Chemical composition and antioxidant activity of Polygonatum kingianum processed by the traditional method of 'Nine Cycles of Steaming and Sun-Drying'

Polygonatum kingianum Coll. et (Hemsl) is a famous Chinese traditional food and medicine analogous plant. The rhizome of P. kingianum showed a decrease in levels of alkaloids, amino acids and derivatives, terpenoids, and an increase in organic acid and saccharides when it was processed by the traditional method of “Nine Cycles of Steaming and Sun-Drying”. The relative content of 341 metabolites were increased (fold change, FC > 2; variable importance in projection, VIP > 1 and P-value, P 1, and P