Effect of Different Harvesting Stages and Processing Methods on the Content of Three Major active Ingredients of Polygonatum cyrtonema Hua

Objective  Comparing the difference of the content of three major bioactive small molecule ingredients of Polygonatum cyrtonema Hua with different growth years, phenological phases and processing status, is for the purpose of providing reference for feasible harvesting and quality evaluation of Polygonati rhizome.

Methods  Rhizomes of P. cyrtonema Hua with 1～4 physiological growth years were harvested every two months within one year round, and the contents of 5-hydroxymethylfurfural (HMF), 4′,5,7-trihydroxy-6,8-dimethylhomoisoflavanone (HIF) and polygonatine A (PA) were detected by using HPLC method. Besides, contents of the three ingredients in six batches of before and after the processed Polygonati rhizome samples from four provinces nationwide were detected and compared.

Results  As the physiological age increased, the contents of HMF and HIF showed a trend of increase, HMF content reaching the peak (27.62 μg·g⁻¹) in 4-year-old rhizomes at primary blossoming stage, HIF content reaching the highest value （14.04 μg·g⁻¹）in 4-year-old underground rhizomes at bud sprouting stage. The effect of physiological age on PA content was not distinct, but the harvesting stage had significant effect on it, with highest value at fruiting stage (more than 9.57 μg·g⁻¹). The contents of HMF and PA in the processed rhizomes significantly increased by approximately 29.6 and 13.8 times, respectively, as compared with those of the non-processed rhizomes.

Conclusion  The harvesting stages and processing methods have distinct effect on the contents of HMF, PA and HIF with different trends, which should be determined in comprehensive consideration of growth yields, drying rate and other ingredient at harvesting stages. The results of this study lay a foundation for feasible harvest and quality evaluation of Polygonati rhizome.