Flavonoids identification of Machaerium acutifolium by ESI-MS

Machaerium acutifolium Vogel (Fabaceae-Papilionoideae) is popularly known for “jacarandá do campo”, “jacarandá-caroba” and “jacarandá bico-de-pato”. It occurs from the Amazon to São Paulo also in Mato Grosso do Sul, Bahia, Piauí and Maranhão mainly in the cerrado area.1,2 This species is traditionally used as a contraceptive to treat painful menstruation and stomach pain.3 The trunkwood of M. acutifolium contains polyphenols (pinsylvin monomethyl ether, (+)-medicarpin and petrostyrene).4
The aqueous fraction (FAFMa) from the partition of the ethanolic extract of leaves from M. acutifolium (EEFMa) was analyzed by ESI-MS in negative mode and HPLC-DAD, using a C18 column with mobile phase MeOH/H2O-AcOH (0.2%), gradient, flow rate 1.0 mL min-1 and =348 nm. HPLC-DAD profile of EEFMa and FAFMa under the same chromatographic conditions revealed similar chemical profiles, with the presence of two high intensity bands (b and d, Figure 1A). UV spectra suggest that bands a, b and c are isoflavonoids, while d is a flavonoid.5 Comparison of FAFMa chromatograms with flavonoids standard (rutin and quercetin), which are commonly found in Fabaceae family, suggested the occurrence of rutin (Rt=27.8 min) and absence of quercetin (Rt=33.3 min) in FAFMa (Figure 1B).
ESI-MS analyze showed the occurrence of the flavonoids kaempferol-3-O-rutinosyl-7-O-dirhaminoside (1), quercetin-3-O-rutinosyl-7-O-rhamnoside (2), rutin (3), kaempferol-3-O-rutinoside (4), kaempferol-3-O-glycoside (5) and isoflavonoids daidzein-8-C-glycoside (6) and genistein (7) (Figure 2 and Table 1). These compounds are being reported for the first time in the Machaerium genus.