Merck 60 f254 plates

Reagent-grade chemicals
were purchased
from Sigma-Aldrich or Fluorochem and were used without further purification.
All reactions were monitored by thin-layer chromatography (TLC) performed
on silica gel Merck 60 F254 plates; the spots were visualized by UV
light (λ = 254 and 366 nm) and an iodine chamber. Melting points
were determined on a Büchi B-450 apparatus in capillary glass
tubes and are uncorrected. Flash chromatography purification was performed
on a Merck silica gel 60, 0.040–0.063 mm (230–400 mesh)
stationary phase using glass columns with a diameter between 1 and
4 cm. Nuclear magnetic resonance spectra (¹H NMR and ¹³C NMR recorded at 500 and 125 MHz, respectively) were obtained
on Varian INOVA spectrometers using CDCl₃, acetone-d₆, CD₃OD, and DMSO-d₆ with a 0.03% of TMS as an internal standard. Coupling
constants (J) are reported in hertz. Signal multiplicities
are characterized as s (singlet), d (doublet), t (triplet), q (quartet),
m (multiplet), br (broad), and app (apparent). Purities of all compounds
were ≥95% as determined by microanalysis (C, H, and N) that
was performed on a Carlo Erba instrument model E1110; all the results
agreed within ±0.4% of the theoretical values.

Emodin was purchased from Fluorochem Ltd. (Glossop, UK). All other reagents and solvents were of reagent-grade quality and were obtained from commercial suppliers Honeywell (Seelze, Germany) and Sigma-Aldrich (Taufkirchen, Germany). TLC was performed on Merck-60-F₂₅₄ plates (Merck, Darmstadt, Germany) using mixtures of EtOAc:EtOH (10:1), CH₂Cl₂:EtOH (100:1) or EtOAc:MeOH (20:1). Crude Emodin preparations were purified by column chromatography on silica gel (63–200 µm, 70–230 mesh ASTM; Honeywell, Seelze, Germany). The isolated compounds were characterized by ¹H, ¹³C NMR spectra, HRMS and IR analysis. ¹H and ¹³C NMR spectra were recorded on Bruker Avance III 500 instruments (Bruker, Billerica, MA, USA). IR spectra were recorded on Bruker Alpha II FTIR Instrument (Bruker, Billerica, MA, USA). HR-MS were recorded on LC MS system Agilent 6224 Accurate Mass TOF LC/MS (Agilent Technologies, Santa Clara, CA, USA).

Solvents were distilled from appropriate drying agents shortly before use. TLC was carried out on DC-plastikfolien Kieselgel 60 F254 and preparative thick-layer (2 mm) chromatography was performed on Merck 60 F254 plates (Merck KGaA, Darmstadt, Germany). (Merck, Merck KGaA, Darmstadt, Germany). NMR spectra were recorded on AV600 and AV300 MHz spectrometers (Bruker BioSpin GmbH, Rheinstetten, Germany), operating at 150.92 or 75.47 MHz for ¹³C and 600.13 or 300.13 MHz for ¹H nuclei using DMSO-d₆ as the internal standard (labels in the spectra: Trp = tryptophan ring; Pyr = pyrene ring). Mass spectrometry was performed on the Agilent 6410 Triple Quad mass spectrometer (Agilent Technologies, Santa Clara, CA, USA) and high-resolution mass spectra (HRMS) were obtained using a Q-Tof2 hybrid quadrupole time-of-flight mass spectrometer (Micromass, Cary, NC, USA). WHW was purchased from GenScript, Treubstraat 1, 1st floor. 2288EG, Rijswijk, the Netherlands, as a 95% pure white solid (TFA salt). Experimental procedures for preparing known compounds 1, 2 and 8 are given in the Supplementary Information.

Solvents were distilled from appropriate drying agents shortly before use. TLC was carried out on TLC Silica gel 60 F254 Plastic sheets, and preparative thin layer (2 mm) chromatography was done on Merck 60 F254 plates (Merck KGaA, Darmstadt, Germany). NMR spectra were recorded on AV600 and AV300 MHz spectrometers (Bruker BioSpin GmbH, Rheinstetten, Germany), operated at 600.13 or 300.13 MHz for ¹H nuclei and at 150.92 MHz or 75.46 MHz for ¹³C, using DMSO-d₆ (δ_H: 2.50 ppm, δ_C: 39.52 ppm) or CDCl₃ (δ_H: 7.26 ppm, δ_C: 77.16 ppm) as the internal standard. Mass spectrometry was performed on an Agilent 6410 Triple Quad mass spectrometer (Agilent Technologies, Santa Clara, CA, USA). High-resolution mass spectra (HRMS) were obtained using a Q-TOF2 hybrid quadrupole time-of-flight mass spectrometer (Micromass, Cary, NC, USA).