A new type of glycolipid, 1-[alpha-mannopyranosyl-(1 alpha-3)-(6-O-acyl-alpha-mannopyranosyl)]-3-O-acylglycerol, from Arthrobacter atrocyaneus

The polar lipids from the bacterium Arthrobacter atrocyaneus LMG 3814T were analyzed and a novel type of glycolipid isolated. Its structure was elucidated by the combination of different NMR techniques and FAB-MS/MS in the positive and negative modes. The glycolipid was identified as 1-[alpha-mannopyranosyl-(1 alpha-3)-(6-O-acyl-alpha-mannopyranosyl)]-3-O-acylglycerol. The main compound had 14-methyl-hexadecanoic acid at the glycerol moiety and 12-methyl-tetradecanoic acid at C-6 of the inner mannose unit. Additionally six minor compounds were also identified with different Fatty acids. Under (+)-FAB ionization dominant daughter ions were observed through neutral loss of hydrocarbons generated from the acyl fatty acids. Negative-ion MS/MS allowed the identification of the phospholipids which consisted of five phosphatidylglycerols and seven cardiolipins. (C) 1997 Elsevier Science Ltd.