Biotransformation of heterocyclic dinitriles by Rhodococcus erythropolis and fungal nitrilases.

2,6-Pyridinedicarbonitrile (1a) and 2,4-pyridinedicarbonitrile (2a) were hydrated by Rhodococcus erythropolis A4 to 6-cyanopyridine-2-carboxamide (1b; 83% yield) and 2-cyanopyridine-4-carboxamide (2b; 97% yield), respectively, after 10 min. After 118 h, the intermediates 1b or 2b were transformed into 2,6-pyridinedicarboxamide (1c; 35% yield) and 2,6-pyridinedicarboxylic acid (1d; 60% yield) or 2-cyanopyridine-4-carboxylic acid (2c; 64% yield), respectively. The nitrilase from Fusarium solani afforded cyanocarboxylic acids 1e and 2c after 118 h (yields 95 and 62%, respectively).

Preparative production and separation of 2-acetamido-2-deoxymannopyranoside-containing saccharides using borate-saturated polyolic exclusion gels.

A new separation method based on the combination of exclusion and ion exchange chromatography in borate buffer was developed. It allows semi-preparatory and preparatory separation of isobaric N-acylhexosamines (C-2 epimers) and corresponding methyl glycosides (anomers and tautomers). Three types of polyolic gels were tested for these separations.

Oxidised derivatives of silybin and their antiradical and antioxidant activity.

Carboxylic acids derived from silybin (1) and 2,3-dehydrosilybin (2) with improved water solubility were prepared by selective oxidation of parent compounds and a new inexpensive method for preparation of 2,3-dehydrosilybin from silybin was developed and optimised. The antioxidative properties of the above-mentioned compounds and of side product 3a from oxidation of compound 1 were determined by cyclic voltammetry, free radical scavenging (DPPH, superoxide) assays, and by inhibition of in vitro generated liver microsomal lipid peroxidation. Dehydrogenation at C((2))-C((3)) in flavonolignans (silybin vs 2,3-dehydrosilybin; silybinic acid vs 2,3-dehydrosilybinic acid) strongly improved antioxidative properties (analogously as in flavonoids taxifolin vs quercetin).

Clustered ergot alkaloids modulate cell-mediated cytotoxicity.

Dimers of agroclavine (1) and terguride (2), as well as a series of terguride oligomers, for example trimers (5, 6), tetramer (7), hexamer (8) and functionalized tergurides for further complex clustering were synthesized. Terguride oligomers were screened for their direct cellular toxicity on lymphoma cell lines in vitro and for their immunomodulating activities, represented by the natural killer (NK) cell-mediated cytotoxicity, as the most sensitive screening marker during immune responses. Dimers linked via aromatic spacer showed a high toxicity (1 microM) to lymphoma cells, which was not detected in other derivatives.