Isolation of high molecular weight components and contribution to the protective activity of coffee against lipid peroxidation in a rat liver microsome system.

One of the most extensively studied and best-established properties of coffee is its antioxidant activity. We have shown that coffee brew has the ability to inhibit lipid peroxidation completely in a rat liver microsome biological system. The inhibitory activity was mainly due to the high molecular weight (HMW) fraction; this consisted of five components that were isolated, purified, and seen to occur in different amounts in the brew. Each component had different spectra and element compositions, although they all contained nitrogen. HMW, nitrogen content, and brown color enabled three components to be attributed to the melanoidin family; the two nonbrown components could not be considered as melanoidins. Each melanoidin and nonmelanoidin component contributes to a different extent to the protective action exerted by coffee brew. None of the isolated components completely inhibited microsomal lipid peroxidation alone, suggesting that each acts at different sites and/or possesses different mechanisms of action. The protective activity of coffee brew is thus underpinned by the antiradical properties, reducing power, and metal chelating ability of the individual components, each contributing to a different extent.

Hydroxycinnamic acid derivatives occurring in Cichorium endivia vegetables.

The hydroxycinnamic acid derivatives found in Chicorium endivia var. crispum and var. latifolium polyphenolic extracts were detected and characterized by high-performance liquid chromatography (HPLC) combined with photodiode array detector (DAD) and electrospray ionization-tandem mass spectrometry (ESI-MS/MS). The method provides data (molecular weight and diagnostic fragment ions) on the molecular structure of compounds. The combined approach enabled identification of four hydroxycinnamic derivatives in each chicory extract; three derivatives (5-O-caffeoylquinic acid, 3,4-di-O-caffeoylquinic acid, and 5-O-feruloylquinic acid) were found in both chicories, while 3,5-di-O-caffeoylquinic acid was typical of var. crispum and cis-caftaric acid of var. latifolium.

Isolation, identification, and quantification of roasted coffee antibacterial compounds.

Coffee brew is a widely consumed beverage with multiple biological activities due both to naturally occurring components and to the hundreds of chemicals that are formed during the roasting process. Roasted coffee extract possesses antibacterial activity against a wide range of microorganisms, including Staphylococcus aureus and Streptococcus mutans, whereas green coffee extract exhibits no such activity. The naturally occurring coffee compounds, such as chlorogenic acids and caffeine, cannot therefore be responsible for the significant antibacterial activity exerted by coffee beverages against both bacteria. The very low minimum inhibitory concentration (MIC) found for standard glyoxal, methylglyoxal, and diacetyl compounds formed during the roasting process points to these alpha-dicarbonyl compounds as the main agents responsible for the antibacterial activity of brewed coffee against Sa. aureus and St. mutans. However, their low concentrations determined in the beverage account for only 50% of its antibacterial activity. The addition of caffeine, which has weak intrinsic antibacterial activity, to a mixture of alpha-dicarbonyl compounds at the concentrations found in coffee demonstrated that caffeine synergistically enhances the antibacterial activity of alpha-dicarbonyl compounds and that glyoxal, methylglyoxal, and diacetyl in the presence of caffeine account for the whole antibacterial activity of roasted coffee.

Isolation and determination of alpha-dicarbonyl compounds by RP-HPLC-DAD in green and roasted coffee.

Glyoxal, methylglyoxal, and diacetyl formed as Maillard reaction products in heat-treated food were determined in coffee extracts (coffee brews) obtained from green beans and beans with different degrees of roast. The compounds have been reported to be mutagenic in vitro and genotoxic in experimental animals in a number of papers. More recently, alpha-dicarbonyl compounds have been implicated in the glycation process. Our data show that small amounts of glyoxal and methylglyoxal occur naturally in green coffee beans. Their concentrations increase in the early phases of the roasting process and then decline. Conversely, diacetyl is not found in green beans and forms later in the roasting process. Therefore, light and medium roasted coffees had the highest glyoxal and methylglyoxal content, whereas dark roasted coffee contained smaller amounts of glyoxal, methylglyoxal, and diacetyl. For the determination of coffee alpha-dicarbonyl compounds, a reversed-phase high performance liquid chromatography with a diode array detector (RP-HPLC-DAD) method was devised that involved the elimination of interfering compounds, such as chlorogenic acids, by solid phase extraction (SPE) and their derivatization with 1,2-diaminobenzene to give quinoxaline derivatives. Checks of SPE and derivatization conditions to verify recovery and yield, respectively, resulted in rates of 100%. The results of the validation procedure showed that the proposed method is selective, precise, accurate, and sensitive.

Antibacterial activity of red and white wine against oral streptococci.

Wine contains a number of biologically active compounds with beneficial effects on human health. The antibacterial action of commercial red and white wines against oral streptococci responsible for caries development and against S. pyogenes responsible for pharyngitis was studied. Its postcontact effect against S. mutans was also studied. Both wines displayed activity. The compounds responsible for such activities were succinic, malic, lactic, tartaric, citric, and acetic acid. The synthetic mixtures of the organic acids tested at the concentrations found in wine had greater antibacterial activity than the beverages, indicating that in wine they are inhibited by other components. Wine polyphenols displayed no activity against oral streptococci or S. pyogenes. Findings show that wine is active against oral streptococci and S. pyogenes and suggest that it enhances oral health.

Isolation of an in vitro and ex vivo antiradical melanoidin from roasted barley.

The antiradical properties of water-soluble components of both natural and roasted barley were determined in vitro, by means of DPPH* assay and the linoleic acid-beta-carotene system, and ex vivo, in rat liver hepatocyte microsomes against lipid peroxidation induced by CCl4. The results show the occurrence in natural barley of weak antioxidant components. These are able to react against low reactive peroxyl radicals, but offer little protection against stable DPPH radicals deriving from peroxidation in microsomal lipids. Conversely, roasted barley yielded strong antioxidant components that are able to efficiently scavenge free radicals in any system used. The results show that the barley grain roasting process induces the formation of soluble Maillard reaction products with powerful antiradical activity. From roasted barley solution (barley coffee) was isolated a brown high molecular mass melanoidinic component, resistant to acidic hydrolysis, that is responsible for most of the barley coffee antioxidant activity in the biosystem.

Purification and characterization of soluble Cichorium intybusVar. silvestre lipoxygenase.

A water-soluble lipoxygenase enzyme (EC 1.13.11.12; LOX) occurring in the red cultivar produced in the geographical area of Chioggia (Italy) of Cichorium intybus var. silvestre was isolated and characterized. The molecular mass of the enzyme was estimated to be 74,000 Da by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration chromatography. The isoelectric point was pH 6.85. The optimum values of pH, ionic strength, and temperature, shown by isoresponse surface calculated by a randomized multilevel factorial design, were 7.58, 30 mM, and 38.5 degrees C, respectively. The enzyme showed high specificity toward linoleic acid, and the study of the variation of linoleic acid concentration between 30 and 300 microM, in the presence of Tween 20 at a concentration lower than the critical micelle concentration (0.01 v/v), resulted in a typical Michaelis-Mentem curve with KM and Vmax values of 1.49 x 10(-4) M and 2.049 microM min(-1) mg(-1), respectively. The biochemical properties, the kinetic parameters found, and the carotene-bleaching activity shown in aerobic conditions seem to indicate that the isolated enzyme is a lipoxygenase type III according to the indications given for soybean isoenzymes.