Cynasibirolide A, One New Humulanolide Sesquiterpene from Cynanchum acutum subsp. sibiricum.

Cynasibirolide A (1), one new humulanolide sesquiterpene, together with four known analogs, asteriscanolide (2), (1S,8S)-8-hydroxyhumula-2Z,6E,9E-trien-1,12-olide (3), (1S,7R)-8-oxohumula-2Z,9E-dien-1,12-olide (4), and (+)-6,7,9,10-tetrahydroasteriscunolide (5) were isolated from the roots and rhizomes of Cynanchum acutum subsp. sibiricum. Their structures and configurations were elucidated by spectroscopic methods, including 2D-NMR techniques, and the structure of 1 was confirmed by single-crystal X-ray diffraction.

[Vibrational spectrum and XPS contrastive studies on pyrochlore-type oxygen-rich Ce2Zr2O8 and oxygen-defective Nd2Zr2O7 phases].

Pyrochlore-type oxygen-rich Ce2Zr2O8 phase was prepared successfully by graphite reduction method. With the oxygen[U8]-defective Nd2Zr2O7 substituting for the oxidized precursor phase CeZrO3.5+Δ was carried out the structure comparative analysis with Ce2Zr2O8.