Vittorio Vinciguerra

Oxirane-immobilized Lentinula edodes laccase: stability and phenolics removal efficiency in olive mill wastewater.

Immobilization of Lentinula edodes laccase on Eupergit C increased pH, thermal and proteolytic stability with slight modifications in laccase oxidation efficiency. Immobilized laccase proved to be efficiently stable in removing olive mill wastewater phenolics.

Characterization of immobilized laccase from Lentinula edodes and its use in olive-mill wastewater treatment

This study is mainly concerned with the characterization of an immobilized laccase from the white-rot fungus Lentinula edodes for use in wastewater treatment. The enzyme was immobilized on chitosan by adsorption and subsequent cross-linking with glutaraldehyde. The immobilized laccase displayed a lower specific activity and a lower substrate affinity than the free enzyme. Nevertheless, the immobilized catalyst exhibited an appreciable catalytic capability (520 units g−1 support) along with remarkably improved stability properties to various parameters, such as temperature, pH and storage time. The treatment of olive mill wastewater with immobilized laccase led to a partial decolorization as well as to significant abatements in its content in polyphenols, ortho-diphenols combined with a decreased toxicity of the effluent.

Correlated effects during the bioconversion of waste olive waters by Lentinus edodes

Waste-olive-waters arising from the solid-liquid processing system were degraded in agitated liquid cultures of the white-rot fungus Lentinus edodes. About 45% of biodecolouration and 75% of total organic carbon reduction were achieved within 4 days. Over the same period, the content of total phenols was reduced by 66%. The release of exo-enzymes involved in the metabolism of phenolic compounds (phenol-oxidases and Mnperoxidase) was greatly enhanced with respect to the control. A highly-significant correlation was observed between decolourization, total organic carbon and total phenols.

Antimicrobial isoflavanones from Desmodium canum.

Bioassay-directed fractionation of Desmodium canum resulted in the isolation and characterization of three antimicrobial isoflavonones. These compounds, namely, desmodianones A, B and C, were assigned the structures 5,7,2-trihydroxy-6,6-dimethyl-6-(4-methylpent-3- enyl)pyrano(2,3;4,5)isoflavanone, 5,2,4-trihydroxy-7-methoxy-6-methyl-8-(3-methylbut-2-enyl)-is oflavanone, and 5,7,2,4-tetrahydroxy-6-methyl-5-(3,7-dimethylocta-2,6-dienyl )-isoflavanone, respectively.

Three isoflavanones with cannabinoid-like moieties from Desmodium canum

Three further derivatives of 5,7,2,4-tetrahydroxy-6-methyl isoflavanone have been isolated from the root extract of Desmodium canum and assigned the structures 2,3-dihydro-5,7-dihydroxy-6-methyl-3-(1a,2,3,3a,8b,8c-hexahydro-6-hydroxy-1,1,3a-trimethyl-1H-4-oxabenzo[f]cyclobut[c,d]inden-7-yl)-4H-1-benzopyran-4-one (1) 2,3-dihydro-5,7-dihydroxy-6-methyl-3-(6a,7,8,10a-tetrahydro-3-hydroxy-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-2-yl)-4H-1-benzopyran-4-one (2) 2,3-dihydro-5,7-dihydroxy-6-methyl-3-(3-hydroxy-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-2-yl) 4H-1-benzopyran-4-one (3). The three compounds and the previously isolated chromene 4 all derive from the geranylated precursor 5 by a series of cannabinoid-like oxidative rearrangements.

Biotransformation of tyrosol by whole-cell and cell-free preparation of Lentinus edodes

Abstract The phenolic components of waste olive waters are degraded by the white-rot basidiomycete Lentinus edodes. Tyrosol is converted by cell-free preparation of the fungus into a dimeric tetracyclic ketone, derived from a Pummerers ketone-like intermediate. Conversely, the alcohol corresponding to the above ketone was isolated after 7 days from whole cells of Lentinus edodes incubated with tyrosol.

4-Arylcoumarins from Coutarea hexandra

Abstract The structures of two neoflavonoids, isolated from a benzene extract of Coutarea hexandra have been established as 3′-hydroxy-5,7,8,4′-tetramethoxy-4-phenylcoumarin and 8,3′-dihydroxy-5,7,4′-trimethoxy-4-phenyl-coumarin. The substitution pattern of 8,3′,4′-trihydroxy-5,7-dimethoxy-4-phenylcoumarin, also isolated, was also confirmed by chemical reactions.

Studies in Cell Suspension Cultures of Cassia didymobotrya. Part III. The Biotransformation of Chalcones to Flavones and Biflavanones

Older (29 day) cell cultures of Cassia didymobotrya are shown to possess enzymes which can effectively catalyze the conversion of chalcones to flavone and novel biflavanone products. The substrates 2,4,4-trihydroxychalcone and 3-methoxy-2,4,4-trihydroxychalcone were evaluated in terms of bioconversion yields versus time of incubation, and the effect, if any, of H 2 O 2 and horseradish peroxidase on such bioconversions

Assessment of the energy needs for the arsenic remediation of drinking water by electrodialysis

AbstractIn this work, three different arsenic-rich well waters from the territory of Viterbo (Italy) were processed via electrodialysis (ED) to remove arsenic. These waters having different chemico-physical parameters (i.e. pH, electric conductivity, main anion and cation, as well as arsenic, concentrations) were preliminarily submitted to limiting current tests to determine the electric current to be applied in constant-current batch desalination trials by using a laboratory-scale electrodialyzer. Arsenic removal was non-selective, its percentage removal (ρAs) being about 71% of the desalination degree (DD) achieved (i.e. 80–85%) at the end of any batch desalination. The specific energy consumption (w) was found to be linearly related to DD in the range of 71–75xa0Wxa0hxa0m−3. Thus, contrary to generally accepted belief, arsenic removal by ED resulted to be by far less energy intensive than reverse osmosis, its specific energy consumption being almost of the same order of magnitude as that associated with the ...

Studies in Cell Suspension Cultures of Cassia didymobotrya. Part II. The Biotransformation of Chalcones to Flavonones

An enzyme system derived from cell cultures of Cassia didymobotrya showed, inter alia, a chalcone - flavanone isomerase which revealed a maximum activity when isolated from 22 day old cultures. Its substrate specificity was demonstrated by using sixteen chalcones featuring different substitutions patterns in rings A and B