Isolation from beer and structural determination of a potent stimulant of gastrin release

Beer was subjected to five successive chromatographic procedures to isolate the gastrin release-inducing activity, guided by bioassay of the fractions in anaesthetized Donryu rats. The procedures were: (1) hydrophobic interac tion chromatography (aqueous effluent with an HP20 column); (2) weak cation -exchange chromatography (1 M acetic acid eluate with a CM Sephadex C-25 co lumn); (3) gel filtration (methanol eluate with a Sephadex LH-20 column); ( 4) same as (2); (5) high-performance liquid chromatography (YMC-Pack ODS-AM with 7% acetonitrile-0.01 M HCl). The active component finally isolated ha d a specific activity similar to 10 000 times higher than that of beer. It was identified by means of mass, H-1- and C-13-nuclear magnetic resonance s pectral analyses as N-methyltyramine (NMT). The dose of NMT giving maximal gastrin-releasing activity was 25 mu g/kg, and the 50% effective dose was s imilar to 10 mu g/kg on oral administration to rats. NMT was isolated and i dentified as a gastrin release inducer in beer. Its concentration in beer i s sufficient to account for most of the activity of beer.