The Lw fraction had no effect on blood pressure in
either type of rat. The main ACE inhibitor in the Hw fraction
was purified by high-performance liquid chromatography
and was identified as nicotianamine (N-[N-(3-amino-
3-carboxypropyl)-3-amino-3-carboxypropyl]-azetidine-2-carboxylic
acid) (Fig. 1). The IC50 of nicotianamine for ACE
was 0.26 µM. It was one-tenth of that of the widely used
antihypertensive drug Captopril.