Haibo Wang

The anthocyanins (1−3) and cyanidin isolated from tart cherries exhibited in vitro antioxidant and antiinflammatory activities comparable to commercial products. The inhibition of lipid peroxidation of anthocyanins 1−3 and their aglycon, cyanidin, were 39, 70, 75, and 57%, respectively, at 2-mM concentrations. The antioxidant activities of 1-3 and cyanidin were comparable to the antioxidant activities of tert-butylhydroquinone and butylated hydroxytoluene and superior to vitamin E at 2-mM concentrations. In the antiinflammatory assay, cyanidin gave IC50 values of 90 and 60 mM, respectively, for prostaglandin H endoperoxide synthase-1 and prostaglandin H endoperoxide synthase-2 enzymes.

A reverse phase HPLC and electrospray interface with ion trap mass spectrometer method was developed for the characterization of anthocyanins in Concord, Rubired, and Salvador grape juices. Rubired and Salvador grapes are hybrids from Vitis vinifera and Vitis rupestris. Concord grape is a grape from the native American cultivar Vitis labrusca. Individual anthocyanins in these three varieties were identified on the basis of UV-vis and MS spectra and further elucidated by MS/MS spectra. Anthocyanins in Salvador and Concord grapes were 3-O-glucosides, 3-O-(6' '-O-p-coumaroyl)glucosides, 3-O-(6' '-O-p-acetyl)glucosides, 3,5-O-diglucosides, and 3-O-(6' '-O-p-coumaroyl)-5-O-diglucosides of delphinidin, cyanidin, petunidin, peonidin, and malvidin. Vitisin B was detected in Salvador grape juice. Anthocyanins in Rubired grape juice were primarily anthocyanin diglucosides: peonidin 3,5-O-diglucoside, malvidin 3,5-O-diglucoside, peonidin 3-O-(6' '-O-p-coumaroyl)-5-O-diglucoside, and malvidin 3-O-(6' '-O-p-coumaroyl)-5-O-diglucoside are the four major anthocyanins. The presence of pelargonidin 3-O-glucoside, not previously reported, has been established for the first time in all three juices.

Montmorency and Balaton tart cherries were lyophilized and sequentially extracted with hexane, ethyl acetate, and methanol. Methanolic extracts of dried Balaton and Montmorency tart cherries (Prunus cerasus) inhibited lipid peroxidation induced by Fe(2+) at 25 ppm concentrations. Further partitioning of this methanol extract with EtOAc yielded a fraction that inhibited lipid peroxidation by 76% at 25 ppm. Purification of this EtOAc fraction afforded eight polyphenolic compounds, 5,7,4'-trihydroxyflavanone (1), 5,7, 4'-trihydroxyisoflavone (2), chlorogenic acid (3), 5,7,3', 4'-tetrahydroxyflavonol-3-rhamnoside (4), 5,7,4'-trihydroxyflavonol 3-rutinoside (5), 5,7,4'-trihydroxy-3'methoxyflavonol-3-rutinoside (6), 5,7,4'-trihydroxyisoflavone-7-glucoside (7), and 6, 7-dimethoxy-5,8,4'-trihydroxyflavone (8), as characterized by (1)H and (13)C NMR experiments. The antioxidant assays revealed that 7-dimethoxy-5,8,4'-trihydroxyflavone (8) is the most active, followed by quercetin 3-rhamnoside, genistein, chlorogenic acid, naringenin, and genistin, at 10 microM concentrations.

The adipocyte integrates crucial information about metabolic needs in order to balance energy intake, storage, and expenditure. Whereas white adipose tissue stores energy, brown adipose tissue is a major site of energy dissipation through adaptive thermogenesis mediated by uncoupling protein 1 (UCP1) in mammals. In both white and brown adipose tissue, nuclear receptors and their coregulators, such as peroxisome proliferator-activated receptor gamma (PPARgamma) and PPARgamma coactivator 1alpha (PGC-1alpha), play key roles in regulating their development and metabolic functions. Here we show the unexpected role of liver X receptor alpha (LXRalpha) as a direct transcriptional inhibitor of beta-adrenergic receptor-mediated, cyclic AMP-dependent Ucp1 gene expression through its binding to the critical enhancer region of the Ucp1 promoter. The mechanism of inhibition involves the differential recruitment of the corepressor RIP140 to an LXRalpha binding site that overlaps with the PPARgamma/PGC-1alpha response element, resulting in the dismissal of PPARgamma. The ability of LXRalpha to dampen energy expenditure in this way provides another mechanism for maintaining a balance between energy storage and utilization.