Thin Layer Chromatography-Surface Enhanced Raman Scattering-Guided Track,Forecast And Discovery Of Active Compounds From Chinese Herbal Medicine

The conventional isolation and identification of active compounds from Chinese herbal medicine have been extensively reported by using various chromatographic and spectroscopic techniques.However,how to quickly discover active ingredients from natural sources still remains a challenging task due to the interference of their similar structures and complex matrix.Here,we put forward a thin layer chromatography(TLC)coupled with surface-enhanced Raman scattering(SERS)-guided strategy for rapid track,forecast and discovery of active compounds from Chinese herbal medicine.The performance of TLC-SERS approach is first evaluated by tracing four main protoberberines berberine(BER),coptisine(COP),palmatine(PAL)and jatrorrhizine(JAT)from a typical herb Coptidis Rhizoma as an example.It has been demonstrated that the coupling method can identify the four target compounds and especially resolve BER and COP(that display almost the same spot on TLC plate)with the Raman intensity ratio of I708 to I728.The corresponding limits of detection of SERS for the four compounds are 0.1 μM,0.05 μM,0.1 μM and 0.5 μM,respectively,which are about 1～2 orders of magnitude lower than those of direct observation under ultraviolet spectrophotometry.Based on these findings,the proposed method further guides forecast and isolation of unknown compounds from traditional Chinese herb Typhonii Rhizoma.Results show that two trace protoberberines(BER and COP)from the n-butanol extract of Typhonii Rhizoma are found for the first time.Moreover,in vitro experiments display that BER can effectively decrease the viability of Human glioma U87 cells by inducing cell cycle arrest in a concentration-dependent manner.