Luca Lazzeri

Suppressive activity of some glucosinolate enzyme degradation products on Pythium irregulare and Rhizoctonia solani in sterile soil

Glucosinolate degradation products (GLDPs), mainly isothiocyanates, obtained by myrosinase-catalysed hydrolysis of glucosinolates (GLs), are an important group of natural bioactive substances. The fungitoxic activity of four GLDPs, chosen on the basis of their side-chain structures, was assayed against Pythium irregulare and Rhizoctonia solani. The effectiveness of the degradation products (DPs) of sinigrin (alkenyl GL), epi-progoitrin (hydroxy-alkenyl GL), glucoiberin and glucoerucin (thiofunctionalised GLs) in inhibiting P irregulare oospore germination and R solani soil colonisation were tested in a closed system, using an artificially infected soil. The fungitoxic activity of these GLDPs varied according to their side-chain structure. As in previous in vitro studies, the thiofunctionalised GLDPs were found the most effective, producing complete inhibition of P irregulare oospore germination (0.01 µmole g−1 soil) and R solani soil colonisation (0.5 µmole g−1 soil), but even sinigrin DP showed a fungitoxic activity higher than that of epi-progoitrin DP. © 2000 Society of Chemical Industry

Some technological characteristics and potential uses of Crambe abyssinica products

Abstract Two Crambe abyssinica varieties have been cultivated for four years (1990–1993) in the Po valley (Italy), with a spring-time sowing. The seed was analysed for its main quality characteristics, showing an interesting oil (ca. 35%) and protein (26%) content with very homogeneous results in all the trial years. The oil was extracted and characterized determining the fatty acid composition (erucic acid more than 56%), some components of its unsaponifiable matter (sterols and aliphatic alcohols) and its main physical properties (smoke point, saponification number, viscosity). In addition, also studied were the heat removal rates of crambe oil as compared to two commercial mineral oils and to a mixture 1:1 of crambe oil and mineral oil. The results confirm the potential interest of crambe oil in some niches of the lubricating, emulsifying and refrigerating fields. These uses could become still more interesting if one considers the possibility to increase its erucic acid content by biotechnology. Finally, the meal composition, the qualitative and quantitative glucosinolates content, the quality of the hull fiber were also determined and evaluated. The results of this study suggest interesting perspectives in different non-food fields.

Biofumigation for control of pale potato cyst nematodes: activity of brassica leaf extracts and green manures on Globodera pallida in vitro and in soil.

The effects of brassica green manures on Globodera pallida were assessed in vitro and in soil microcosms. Twelve of 22 brassica accessions significantly inhibited the motility of G. pallida infective juveniles in vitro. Green manures of selected brassicas were then incorporated into soil containing encysted eggs of G. pallida. Their effect on egg viability was estimated by quantifying nematode actin 1 mRNA by RT-qPCR. The leaf glucosinolate profiles of the plants were determined by high-performance liquid chromatography. Three Brassica juncea lines (Nemfix, Fumus, and ISCI99) containing high concentrations of 2-propenyl glucosinolate were the most effective, causing over 95% mortality of encysted eggs of G. pallida in polyethylene-covered soil. The toxic effects of green manures were greater in polyethylene-covered than in open soil. Toxicity in soil correlated with the concentration of isothiocyanate-producing glucosinolate but not total glucosinolate in green manures.

Crambe oil ‐ a potential new hydraulic oil and quenchant

The technical properties of Crambe abyssinica oil prompted the co‐operation between a research institute and a lubricant producer to determine some possible industrial applications. The results confirm the special physico‐chemical characteristics of crambe oil which, compared with some vegetable or synthetic oils, shows a higher heat removal capability and interesting lubrication characteristics. The research establishes that crambe oil could be a good hydraulic fluid. These findings led to the cultivation of a suitable area with Crambe abyssinica to obtain a sufficient amount of oil for lubricant formulation on a commercial scale.

Protective effect of Tuscan black cabbage sprout extract against serum lipid increase and perturbations of liver antioxidant and detoxifying enzymes in rats fed a high-fat diet

A diet rich in fat is considered a primary risk factor for CVD, cancer and failures in metabolism and endocrine functions. Hyperlipidaemia generates oxidative stress and weakens antioxidant defences as well as metabolic detoxification systems. Brassicaceae are vegetables rich in glucosinolates and isothiocyanates, affecting enzymatic antioxidant as well as phase II enzymes and conceivably counteracting high-fat diet (HFD)-associated pathologies. The protective role of Tuscan black cabbage (a variety of kale) sprout extract (TBCSE) intake against HFD alterations was here studied. The effects on rat hepatic antioxidant as well as detoxifying enzymes, and serum lipid- and body weightlowering properties of TBCSE, were investigated. Feeding the animals with a HFD for 21 d increased body as well as liver weights, and induced hyperlipidaemia, as confirmed by a higher serum lipid profile v. control diet. Daily intragastric administration of TBCSE to HFD-fed rats lowered serum total cholesterol, TAG and NEFA. Body and liver weight gains were also reduced. Antioxidant (catalase, NAD(P)H:quinone reductase, oxidised glutathione reductase and superoxide dismutase) and phase II (glutathione S-transferase and uridine diphosphate glucuronosyl transferase) enzymes were down-regulated by the HFD, while the extract restored normal levels in most groups. Generation of toxic intermediates, and membrane fatty acid composition changes by the HFD, might account for the altered hepatic antioxidant and detoxifying enzyme functions. The recovering effects of TBCSE could be attributed to high flavonoid, phenolic and organosulphur compound content, which possess free-radical-scavenging properties, enhance the antioxidant status and stimulate lipid catabolism. TBCSE intake emerges to be an effective alimentary strategy to counteract the perturbations associated with a diet rich in fat.

Control of postharvest fungal pathogens by antifungal compounds from Penicillium expansum.

The fungicidal effects of secondary metabolites produced by a strain of Penicillium expansum (R82) in culture filtrate and in a double petri dish assay were tested against one isolate each of Botrytis cinerea, Colletotrichum acutatum, and Monilinia laxa and six isolates of P. expansum, revealing inhibitory activity against every pathogen tested. The characterization of volatile organic compounds released by the R82 strain was performed by solid-phase microextraction-gas chromatographic techniques, and several compounds were detected, one of them identified as phenethyl alcohol (PEA). Synthetic PEA, tested in vitro on fungal pathogens, showed strong inhibition at a concentration of 1,230 μg/ml of airspace, and mycelium appeared more sensitive than conidia; nevertheless, at the concentration naturally emitted by the fungus (0.726 ± 0.16 m g/ml), commercial PEA did not show any antifungal activity. Therefore, a combined effect between different volatile organic compounds produced collectively by R82 can be hypothesized. This aspect suggests further investigation into the possibility of exploiting R82 as a nonchemical alternative in the control of some plant pathogenic fungi.

Native Crambe abyssinica oil and its derivatives as renewable lubricants: an approach to improve its quality by chemical and biotechnological processes

Abstract Crambe abyssinica oil contains more than 55% of erucic acid. The high content of this unsaturated long chain fatty acid seems to be very interesting for some industrial applications, although its high di- and tri-unsaturated fatty acid content (more than 13%) negatively affects its resistance to the oxidative processes. This study describes a characterisation of crambe oil extracted by screw press, solvent extraction and after the refining process. This paper also reports the results regarding the synthesis of some triglycerides with different oleic/erucic acid ratio to evaluate their main technological characteristics (viz. viscosity, cold and oxidative stability, pour point). These properties appeared to be greatly improved and so we propose the possibility of modifying the triglyceride composition of crambe oil by biotechnology. Therefore, a mild technique such as the use of lipolytic enzymes, should improve the quality of crambe oil for all those industrial uses which require a stronger resistance to high oxidative conditions.

A natural fungicide for the control of Erysiphe betae and Erysiphe cichoracearum

This study examines the effects of a vegetable fungicide on sugar beet powdery mildew (Erysiphe betae) and cucumber powdery mildew (Erysiphe cichoracearum). The formulations consisting of a dispersion of Brassicaceae meal in vegetable or mineral oils on infected leaves of sugar beet, reared in the greenhouse, and of musk melons cultivated under plastic tunnels, were tested in comparison to each oil taken separately. Both formulations containing Brassicaceae meals, caused 94% of conidia to be distorted while for the untreated group only 2% were distorted. Furthermore, the leaf area infected by E. betae was 56% for untreated plants and 2.7 and 9.9% respectively, for plants treated with meal containing mineral and vegetable oil. Vegetable oil considered separately or with Brassicaceae meals showed no phytotoxicity, while the formulations based on mineral oil showed a significantly lower fresh and dry weight on tomato plants. The low level or absence of phytotoxicity of plants treated with vegetable oil formulations suggests that to improve the efficacy of powdery mildew control, they could be used mixed with sulphur. The efficiency of the vegetable formulations in the powdery mildew control observed during these trials encourages further investigation on other parasitic fungi and foliar pathogens.

A simple analytical method for dhurrin content evaluation in cyanogenic plants for their utilization in fodder and biofumigation.

Cyanogenic plants have some potential as biocidal green manure crops in limiting several soilborne pests and pathogens. Sorghum (Sorghum bicolor (L.) Moench) and Sudangrass (Sorghum bicolor subsp. sudanense (P.) Stapf), in fact, contain the cyanogenic glucoside p-hydroxy-(S)-mandelonitrile-β-D-glucoside (dhurrin) as a substrate of its secondary defensive system able to release hydrogen cyanide following tissue lesions due to biotic or abiotic factors. Given that dhurrin content is correlated with the biofumigant efficacy of the plants, a high dhurrin content could be a positive character for utilization of sorghum and Sudangrass as biocidal green manure plants. For chemical characterization of the available germplasm, a simple, safe, and accurate method is necessary. In this paper, a new method for dhurrin analysis, based on methanol extraction and high-performance liquid chromatography, is reported and discussed. The feasibility of this analytical procedure was tested by evaluating dhurrin level in roots and stems during cultivation of four different sorghum and Sudangrass varieties in agronomic trials performed in 2008 in the Po valley (Italy). The dhurrin content ranged from 0.16 ± 0.04 to 7.14 ± 0.32 mg g(-1) on dried matter (DM) in stems and from 1.38 ± 0.02 to 6.57 ± 0.09 mg g(-1) on DM in roots, showing statistical differences among the tested germplasms that could be linked to the efficacy of their utilization as biofumigant plants. The method also opens new perspectives for the characterization of sorgum plants as fodder, for which the presence of dhurrin is considered to be negative for its well-known toxicity.

The expression of the Cuphea palustris thioesterase CpFatB2 in Yarrowia lipolytica triggers oleic acid accumulation.

The conversion of industrial by‐products into high‐value added compounds is a challenging issue. Crude glycerol, a by‐product of the biodiesel production chain, could represent an alternative carbon source for the cultivation of oleaginous yeasts. Here, we developed five minimal synthetic glycerol‐based media, with different C/N ratios, and we analyzed the production of biomass and fatty acids by Yarrowia lipolytica Po1g strain. We identified two media at the expense of which Y. lipolytica was able to accumulate ∼5 g L−1 of biomass and 0.8 g L−1 of fatty acids (0.16 g of fatty acids per g of dry weight). These optimized media contained 0.5 g L−1 of urea or ammonium sulfate and 20 g L−1 of glycerol, and were devoid of yeast extract. Moreover, Y. lipolytica was engineered by inserting the FatB2 gene, coding for the CpFatB2 thioesterase from Cuphea palustris, in order to modify the fatty acid composition towards the accumulation of medium‐chain fatty acids. Contrary to the expected, the expression of the heterologous gene increased the production of oleic acid, and concomitantly decreased the level of saturated fatty acids.