Synthesis of the A/D/E-ring Core Compounds of Maoecrystal V.

Synthesis of the A/D/E-ring core compounds of maoecrystal V was achieved. The key Diels-Alder reactions between tricyclic α-methylene lactones and Kitahara-Danishefsky dienes afforded the spirocyclic core compounds in a regioselective and stereoselective manner.

Isolation of endosulfan sulfate-degrading Rhodococcus koreensis strain S1-1 from endosulfan contaminated soil and identification of a novel metabolite, endosulfan diol monosulfate.

An aerobic endosulfan sulfate-degrading bacterium, Rhodococcus koreensis strain S1-1, was isolated from soil to which endosulfan had been applied annually for more than 10 years until 2008. The strain isolated in this work reduced the concentration of endosulfan sulfate (2) from 12.25 µM to 2.11 µM during 14 d at 30 °C. Using ultra performance liquid chromatography-electrospray ionization-mass spectroscopy (UPLC-ESI-MS), a new highly water-soluble metabolite possessing six chlorine atoms was found to be endosulfan diol monosulfate (6), derived from 2 by hydrolysis of the cyclic sulfate ester ring. The structure of 6 was elucidated by chemical synthesis of the candidate derivatives and by HR-MS and UPLC-MS analyses. Therefore, it was suggested that the strain S1-1 has a new metabolic pathway of 2. In addition, 6 was expected to be less toxic among the metabolites of 1 because of its higher water-solubility.