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Biodegradation of two amphiphilic "soft" antimicrobially active derivatives of lauric (dodecanoic) acid, a quaternary ammonium salt and an amine oxide bearing an amide or ester group, was followed using microorganisms from activated sludge. Primary biodegradation was determined by ion-selective electrodes, total biodegradation as the chemical oxygen demand. Though organic ammonium salts quickly undergo primary biodegradation, the rest of the molecule is difficult to destroy. In contrast, amine oxides are easily biodegradable.

Bacterial strains with a high biodegradation potential were isolated from activated sludge. Their ability to decompose the hard bis-quaternary ammonium salt FB was determined by the method of chemical oxygen demand (COD) in a mineral medium, where the compound FB was the only source of carbon. The COD values were very low after 21 d and in the course of this period they reached zero level twice. The contribution of adsorption to decrease the COD value was small. The maximum COD decrease was accompanied by an increase of cell respiration. It is suggested that FB is effectively decomposed in spite of the fact that according to its structure it is a typical hard detergent.

The effect of the homologous series of 1,1-dialkylpiperidinium bromides on the potassium leakage from Escherichia coli cells has been studied. The minimum concentration for each compound which is able to release maximum of cellular potassium has been determined and correlated with the inhibitory activities of the compounds. The relationship between the structure and the activity enables to consider the K+ leakage as the marker of inhibitory activity of the membrane active antimicrobials.

The reported investigation of the constituents of the petroleum ether extract of the root of Salvia officinalis L. confirmed the presence of the following diterpene quinones: 12.hydroxy-8, 12-abietadiene-11, 14-dione (royleanone), 7 alpha, 12-dihydroxy-8.12-abistadiene-11-14-dione (horminone) and 7 alpha-acetoxy-12-hydroxy-8, 12-abietadiene-11,14-dione (7-O-acetylhorminone). The compounds were identified on the basic of the interpretation of results of spectral analysis. Isolated royleanones show antimicrobial activity against gram-positive bacteria (Staphylococcus aureus). A study of abietate diterpenoids in the root of Salvia officinalis L. of Slovak provenance has been performed for the first time.