Synthesis of (12R,13S)-pyriculariol and (12R,13S)-dihydropyriculariol revealed that the rice blast fungus, Pyricularia oryzae, produces these phytotoxins as racemates.

Synthesis of assumed natural (12R,13S)-enantiomers of pyriculariol (1) and dihydropyriculariol (2), phytotoxins isolated from rice blast disease fungus, Pyricularia oryzae, was achieved using Wittig reaction or microwave-assisted Stille coupling reaction as the key step. The synthesis revealed that the natural 1 and 2 are racemates. Foliar application test on a rice leaf indicated that both the salicylaldehyde core and side chain were necessary for phytotoxic activity. The fungus is found to produce optically active phytotoxins when incubated with rotary shaker, but racemic ones when cultured using an aerated jar fermenter.

Functional characterization of DNAM-1 (CD226) interaction with its ligands PVR (CD155) and nectin-2 (PRR-2/CD112).

CD226 (DNAM-1) is an adhesion molecule involved in NK and T cell-mediated cytotoxicity against certain tumors. Here, we have identified the human poliovirus receptor-related (PRR) family members CD155 [poliovirus receptor (PVR)] and CD112 (nectin-2/PRR-2) as the ligands for human CD226. Ectopic expression of human CD155 and/or CD112 rendered mouse BW5147 T cells more susceptible to IL-2-activated T and NK cell-mediated cytotoxicity, and killing was specifically inhibited by anti-CD226 mAb, demonstrating functional interactions of CD226 with CD155 and CD112. Although the binding affinities between soluble CD226 and CD155 or CD112 were comparable, the homophilic interaction of cell-surface CD112 may adversely affect CD226 binding to CD112. We also demonstrate that ligation of CD226 and LFA-1 with their respective ligands cooperates in triggering cytotoxicity and cytokine secretion by T and NK cells.