Dávila S. Zampieri

Harvestman Phenols and Benzoquinones: Characterisation and Biosynthetic Pathway

Benzoquinones are usually present in arthropod defence exudates. Here, we describe the chemical profiles of 12 harvestman species belonging to the neotropical family Gonyleptidae. Nine of the studied species produced benzoquinones, while three produced alkyl phenols. Two benzoquinones and one phenol exhibited biological activity against bacteria and fungi. We also studied the biosynthesis of 2-ethyl-1,4-benzoquinone by feeding Magnispina neptunus individuals with 13C-labelled precursors; the benzoquinones were biosynthesised through a polyketide pathway using acetate and propionate building blocks.

Microorganisms in cryopreserved semen and culture media used in the in vitro production (IVP) of bovine embryos identified by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS)

Commercial cattle breeders produce their own herd offspring for the dairy and beef market using artificial insemination. The procedure involves sanitary risks associated with the collection and commercialization of the germplasm, and the in vitro production and transfer of the bovine embryos must be monitored by strict health surveillance. To avoid the spreading of infectious diseases, one must rely on using controlled and monitored germplasm, media, and reagents that are guaranteed free of pathogens. In this article, we investigated the use of a new mass spectrometric approach for fast and accurate identification of bacteria and fungi in bovine semen and in culture media employed in the embryo in vitro production process. The microorganisms isolated from samples obtained in a commercial bovine embryo IVP setting were identified in a few minutes by their conserved peptide/protein profile, obtained applying matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), matched against a commercial database. The successful microorganisms MS identification has been confirmed by DNA amplification and sequencing. Therefore, the MS technique seems to offer a powerful tool for rapid and accurate microorganism identification in semen and culture media samples.

Stereoselective Oxidation of 1-Phenyl-1,2-propanediol Mediated by Microorganisms

The enantioselective oxidation of (1R,2S)‐1‐phenyl‐1,2‐propanediol [(1R,2S)‐1], mediated by baker’s yeast, gave (−)‐(S)‐1‐phenyl‐2‐hydroxy‐1‐propanone [(S)‐2] in 64 % isolated yield and 93 % ee. Kinetic experiments of the bio‐oxidation of (±)‐anti‐1 revealed that the enantiomer (1R,2S)‐1 was more reactive than (1S,2R)‐1. Therefore, this result allowed us to devise a kinetic resolution experiment to obtain (1S,2R)‐1 in >99 % ee from (±)‐anti‐1. The preparation of (1S,2R)‐1 is interesting, as it is the antipode of the product obtained by the reduction of 1‐phenyl‐1,2‐propanedione using baker’s yeast. Other microorganisms, such as Micrococcus luteus, Candida albicans, and Geotrichum candidum, were also used for kinetic resolution experiments of (±)‐anti‐1. The best result was obtained using Geotrichum candidum, which gave (1S,2R)‐1 in 32 % yield and 99 % ee.

Bioreduction of (Z)-3-halo-4-phenyl-3-buten-2-one mediated by Pichia stipitis in ionic liquids

Ionic liquids are substances that are completely composed of ions and are liquid at or close to room temperature. 1 Biocatalysis in ionic liquids media was first reported in 2000. In our studies towards the synthesis of chiral halohydrins using [bmim(BF4)] (water-miscible) and [bmim(PF6)] (water-immiscible), one of the approaches was the bioreduction of the correspondent α-haloenones mediated by Pichia stipitis, so as to generate two stereogenic centers in the same reaction.

Lanthanide nitrates as Lewis acids in the one-pot synthesis of 1,2,4-oxadiazole derivatives

In this work we report the use of lanthanide nitrates [Ln(NO3)3] acting as catalyst in direct one-pot synthesis of 3-benzoyl- and 3-acetyl-1,2,4-oxadiazoles derivatives from ketones, nitriles and nitric acid. This is the first example of one-pot synthesis of benzoyl- and acetyl 1,2,4-oxadiazoles derivatives preparation using acetophenones derivates with electron-donator groups.