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. Conclusions: 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.