Maxis esi q tof

After a 72-h incubation of A. niger RAF106 in SDB with 2 μg/mL AFB1, the metabolites were extracted with chloroform as described above and separated using an Agilent 1260 series HPLC system equipped with an auto-injector and quaternary HPLC pump (Agilent Technologies, Santa Clara, CA, USA) [38 (link),46 (link),49 (link)]. The chromatography was conducted on a Phenomenex Luna 5u C18(2)100A column (250 × 4.60 mm, 5 μm) (Torrance, CA, USA). Samples (10 μL) were injected and eluted with the mobile solvent that contained 45:55 of methanol and water (v/v) with 0.1% formic acid. The total run time was 30 min with a flow rate of 0.5 mL/min. An MS analysis was performed with a Bruker maXis ESI Q-TOF (Bruker Daltonik, Bremen, Germany). The acquisition parameters were as follows: the capillary voltage was set at 4.5 kV in the positive ionization mode and the dry temperature was 180 °C. The drying gas flowed at 5.0 L/min and the nebulizer was at 0.8 bar. The MS was operated in full scan mode, and the data were collected within the range of m/z 100–2000. Samples extracted from SDB with 2 μg/mL AFB1 were used as the positive control and samples extracted from SDB and cultures of A. niger RAF106 in SDB were used as the negative control.

Preparation of the ligands is described in Electronic Supporting Information, Part S1. All reagents were purchased from commercial sources and were used as received. ¹H and ¹H-¹H COSY NMR spectra were recorded on a Bruker Avance 400 MHz instrument. Chemical shifts are reported in parts per million (ppm) and referenced to residual peaks of deuterated solvents (Acetone-d₆ (2.05 ppm), or DMSO-d₆ (2.50 ppm)). High-resolution mass spectra (HRMS) were measured on a Bruker Daltonik MaXis ESIQTOF instrument in the ESI⁺ mode. Microanalyses were carried out by using Euro EA3028-HT.

Melting point determination was performed on a PTP-M apparatus (Khimlabpribor, Klin, Russia). The infrared (IR) spectrum was recorded in CHCl₃ on a Specord 75IR spectrometer (Analytik Jena, Jena, Germany) and the ultraviolet (UV) spectrum was recorded in EtOH on a Beckman Coulter DU 800 spectrometer (Beckman Coulter Inc., Brea, CA, USA). ¹H and ¹³C nuclear magnetic resonance (NMR) spectra were recorded on a Varian DirectDrive NMR System (Varian, Palo Aho, CA, USA) in CDCl₃ at 700 and/or 175.8 MHz. CDCl₃ was used as an internal standard. Mass spectrometry with electrospray ionization MS (ESI) was performed using LC-MS high-resolution spectrometer MaXis (ESI-QTOF) (Bruker Corporation, Billerica, MA, USA), with direct injections of sample solutions into the ionization chamber. X-ray diffraction was measured on Kappa Apex II device (Bruker Corporation, Billerica, MA, USA) by use of CuKα radiation (λ = 1.54178 Å). Intensity of reflexes was integrated and scaled by means of the Saint and Sadabs programs from an Apex II package (Bruker AXS Inc., Madison, WI, USA). All subsequent procedures for the decision and specification of the compound structure were held in the software package of Olex2 (https://www.olexsys.org/olex2/, accessed on 1 January 2020) [44 (link)].