Complementary Strategy Enhancing Broad-Specificity for Multiplexed Immunoassay of Adulterant Sulfonylureas in Functional Food.

Sulfonylureas, a family of anti-diabetic drugs widely used in the clinical treatment of type 2 diabetes, have recently emerged as an illegal adulterant in functional foods, to enhance the claimed anti-diabetic activity. To establish a screening assay method against their adulteration, with the aid of molecular simulation of hapten, two antibodies were raised and complementarily used to enhance the broad-specificity of an enzyme-linked immunosorbent assay (ELISA), which demonstrated simultaneous detection capability to 6 sulfonylureas; the detection limits ranged from 0.02 to 1.0 ng/mL, and recoveries were between 78.3% to 104.5%. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) confirmed the reliability of the proposed ELISA, based on real samples. These results suggest that the proposed ELISA could be an ideal method for screening to monitor for illicit adulteration of sulfonylureas in functional pill products.

A ratiometric fluorescent probe for sensitive determination of the important glycopeptide antibiotic vancomycin.

A novel sensitive and selective probe for the important antibiotic vancomycin (Van) has been synthesized by integrating a coumarin and a fluorescein as dual fluorescence reporters and a Van binding peptide D-Ala-D-Ala. Only weak green fluorescence was initially observed, which was mostly attributed to fluorescence self-quenching induced by fluorophore stacking. Upon the binding of Van with the D-Ala-D-Ala peptide, the fluorescence turned on, probably due the disaggregation of fluorophores. The intensity ratio of the dual emission bands I519/I446 exhibited an excellent linear relationship with the concentration of Van increasing from 0-20 µM in synthetic urine. The lowest detection limit was calculated to be 92.8 nM in urine, which made the probe applicable in clinically relevant concentration ranges. The synthetic probe has also shown the potential for Van detection in human serum. More interestingly, this probe has been successfully applied for in vivo imaging of Van in zebrafish. Graphical Abstract.

Three Pairs of New Spirocyclic Alkaloid Enantiomers From the Marine-Derived Fungus Eurotium sp. SCSIO F452.

Three pairs of new spirocyclic alkaloid enantiomers eurotinoids A-C (1-3), as well as a known biogenetically related racemate dihydrocryptoechinulin D (4) were isolated from a marine-derived fungus Eurotium sp. SCSIO F452. Their structures were determined by spectroscopic analyses and electronic circular dichroism (ECD) calculations. Compounds 1 and 2 represent the first two "meta" products from a non-stereoselective [4 + 2] Diels-Alder cycloaddition presumably between an enone group of a diketopiperazine alkaloid and a diene group of a benzaldehyde derivative via a new head-to-tail coupling mode biosynthetically, while 3 and 4 were "ortho" products. Their enantiomers exhibited different antioxidative and cytotoxic activities. The modes of action were investigated by a preliminary molecular docking study.

Variecolortins A-C, Three Pairs of Spirocyclic Diketopiperazine Enantiomers from the Marine-Derived Fungus Eurotium sp. SCSIO F452.

Three pairs of spirocyclic diketopiperazine enantiomers, variecolortins A-C (1-3), were isolated from marine-derived fungus Eurotium sp. SCSIO F452. Compound 1 possesses an unprecedented highly functionalized seco-anthronopyranoid carbon skeleton featuring a 2-oxa-7-azabicyclo[3.2.1]octane core. Compounds 2 and 3 represent rare examples of a 6/6/6/6 tetracyclic cyclohexene-anthrone carbon scaffold. Their structures were determined by spectroscopic analyses, X-ray diffraction, and ECD calculations. Their enantiomers exhibited different antioxidative and cytotoxic activities, and their modes of action were investigated.