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Caffeic acid, rosmarinic acid and oligomers of caffeic acid with multiple catechol groups are all constituents of Salvia officinalis. Their antioxidant potential was investigated with regard to their radical scavenging activity and the stability and structure of the intermediate radicals. Pulse-radiolytic studies revealed very high rate constants with hydroxyl radicals. Evidence from kinetic modeling calculations suggested an unusual complex behavior due to the presence of both O4- and O3-semiquinones and formation and decay of a hydroxyl radical adduct at the vinyl side chain. The radical structures observed by EPR spectroscopy after autoxidation in slightly alkaline solutions were only partially identified due to their instability and generally represented dissociated O4-semiquinones. Hybrid density-functional calculations of the potential radical structures showed distinct differences between the resonance stabilization of the O4- and O3-semiquinones of caffeic and dihydrocaffeic acids, reflected also in the considerably faster decay of the O3-semiquinone observed by pulse radiolysis. No evidence was found for dimerization reactions via Cb radicals typical for lignin biosynthesis

A comparative study of the NMR data of kamahine A and B acetates with those of kamahine E acetate helps determine the relative stereochemistries of the diasteroisomeric kamahines A and B, novel non-sesquiterpenoids in New Zealand honeys. NMR and molecular modeling of diastereoisomeric hemiacetal methoxymandelate esters help establish the absolute configurations of the kamahines. Mosher-Trost model efficiently predicts the absolute by considering the positive torsion angle between methine hydrogen and carbonyl of hemiacetate mandelate esters.

Chemical investigation of blackcurrant seed residue from oil extraction revealed the presence of an array of polyphenols which were dominated by four anthocyanins consisting of the rutinosides and glucosides of delphinidin and cyanidin. Also isolated were the glucosides and rutinosides of myricetin and quercetin, kaempferol-3-glucoside, dihydroquercetin and aureusidin, as well as the phenolic acids 1-cinnamoyl- and 1-p-coumaroyl-β-d-glucosides. This is the first report of aureusidin and 1-cinnamoyl-β-d-glucoside as blackcurrant constituents. [Copyright &y& Elsevier]

Four new pyranoanthocyanins, namely pyranocyanin C and D and pyranodelphinin C and D, possessing the pyrano[4,3,2-de]-1-benzopyrylium core structure were isolated from an extract of blackcurrant seeds. Their chemical structures were elucidated by spectral methods and confirmed by chemical synthesis involving blackcurrant anthocyanins and p-coumaric acid. It is postulated that this condensation reaction plays a significant part in the evolution of red wine colour. [Copyright &y& Elsevier]

Addition of anthocyanins with nucleophilic agents normally occurs at the C-4 centre and the isolation of C-2 adducts between acetone and cyanidin-3- and delphinidin-3-rutinosides is the first definitive demonstration of the reactivity of this carbon site. These C-2 addition products were isolated as diastereoisomers and their chemical structures elucidated by 1D and 2D NMR spectroscopy. [Copyright &y& Elsevier]

Pyranoanthocyanidins generated from the respective glycosides on hydrolysis were found to undergo rearrangement to form a new type of furoanthocyanidins with a core structure of furo[2,3-c]-1-benzopyrylium. [Copyright &y& Elsevier]

Near-UV irradiation of aqueous solutions of 7-hydroxy-6-methoxycoumarin (scopoletin) and 6,7-dihydroxycoumarin (esculetin) resulted in the formation of dimers. Substantially greater amounts of the 7-hydroxy-6-methoxycoumarin photodimer were produced compared with that of 6,7-dihydroxycoumarin. Fluorescence spectra indicated that the initial photolytic reaction involves the excited state of the phenolate form of the monomeric coumarin. The electro-spray ionization (ESI) mass spectrum suggested that the major product (with a sodiated quasimolecular ion at m/z 405) from the photolysis of scopoletin in water had formed by oxidative dimerisation and possibly had a 3,3′-bond. A second dimer (with a sodiated quasimolecular ion at m/z 407) was probably a 2 + 2 cyclodimer. This work concluded that photolysis of coumarins in water results in oxidative dimerisation whereas photolysis in the solid state or in organic solvents results in cyclodimerisation. Minor monomeric photoproducts were a dihydroxy-6-methoxycoumarin from 7-hydroxy-6-methoxycoumarin and a trihydroxycoumarin from 6,7-dihydroxycoumarin. During ESI-mass spectrometry (ESI-MS), sodiated quasimolecular ions of the photodimer formed more readily than protonated quasimolecular ions and the sodiated ions did not fragment readily. Protonated quasimolecular ions of the monomeric coumarins formed more readily than their sodiated counterparts and the protonated ions fragmented to create daughter ion spectra that were useful for chemical structural assignment. [ABSTRACT FROM AUTHOR]

Caffeic acid, rosmarinic acid and oligomers of caffeic acid with multiple catechol groups are all constituents of Salvia officinalis. Their antioxidant potential was investigated with regard to their radical scavenging activity and the stability and structure of the intermediate radicals. Pulse-radiolytic studies revealed very high rate constants with hydroxyl radicals. Evidence from kinetic modeling calculations suggested an unusual complex behavior due to the presence of both O4- and O3-semiquinones and formation and decay of a hydroxyl radical adduct at the vinyl side chain. The radical structures observed by EPR spectroscopy after autoxidation in slightly alkaline solutions were only partially identified due to their instability and generally represented dissociated O4-semiquinones. Hybrid density-functional calculations of the potential radical structures showed distinct differences between the resonance stabilization of the O4- and O3-semiquinones of caffeic and dihydrocaffeic acids, reflected also in the considerably faster decay of the O3-semiquinone observed by pulse radiolysis. No evidence was found for dimerization reactions via Cbeta radicals typical for lignin biosynthesis.

A series of sage phenolics was tested for activity against a panel of Leishmania parasites and for immunomodulatory effects on macrophage functions including release of tumour necrosis factor (TNF), interleukin-6 (IL-6), and interferon (IFN)-like activities. For this, functional bioassays were employed including an in vitro model for leishmaniasis in which macrophage-like RAW 264.7 cells were infected with Leishmania parasites, an extracellular Leishmania growth-inhibition assay, a fibroblast-lysis assay for TNF-activity, a cell proliferation assay using IL-6 sensitive murine B9 hybridoma cells, and a virus protection assay for IFN-like activity. Whereas none of the test samples exhibited marked activities against extracellular Leishmania promastigotes (IC50 > 700 to > 2800 nM; > 500 microg/ml), caffeic acid, salvianolic acids K and L as well as the methyl ester of salvianolic acid I showed pronounced antileishmanial activities against intracellular amastigote stages within RAW cells (IC50 3-23 nM vs. 10-11 nM for the reference Pentostam). Noteworthy, the phenolic samples showed no cytotoxicity against the host cells (IC50 > 600 to > 2200 nM; > 400 microg/ml). Tested sage phenolics activated Leishmania-infected RAW 264.7 for release of TNF ranging 22-117 U/ml and IL-6 ranging 3-42 U/ml. In contrast, their TNF- or IL-6-inducing potential in experiments with non-infected host cells was negligible. Furthermore, caffeic acid and salvianolic acid K induced a modest release of IFN-like activity (5-9 and 2-4 U/ml, respectively) as reflected by inhibition of the cytopathic effect of encephalomyocarditis virus on L929 cells. The results support the emerging picture that plant polyphenols may be credited for the profound health-beneficial properties of various herbal medicines and agricultural products.