Nitrification Inhibitors from the Roots of Leucaena leucocephala

The nitrification inhibition (NI) bioassay guided fractionation of the methanol extract of lyophilized and milled roots of Leuceana leucocephala resulted in the isolation of four compounds, 1 – 4, as confirmed from their 1 H and 13 C NMR spectral data. Compound 1, gallocatechin, was the most active NI inhibitor at 12 μg/mL. Epigallocatechin, 2, and epicatechin, 4, isolated as mixtures, were not assayed individually for their NI inhibitory activities against the nitrification bacterium Nitrosomonas europaea .