Seasonal variation of bioactive alkaloid contents in Macleaya microcarpa (Maxim.) Fedde

Macleaya microcarpa (Maxim.) Fedde belongs to the genus Macleaya, family Papaveraceae. Together with the better known and more frequently studied species M. cordata (Willd.) R. Br. it is a main source of quaternary benzo[c]phenanthridine alkaloids. Using HPLC we determined the content of eight isoquinoline alkaloids in the aerial and underground parts of 1-, 2-, 12- and 13-year old plants and followed their changes during the vegetative period. The dominant alkaloid of all samples collected in the end of this period was allocryptopine (3.8-13.6 mg/g for aerial parts, 24.2-48.9 mg/g for underground parts). Chelerythrine, sanguinarine and protopine were also present in both parts of the plant. Additionally, measurable concentrations of chelilutine (CL), chelirubine (CR), macarpine (MA) and sanguirubine (SR) were detected in underground parts. The most important finding was that contents of CR, CL, SR and MA in the 12- and 13-year old plant roots were significantly higher (approximately 3-fold for CR, 6-fold for CL, 5-fold for SR, and at least 14-fold for MA) than in 1- or 2-year old plants. The proportion of individual alkaloids in aerial and underground parts thus changed significantly during the vegetative period.