Isolation and identification of hypotensive principles in red-mold rice.

During an initial search for pharmacologically active principles in red-mold rice, two hypotensive compounds were isolated and identified. The active principles, A-3 and B-1, were fractionated and purified from the EtOH extract of red-mold rice prepared with Monascus pilosus through extraction with H2O, Amberlite CG-120 column chromatographies and high-performance liquid chromatography on an ODS column. A-3 was identified as acetylcholine chloride by comparison with an authentic sample, and B-1, colorless needles of mp 203-205 °C, was proved to be identical with authentic γ-aminobutyric acid. Intravenously administered A-3 (0.5 μg/kg) and B-1 (250μg/kg) produced potent depression of the carotid arterial blood pressure in spontaneously hypotensive rats, as did the corresponding authentic samples.