There is increasing evidence that ␥␦ T cells have potent innate antitumor activity. We described previously that synthetic aminobisphosphonates are potent ␥␦ T cell stimulatory compounds that induce cytokine secretion (ie, interferon ␥

Human V␥9␦2 T lymphocytes are suggested to play an important role in the immune response to various microbial pathogens. In contrast to ␣␤ T cells, ␥␦ T lymphocytes recognize small, non-protein, phosphate-bearing antigens (phosphoantigens) in a major histocompatibility complex-independent manner. Four different phosphoantigens termed TUBag1 to TUBag4 with a common 3-formyl-1-butyl-pyrophosphate moiety and isopentenyl-pyrophosphate have been isolated and identified from mycobacteria. However, natural occurring ␥␦ T cell ligands from other bacterial species were not characterized so far. Here, we describe the structural identification of the two compounds responsible for the ␥␦ T cell-stimulating capacity of Escherichia coli as similar to the mycobacterial phosphoantigens 3-formyl-1-butylpyrophosphate and its M r 275 homologue TUBag2. In addition, E. coli phosphoantigens exert bioactivities on ␥␦ T cells with similar potencies to the mycobacterial phosphoantigens at 5-15 nM concentration. Furthermore, our results clearly prove that the deoxyxylulose 5-phophate pathway (also referred to as Rohmer metabolic route of isoprenoid biosynthesis) is essential for the biosynthesis of the phosphoantigens in E. coli. Because this pathway is absent from human cells, it proves an ideal target for focusing efficiently the antimicrobial selectivity of human ␥␦ T lymphocytes.

The methanolic extract of saffron was separated with the aid of multilayer coil countercurrent chromatography. After purification by HPLC, the following seven novel carotenoid metabolites were identified on the basis of their spectral (UV, FTIR, MS, NMR, CD) data:  (4R)-4-hydroxy-2,6,6-trimethylcyclohex-1-enecarbaldehyde O-β-d-gentiobioside (1), (4R)-4-hydroxy-2,6,6-trimethylcyclohex-1-enecarboxylic acid O-β-d-glucopyranoside (2), 6-hydroxy-3-(hydroxymethyl)-2,4,4-trimethylcyclohexa-2,5-dienone 6-O-β-d-glucopyranoside (3), (2Z)-3-methylpent-2-enedioic acid 1-[1-(2,4,4-trimethyl-3,6-dioxocyclohexenyloxy)-O-β-d-glucopyranosid-6-yl] ester (4), (5S)-5-hydroxy-7,7-dimethyl-4,5,6,7-tetrahydro-3H-isobenzofuran-1-one O-β-d-glucopyranoside (5), (1R,5S,6R)-5-(hydroxymethyl)-4,4,6-trimethyl-7-oxabicyclo[4.1.0]heptan-2-one O-β-d-glucopyranoside (6), and (1R)- 3,5,5-trimethylcyclohex-3-enol O-β-d-glucopyranoside (7). Keywords: Carotenoid metabolites; glycosides; aroma precursor; multilayer coil countercurrent chromatography; saffron; Crocus sativus

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