Marco Vincenzo Piretti
University of Bologna
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Journal of Phycology | 1997
Marco Vincenzo Piretti; Giampiero Pagliuca; Laurita Boni; Rossella Pistocchi; Maurizio Diamante; Teresa Gazzotti
The marine dinoflagellates Prorocentrum micans, Gonyaulax polyedra, Gymnodinium sp., and Alexandrium tamarense, collected from the Adriatic Sea during red‐tide blooms, were cultured to investigate the 4‐methyl sterol constituents. To ascertain a possible influence of cell age on the 4‐methyl sterol content, for one strain (Gymnodinium sp.)we investigated the composition of these constituents at exponential and stationary growing phases. The lipid material extracted with acetone from the lyophilized algal samples was fractionated by thin‐layer chromatography. The 4‐methyl sterols recovered from the layer were converted into the corresponding OTMS derivatives. Nine of 11 constituents were identified by gas chromatography and gas chromatography‐mass spectrometry; only two minor constituents were characterized by their gas chromatographic parameters. All free methyl sterols identified in the algal samples had been detected previously in various dinoflagellates. The 4‐methyl sterol fractions generally contained very few constituents. Except for the Gymnodinium sp. sample, collected at the exponential growing phase (GyD2 exp), which contains 4,24‐dimethylcholestan‐3‐ol as a unique constituent, dinosterol was the major component. Moreover, 4,24‐ethylcholestan‐3‐ol was also an important constituent of both Prorocentrum and Gonyaulax strains, whereas considerable amounts of dinostanol characterized all the Gymnodinium sp. strains. In addition, the latter contained several minor constituents such as 4‐methylcholestan‐3‐ol, 4,24‐dimethylcholesta‐22‐en‐3‐ol, and 4‐methyl‐24‐ethylcholestan‐3‐ol. 4‐Methyl‐24‐methylene‐cholestan‐3‐ol was a constituent of the Gymnodinium sp. sample, collected at the stationary growing phase (GyD2 stat)only, whereas 4‐methylgorgostanol was identified only in the Alexandrium tamarense Gt4 strain. Except for 4‐methyl‐24‐ethylcholesta‐8(14)‐en‐3‐ol, all the methyl sterol constituents from our algae show a saturated polynuclear system. The pathways by which side‐chain modifications occur in dinoflagellate 4‐methyl sterols are considered, and a map of the fragmentation pattern of the trimethylsilyl‐4‐methyl sterols under electronic impact is also reported.
Comparative Biochemistry and Physiology B | 1988
Marco Vincenzo Piretti; F. Zuppa; Giampiero Pagliuca; F. Taioli
Abstract 1. 1. The seasonal variations in the fatty acid composition of the total lipids were studied in four selected tissues of Scapharca inaequivalvis : gills, I; mantle, II; foot together with digestive diverticula, III and haemolymph, IV. 2. 2. Forty-eight main fatty acids were found. Of these 30 were identified through the mass spectra of the corresponding methyl esters and/or by the increase in the gas chromatographic peak with suitable standards. 3. 3. The remaining fatty acids were characterized exclusively by means of the corresponding ECL values. 4. 4. The constituents identified are those that have normally been found in bivalve molluscs and phytoplankton. 5. 5. The qualitative composition of the fatty acid mixtures from I, II and III is very similar and clearly differs from that of IV. 6. 6. Fluctuations in the percentages of the single constituents were observed over the course of the year. 7. 7. A percentage increase in the unsaturated constituents was noted in the cold months. 8. 8. The percentage composition variations in the fatty acids from the lipid extracts of the different tissues and from the whole organism would seem to be linked to the feeding—growth, nonfeeding—maturation cycle of the mollusc.
Annals of the New York Academy of Sciences | 1988
L. Masotti; Emanuela Casali; Nicola Gesmundo; Giorgio Sartor; Tommaso Galeotti; Silvia Borrello; Marco Vincenzo Piretti; Giampiero Pagliuca
Our studies on the biochemical composition and the structural organization of smooth and rough endoplasmic reticulum isolated from Morris hepatomas 9618A and 3924A confirm the results obtained employing the total microsomal fraction. We have definitely established the following facts: (1) Tumor subcellular organelles exhibit the very low degree of peroxidizability that has been shown to be related to the growth rate of the tumor. (2) Associated with such a low susceptibility to peroxidation are (a) changed lipid composition of cellular membranes, whose content in polyunsaturated fatty acid is markedly decreased, and (b) changed static and dynamic properties of the membrane. Previously it was also found that cellular oxy-radical scavenging enzymes are markedly reduced. From these data, it is possible to infer that tumor membranes are altered structurally and functionally in part as the result of an oxy-radical-induced damage that occurs in vivo under conditions of oxygen toxicity. This seems to be supported by recent findings that the spontaneous increase in growth rate of the originally very slow-growing Morris hepatoma 9618A results also in the loss of cytochrome P-450 (an important intramembraneous propagator of lipid peroxidation) as well as of C20:4 and C22:6. Studies performed by GLC and GC-MS on the fatty acid residues of phospholipids of rat liver microsomes show the presence of C20:3-OH and C18:1-OH, but no hydroxyl derivatives of low molecular weight aldehydes. The hydroxyl derivatives of arachidonic acid and linoleic acid are present in much smaller amounts in the microsomes isolated from H9618A and H3924A.
Journal of Essential Oil Research | 1997
Zsuzsa Récsán; Giampiero Pagliuca; Marco Vincenzo Piretti; L. Pénzes; Kuresh A. Youdim; Raymond C. Noble; Stanley G. Deans
Abstract A study has been made on the effects of the dietary administration of a selection of volatile oils from medicinal plants on the polyunsaturated fatty acid composition in the retina of aged (28 month old) rats. Polyunsaturated fatty acids comprised by far the major proportion of the total unsaturated content within the retinal phospholipids with docosahexaenoic acid predominating. The administration daily of 3-9 mg of the essential oils from clove, nutmeg, pepper and thyme over a period of 17 months resulted in the maintenance of very much higher levels of polyunsaturated fatty acids, in particular docosahexaenoic acid, within the retinal phospholipids. This increase occurred mainly at the expense of a reduction in the level of oleic acid. The possible efficacy for the application of the oils from such medicinal plants through their antioxidant capacities in the prevention of age-related macular degeneration is discussed.
Chemistry and Physics of Lipids | 1988
Marco Vincenzo Piretti; Giampiero Pagliuca; Marco Vasina
Abstract The chemism of the transmethylation of neutral and/or polar glycerides, carried out using methanolic NaBH 4 in the presence of 2N NaOH added, is discussed. One millilitre of the reagent proposed here enables quantitative transmethylation of 2 mg of neutral lipid and up to 300 mg of polar lipid. The reaction is complete within 20 min at room temperature. This reagent seems particularly useful for the study of the fatty acid composition of high unsaturated lipids or when studying the structure of lipid oxidation products.
Comparative Biochemistry and Physiology B | 1987
Marco Vincenzo Piretti; F. Taioli; Giampiero Pagliuca
Abstract 1. 1. An investigation was carried out on the bivalve molluscs Venus gallina and Scapharca inaequivalvis (Bruguiere) with the aim of evaluating the seasonal variations of the sterols and of the fatty acids present in the lipid fraction. 2. 2. The samples were collected monthly from the Adriatic Sea, near Cesenatico, at a distance of approx. 500 m from the shore, where the water is approx. 3.5–4 m deep, the average salinity is approx. 31% and the temperature of the water goes from a minimum of roughly 8°C in the winter up to a maximum of approx. 24°C in the summer. 3. 3. The sterols, as well as the fatty acids, extracted from the tissues of V. gallina are practically the same as those isolated from the tissues of S. inaequivalvis and coincide with those found previously in other bivalve molluscs. 4. 4. This confirms the close link between the lipid fraction of the molluscs and their diet, which in this area consists mainly of bentonic diatoms or, alternatively, of plantonic dinoflagellates that have settled on the sea-bed. 5. 5. Some quantitative variations occurring in the composition of the constituents analysed would seem to depend more on internal factors, typical of the two different species of bivalve molluscs, rather than on different diet.
Comparative Biochemistry and Physiology B | 1976
Marco Vincenzo Piretti; R. Viviani
Abstract 1. 1. The procedure used for the extraction of the constituent sterols from Venus gallina was aimed at allowing, at the same time, the extraction of possible non-lipidic constituents, such as the polyphenols flavanoids and flavonoids. The presence of these substances in the mollusc has not, however, been detected. 2. 2. The constituent sterols of Venus gallina, identified by the mass spectra of the corresponding acetyl derivatives, are practically the same as those previously characterized in other bivalve molluscs. As result from the obtained values: 24-norcholesta-5,22-diene-3-ol (3,2%); cholesta-5,22-diene-3-ol (13,1%); cholest-5-ene-3-ol (55,1%); 24-methylcholesta-5,22-diene-3-ol (11,0%); 24-methylenecholest-5-ene-3-ol (13,0%); 24-ethylcholesta-5,22-diene-3-ol (2,2%); 24-ethylcholest-5,22-diene-3-ol (2,4%), the percentage composition, instead, is considerably different from that which seemed to characterize this class of molluscs. 3. 3. In Venus gallina the C27 sterols are the principal constituents (68%), whereas the C28 sterols together constitute 24%.
Free Radical Biology and Medicine | 1989
Marco Vincenzo Piretti; Giampiero Pagliuca
This report discusses the analytical procedure by which it is possible to isolate and identify the oxidation products of cellular and subcellular membrane lipids. The key point of this procedure is the method used for the transmethylation of the lipid material isolated from the tissues. In effect, both the conversion of the glycerides into methyl esters and the reduction of the hydroperoxyl groups into the corresponding hydroxyl groups is performed in one step, without breaking any oxirane rings that may be present. The methyl esters containing functional groups introduced by oxidative processes are separated from the non-modified ones by preparative TLC and are identified by GLC and GC-MS.
Comparative Biochemistry and Physiology B | 1982
Marco Vincenzo Piretti; G.P. Serrazanetti; R. Viviani
Abstract 1. 1. The sterols found in the tissues of Scapharca inaequivalvis are all 3-β-hydroxysterols. The various constituents were identified on the basis of the respective retention times (relative to acetyl cholesterol) and on the basis of the mass spectra of the corresponding acetyl derivatives. 2. 2. The following seven constituents have been found in all tissues : 24-norcholesta-5,22-dien-3-β-ol; cholesta-5,22-dien-3-β-ol; cholest-5-en-3-β-ol; 24-methylcholesta-5,22-dien-3-β-ol; 24-methylenecholest-5-en-3-β-ol; 24-ethylcholesta-5,22-dien-3-β-ol; 24-ethylcholest-5-en-3-β-ol. 3. 3. The various sterol mixtures extracted from the different tissues differ quantitatively: the gills and the mantle contain lower sterol quantities than the foot and the digestive diverticula, while the sterol content of the haemolymph is even higher. 4. 4. In all S. inaequivalvis tissues the C 27 sterols are the principal constituents (44–56%), the C 28 sterols are present in lower amounts (33–39%), and cholesterol is the major constituent (31–43%).
Comparative Biochemistry and Physiology B | 1982
G.P. Serrazanetti; O. Cattani; Marco Vincenzo Piretti
Abstract 1. 1. An investigation was carried out on the constituent sterols of the Idotea halthica basteri (Audoin) shrimp. The specimens analyzed were collected in the Adriatic Sea at Cesenatico (Forli, Italy) in June 1980. 2. 2. The only measurable component contained in the sterol fraction is cholesterol. The following minor acetylated constituents were isolated by thin layer argentation chromatography of an acetylated portion of the extract: cholesta-5,22-dien-3-β-ol; cholesta-5,24-dien-3-β-ol; 24-methylenecholest-5-en-3-β-ol and 24 ethylidenecholest-5-en-3-β-ol. These compounds were identified by the corresponding mass spectrum and by the respective retention time relative to acetylated cholesterol. 3. 3. The sterol content of the analyzed specimens was equal to 1.9 g/kg of whole crustaceans. 4. 4. The presence of 24-ethylidenecholest-5-en-3-β-ol and of cholest-5,24-dien-3-β-ol intermediates in the dealkylation process of the 24-ethylsterols, allows us to assume that the cholesterol found in the shrimp comes from algaeic phytosterols introduced into the shrimp with its diet.