10 tumor cell lines. Compounds 1-5, 8, 9, 11, and 12 showed inhibitory activities against Influenza A virus subtype (H3N2) and Swine Flu (H1N1) viruses. Compound 2 also showed inhibitory activity against tuberculosis.

[Sterols of marine bryozoan Bugula neritina from the South China Sea].

OBJECTIVE: To study the sterol constituents of Bugula neritina from the South China Sea. METHODS: The alcohol extract of Bugula neritina was purified by silica gel column and Sephadex LH-20 column chromatography, and structures of the isolated compounds were identified by spectroscopic analysis and comparison with those of literatures. RESULTS: Ten sterols were isolated and identified from the petroleum ether fraction of alcohol extract of B. neritina L.:Cholest-4-en-3-one(I); cholesterol(II);3beta,5alpha,9alpha-trihydroxy-(22E,24R)-ergosta-7,22-dien-6-one(III); 24-methyl-5alpha-cholesta-7,22-diene-3beta,5,6beta-triol(IV); 3beta-Hydroxy-7-methoxy-Cholesta-5-en(V);5alpha, 8alpha-epidioxy-(22E,24R)-ergosta-6, 22-dien-3beta-ol(VI); 3beta-hydroxycholest-5-en-7-one (VII); and 6beta-hydroxy-cholest-4-en-3-one(VIII); Cholesta-5-ene-3beta,7beta-diol(IX); Cholesta-5,22(E)-dien-3beta,7alpha-diol(X). CONCLUSION: Compounds IV-X were isolated from Bugula neritina for the first time.

A novel cyclopentene derivative and a polyhydroxylated steroid from a South China Sea gorgonian Menella sp.

A chemical investigation on a South China Sea gorgonian, Menella sp. resulted in the isolation and elucidation of menellin A (1), a highly oxygenated racemate with C(8) skeleton, and a polyhydroxylated steroid, menellsteroid C (2), along with eight known compounds (3-10). The structures of the new compounds were elucidated by means of MS, 1D and 2D NMR spectra, and the relative stereochemistry of 1 was determined by X-ray single-crystal diffraction analysis. In addition, compound 7 was isolated as a new natural product. Compounds 1-3 and 7 were selected to test the anti-inflammatory inhibition against lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 macrophages. 1 and 3 exhibited modest inhibitory effects with IC(50) of 71.3, 33.9 µM, respectively, compared to the positive control aminoguanidine (IC(50) 25.0 µM).

[Study on the chemical constituents qf Spongilla Wagner].

OBJECTIVE: To study the chemical constituents in the fresh marine sponge Spongilla Wagner. METHODS: Compounds were separated and purified through various chromatographic methods and their structures were identified by spectroscopic data. RESULTS: Seven compounds were isolated and identified as 4-hydroxybenzoic acid (I), p-hydroxycinnamic acid (II), Pyrimidine-2, 4 (1H, 3H)-dione (III), Ferulic acid methyl ester (IV), Dodecyl ethers of glycerol (V), Tetracosane( VI). CONCLUSION: All compounds are isolated from this sponge for the first time.