Bispolides, novel 20-membered ring macrodiolide antibiotics from microbispora.

Seven new related compounds named bispolides A1, A2, A3, B1, B2a, B2b and B3, have been found in a culture of Microbispora sp. A34030, isolated from a Malaysian soil sample. The planar structures were elucidated to be new 20-membered ring macrodiolide antibiotics on the basis of MS and NMR spectroscopic analyses.

Critical fluctuations near the smectic-hexatic phase transition with anticlinic structure.

Layer compression modulus B measurements have been conducted near the transitions between smectic and hexatic phases with synclinic and anticlinic structures. In the synclinic structure, B shows no pretransitional softening near the phase transition. However, in the anticlinic structure, we observed evident critical softening of B near the smectic-hexatic phase transition.