Search results for "lactone"
showing 10 items of 335 documents
Sesquiterpene lactones and dihydroflavonols from Andryala and Urospermum species
1994
Abstract The aerial parts of two Andryala species yielded several guaianolides and guaianolide glycosides, three of them being new. The aerial parts of Urospermum dalechampii yielded several known germacranolides and the new dihydroflavonol 3- O -methyltaxifolin.
Production of Dicarboxylic Acids and Flagrances by Yarrowia lipolytica
2013
Yeasts are excellent biocatalysts in the field of alkane and fatty acids transformation into dicarboxylic acids and lactones. Their ability to produce some diacids through simple, less expensive and more environment friendly routes than chemical pathways and to produce particular diacids (e.g. unsaturated ones) but also to transform natural substrates into lactones with a natural label has made them the subject of many researches. Although Candida species were often first studied, the development of genetic tools, the knowledge of the genome and some genomic and biotechnological particularities of Yarrowia lipolytica resulted to interesting developments with this species. This chapter aims …
Cytotoxicity and antileishmanial activity of Annona muricata pericarp
2000
Abstract Hexane, ethyl acetate and methanol extracts of Annona muricata pericarp were tested in vitro against Leishmania braziliensis and L. panamensis promastigotes, and against cell line U-937. The ethyl acetate extract was more active than the other extracts and even of Glucantime® used as reference substance. Its fractionation led to the isolation of three acetogenins — annonacin, annonacin A and annomuricin A.
Polycaprolactone/gelatin-based scaffolds with tailored performance: in vitro and in vivo validation
2019
Abstract Nanofibrous scaffolds composed of polycaprolactone (PCL) and gelatin (Ge) were obtained through a hydrolytic assisted electrospinning process. The PCL-to-Ge proportion (100/0 to 20/80), as well as the dissolution time (24, 48, 72, 96, 120 h) into a 1:1 formic/acetic acid solvent before electrospinning were modified to obtain the different samples. A strong influence of these factors on the physicochemical properties of the scaffolds was observed. Higher Ge percentage reduced crystallinity, allowed a uniform morphology and increased water contact angle. The increase in the dissolution time considerably reduced the molar mass and, subsequently, fibre diameter and crystallinity were a…
ChemInform Abstract: Stereoselective Synthesis of 7,11-Guaien-8,12-olides from Santonin. Synthesis of Podoandin and (+)-Zedolactone A.
2001
Photochemical rearrangement of hydroxy ester 2, easily obtained from santonin (1), afforded butenolide 4, a good starting material for the synthesis of 7,11-guaien-8,12-olides. Compound 4 has been transformed into compound 10, which has been used for the synthesis of podoandin (5) and (+)-zedolactone A (ent-6). Regioselective elimination of the acetyl group on C10 afforded directly podoandin (5). For the synthesis of ent-6, a hydroxyl group has been regio- and stereoselectively introduced at the 4α-position through the 3α,4α-epoxide 15. The basic hydrolysis of the 10-acetyl group in compound 18 took place with concomitant intramolecular conjugated addition of the alkoxide to the butenolide …
Enantiospecific semisynthesis of (+)-almuheptolide-A, a novel natural heptolide inhibitor of the mammalian mitochondrial respiratory chain.
1998
The development of novel styryl lactone derivatives as bioactive compounds and the semisynthesis of both 4,5-dialkoxylated eight-membered-ring lactones with a heptolide skeleton (almuheptolide-A (1) type) and 7-alkoxylated delta-lactones with a saturated furanopyrone skeleton (etharvensin (8) type) have been successfully achieved from the chiral unsaturated alpha-pyrone altholactone (7). This new method is a direct and one-step enantiospecific alkoxylation of altholactone (7) in concentrated acid medium, followed by formation of the eight-membered-ring zeta-lactone. The reaction mechanism operating in the synthesis of the heptolide skeleton is postulated to be a direct Michael-type addition…
Core–shell-type multiarm star polyethylenimine-block-poly(ɛ-caprolactone): Synthesis and guest encapsulation potential
2006
Novel multiarm star copolymers with poly(e-caprolactone) (PCL) as the arms and hyperbranched polyethylenimine (HPEI) as the core have been successfully prepared by the tin(II) 2-ethylhexanoate catalyzed ring-opening polymerization of e-caprolactone (CL) with HPEI used directly as a macroinitiator. Not only primary but also secondary amine groups of HPEI participate in initiating the ring-opening polymerization of CL with almost 100% initiation efficiency. The average degree of polymerization of the PCL arms can be controlled by the feed ratio of the monomers to the initiating sites. Because of the polarity difference of the PCL arms and HPEI core, the obtained multiarm star polymers display…
Assessment of the Optimum Linker Tethering Site of Alternariol Haptens for Antibody Generation and Immunoassay Development
2021
Immunochemical methods for mycotoxin analysis require antigens with well-defined structures and antibodies with outstanding binding properties. Immunoreagents for the mycotoxins alternariol and/or alternariol monomethyl ether have typically been obtained with chemically uncharacterized haptens, and antigen conjugates have most likely been prepared with mixtures of functionalized molecules. For the first time, total synthesis was performed, in the present study, to obtain two haptens with opposite linker attachment locations. The functionalized synthetic haptens were purified and deeply characterized by different spectrometric methods, allowing the preparation of bioconjugates with unequivoc…
Lanthanides benzimidinates: initiators or real catalysts for theɛ-caprolactone polymerization
2000
Diene/olefin/polar monomer copolymerisation: unprecedented functional polymers from a rare earth catalyst
2002
An ansasamarocene allyl system is an efficient initiator which polymerises 1,3-dienes, copolymerises dienes and long-chain α-olefins or α,ω-dienes to give functionalisable polymers. It also polymerises caprolactone and allows the controlled diblock copolymerisation of isoprene or isoprene/ α-olefin copolymer and caprolactone.