Pesticide residues in essential oils: evaluation of a database.

In the context of a revision of the European Pharmacopoeia (Ph. Eur.) general monograph Essential oils (2098), the need to include a test for pesticides is being discussed.

Evaluation of the risk of aflatoxin contamination in fresh medicinal plants.

Based on experimental results of aflatoxin analysis as well as information from literature, this contribution discusses the likelihood of aflatoxin contamination in fresh medicinal plants. As cultivation and collection of medicinal plants in accordance with Good Agricultural and Collection Practice (GACP) and the local climatic conditions minimise aflatoxin contamination and, as fresh raw material is normally processed immediately, aflatoxin contamination of fresh medicinal plants from Central European countries is extremely unlikely. As a result of the risk-based approach to aflatoxin testing, 3 options are proposed depending on the origin of the material and the plant parts used: no testing, skip lot testing or routine testing.

Analytical characterisation of homoeopathic mother tinctures.

Quality of homoeopathic mother tinctures is assured by the definition of the starting material, the manufacturing process and the analytical characteristics described in the monograph. Traditionally analytical characterisation of the mother tincture comprises appearance, odour, identity, density and dry residue. According to annex I of directive 2001/83/EC an assay is only performed in case of a health hazard due to toxic compounds.

Direct ring fission of salicylate by a salicylate 1,2-dioxygenase activity from Pseudaminobacter salicylatoxidans.

In cell extracts of Pseudaminobacter salicylatoxidans strain BN12, an enzymatic activity was detected which converted salicylate in an oxygen-dependent but NAD(P)H-independent reaction to a product with an absorbance maximum at 283 nm. This metabolite was isolated, purified, and identified by mass spectrometry and (1)H and (13)C nuclear magnetic resonance spectroscopy as 2-oxohepta-3,5-dienedioic acid. This metabolite could be formed only by direct ring fission of salicylate by a 1,2-dioxygenase reaction.

Altering catalytic properties of 3-chlorocatechol-oxidizing extradiol dioxygenase from Sphingomonas xenophaga BN6 by random mutagenesis.

The 2,3-dihydroxybiphenyl 1,2-dioxygenase from Sphingomonas xenophaga strain BN6 (BphC1) oxidizes 3-chlorocatechol by a rather unique distal ring cleavage mechanism. In an effort to improve the efficiency of this reaction, bphC1 was randomly mutated by error-prone PCR. Mutants which showed increased activities for 3-chlorocatechol were obtained, and the mutant forms of the enzyme were shown to contain two or three amino acid substitutions.

Catalytic properties of the 3-chlorocatechol-oxidizing 2, 3-dihydroxybiphenyl 1,2-dioxygenase from Sphingomonas sp. strain BN6.

The 2,3-dihydroxybiphenyl dioxygenase from Sphingomonas sp. strain BN6 (BphC1-BN6) differs from most other extradiol dioxygenases by its ability to oxidize 3-chlorocatechol to 3-chloro-2-hydroxymuconic semialdehyde by a distal cleavage mechanism. The turnover of different substrates and the effects of various inhibitors on BphC1-BN6 were compared with those of another 2,3-dihydroxybiphenyl dioxygenase from the same strain (BphC2-BN6) as well as with those of the archetypical catechol 2,3-dioxygenase (C23O-mt2) encoded by the TOL plasmid.

Distal cleavage of 3-chlorocatechol by an extradiol dioxygenase to 3-chloro-2-hydroxymuconic semialdehyde.

A 2,3-dihydroxybiphenyl 1,2-dioxygenase from the naphthalenesulfonate-degrading bacterium Sphingomonas sp. strain BN6 oxidized 3-chlorocatechol to a yellow product with a strongly pH-dependent absorption maximum at 378 nm. A titration curve suggested (de)protonation of an ionizable group with a pKa of 4.