Silica gel 60 gf

Shimadzu 1700 spectrophotometer was used for UV absorption spectra. Melting points were determined on Electrothermal 9100 equipment. Mass spectra were measured on a Jeol Mass Spectrometer SSQ 7000, Digital DEC 300. NMR spectra were measured in DMSO or CD₃OD or CDCl₃; ¹H–NMR spectra were obtained at 400 MHz and ¹³ C-NMR spectra at 100 MHz on a JEOL GX-400 spectrometer with the chemical shifts (δ ppm) expressed relative to TMS as internal standard. Pre-coated silica gel 60 F₂₅₄ (Merck, Darmstadt, Germany) was used for the TLC analysis. Vacuum liquid chromatography (VLC) was performed on silica gel 60 GF (Merck, Darmstadt, Germany). Sephadex LH-20 (Sigma-Aldrich, St. Louis, Missouri, United States) and silica gel 100 C₁₈-Reversed Phase (Fluka, Switzerland) were also used. Analysis of phenolics was performed on Hewlett Packard HPLC (HP 1050HPLCDADw/Data System) equipped with a Hypersil-ODS (4.6 X 250 mm, 5 μm) column and a UV detector.

Purification processes were performed through column chromatography (CC) using silica gel 60 (0.063-0.200 mm) as the stationary phase. Organic solvents or mixtures of increasing polarity were used as mobile phases. Silica gel 60 GF (Merck, Darmstadt, Germany) was used to perform analytical (0.25 mm) or preparative (0.75 mm) thin layer chromatographic (TLC) processes.
The ¹H (400 MHz) and ¹³C (100 MHz) nuclear magnetic resonance (NMR) spectra were obtained on a Bruker Avance DRX-400 spectrometer (Bruker, Rheinstetten, Germany), operating at 300 K. The chemical shifts (δ) were expressed in units of ppm, using tetramethylsilane (TMS) as a reference (δ_H = δ_c = 0), and the coupling constants (J) were expressed in Hz. Chloroform-d was used as the solvent for the samples.

N-Hexane, chloroform, n-butanol and ethanol were purchased from Fisher Scientifics (UK). Silica Gel 60, xanthine oxidase, xanthine, allopurinol, and uric acid assay kit were purchased from Sigma (USA). All other chemicals were of analytical grade. Melting point was determined on Electrothermal 9100 equipment. Mass spectrum was measured on a Jeol Mass Spectrometer SSQ 7000, Digital DEC 300. NMR spectrum was measured in DMSO. ¹H–NMR spectrum was obtained at 400 MHz on a JEOL GX-400 spectrometer with the chemical shifts (δ ppm) expressed relative to TMS as internal standard. Precoated Silica Gel 60 F254 (Merck, Darmstadt, Germany) was used for the TLC analysis. Vacuum liquid chromatography (VLC) was performed on Silica Gel 60 GF (Merck, Darmstadt, Germany)