Accumulation of L-DOPA in various organs of faba bean and influence of drought, nitrogen stress, and processing methods on L-DOPA yield

摘要

Faba bean (Vicia faba L.) has been identified as a rich source of L-DOPA, which is used in treating Parkinson's disease. Biosynthesis and accumulation of active substances such as L-DOPA in plant tissues may interact with growing conditions and processing methods. Accumulation trends of L-DOPA in various faba bean organs and the effect of drought stress and N fertilization on L-DOPA content were studied in a field and two greenhouse experiments. The influence of various processing methods on L-DOPA content of faba bean tissues was evaluated. The highest L-DOPA content was detected in fresh leaves (22.4 mg g–1) followed by flowers, young pods, mature seeds, and roots. Regardless of processing method, L-DOPA concentration in faba bean tissues was significantly reduced when tissues were boiled or dried. Among various methods of processing, freezing had the lowest detrimental effect, reducing L-DOPA concentrations by 24.1％and 21.1％in leaves and seeds, respectively. Drought stress elevated L-DOPA concentration, and maximum L-DOPA (23.3 mg g–1 of biomass) was extracted from plants grown under severe drought stress. However, L-DOPA yield (L-DOPA concentration × biomass) was compromised, owing to the adverse influence of drought stress on dry matter production. No significant difference in L-DOPA concentration was detected among various N application rates.