Raffaella Boggia

Transfer of calibration function in near-infrared spectroscopy

Abstract A procedure for the transfer of the regression equation in near-infrared spectroscopy (NIRS), from a first instrument to a second instrument, is presented. The procedure uses partial least squares (PLS) regression twice: in the first step to compute the relationship between the spectra of transfer samples of the two instruments, and in the second step to compute the regression equation (relationship between chemical variables and spectral variables) of the first instrument. These two PLS steps are combined to predict the regression equation of the second instrument. Sometimes the PLS relationship between the two instruments is obtained from the principal components of the spectra of the two instruments. The procedure is applied to a set of 60 samples of soy flour, representative of the Italian soy production. 40 samples were used both as transfer samples and to compute the regression equation. 20 samples were used as evaluation set. Spectra were recorded with four different instruments, in four different laboratories. The result of the transfer procedure were evaluated by means of the standard error of prediction ( SEP ) with the predicted regression equation. Owing also to the great number of samples in the transfer set, and to the noise filtering effect of the twin PLS procedure, SEP with the predicted regression equation is not greater than that with the regression equation computed directly from the second instrument. The effect of some parameters, such as the number of PLS latent variables in the two steps, is also studied.

Phytochemical fingerprint and chemometrics for natural food preparation pattern recognition: an innovative technique in food supplement quality control.

Recently, the fingerprint approach using chromatography has become one of the most effective tools for quality assessment of herbal medicines and food supplements: due to the complexity of the chromatographic fingerprint and the irreproducibility of chromatographic instruments and experimental conditions, chemometric approach is employed to deal with the chromatographic fingerprint. The study was aimed at developing new analytical methods for the multivariate phytochemical fingerprinting of bioactive compounds in eight tree-species bud-preparations, commonly used in phytotherapy. Methods was used to identify and quantify the main bioactive compounds (polyphenols, organic acids and vitamins), and obtain a specific botanical profile in order to assess the contribution of each single bioactive class to the total bud preparation phytocomplex. A chemometric approach was used to distinguish among different genotypes assuring the identity, safety and quality of the botanical raw materials. The established protocol was simple, sensitive and reliable and it could be used for the evaluation and quality control of bud-extracts and natural food supplements: the proposed method was successfully applied to the characterization of commercial bud-preparations, demonstrating to be an effective tool for the fingerprinting of this plant material. The new approach developed in this study represents a good alternative for improving the classification results of herbal materials with complex chromatograms. It should be necessary to develop a “multivariate chromatographic fingerprint”, in order to differentiate the herbal preparations according to their genotype, avoiding substitutions, changes or adulterations with other species or synthetic drugs.

3-Acetyl-5-acylpyridin-2(1H)-ones and 3-acetyl-7,8-dihydro-2,5(1H,6H)-quinolinediones: synthesis, cardiotonic activity and computational studies

A series of milrinone analogues, namely 6-substituted 3-acetyl-5-acylpyridin-2(1H)-ones 4a-c, e, f and 7-substituted or unsubstituted 3-acetyl-7,8-dihydro-2,5(1H,6H)-quinolinediones 4g-j, in which the cyano group was replaced by the acetyl function, was prepared. In a preliminary pharmacological investigation on spontaneously beating atria from reserpine-treated guinea-pigs, all new compounds did not induce any inotropic effect equivalent or higher than that of the milrinone chosen as the reference compound. In order to rationalise how the structure modifications influence the activity and the selectivity of the title compounds, a computational study has been performed. The important role of the substituents in positions-3 and -6 on the pyridone nucleus has been highlighted.

A screening method based on UV–Visible spectroscopy and multivariate analysis to assess addition of filler juices and water to pomegranate juices

Consumer demand for pomegranate juice has considerably grown, during the last years, for its potential health benefits. Since it is an expensive functional food, cheaper fruit juices addition (i.e., grape and apple juices) or its simple dilution, or polyphenols subtraction are deceptively used. At present, time-consuming analyses are used to control the quality of this product. Furthermore these analyses are expensive and require well-trained analysts. Thus, the purpose of this study was to propose a high-speed and easy-to-use shortcut. Based on UV-VIS spectroscopy and chemometrics, a screening method is proposed to quickly screening some common fillers of pomegranate juice that could decrease the antiradical scavenging capacity of pure products. The analytical method was applied to laboratory prepared juices, to commercial juices and to representative experimental mixtures at different levels of water and filler juices. The outcomes were evaluated by means of multivariate exploratory analysis. The results indicate that the proposed strategy can be a useful screening tool to assess addition of filler juices and water to pomegranate juices.

Validation procedures in near-infrared spectrometry

Abstract Three validation procedure, single evaluation set, cross-validation and repeated evaluation set, were tested on near-infrared spectrometric data to evaluate the predictive residual standard deviation and the complexity of the regression model based on partial least-squares (PLS) regression. Thirty-six combinations of response variables and predictor variables (originating from three response variables and spectra recorded on the same 60 samples in four laboratories with different instruments) were tested. Each validation method was used with several different percentages of objects in the evaluation sets, from very low percentages (leave-one-out) to 33%. The results show that the frequently used technique of the single evaluation set gives a bad estimate both of the residual standard deviation and of the complexity of PLS model. Cross-validation gives acceptable estimates when at least ten cancellation groups are used. The validation technique based on the repeated evaluation set, with a large number of repetitions of prediction, gives excellent estimates of residual standard deviation and of model complexity, but it requires a very long computing time.

Direct GC-(EI)MS determination of fatty acid alkyl esters in olive oils.

A new analytical method for fatty acid alkyl esters (FAAEs) determination by GC-MS in virgin olive oils is proposed. No sample preparation is required and FAAEs are directly thermo-desorbed and cryo-focalised in the cooled injector of a GC-MS (EI) instrument. The analytical conditions were optimized by Design of Experiment (DoE) techniques (an exploratory Plackett-Burman design followed by a factorial design on three selected variables). After the improvement of method performances, several samples of extra virgin and low quality virgin olive oils were analyzed both by the new method and by the Official EU Method of analysis. The application of Principal Component Analysis to the obtained results confirmed that the ability of the proposed method to discriminate between extra virgin and lower quality olive oils is at least equal to that of the Official Method, but the new method is faster, simpler, requires a much lower amount of organic solvents and significantly enhances method repeatability.

Toward the identification of the cardiac cGMP inhibited-phosphodiesterase catalytic site

Cyclic nucleotide phosphodiesterases (PDEs) comprise a complex group of enzymes; five major PDE families or classes with distinctive properties have been identified. Among these a great deal of interest has recently been focused on the so called cGMP-inhibited low Km cAMP phosphodiesterase (cGI PDE) or PDE III. A number of positive inotropic agents, including the well-known milrinone, display a specific inhibition of PDE III as primary mechanism of action. Recent studies have been carried out to develop a pharmacophore model of the PDE III active site. We therefore performed molecular modelling and 3D-SAR studies so as to better define structural requirements for potent and selective enzymatic inhibition. The DISCO (DIStance COmparison) strategy has been applied on a set of compounds taken from literature and a milrinone analogue previously synthesized by us, all of which are characterized by a marked inotropic effect but with varying degrees of enzyme selectivity. A common pharmacophoric model was derived, validated and considered as starting point to perform a 3D-SAR study using the GRID force field and PCA (Principal Component Analysis) with the aim of rationally designing more selective inhibitors. This paper presents the results of this theoretical approach.

DNA–psoralens molecular recognition using molecular dynamics

Furocoumarins are an important class of compounds for photochemotherapy used in the treatment of numerous diseases characterised by hyperproliferative conditions. Their photosensitising activity has been related to the ability to form covalent linkage with the pyrimidine bases of DNA upon UV-A irradiation. Using the published experimental data of the 3D-structure of the furan-side monoadduct between the 4′-(hydroxymethyl)-4,5′,8-trimethylpsoralen and the DNA oligonucleotide d(GCGTACGC)2 as starting point, a computational procedure to study the dark intercalation complexes by molecular dynamics was built and then preliminary validated on another psoralen. This docking procedure provides a tool to better understand the mechanism of the DNA-intercalation of these linear furocoumarins and it can be useful in the design of new photochemotherapeutic agents with an improved therapeutic profile.

Green Extraction from Pomegranate Marcs for the Production of Functional Foods and Cosmetics.

The aim of this study was to investigate the potential of retrieving polyphenolic antioxidants directly from wet pomegranate marcs: the fresh by-products obtained after pomegranate juice processing. These by-products mainly consist of internal membranes (endocarp) and aril residues. Even if they are still edible, they are usually discharged during juice production and, thus, they represent a great challenge in an eco-sustainable industrial context. Green technologies, such as ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE), have been employed to convert these organic residues into recycled products with high added value. UAE and MAE were used both in parallel and in series in order to make a comparison and to ensure exhaustive extractions, respectively. Water, as an environmentally friendly extraction solvent, has been employed. The results were compared with those ones coming from a conventional extraction. The most promising extract, in terms of total polyphenol yield and radical scavenging activity, has been tested both as a potential natural additive and as a functional ingredient after its incorporation in a real food model and in a real cosmetic matrix, respectively. This study represents a proposal to the agro-alimentary sector given the general need of environmental “responsible care”.

Optimization of the Ultrasonic-Assisted Extraction of Phenolic Compounds from Oryza Sativa L. ‘Violet Nori’ and Determination of the Antioxidant Properties of its Caryopses and Leaves

‘Violet Nori’ is a new spontaneous growing violet rice variety showing a peculiar violet color in its fresh leaves as well. In this paper, the antioxidant properties and the content of total phenols, radical scavengers, and anthocyanins in ‘Violet Nori’ caryopses, flour, and leaves are explored and compared. Ultrasonic-Assisted Extraction (UAE) is employed for the extraction of phenolic compounds, improving the extraction conditions by Design of Experiments (DoE). The obtained results show that the Radical Scavenging Activities (RSAs), the Total Phenolic Contents (TPCs), and the anthocyanin amounts (1000–1500 μg/g, expressed as cyanidin-3-glucoside) of ‘Violet Nori’ caryopses are higher than those in the other analyzed colored rice samples (300–900 μg/g as cyanidin-3-glucoside), with the exception of the cultivars ‘Artemide’ and ‘Nerone’, which show comparable values of RSAs and TPCs. The study of ‘Violet Nori’ leaves at different plant maturation stages shows that their anthocyanin content is 2–3 times higher than in the caryopses and in the flour, reaching the highest levels at about 60 days from seeding. Thus, the estimated extraction yield of 4 kg anthocyanins/t makes fresh leaves very interesting for the extraction of anthocyanins on an industrial scale, whereas violet caryopses are a very interesting dietetic source of valuable anthocyanins and other antioxidant compounds.