Pack polymer c18

The EtOAc residue (60 mg) was purified by HPLC (column: YMC‐Pack ODS‐AQ; 20 mm I.D. × 250 mm; YMC Co., Ltd.) with a similar method as described above to yield a pale yellow powder (6.3 mg). This powder was further purified by HPLC (column: YMC‐Pack Polymer C18; 10 mm I.D. × 250 mm; YMC Co., Ltd.) with 55% B in 40 min (solvent A: 0.1% trifluoroacetic acid in H₂O; solvent B: CH₃OH) to yield chrysin‐7G (0.5 mg).

Optical rotation was measured with a Jasco P-2000 polarimeter (Tokyo, Japan). UV spectra were recorded in methanol on a Hitachi U-3310 UV-vis spectrophotometer (Tokyo, Japan). IR spectra were acquired using a Nicolet 380 FT-IR spectrophotometer (Waltham, MA, USA). The NMR spectra were obtained using a Bruker AVANCE III 400 instrument (400 MHz for ¹H-NMR and 100 MHz for ¹³C-NMR; Bruker Biospin AG, Fällanden, Switzerland) using TMS as an internal standard. ¹H-¹H COSY, HSQC, HMBC, and ROESY NMR experiments were also performed on the Bruker AVANCE III 400 instrument, using standard pulse sequences. The high-resolution mass spectra were recorded on a Varian 7.0 T ESI-MS (Palo Alto, CA, USA). HPLC was performed using a JASCO Gulliver Series (Tokyo, Japan) with PU-2089 pump, RI-2031, and UV-2075 detector. Semi-preparative HPLC column chromatography was carried out on YMC-Pack Polymer-C18 (6 μm, 10 mm × 200 mm), YMC-pack SIL-06 (YMC Co., Ltd., Kyoto, Japan). Open column chromatography was performed using silica gel (Qingdao Haiyang Chemical Co., Ltd., Qingdao, China). The chemotaxis chambers and membranes were purchased from Neuroprobe (Gaithersburg, MD, USA) and human EGF was obtained from Peprotech (Rocky Hill, NJ, USA).