Simultaneous quantitative determination and validation of quercetin glycosides with peroxynitrite-scavenging effects from Saussurea grandifolia

► Four quercetin glycosides were identified and quantified in Sussurea grandifolia. ► An uncommon quercetin glycoside, saxifragin (Qc-5-glc) was isolated from that plant. ► One gram of the MeOH extract contains 33.74 mg of saxifragin. ► That compound has also a potent peroxynitrite-scavenging activity (IC 50, 0.67 μM). The leaves of Saussurea grandifolia (Compositae) are used as chwinamul, a well-known Korean mountainous vegetable, or to treat hepatitis and hematuria. Since the methanolic extract of S. grandifolia leaves exhibit a potent peroxynitrite-scavenging effect, phytochemical and high-performance liquid chromatographic (HPLC) analyses were employed to identify and simultaneously quantify the active components: chlorogenic acid and 3,5-di-O-caffeoylquinic acid (3,5-DQ) as caffeoylquinic acids, and quercetin, isoquercitrin (quercetin-3-glucoside), saxifragin (quercetin-5-glucoside), and rutin (quercetin-3-rutinoside). Validation of HPLC methods was performed to verify the linearity, LOD, LOQ, intra-day and inter-day variabilities, recovery, and repeatability to ensure that this method is selective, sensitive, precise, accurate and reproducible. In particular, leaves contained saxifragin with potent peroxynitrite-scavenging activity (IC 50, 0.67 μM) as 4.65 mg/g dry weight, which is equivalent to 33.74 mg/g extract.