Structure and bioactivity of steroidal saponins isolated from the roots of Chamaelirium luteum (false unicorn).

Phytochemical investigation of Chamaelirium luteum ("false unicorn") resulted in the isolation of 15 steroidal glycosides. Twelve of these (1, 2, 4-9, 11-13, and 15) are apparently unique to this species, and eight of these (6-9, 11-13, and 15) are previously unreported compounds; one (15) possesses a new steroidal aglycone. In addition, the absolute configuration of (23R,24S)-chiograsterol A (10) was defined, and its full spectroscopic characterization is reported for the first time. The structures and configurations of the saponins were determined using a combination of multistage mass spectrometry (MS(n)), 1D and 2D NMR experiments, and chemical degradation. The antiproliferative activity of nine compounds obtained in the present work, and eight related compounds generated in previous work, was compared in six human tumor cell lines, with aglycones 3 and 10 and related derivatives 16, 17, 19, and 20 all displaying significant antiproliferative activity.

Selectively inducing the synthesis of a key structural exopolysaccharide in aerobic granules by enriching for Candidatus "Competibacter phosphatis".

A gel-forming exopolysaccharide was previously shown to play an important structural role in aerobic granules treating nutrient-rich industrial wastewater. To identify whether this exopolysaccharide performs a similar role in other granular biomass and if conditions favouring its production can be more precisely elucidated, extracellular polymeric substances (EPS) were extracted from granules grown under four different operating conditions. (1)H nuclear magnetic resonance (NMR) spectroscopy of their EPS indicated that the gel-forming exopolysaccharide was expressed in two granular sludges both enriched in Candidatus "Competibacter phosphatis". In contrast, it was not expressed in granules performing denitrification with methanol as a carbon source and nitrate as the electron acceptor or granules enriched in Candidatus "Accumulibacter phosphatis" performing enhanced biological phosphorus removal from synthetic wastewater. In one of the first two sludges, the exopolysaccharide contained in the seeding granular sludge continued to be a major component of the granule EPS while Competibacter was being enriched. In the second sludge, a floccular sludge not containing the gel-forming exopolysaccharide initially was also enriched for Competibacter. In this sludge, an increase in particle size was detected coinciding with a yield increase of EPS. NMR spectroscopy confirmed its yield increase to be attributable to the production of this structural gel-forming exopolysaccharide. The results show that (1) the particular gel-forming exopolysaccharide previously identified is not necessarily a key structural exopolysaccharide for all granule types, and (2) synthesis of this exopolysaccharide is induced under conditions favouring the selective enrichment of Competibacter. This indicates that Competibacter may be involved in its production.

Synergistic antimicrobial activity of galangal (Alpinia galanga), rosemary (Rosmarinus officinalis) and lemon iron bark (Eucalyptus staigerana) extracts.

BACKGROUND: In this study the synergistic antimicrobial activities of combinations of extracts from galangal (Alpinia galanga), rosemary (Rosmarinus officinalis) and lemon iron bark (Eucalyptus staigerana) were evaluated against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium and Clostridium perfringens. Chemical compositions of these extracts were also determined to provide further insight into antimicrobial constituents and their potential mechanisms of action. RESULTS: Combinations of galangal with either rosemary or lemon iron bark showed synergistic antimicrobial activity. Specifically, galangal and rosemary showed synergistic activity against S. aureus and L. monocytogenes only, while galangal and lemon iron bark showed synergistic activity against E. coli and S. typhimurium. Chemical compositions of the extracts were determined by gas chromatographic-mass spectrometric analysis. The major chemical components of the galangal and lemon iron bark extracts were 1'-acetoxy-chavicol acetate (1'ACA) (63.4%) and neral (15.6%), respectively, while 1,8-cineole (26.3%) and camphor (20.3%) were identified as major chemical components of the rosemary extract. CONCLUSION: The results of this study show that galangal, rosemary and lemon iron bark extracts contain components that may have different modes of antimicrobial action and combinations of these extracts may have potential as natural antimicrobials to preserve foods.