Gerhard Seibert

Antibacterial and antifungal activity of Avarone and Avarol.

The sesquiterpenoid hydroquinone and quinone, Avarol and Avarone, were previously found to be potent antitumor agents (Müller et al., 1984). In the present study it is reported that in aqueous solution (pH 7.2), in the presence of dimethylsulfoxide, Avarol is converted to Avarone. Avarone and to a smaller extent also Avarol were active against a variety of grampositive bacterial species. The highest activity was determined for Streptococcus pneumoniae and Erysipelothrix rhusiopathiae (MIC 0.781 mg/l). The antibacterial activity can be augmented 2 to 4-fold by lowering the pH in the culture medium from 7.0 to 6.0. The efficiency of Avarone and Avarol was abolished in the presence of serum. No antibacterial activity was determined in gramnegative bacterial species. In addition, Avarol and to a smaller extent also Avarone displayed an antifungal activity on Trichophyton species and Microsporum canis (MIC: 15.6-62.5 mg/l), while Avarone and not Avarol was active on Aspergillus niger, no activity was found against Candida species. These data indicate that the antitumor agents Avarol/Avarone display also antibacterial- and antifungal activities against a limited range of microorganisms.

Single-step separation of major and rare ribonucleosides and deoxyribonucleosides by high-performance liquid cation-exchange chromatography for the determination of the purity of nucleic acid preparations

A method is described for the separation of 13 major and minor ribo- and deoxyribonucleosides in a single chromatographic run using high-performance liquid chromatography on strongly acidic cation-exchange columns. The method proved useful for the routine determination of small amounts of ribonucleic acid impurities in deoxyribonucleic acid preparations and vice versa. About 3% or even less of nucleic acid contamination in a given sample can be easily detected and quantitatively determined under the conditions used.

Properties of an inducible β-lactamase from Proteus vulgaris

Summary The inducible β-lactamase of the clinical Proteus vulgaris isolate 4917/81 was highly purified by column chromatography and by FPLC (cation ion exchange column). Molecular weight of the enzyme amounted 33 000 daltons, as revealed by SDS-electrophoresis. The enzyme was not inhibited by p-chloromercuribenzoate, but by low concentrations of oxacillin and clavulanic acid. The enzyme inactivated not only penicillin derivatives (including ureidopenicillins), but also first-generation cephalosporins and above all oxime-cephalosporins such as cefuroxime, cefotaxime and related derivatives. Turnover rates of these agents were mainly influenced by the nature of substitution in 3′ position of the cephalosporin nucleus. Breakdown was not detectable in compounds which were substituted in 6α or 7α position, respectively. The enzyme proved to be very sensitive to the nature of 6α or 7α substituent, as revealed by the study of enzyme kinetics; no turnover could be detected for the penem Sch29 482, imipenem, latamoxef, and aztreonam.

The Separation of High and Low Molecular Weight RNA by Precipitation with N-Cetyl- N,N,N-trimethyl-ammoniumbromide

Abstract RNA with a sedimentation constant of 28S and 18S can easily be separated from 4S and 5S RNA. The method depends on the different solubulities of nucleic acids in solutions of the cationic detergent N-cetyl-N,N,N-trimethyl-ammoniumbromide at various ionic strengths. The separation can be achieved with high efficiency in one step.

Fractionated precipitation of acid macropolyanions by dialysis, a simple method for the estimation of DNA in complex biological samples.

Abstract After efficient extraction by para-aminosalicylate, (hopping, grinding and eventual sonication, the macropolyanions are transformed into their cetyltrimethylammonium salts. These have differing solubilities, strongly depending on ionic strength. The cationic detergent-macropolyanionic salts are solubilized by high salt concentration. Salt is then dialysed out, rendering the polyanions highly insoluble in a sequential fashion. The insolubilized components are determined quantitatively by monitoring turbidity, which in case of DNA is strictly proportionate to its concentration. This relation is not affected by other components. This makes DNA determination possible even in crude aqueous extracts. The method has been applied to different objects, such as bacteria, plants, animals, soil and activated sludge. The method may prove to be especially useful in research of environmental poisons e. g. in rivers, lakes or clarifiers.