A rapid screening method for prenylated flavonoids with ultra‐high‐performance liquid chromatography/electrospray ionisation mass spectrometry in licorice root extracts

Abstract

Due to their substitution with an isoprenoid group, prenylated flavonoids have an increased affinity for biological membranes and target proteins, enhancing their potential bioactivity. Although many prenylated flavonoids have been described, there are no methods that specifically screen for their presence in complex mixtures, prior to purification. We describe a method based on ultra-high-performance liquid chromatography (UHPLC) with electrospray ionisation mass spectrometry (ESI-MS) that allows rapid screening for prenylated flavonoids in multi-component plant extracts. Identification of the prenylated flavonoids is based on screening for neutral losses of 42 u and 56 u in the positive-ion mode MS(2) and MS(3) spectra within the MS chromatograms. In addition, this method discriminates between a prenyl chain and a ring-closed prenyl (pyran ring), based on the ratio of the relative abundances of the ions that lose 42 u and 56 u (42:56). The application of this screening method on a 70% aq. ethanol, ethanol and ethyl acetate extract of the roots of Glycyrrhiza glabra indicated the presence of 70 mono- and di-prenylated flavonoids. In addition, of each prenylated flavonoid the type of prenylation, chain or pyran ring was determined.

Characterization of phenolic compounds and antioxidant properties of Glycyrrhiza glabra L. rhizomes and roots

“…The RSA obtained for the studied methanol/water extract (EC 50 The resultant blue colour is linearly correlated with the total reducing potential of electron-donating antioxidants, being measured spectrophotometrically at 700 nm. 55 The RP value obtained in the present study (EC 50 ¼ 129 mg mL À1 ) was similar to the one described by Tohma & Gulçin (2010) for aqueous (EC 45 ¼ 62 mg mL À1 ) and ethanolic (EC 76 ¼ 50 mg mL À1 )…”

“…Many papers have been published proling phenolic compounds in G. glabra samples from different origins and using different extraction methodologies, some of them cited in the previous discussion. 34,35,[37][38][39][40][41][42][43][44][45][46] However, from all of them, only Montoro et al (2011) presented quantitative results, although they cannot be compared with ours results since they are expressed differently (mg g À1 of dry plant), thus these authors revealed liquiritin apioside as the main avonoid present in their sample, which is in agreement with the sample studied herein. In our case, the results were expressed in mg g À1 of extract in order to relate the amounts of phenolic compounds found in the extract to the antioxidant activity.…”

Involvement of a Hydrophobic Pocket and Helix 11 in Determining the Modes of Action of Prenylated Flavonoids and Isoflavonoids in the Human Estrogen Receptor

“…Figure S1 As hows the chromatogram of the licorice root extract. As an example, the two-step purification of peak number 1, eluting at 13.7 min and identifieda s glabrene [18] (Table 1), is shown in Figure S1 Ba nd C. After purification by flash chromatography (Figure S1 Table 1). In addition, six compounds were purchased.B oth purifieda nd purchased compounds were analyzed by UHPLC-MS to verify their purities and to obtain their fragmentationp atternsi nM S 2 .U HPLC-MS analysiso fc ompound 5 (4'-O-methylglabridin) showed ap urity at 280 nm of 98 %; however,s ome impurities were visible in the NI and PI mode MS spectra.…”

“…[18] Five prenylated isoflavonoids ando ne prenylated flavonoid were purifiedf rom the licorice root extract in at wo-step purification procedure. Glabrone, the peak indicated with a star (Figure S1 A), could not be purified, and peak number 2, identified as glabridin, was not purified, because glabridin was commercially available.…”

“…The source voltages were 4.50 and 3.50 kV for PI and NI modes, respectively.I nb oth ionization modes the ion transfer tube temperature and the probe temperature were 400 and 50 8C, respectively.T he identification of isoflavonoids was based on UV and MS spectra with use of the approach reported earlier. [18] Data acquisition and reprocessing were done with Xcalibur (version 2.2, Thermo Scientific).…”