Mary B. Satterfield

Structural characterization of flavonoid glycosides by collisionally activated dissociation of metal complexes

Collisionally activated dissociation is used for structural characterization of a series of flavonoid glycosides. Dissociation of transition metal/flavonoid binary complexes of the type [MII(L − H+)]+ and transition metal/2,2′-bipyridine/flavonoid ternary complexes of the type [MII(L − H+)bpy]+ give fragmentation patterns that are complementary and more diagnostic than those of the protonated, deprotonated, or sodium-cationized flavonoids. Analysis of fragmentation patterns of the [M (L − H+)bpy]+ complexes permits determination of the disaccharide as a rutinose or neohesperidose and the relative placement of the disaccharide (i.e., 3 vs. 7 positions).

Detection of the isoflavone aglycones genistein and daidzein in urine using solid-phase microextraction-high-performance liquid chromatography-electrospray ionization mass spectrometry

An improved method of detection of the isoflavone aglycones, genistein and daidzein, is reported using solid-phase microextraction-high-performance liquid chromatography-electrospray ionization mass spectrometry (SPME-HPLC-ESI-MS). Extraction of the isoflavonoids from urine using SPME with a Carbowax-templated resin fiber coating allows rapid preconcentration of the analytes without the usual sample preparation required by other methods. Detection of the analytes is accomplished by HPLC-ESI-MS. Analysis of spiked samples of urine resulted in a linear range of 0.25 to 250 ng/ml for daidzein and 0.27 to 27.0 ng/ml for genistein. Limits of detection of daidzein and genistein were measured at 25.4 pg/ml for daidzein and 2.70 pg/ml for genistein. Daidzein and genistein were detected in urine following consumption of a soy drink.

Sites of reaction of pilocarpine

Analysis of the sites of reaction of a biologically important compound, pilocarpine, a molecule with imidazole and butyrolactone rings connected by a methylene bridge, has been accomplished in a quadrupole ion trap with the aim of characterizing its structure/reactivity relationships. Ion-molecule reactions of pilocarpine with chemical ionizing agents, dimethyl ether (DME), 2-methoxyethanol, and trimethyl borate (TMB), along with collision-activated dissociation elucidated the reaction sites of pilocarpine and made possible the comparison of structural features that affect sites of reaction. Based on MS/MS experiments, methylation occurs on the imidazole ring upon reactions with CH3OCH2+ or (CH3OCH2CH2OH)H+ ions but methylation occurs on the lactone ring for reactions with (CH3O)2B+ ions. Bracketing experiments with two model compounds, α-methyl-γ-butyrolactone and N-methyl imidazole, show the imidazole ring to have a greater gas-phase basicity and methyl cation affinity than the lactone ring. The contrast of methylation by TMB ions on the lactone ring is explained by initial addition of the dimethoxyborinium ion, (CH3O)2B+, on the imidazole ring with subsequent collisional activation promoting an intramolecular transfer of a methyl group to the lactone ring with concurrent loss of CH3OBO. Semiempirical molecular orbital calculations are undertaken to further address the favored reaction sites.