Discovery of Coracanols A and B, Two Biological Nitrification Inhibition Diterpenoids from Finger Millet.

Natural products with biological nitrification inhibition (BNI) activity released from plant roots show potential for increasing the nitrogen-use efficiency and decreasing the extent of environmental pollution. We isolated two diterpenoids, coracanols A (1) and B (2), from finger millet grown under low-nitrogen conditions. Both compounds showed BNI activity against nitrifying bacterium Nitrosomonas europaea. The novel skeletons (1 and 2) featuring a tetracyclo[10.2.2.0¹,¹⁰.0²,⁷]hexadecane core were elucidated by spectroscopic and X-ray crystal structure analyses utilizing the crystalline sponge method.