High-temperature Condition Increases Lignanoid Biosynthesis of Schisandra chinensis Seeds via Reactive Oxygen Species

Introduction: The herbal medicine used in many countries came mainly from the wild in the past; now, declining yield resource and laborious gathering result in prevailing cultivated medicine, with a result of prevailing inferior quality of herbal medicine. The contents of major functional ingredients varies greatly in the fruits of Schisandra chinensis, a herbal medicine in many Asian countries. Materials and Methods: These fruits were placed at 20°C, 35°C, 45°C, and 55°C for 1–6 days, respectively, covered with plastics to prevent cells from anhydration during treating. The contents of H2O2, phenylalanine, and lignanoids and activities of antioxidant enzymes and phenylalanine ammonia lyase (PAL) were monitored. Results: The fresh seeds were exposed to 35°C, 45°C, and 55°C for 1 week; the H2O2 was rose sharply at 1 day and then declined but still with a higher level. The superoxide dismutase, catalase, and peroxidase activities were lowered, with inefficient antioxidant capacity. The PAL activities had a certain degree of high‑temperature tolerance, remained largely unchanged at 35°C, but reduced gradually as temperature increased. High temperature activated the glycolytic pathway and rose the phenylalanine contents, which increased sharply at 1 day for 35°C and 45°C and at the 2 days for the 55°C and then maintained a stable level with almost 1–3 times than the 0 day. Conclusion: The increased phenylalanine as substrate accelerated the synthesis of lignanoids; the contents of five lignanoids were increased by as much as 31.2%–81.5%, respectively.