HPLC-PDA-MS and NMR Characterization of C-Glycosyl Flavones in a Hydroalcoholic Extract of Citrus aurantifolia Leaves with Antiplatelet Activity

Abstract

A hydroalcoholic extract of lime ( Citrus aurantifolia) leaves has been developed in Cuba to be used as a nutritional supplement and phytomedicine in the form of tincture (TLL). A HPLC-PDA-ESI/MS/MS method has been used for the comprehensive analysis of C-glycosyl flavones in TLL. Six C-glycosyl flavones were characterized and, to confirm the proposed structures and to elucidate the nature of the sugar units, a preparative procedure was applied, and isolated compounds were characterized by NMR. Apigenin-6,8-di-C-beta-D-glucopyranoside (vicenin II) (1), diosmetin-6,8-di- C-beta- d-glucopyranoside (2), apigenin-8-C-beta-D-glucopyranoside (vitexin) (3), apigenin-8-C-[alpha-L-arabinopyranosyl-(1-->6)]-O-beta-D-glucopyranoside (4), apigenin-6-C-[alpha-l-arabinopyranosyl-(1-->6)]-O-beta-D-glucopyranoside (5). and apigenin-6-C-beta-D-glucopyranoside (isovitexin) (6) were identified in TLL and quantified by HPLC-PDA. Compounds 4 and 5 were two new arabinosyl derivatives of vitexin and isovitexin. Inhibitor effect of TLL on platelet aggregation induced by physiological agonists of platelets was evaluated in human plasma. TLL inhibited significantly ADP and epinephrine-induced platelet aggregation in a concentration-dependent manner (IC 50=0.40 and 0.32 mg/mL, respectively).

Chemical composition of hydroethanolic extracts from Siparuna guianensis, medicinal plant used as anxiolytics in Amazon region

“…Comparing with MS literature data (Piccinelli et al, 2008;Figueirinha et al, 2008) this compound was characterized as 6,8-di-C-glucosylapigenin, also known as vicenin-2.…”

Chemical composition of hydroethanolic extracts from five species of the Passiflora genus

“…The ESI-MS spectra of compound 2 at 17.9 min (Table 1) Table 3. Comparing with MS literature data (Piccinelli et al, 2008), this compound was characterized as 6,8-di-C-glucosylapigenin, also known as vicenin-2. No commercial standard of vicenin-2 are available, therefore, this peak was compared with vicenin-2, present in P. incarnata extract, used as a surrogate standard (Negri et al, 2012).…”

Identification of phenolic constituents of Cytisus multiflorus

“…3). Attending that 8-C-glucosyl-apigenin elutes before 6-C-glucosyl-apigenin under HPLC reverse phase conditions (Kazuno et al, 2005;Pereira et al, 2005;Piccinelli et al, 2008), compounds of MW 564 Da in fractions 4 and 5 were respectively assigned to 2 00 -O-pentosyl-vitexin and 2 00 -O-pentosyl-isovitexin. To our knowledge, these compounds were here detected for the first time in Fabaceae family.…”

“…The presence of these two isomers in contiguous fractions were confirmed by HPLC-MS analysis (results not shown). Moreover, considering that in nature the C-glycosyl moieties appear almost exclusively at 6 and/or 8-positions of flavones (Cuyckens & Claeys, 2004) and that the 8-C-glycosyl-luteolin isomer elutes before the 6-C-glycosyl-luteolin under reversed phase conditions (Kazuno, Yanagida, Shindo, & Murayama, 2005;Pereira, Yariwake, & McCullagh, 2005;Piccinelli et al, 2008), the phenolic compounds in fractions 1 and 2 were respectively assigned to 2 00 -O-pentosyl-6-C-hexosyl-luteolin and 2 00 -O-pentosyl-8-C-hexosylluteolin. The structures of these two compounds are depicted in Fig.…”