Rhizoleucinoside, a Rhamnolipid–Amino Alcohol Hybrid from the Rhizobial Symbiont Bradyrhizobium sp. BTAi1
Rhizoleucinoside (1), a unique rhamnolipid–amino alcohol hybrid, was isolated from the rhizobial symbiont bacterium Bradyrhizobium sp. BTAi1. Compound 1 features a rare rhamnolipid core attached to an unprecedented leucinol moiety. Its structure and absolute configuration were determined by spectroscopic analysis, tandem mass spectrometry, chemical degradation, and application of the Marfey’s method. Compound 1 possesses moderate cytotoxicity to BV-2 murine microglia and highly aggressive proliferating immortalized (HAPI) rat microglia cells.