Identification of Cardioactive Leonurus and Leonotis Drugs by Quantitative HPLC Determination and HPTLC Detection of Phenolic Marker Constituents.

Officinal European Leonurus cardiaca, East Asian L. japonicus, and South African Leonotis leonurus are traditionally used for cardiovascular, gynecological, and neurological disorders. Nevertheless, a phytochemical assessment as a basis for their quality control and comparison amongst them has not yet been reported up to now. Here, a novel RP-HPLC method is presented for quantifying twelve phenolics, lavandulifolioside, verbascoside, hyperoside, ferulic acid, isoquercitrin, rutoside, apigenin-7-0-D-glucoside, and quercitrin, as well as chlorogenic, caffeic, rosmarinic, and cichoric acids, in 18 herbal and fruit samples of the three species, as well as in a L. cardiaca refined extract. Only ferulic acid was found in every sample, whereas rosmarinic acid and apigenin-7-0-D- glucoside were not detected in any sample. Chlorogenic, caffeic, and cichoric acids and rutoside were detected in all three species. Lavandulifolioside and verbascoside, the dominant phenolics of L. cardiac, were not present in any sample of L. japonicus. Lavandulifolioside was found in this first ever HPLC analysis on phenolics of L. leonurus. Hyperoside was not found in L. cardiaca, but in both L. japonicus and L. leonurus, whereas isoquercitrin was detected in L. cardiaca and L. leonurns, but not in L. japonicus. This approach facilitates identification and quality control via HPLC/HPTLC fingerprints.

Screening of microalgae for species excreting norharmane, a manifold biologically active indole alkaloid.

A screening of microalgae strains is described, with the objective to discover more species besides the known cyanobacterium Nodularia harveyana which excrete the manifold biologically active and co-mutagenic indole alkaloid norharmane (9H-pyrido(3,4-b)indole) into their environment. Seven more cyanobacterial species, Anabaena cylindrica, Anabaena inaequalis, Anabaenopsis siamensis, Chroococcus minutus, Nostoc carneum, Nostoc commune and Phormidium foveolarum, were newly discovered. The norharmane concentrations detected for cyanobacterial culture media varied in a species-dependent manner from less than 1 up to 525 microg l(-1). The risk for humans and livestock, resulting from the natural appearance of norharmane as an extracellular metabolite of various cyanobacteria, is discussed.

A newly developed assay for the quantitative determination of antimicrobial (anticyanobacterial) activity of both hydrophilic and lipophilic test compounds without any restriction.

This paper reports about a newly developed assay which enables the user to quantify and compare the antimicrobial (anticyanobacterial) activity of both hydrophilic and lipophilic test compounds without any restriction. The assay is characterised by the application of a test compound solution on a porous matrix (silica gel) in well-defined concentrations per unit area, and by the coating of this matrix by a concentrated suspension of the tested living cyanobacterium (using a spraying or a dipping technique). The organism was only applied after the complete evaporation of the solvent used for preparation of the test compound solution to avert potential influences of this solvent on micro-organisms' viability. Toxic concentrations of a test compound caused a clearly contoured regional damage in the blue-green coloured uniform layer of the cyanobacterial test organism. The resulting regional decolourisation was readily identifiable within a species-dependent short time (e.g. for the species Arthrospira laxissima after 24h). This newly developed assay is applied for a patent in Germany.

Complement modulating and anticoagulant effects of a sulfated exopolysaccharide released by the cyanobacterium Synechocystis aquatilis.

During batch cultivation, the cyanobacterial strain Synechocystis aquatilis Sauvageau B90.79 was found to release a fucose-rich sulfated polysaccharide, which was mainly composed of arabinose (45%) and fucose (47%) and had a degree of sulfation of 0.43. The released polysaccharide showed merely an anticoagulant activity of less than 10% compared to the reference compound, unfractionated heparin. However, distinctive effects on the complement activation were observed: its inhibitory effect on the classical pathway of complement activation was 600-fold stronger than that of unfractionated heparin, whereas that on the alternative pathway of complement activation was 2- to 3-fold weaker. The results indicate that this biotechnologically producible, released polysaccharide represents a specifically acting complement modulator.

Antialgal, antibacterial and antifungal activity of two metabolites produced and excreted by cyanobacteria during growth.

The antimicrobial activity of two cyanobacterial exometabolites, norharmane (9H-pyrido(3,4-b)indole) and 4,4'-dihydroxybiphenyl, was determined in suspension assays. Good anticyanobacterial activities (concentrations of 8-80 microg ml(-1)) and moderate antibacterial (16-160 microg ml(-1)) and antifungal (32-40 microg ml(-1)) activities were found for both compounds. The natural function as allelopathic chemicals and a possible applicability as antifouling agents or leads for the development of new antifouling chemicals are discussed.