The trend to search novel microbial natural biocides has recently been increasing in order to avoid the environmental pollution from use of synthetic pesticides. Among these novel natural biocides are the bioactive secondary metabolites of Burkholderia gladioli pv. agaricicola (Bga). The aim of this study is to determine antifungal activity of Bga strains against some phytopathogenic fungi. The fungicidal tests were carried out using cultures and cell-free culture filtrates against Botrytis cinerea, Aspergillus flavus, Aspergillus niger, Penicillium digitatum, Penicillium expansum, Sclerotinia sclerotiorum and Phytophthora cactorum. Results demonstrated that all tested strains exert antifungal activity against all studied fungi by producing diffusible metabolites which are correlated with their ability to produce extracellular hydrolytic enzymes. All strains significantly reduced the growth of studied fungi and the bacterial cells were more bioactive than bacterial filtrates. All tested Bulkholderia strains produced volatile organic compounds (VOCs), which inhibited the fungal growth and reduced the growth rate of Fusarium oxysporum and Rhizoctonia solani. GC/MS analysis of VOCs emitted by strain Bga 11096 indicated the presence of a compound that was identified as 1-methyl-4-(1-methylethenyl)-cyclohexene, a liquid hydrocarbon classified as cyclic terpene. This compound could be responsible for the antifungal activity, which is also in agreement with the work of other authors.

Abstract:The Paternò-Büchi reaction is a photochemical reaction between a carbonyl compound and an alkene to give the corresponding oxetane. In this review the mechanism of the reaction is discussed. On this basis the described use in the reaction with electron rich alkenes (enolethers, enol esters, enol silyl ethers, enanines, heterocyclic compounds has been reported. The stereochemical behavior of the reaction is particularly stressed. We pointed out the reported applications of this reaction to the synthesis of naturally occuring compounds.

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This research was carried out to study antibacterial activity of 4 strains of pv. () against G+ve and G-ve, haemolytic activity against the cell membrane of erythrocytes, the production of extracellular hydrolytic enzymes and finally, the pathogenicity against flesh blocks. Chemical structure of bioactive substances of the most bioactive strain (ICMP 11096) was established using gas chromatography-mass spectrometry (GC-MS). All the studied strains inhibited the growth of the two tested bacteria although some growing substrates negatively influenced the antimicrobial substance production. The same strains showed highly haemolytic activity and were able to produce 3 hydrolytic enzymes, i.e. chitinase, glucanase and protease. In pathogenicity assays, the considered strains resulted virulent for .. The GC-MS for compounds from ICMP 11096 were compatible with the structure of two bioactive fatty acids identified as methyl stearate and ethanol 2-butoxy phosphate with mass spectrum m/e 298 and 398, respectively.

The reaction of (S)-1-methylpropylbenzoylformate with furan gave (1'S)-1'-methylpropyl (1S,5R,6R)-6alpha-phenyl-2,7-dioxabicyclo[3.2.0]hept-3-en-6beta-carboxylate with de = 15%. The reaction of (S)-2-methylbutyl benzoylformate with furan gave (2'S)-2-methylbutyl (1SR,5RS,6RS)-6alpha-phenyl-2,7-dioxabicyclo[3.2.0]hept-3-en-6beta-carboxylate as a mixture of stereoisomers. (1R,2S,5R)-5-Methyl-2-(1-methylphenylethyl)cyclohexyl benzoylformate gave (1R,2S,5R)-5-methyl-2-(1-methylphenylethyl)cyclohexyl (1R,5S,6S)-6alpha-phenyl-2,7-dioxabicyclo[3.2.0]hept-3-en-6beta-carboxylate with de = 95%. The stereochemical behaviour can be explained considering the energy gap between the biradical intermediates in the coupling reaction. When the reaction was performed in the presence of zeolite, the diastereoisomeric excess increased (37, 18 and 98%, respectively). The reaction of (S)-1-methylpropylbenzoylformate with 2-methylfuran gave (1'S)-1'-methylpropyl (1S,5R,6R)-1-methyl-6alpha-phenyl-2,7-dioxabicyclo[3.2.0]hept-3-en-6beta-carboxylate (yield: 12%) with de = 94%. The main product was (1'S)-1'-methylpropyl (1SR,5RS,6RS)-3-methyl-6alpha-phenyl-2,7-dioxabicyclo[3.2.0]hept-3-en-6beta-carboxylate as a mixture of diastereoisomers. The reaction of (S)-2-methylbutyl benzoylformate with 2-methylfuran gave (2'S)-2-methylbutyl (1S,5R,6R)-1-methyl-6alpha-phenyl-2,7-dioxabicyclo[3.2.0]hept-3-en-6beta-carboxylate (yield: 9%) with de = 10%. The main product was (2'S)-2-methylbutyl (1SR,5RS,6RS)-3-methyl-6alpha-phenyl-2,7-dioxabicyclo[3.2.0]hept-3-en-6beta-carboxylate as a mixture of stereoisomers. The stereochemical behaviour can be explained on the basis of the energy gap between the possible biradical intermediates. The reaction of (S)-1-methylpropylbenzoylformate and (S)-2-methylbutyl benzoylformate with 2-furylmethanol gave the corresponding adducts as a mixture of diastereoisomers. The reaction of (S)-1-methylpropylbenzoylformate and (S)-2-methylbutyl benzoylformate with 2-furylphenylmethanol gave the corresponding adducts with high diastereoselectivity. In this case, the stereochemical behaviour is determined by the presence of the hydroxy group in a molecule with a preferntial conformation.

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Solid-phase microextraction gas chromatography-mass spectrometry analysis of nineteen samples of honey from Basilicata (southern Italy) showed the presence of some flavour components never described before in honey. Furthermore, some phenyl-substituted hydrocarbons were detected. These compounds may be derived from the wastewater treatment plant in the area. Furthermore, in honey collected near an oil extraction plant, hydrocarbons were found; these may be derived from such plants present in the area.