Gerardo Palla

Conformational behaviour and E/Z isomerization of N-acyl and N-aroylhydrazones

Abstract The stereochemical behaviour of N -acyl and N -aroylhydrazones of aromatic aldehydes, of pyruvates and of acetone, in polar and less polar solvents, has been studied by HPLC and by NMR techniques. Z/E Geometrical isomers and cis / trans amide conformers have been found for N -acylhydrazones, while for N -aroylhydrazones only geometrical isomers were detected. Energy barriers of isomers are reported, and solvent effects are discussed with regard to hydrogen bond interactions.

Characterisation of Italian Vinegar by Pyrolysis-Mass Spectrometry and a Sensor Device (Electronic Nose).

Abstract Industrially made vinegar ‘Aceto Balsamico di Modena’ and traditionally produced vinegar ‘Aceto Balsamico Tradizionale di Modena e di Reggio Emilia’ were analysed by means of pyrolysis–mass spectrometry (Py–MS) and a sensor technique (‘electronic nose’). Both methods allow a fast classification (typically about 5 min). While the ‘electronic nose’ is analysing the volatile compounds of the samples simultaneously with 32 sensors, Py–MS applies thermal decomposition of the samples, subsequently analysing the pyrolysate with a mass spectrometer. Both techniques were demonstrated to be capable of discriminating between the two groups of vinegar. Although the number of samples available for this study did not seem to be sufficient for detailed analysis, both methods indicated possible discrimination of the samples within the group of ‘Aceto Balsamico Tradizionale di Modena’ regarding the age of the sample.

The potential of enantioselective analysis as a quality control tool

Many food components are chiral: some are present as optically pure enantiomers, others are present in specific enantiomeric ratios. The enantiomeric ratio of some compounds, such as amino acids, can be affected by thermal treatments, fermentation and ageing. In the case of flavours, the enantiomeric ratio can be modified by the addition of synthetic racemic ingredients (adulteration). Enantiomers generally have different organoleptic properties, and may have different metabolic fates. The availability of highly sensitive chromatographic methods for chiral discrimination allows the determination of most enantiomers in foods. Thus, the enantiomeric ratio of food components is a reliable parameter to assess quality because it may be indicative of a technological process, contamination, adulteration, ageing and shelf life.

Aroylhydrazones as chelating agents: d10-metal complexes of pyridine-2-carbaldehyde salicyloylhydrazone and x-ray structure of the zinc derivative

Abstract The title organic ligands (Hsip) gave, by reaction with d10-metal acetates, complexes of the type M(sip)2 (M = Zn, Cd, Hg), in which the ligand behaved as terdentate, producing a distorted octahedral environment around the metal. The 1H and 13C chemical shifts found for these complexes in DMSO are compared with the corresponding ones of the free ligand. The crystal structure of the zinc derivative has been determined from diffractometer data to R = 0.072 for 1086 independent reflections. Crystals are monoclinic, space group C2/c, with unit-cell dimensions a = 18.193(2), b = 24.532(6), c = 11.535(2) A,β = 103.71(1)° and Z = 8. Coordination occurs through the carbonyl oxygens (Zn−O = 2.10, 2.16(1) A), the azomethine nitrogens (Zn−N = 2.04, 2.07(1) A) and the pyridine nitrogen s(Zn−N = 2.24, 2.26(1) A).

Occurrence of D-amino acids in food : Detection by capillary gas chromatography and by reversed-phase high-performance liquid chromatography with L-phenylalaninamides as chiral selectors

Abstract The presence of D -amino acids was investigated in dairy products, in raw ham and in roasted coffee. The analysis was carried on by capillary gas chromatography, using a very stable tetraamidic selector derived from L -phenylalanine, which allowed the detection of D -alanine, D -aspartic acid, D -glutamic acid and other D -amino acids. Moreover, D -glutamic acid and D -alanine were detected also by reversed-phase high-performance liquid chromatography, using L -phenylalaninamide and copper(II) acetate as chiral additives to the eluent. The presence of D -amino acids may be ascribed to thermal racemization or to microbial activity.

A simple GC–MS method for the screening of betulinic, corosolic, maslinic, oleanolic and ursolic acid contents in commercial botanicals used as food supplement ingredients

The occurrence of triterpene pentacyclic acids in plants is extensive, but little is known about their availability in commercial extracts. A simple GC-MS method for the simultaneous determination of betulinic, corosolic, maslinic, oleanolic and ursolic acids was developed and applied to 38 different commercial plant extracts sold as ingredients for dietary supplements. A suitable protocol was set up to perform routine control of a diverse array of samples with different botanical, chemical and physical characteristics. Remarkable quantities of corosolic acid were found in dried extracts from aerial parts of Lagerstroemia speciosa and Ortosiphon stamineus (14233 and 1132 mg/kg, respectively), while oleanolic acid was abundant in O. stamineus and Crataegus monogyna flowers (2774 and 2339 mg/kg); ursolic was identified in O. stamineus, C. monogyna, L. speciosa and Arctostaphylos uva-ursi leaves (7773, 4165, 2108 and 1034 mg/kg). Only L. speciosa was rich in maslinic acid (4958 mg/kg), while minor amounts of betulinic acid (257 and 80 mg/kg) were detected in L. speciosa and C. monogyna extracts. Lower quantities of triterpenic acids were identified in dried extracts of Harpagophyton procumbens root, propolis, Punica granatum root, Styrax benzoin, Vaccinium myrtillus fruits and Vitis vinifera seeds. Decoctions and fluid extracts lacked or contained very low amounts of triterpenic acids. Results are discussed in terms of quality and safety of these ingredients.

The species-specific ratios of 2,3-butanediol and acetoin isomers as a tool to evaluate wine yeast performance

The isomers of 2,3-butanediol [R,R; S,S; R,S (meso-form)] and of acetoin (R,S) were determined in laboratory wine fermentations carried out by 50 yeast strains, 10 for each of the following species, Saccharomyces cerevisiae, Kloeckera apiculata, Candida stellata, Metschnikowia pulcherrima and Brettanomyces bruxellensis, in order to evaluate if such parameters might be used to differentiate wines obtained with different yeast species. According to analysis of variance (ANOVA), the strains of the same species behaved similarly, whereas the five yeast species behaved differently so that species-specific profiles were recognized. Moreover, the discriminant analysis grouped the wines into five groups, each including the 10 wines obtained by the 10 yeast strains of the same species. Trials were also included where musts partially fermented by non-Saccharomyces species were inoculated with a selected strain of S. cerevisiae to complete fermentation, and the content in 2,3-butanediol and acetoin isomers was again determined and statistical analysis was performed. Although the final values of these parameters resembled those obtained in pure fermentation with S. cerevisiae, statistical analysis discriminated wines according to the yeast species performing the first fermentation phase.

Synthesis and characterization of new indole trimers and tetramers

Abstract A new method has been achieved to synthesize indole trimers and tetramers starting from indoles and 3-bromoindoles. Unusual open and cyclic trimers have been isolated and characterized, and the mechanism of formation is proposed.

Concentration of DL-PCBs in fish from market of Parma city (north Italy): estimated human intake.

The concentrations of 12 congeners of non-ortho and mono-ortho dioxin-like polychlorinated biphenyls (ΣDL-PCB) were measured in 30 fish samples from Parma markets by GC/MS technique. The samples were randomly purchased, choosing the species commonly found in supermarkets. The concentration of DL-PCBs estimated remained under the fixed Italian limit of 4 pg g(-1)ww WHO-TEQ (World Health Organization-Toxic Equivalent) in the major part of the samples, so the situation seems to be not at a level sufficient to pose a risk to human health of the Parma population. The medium daily intake for DL-PCBs for Italian consumers (Parma) was also estimated. This value generally resulted minor than 2 pg g(-1) ww WHO-TEQ kg(-1) body weight, exceeding only in four cases: eel, smooth hound, starry smooth hound and tuna.

1H NMR study of fermented cocoa (Theobroma cacao L.) beans.

This study reports for the first time the metabolic profile of cocoa (Theobroma cacao L.) beans using the (1)H NMR technique applied to polar extracts of fermented cocoa beans. The simultaneous detection and quantification of amino acids, polyalcohols, organic acids, sugars, methylxanthines, catechins, and phenols were obtained by assigning the major signals of the spectra for different varieties of cocoa beans (Forastero, Criollo, and Trinitario) from different countries (Ecuador, Ghana, Grenada, and Trinidad). The data set obtained, representative of all classes of soluble compounds of cocoa, was useful to characterize the fermented cocoa beans as a function of the variety and geographic origin.