Isolation, identification, biological estimation, and profiling of glucosinolates in Isatis indigotica roots

Abstract

Four main glucosinolates (progoitrin, epiprogoitrin, gluconapin, and neoglucobrassicin) were isolated and identified from Isatis indigotica roots (Isatidis Radix). Among these, neoglucobrassicin was the first indole glucosinolate isolated from this herb, and its structure was elucidated by NMR, MS, and X-ray diffraction analysis. The glucosinolate components of Isatidis Radix have been profiled by combined use of a conventional preparative column chromatography method and a new UHPLC-QTOF-MS/MS method, and validated by simultaneous analysis of intact and desulfurized GLS. A total of 16 glucosinolates (GLS) including 12 aliphatic GLS, two aromatic GLS, and two indole GLS were identified on the basis of their UV profiles, MS/MS data, and/or by comparison with reference substances. Among these nine GLS were reported from I. indigotica for the first time. The total GLS, four isolated GLS, and (R,S)-goitrin (a degraded product of progoitrin and epiprogoitrin) have been estimated in vitro for anti-influenza viral, anti-bacterial, and anti-inflammatory activities. All the glucosinolate samples were inactive against H3N2 virus and four pathogenic bacteria, and two previously unnoticed GLS (gluconapin and neoglucobrassicin) showed significantly anti-inflammatory activity against the respiratory burst of mouse macrophages.