Fredrik Björkling

The future impact of industrial lipases

Abstract Recognition of the advantages of the use of lipases relative to traditional chemical processes indicates that lipases may be expected to gain in importance in the enzyme market. Development of lipase technologies for the synthesis of novel compounds will probably also result in their expansion into new areas, and a major impact on a range of industries.

Lipase catalyzed synthesis of peroxycarboxylic acids and lipase mediated oxidations.

Abstract Lipase catalyzed synthesis of long chain peroxycarboxylic acids from hydrogen peroxide and free carboxylic acid was investigated. A 51% yield of peroxytetradecanoic acid was achieved when using a two phase system of toluene and water. The peroxy acids thus formed were applied for in situ oxidation of alkenes, in general leading to high yields of the corresponding epoxide. For example, a quantitative yield of cyclohexene oxide and a 94% yield of 1-hexadecene oxide was achieved in a solvent-free process.

Lipase-mediated formation of peroxycarboxylic acids used in catalytic epoxidation of alkenes

Epoxidation of alkenes was achieved under extremely mild conditions by employing peroxycarboxylic acids formed continuously in situ by lipase-catalysed perhydrolysis of the corresponding carboxylic acids.

Anticancer agent CHS-828 inhibits cellular synthesis of NAD

Malignant cells display increased demands for energy production and DNA repair. Nicotinamide adenine dinucleotide (NAD) is required for both processes and is also continuously degraded by cellular enzymes. Nicotinamide phosphoribosyltransferase (Nampt) is a crucial factor in the resynthesis of NAD, and thus in cancer cell survival. Here, we establish the cytotoxic mechanism of action of the small molecule inhibitor CHS-828 to result from impaired synthesis of NAD. Initially, we detected cross-resistance in cells between CHS-828 and a known inhibitor of Nampt, FK866, a compound of a structurally different class. We then showed that nicotinamide protects against CHS-828-mediated cytotoxicity. Finally, we observed that treatment with CHS-828 depletes cellular NAD levels in sensitive cancer cells. In conclusion, these results strongly suggest that, like FK866, CHS-828 kills cancer cells by depleting NAD.

A highly selective enzyme-catalysed esterification of simple glucosides

Regioselective 6-O-esterification of alkyl glucosides with long chain fatty acids, yielding more than 95% of 6-O-monoesters, can be achieved using lipases as catalysts in a solvent-free process.

Fatty Acid Specificity in Lipase-Catalyzed Synthesis of Glucoside Esters

The fatty acid specificity of the B-lipase derived from Candida antarctica was investigated in the synthesis of esters of ethyl D-glucopyranoside. The specificity was almost identical with respect to straight-chain fatty acids with 10 to 18 carbon atoms. However, lower fatty acids such as hexanoic and octanoic acid and the unsaturated 9-cis-octadecenoic acid were found to be poor substrates of the enzyme. As a consequence of this selectivity, these fatty acids were accumulated in the unconverted fraction when ethyl D-glucopyranoside was esterified with an excess of a mixture of fatty acids. This accumulation can reduce the overall effectiveness of the process as the activity of the lipase was found to be reduced when exposed to high concentrations of short-chain fatty acids. Finally, using a simplified experimental set-up, the specificity of the C. antarctica B-lipase was compared to the specificity of lipases derived from C. rugosa, Mucor miehei, Humicola, and Pseudomonas. Apart from the C. rugosa lipase...

Enzyme catalysed hydrolysis of dialkylated propanedioic acid diesters, chain length dependent reversal of enantioselectivity

Abstract Enzyme catalysed hydrolyses of dialkylated propanedioic acid diesters have been studied. A novel change of enantioselectivity from pro- S to pro- R in the hydrolysis of ester groups was observed, depending on the chain length of the alkyl substituents of the substrate. Optically pure ( S )-(-)-α-methylphenylalanine was prepared by α-chymotrypsin catalysed hydrolysis of benzylmethylpropanedioic acid dimethyl ester.

Novel cyanoguanidines with potent oral antitumour activity

4-Pyridyl cyanoguanidines with hydrophobic aromatic side chains showed potent antiproliferative activity in the human breast and lung cancer cell lines MCF-7, NYH and H460. In vivo, treatment with N-(6-chlorophenoxyhexyl)-N′-cyano-N″-4-pyridylguanidine (18, 20 mg/kg/day po.), gave a complete remission of tumours in a model of NYH inoculated nude mice.

Evaluation of the topoisomerase II-inactive bisdioxopiperazine ICRF-161 as a protectant against doxorubicin-induced cardiomyopathy

Anthracycline-induced cardiomyopathy is a major problem in anti-cancer therapy. The only approved agent for alleviating this serious dose limiting side effect is ICRF-187 (dexrazoxane). The current thinking is that the ring-opened hydrolysis product of this agent, ADR-925, which is formed inside cardiomyocytes, removes iron from its complexes with anthracyclines, hereby reducing the concentration of highly toxic iron-anthracycline complexes that damage cardiomyocytes by semiquinone redox recycling and the production of free radicals. However, the 2 carbon linker ICRF-187 is also is a catalytic inhibitor of topoisomerase II, resulting in the risk of additional myelosuppression in patients receiving ICRF-187 as a cardioprotectant in combination with doxorubicin. The development of a topoisomerase II-inactive iron chelating compound thus appeared attractive. In the present paper we evaluate the topoisomerase II-inactive 3 carbon linker bisdioxopiperazine analog ICRF-161 as a cardioprotectant. We demonstrate that this compound does chelate iron and protects against doxorubicin-induced LDH release from primary rat cardiomyocytes in vitro, similarly to ICRF-187. The compound does not target topoisomerase II in vitro or in cells, it is well tolerated and shows similar exposure to ICRF-187 in rodents, and it does not induce myelosuppression when given at high doses to mice as opposed to ICRF-187. However, when tested in a model of chronic anthracycline-induced cardiomyopathy in spontaneously hypertensive rats, ICRF-161 was not capable of protecting against the cardiotoxic effects of doxorubicin. Modulation of the activity of the beta isoform of the topoisomerase II enzyme by ICRF-187 has recently been proposed as the mechanism behind its cardioprotection. This concept is thus supported by the present study in that iron chelation alone does not appear to be sufficient for protection against anthracycline-induced cardiomyopathy.

Enzyme catalysed hydrolysis of dialkylated propanedioic acid diesters synthesis of optically pure (s)-α-methylphenylalanine, (s)-α-methyl-tyrosine and (s)-α-methyl-3,4-dihydroxyphenylalanine

Abstract Pig liver esterase and α-chymotrypsin catalysed hydrolysis of the meso-diesters 1, 2 and 3 gave the corresponding monoesters which then could be transformed into enantiomerically pure ( S )-α-methyphenylanine and ( S )-α-methyltyrosine and ( S )-α-methyl-3,4-dihydroxyphenylalanine.