Quercetin rutinoside

The methanol extract of the stem and leaves of Guettarda speciosa Linn. (MGS; voucher #: FBM224–095) was obtained from the International Biological Material Research Center at the Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea. Fingerprinting MGS was conducted with Agilent 1200 series high-performance liquid chromatographic (HPLC) system. MGS (15 μl in methanol) was injected onto a column (CapcellPAK MGII C18, Shiseido, Japan, 4.6 × 150 mm ID, 3 μm). The column temperature was 35 °C, and the flow rate was 0.5 mL/min. Samples were eluted in a gradient of 0.1% formic acid and incremental acetonitrile in water. Standards and samples were detected at wavelengths of 254 ~ 320 nm. Index chemicals, including 3-O-caffeoylquinic acid, quercetin 3-O-galactoside, quercetin 3-O-glucoside, 3,4-di-O-caffeoylquinic acid, apigenin 7-O-glucuronide, and quercetin rutinoside, were purchased from Sigma-Aldrich (St. Louis, MO, USA). Chemstation software (Agilent Corporation, Germany) was used for data acquisition. The chemical constituents of MGS were identified by comparing their retention times to those of standard chemicals under identical analysis conditions and the UV spectra.

All HPLC and LC–MS grade solvents were obtained from Fisher Scientific (Loughborough UK). (+)-catechin, (−)-epicatechin, procyanidin B1, procyanidin B2, neochlorogenic acid, caffeic acid, sinapic acid, p-coumaric acid, quercetin-rutinoside, quercetin-glucoside, isorhamnetin-glucoside, isorhamnetin-rutinoside were purchased from Sigma–Aldrich (Dorset, UK). Cyanidin-3-glucoside and cyanidin-3-rutinoside, were purchased from Extrasynthese (Genay Cedex, France). Metaphosphoric acid (Bioxtra ≥ 33.5%), l-ascorbic acid and d-fructose were obtained from Sigma–Aldrich (Dorset, UK). d-glucose and sucrose, were purchased from Fisher Scientific (Loughborough UK).

Several standards were used for all individual primary and secondary metabolites. For the sugars sucrose, glucose, and fructose (Sigma–Aldrich Chemie GmbH, Steinheim, Germany); for organic acids oxalic acid, citric acid, malic acid, succinic acid, quinic acid, ascorbic acid, and fumaric acid (Sigma–Aldrich Chemie GmbH, Steinheim, Germany); for individual phenolics caffeic acid, p-coumaric acid, ferulic acid, 5-caffeoxlquinic acid, apigenin-7-glucoside, luteolin-7-glucoside, kaempferol-3-glucoside, quercetin rhamnoside, quercetin rutinoside, and isorhamnetin-3-glucoside (Sigma–Aldrich Chemie GmbH, Steinheim, Germany); and for capsaicnoids capsaicin, dihydrocapsaicin, and nordihydrocapsaicin (Sigma–Aldrich Chemie GmbH, Steinheim, Germany).