Biodegradation of polyethylene by the thermophilic bacterium Brevibacillus borstelensis.

AIM: To select a polyethylene-degrading micro-organism and to study the factors affecting its biodegrading activity. METHODS AND RESULTS: A thermophilic bacterium Brevibaccillus borstelensis strain 707 (isolated from soil) utilized branched low-density polyethylene as the sole carbon source and degraded it. Incubation of polyethylene with B. borstelensis (30 days, 50 degrees C) reduced its gravimetric and molecular weights by 11 and 30% respectively. Brevibaccillus borstelensis also degraded polyethylene in the presence of mannitol. Biodegradation of u.v. photo-oxidized polyethylene increased with increasing irradiation time. Fourier Transform Infra-Red (FTIR) analysis of photo-oxidized polyethylene revealed a reduction in carbonyl groups after incubation with the bacteria. CONCLUSIONS: This study demonstrates that polyethylene--considered to be inert--can be biodegraded if the right microbial strain is isolated. Enrichment culture methods were effective for isolating a thermophilic bacterium capable of utilizing polyethylene as the sole carbon and energy source. Maximal biodegradation was obtained in combination with photo-oxidation, which showed that carbonyl residues formed by photo-oxidation play a role in biodegradation. Brevibaccillus borstelensis also degraded the CH2 backbone of nonirradiated polyethylene. SIGNIFICANCE AND IMPACT OF THE STUDY: Biodegradation of polyethylene by a single bacterial strain contributes to our understanding of the process and the factors affecting polyethylene biodegradation.

Ex vivo bioadhesion and in vivo testosterone bioavailability study of different bioadhesive formulations based on starch-g-poly(acrylic acid) copolymers and starch/poly(acrylic acid) mixtures.

Starch-g-poly(acrylic acid) copolymers or grafted starches synthesized by 60Co irradiation or chemical modification and co-freeze-dried starch/poly(acrylic acid) mixtures were evaluated on their ex vivo bioadhesion capacity. The buccal absorption of testosterone from a bioadhesive tablet formulated with the grafted starches or starch/poly(acrylic acid) mixtures was investigated. The results were compared to a reference formulation (physical mixture of 5% Carbopol 974P and 95% Drum Dried Waxy Maize). Rice starch-based irradiated grafted starches showed the best bioadhesion results. Partial neutralization of the acrylic acid with Ca(2+) ions resulted in significantly higher bioadhesion values compared to the reference. Ca(2+) and Mg(2+) partially neutralized maltodextrin-based irradiated grafted starches showed significantly higher bioadhesion values compared to the reference formulation. The chemically modified grafted starches showed significantly higher adhesion force values than for the reference tablet. None of the co-freeze-dried starch/poly(acrylic acid) mixtures showed significantly higher bioadhesion results than the reference (Bonferroni test, P<0.05). A chemically modified grafted starch could sustain the 3 ng/ml plasma testosterone target concentration during +/- 8 h (T(>3 ng/ml)). By lyophilization of a partially neutralized irradiated grafted starch, the in vivo adhesion time (22.0 +/- 7.2 h) and the T(>3 ng/ml) (13.5 +/- 1.3 h) could be increased. The absolute bioavailability of the lyophilized formulation approached the reference formulation. Some of the grafted starches showed to be promising buccal bioadhesive drug carriers for systemic delivery.

Betacyanins from vine cactus Hylocereus polyrhizus.

The presence of betacyanin pigments and their isoforms has been detected in the fruit of Hylocereus polyrhizus, a vine cactus native to South America. Along with the known betanin and phyllocactin (6'-O-malonylbetanin), a new betacyanin was structurally elucidated as betanidin 5-O-[6'-O-(3"-hydroxy-3"-methyl-glutaryl)-beta-D-glucopyranoside] (proposed trivial name hylocerenin) by means of electrospray MS/MS, HPLC, and NMR techniques.

Trypsin inhibition, calcium and zinc ion binding of starch-g-poly(acrylic acid) copolymers and starch/poly(acrylic acid) mixtures for peroral peptide drug delivery.

Newly synthesised starch-g-poly(acrylic acid) copolymers and starch/poly(acrylic acid) mixtures were evaluated for their in vitro inhibition potency towards the proteolytic enzyme trypsin. Their Ca2+ and Zn2+ binding capacity was measured. Carbopol 934P was used as reference polymer. Starch-g-poly(acrylic acid) copolymers were prepared by chemical grafting and 60Co irradiation, the starch/poly(acrylic acid) mixtures by freeze-drying. The influence of preparation method, the ratio starch:acrylic acid, the neutralisation degree and for the freeze-dried polymers the influence of heat treatment after freeze-drying was investigated. All freeze-dried polymers showed a higher inhibition factor (IF) than the chemically grafted and 60Co irradiated starches, which all showed significantly lower IF than Carbopol 934P. The heat treated freeze-dried polymer Amioca/poly(acrylic acid) (1:1) showed a significantly higher IF than the reference polymer (Mann-Whitney test, p<0.05). The Ca2+ and Zn2+ binding capacity of all chemically grafted starches was much lower than for Carbopol 934P. Only the 60Co irradiated starches and freeze-dried polymers with ratio 1:3 approached the binding capacity of the reference polymer. The freeze-dried polymers showed the highest proteolytic enzyme inhibition potency. Freeze-drying and 60Co irradiation could result in the highest ion binding capacity. This combination of proteolytic enzyme inhibition activity and ion binding capacity makes these polymers hopeful excipients for successful oral peptide delivery.

A novel system consisting of Rh-DuPHOS and ionic liquid for asymmetric hydrogenations.

The ionic liquid [bmim][PF6] was found to provide extra stability to the air-sensitive chiral catalyst Rh-MeDuPHOS in asymmetric hydrogenation of enamides.

Solid-state stereochemistry and activity of 3-methylnefopam diastereomers: manipulation of eight-membered ring conformations in analogues of the non-narcotic analgesic drug.

The solid-state structures of (+/-)-(1R,3S,5S)/(1S,3R,5R)- and (+)/(-)-(1R,3R,5R)/(1S,3S,5S)-3-methylnefopam hydrochloride, epimeric 3-methyl derivatives of the non-narcotic analgesic drug, were determined by single-crystal X-ray diffraction analyses. (+/-)-(1R,3S,5S)/(1S,3R,5S)-3-Methylnefopam hydrochloride gave crystals belonging to the monoclinic space group P2(1)/c, and at ambient temperature, a = 7.993(2), b = 34.376(4), c = 11.785(2) A, beta = 93.06 degrees, V = 3234(2) A3, Z = 8, R(F = 0.070, and Rw(F) = 0.053. (+)/(-)-(1R,3R,5R)/(1S,3S,5S)-3-Methylnefopam hydrochloride gave chiral crystals belonging to the orthorhombic space group P2(1)2(1)2(1), and at 92 K, a = 9.261(2), b = 10.280(2), c = 16.668(4) A, V = 1587(1) A3, Z = 4, R(F) = 0.034, and Rw(F) = 0.035. The two molecules in the asymmetric unit of the (1R,3S,5S)/(1S,3R,5R)-racemic modification had twist-chair-(flattened chair) [TCfC] conformational geometries for the eight-membered ring. Both molecules are virtually identical as shown by a root mean squares fit of 0.077 A in the superimposition of all nonhydrogen atoms in both molecules. The (+)/(-)-(1R,3R,5R)/(1S,3S,5S)-epimers were found in the same boat-(flattened chair) [BfC] conformation previously noted for crystalline nefopam hydrochloride. The TCfC and BfC eight-membered ring conformations of the two 3-methylnefopam diastereomers differ in the -N+H(CH3)CH2CH-fragment chair or boat arrangement vis-a-vis the adjacent flattened region. In both 3-methyl diastereomers, the C(3)-methyl group was disposed in an equatorial orientation, the phenyl group resided in an exo-position, and the -OCH(Ph)-o-C6H4- fragment occupied the flattened region of the eight-membered ring.(ABSTRACT TRUNCATED AT 250 WORDS)

Solution- and solid-state structures of N-desmethylnefopam hydrochloride, a metabolite of the analgesic drug.

The solid-state structure of (+/-)-N-desmethylnefopam hydrochloride (1), a metabolite of the analgesic drug, was determined by single-crystal X-ray diffraction analysis. Compound 1 gave crystalline prisms belonging to the orthorhombic Pcab space group, and at ambient temperature (293 K), a = 9.939(2), b = 14.479(1), c = 20.148(3) A, V = 2899.5(8) A3, Z = 8, R(F) = 0.045, and Rw(F) = 0.025. The benzoxazocine ring of crystalline 1 is twisted into the boat-flattened (chair) [BfC] conformation, the phenyl ring resides in a relatively sterically unhindered exo-type ring position, whereas the O atom and NCH2Ar occupy sterically hindered positions between "boat" and "chair" regions. Dissolution of BfC crystalline 1 in CD2Cl2 solvent affords a dynamic conformational equilibrium (involving the putative twist-chair-flattened (chair) conformer) as shown by line broadening and weighted time-averaged vicinal coupling constants [-OCH2CH2N- segment] in the 1H NMR spectrum. The solution-state weighted time-averaged 50(1) degrees O-CH2-CH2-N dihedral angle, calculated by the R-ratio method, shows that the BfC conformation is the major contributor to time-averaged structure.

Enzymatic synthesis of alkyds.

Lipases were used as catalysts in the synthesis of "all-trans" polyester oligomers in organic solvents. Esters of fumaric acid and 1,4-butane diol served as the substrates in the enzyme-catalyzed polytransesterification. No isomerization of the double bond was found under the mild conditions of enzymatic catalysis used by us, as opposed to the extensive isomerization found during chemical polycondensation. The alkoxy leaving group of the ester fumarate was found to be responsible for the rate of transesterification. Low (M(w) approximately 600-800) and high (M(w) = 1250) molecular weight alkyds were synthesized depending on whether tetrahedrofuran or acetonitrile, respectively, was used as the solvent.

Enzymatic synthesis of S-adenosyl-L-methionine from L-methionine and ATP.

S-Adenosyl-L-methionine (SAM) has been synthesized on 7-mmol scale from L-methionine and ATP. The ATP was generated in situ from AMP, and the synthesis of SAM was catalyzed by the enzyme ATP:L-methionine S-adenosyltransferase (EC 2.5.1.6). Although substantial effort was required to obtain even small quantities of enzyme, it has good stability once isolated and immobilized. The SAM produced by this procedure contains 89% of the (-) diasterioisomer and 11% of the (+) diasterioisomer.