Metabolites of orally administered Perilla frutescens extract in rats and humans

As a part of our search for bioactive substances from the leaves of Perilla frutescens BRITTON var. acuta KUDO (Perillae Herba, Labiatae), the aqueous extract was orally administered to rats and humans, and metabolites in the urine, plasma, and/or bile were analyzed by a high-performance liquid chromatograph (HPLC) equipped with a photodiode array detector. When the extract was administered to rats, 10 metabolites, trans-caffeic acid-4-O-sulfate (1), trans-p-coumaric acid-4-O-sulfate (2), trans-ferulic acid-4-O-sulfate (3), trans-m-coumaric acid-3-O-sulfate (4), trans-caffeic acid (5), m-hydroxyphenylpropionic acid (6), trans-p-coumaric acid (7), trans-m-coumaric acid (8), luteolin (9), and apigenin (10) were detected in the urine, whereas four metabolites, scutellarein-6, 7-di-O-beta-glucuronide (11), apigenin-4'-O-sulfate-7-O-beta-glucuronide (12), apigenin-7-O-beta-glucuronide (13), and diosmetin-7-O-beta-glucuronide (14) were found in the bile. Compounds 1-8 and 11-14 were also found in the plasma. When the extract was given to humans, however, two metabolites, 1-O-(2,4,5-trimethoxycinnamoyl)-beta-glucuronic acid (15) and apigenin-4'-O-beta-glucuronide (16), were found in the urine and plasma. Thus, a species difference in the metabolism of the extract constituents was observed between rats and humans. Structures 1-16 were identified based on their chemical and spectral data.