Absolute Stereochemistry of 1,2-Diols from Lipids of Thermomicrobia

1,2-Diol based phospholipids are a well-known feature of bacteria from the class Thermomicrobia . Since these bacteria contain only lipids with an alkyldiol- 1 -phosphate backbone instead of sn -glycero-3-phosphate, it is important to elucidate the stereochemistry of the 1,2-diols. We have studied the absolute stereochemistry of long-chain 1,2-diols isolated from Thermorudis pharmacophila (formerly known as Thermomicrobia sp. WKT50.2) by nuclear magnetic resonance (NMR) using α-methoxyphenylacetic acid (MPA). Low-temperature (−60 °C) NMR of bis-( R )-MPA ester showed ( R ) stereochemistry of the 1,2-diols. This is the first report concerning the stereochemistry of natural 1,2-diols, which replace the glyceride moiety in phospholipids. The ( R ) stereochemistry of the diols is expected as it is the same configuration as for the common bacterial lipid backbone— sn -glycero-3-phosphate. This is the first application of low-temperature NMR of a single MPA derivative for assignment of stereochemistry of natural 1,2-diols. The results were confirmed by the comparison of NMR data with bis-( R )-MPA ester of ( R ) and rac- 1,2-octanediol.