Volatile Profile in Yogurt Obtained from Saanen Goats Fed with Olive Leaves.

The aim of this study was to evaluate the development of volatile compounds in yogurt samples obtained from goats fed a dietary supplementation with olive leaves (OL). For this purpose, thirty Saanen goats were divided into two homogeneous groups of 15 goats each: a control group that received a standard diet (CG) and an experimental group whose diet was supplemented with olive leaves (OLG). The trial lasted 28 days, at the end of which the milk of each group was collected and used for yogurt production. Immediately after production, and after 7 days of storage at 4 °C in the absence of light, the yogurt samples were characterized in terms of fatty acid profile, oxidative stability and volatile compounds by the solid-phase microextraction (SPME)-GC/MS technique. Dietary OL supplementation positively affected the fatty acid composition, inducing a significant increase in the relative proportion of unsaturated fatty acids, mainly oleic acid (C18:1 cis9) and linolenic acid (C18:3). With regard to the volatile profile, both in fresh and yogurt samples stored for 7 days, the OL supplementation induced an increase in free fatty acids, probably due to an increase in lipolysis carried out by microbial and endogenous milk enzymes. Specifically, the largest variations were found for C6, C7, C8 and C10 free fatty acids. In the same samples, a significant decrease in aldehydes, mainly heptanal and nonanal, was also detected, supporting-at least in part-an improvement in the oxidative stability. Moreover, alcohols, esters and ketones appeared lower in OLG samples, while no significant variations were observed for lactones. These findings suggest the positive role of dietary OL supplementation in the production of goats' milk yogurt, with characteristics potentially indicative of an improvement in nutritional properties and flavor.

Formation of categories from structure-activity relationships to allow read-across for risk assessment: toxicity of alpha,beta-unsaturated carbonyl compounds.

alpha,beta-Unsaturated carbonyl compounds are common environmental pollutants that are able to interact with proteins, enzymes, and DNA through various mechanisms. As such, they are able to stimulate a range of environmental toxicities and adverse health effects. In this study, a "category" of alpha,beta-unsaturated carbonyl compounds (aldehydes and ketones), assumed to act by a common mechanism of action (Michael type addition), was formed. This toxicologically and mechanistically important category was formed on the premise of structure-activity relationships. The acute aquatic toxicities to Tetrahymena pyriformis of compounds within the category were obtained in an effort to develop approaches for (qualitative) read-across. In addition, Salmonella typhimurium (strain TA100) mutagenicity data were analyzed to establish the structural differences between mutagenic and nonmutagenic compounds. These structural differences were compared with the structural characteristics of molecules associated with acute aquatic toxicity in excess of narcosis as well as other end points, for example, skin sensitization. The results indicate that a category can be formed that allows structural information and boundaries to be elucidated. This knowledge will guide future toxicity prediction within this category and assist in the development of category formation.

Urease inhibitory activity of simple alpha,beta-unsaturated ketones.

A variety of alpha,beta-unsaturated ketones were evaluated for their effect on the jack bean urease. Of 35 compounds tested, 2-cyclohepten-1-one (1), 2-cyclohexen-1-one (2), 2-cyclopenten-1-one (3), and 5,6-dihydro-2H-pyran-2-one (4) showed potent inhibitory activities against the enzyme. The most potent compound (1) (IC50=0.16 mM) showed similar inhibitory potency to hydroxyurea (IC50=0.095 mM). The inhibitory effects of 1, 2, 3, and 4 were significantly reduced by 2-mercaptoethanol or dithiothreitol. These data suggest that alpha,beta-unsaturated ketones inhibited the urease activity, possibly by a Michael-like addition of a protein SH group to the double bond of the alpha,beta-unsaturated carbonyl group.

Molecular mechanisms of DNA damage initiated by alpha, beta-unsaturated carbonyl compounds as criteria for genotoxicity and mutagenicity.

alpha, beta-Unsaturated carbonyl compounds are important not only from a theoretical but also a practical standpoint. These ubiquitous compounds can interact with DNA through various mechanisms. The predominant interaction is the formation of cyclic 1,N2-deoxyguanosine adducts; 7,8-cyclic guanine adducts are also found. We have synthesized and characterized the stereoisomers of adducts formed by about 20 alpha, beta-unsaturated carbonyl compounds. The different types of adducts and the mutagenic and genotoxic response can be explained by the molecular structures of the agents. Compounds forming saturated cyclic adducts are mutagenic in S. typhimurium strain TA100 and to a lesser extent in TA1535. Substances with a leaving group at the C-3 position form unsaturated conjugated cyclic adducts and are mutagenic only in the His D3052 frameshift strains with an intact excision repair system (no urvA mutation). Metabolic epoxidation of the double bond and other metabolic activation, e.g., activation of the nitrogroups via nitroreductases, were also found to contribute to genotoxic and mutagenic activities. Our results have further elucidated the genotoxic mechanisms of these compounds; however, additional investigations are required for a complete understanding of the genotoxic activity of this class of compounds.

On robust partial discriminant analysis as a decision-making tool with clinical and analytical chemical data.

Classification is one of the fundamental goals of science and is basic to the diagnosis of disease. Unfortunately, classifying objects (e.g., patients) on the basis of clinical and/or laboratory experimental observations into various groups can be difficult when the groups overlap or contain outlying points. Recently, Broffitt, Randles, and co-workers proposed a procedure, robust partial discriminant analysis (RPDA) for dealing with such problems, but testing of the procedure was limited to Monte Carlo simulation. In this study, RPDA was applied to real data, in order to compare its effectiveness with ordinary discriminant analysis, as well as to determine if RPDA was a suitable procedure to use to classify chemical compounds on the basis of experimental observations and as a tool in the diagnosis of disease (in particular, multiple sclerosis and thyrotoxicosis), with data based on experimental and clinical observations. The resulting RPDA classifications were an improvement over those obtained from ordinary discriminant analysis.

Aliphatic ketones are acetylcholinesterase inhibitors but not transition state analogs.

A number of C4--C9 aliphatic ketones are acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) inhibitors, with Ki values in the 0.7--5 mM range. Comparison to analogous substrates would suggest that these ketones are transition state analogs; e.g. 2-pentanone binds to the enzyme approx. 550 times more tightly than ethylacetate. However, a number of other criteria contradict this conclusions: (1) the binding is insensitive to ketone structure: isomeric ketones, cycloalkanones, and sterically hindered ketones have similar inhibitory potencies. (2) Analogous alcohols are also good inhibitors even though they cannot form hemiketals with the enzyme. (3) Representative ketones are relatively ineffective at blocking inactivation of the enzyme by methylsulfonyl fluoride, indicating that ketones do not bind principally at the hydrolytic site. (4) A competition experiment shows that binding of tetramethylammonium chloride excludes binding of 2-pentanone, suggesting that ketones bind to the anionic rather than the hydrolytic site. Thus, observation of tight binding relative to a substrate is not a sufficient criterion to establish that an inhibitor is a transition state analog.