Neo-Clerodane Diterpenes from Ajuga turkestanica.

The ethyl acetate extract of the aerial parts of Ajuga turkestanica afforded 6 neo-clerodane diterpenes, including two novel compounds, 14, 15-dihydroajugachin B (1) and 14-hydro-15-methoxyajugachin B (2), in addition to the known diterpenoids chamaepitin (3), ajugachin B (4), ajugapitin (5) and lupulin A (6). Structures were established through exhaustive NMR spectroscopic analysis and chemical transformation in the case of 1. The full (1)H and (13)C NMR assignment of the C-15 R and S configurations of 14-hydro-15-methoxyajugachin B and chamaepitin were elucidated.