Seasonal variation and gender pattern of phenolic and flavonoid contents in Pistacia chinensis Bunge inflorescences and leaves

Pistacia chinensis Bunge (P. chinensis) is a deciduous and dioecious perennial arbor of the family Anacardiaceae that flowers from March to April and bears fruit from September to October. There are three rapidly growing stages in the annual growth process of P. chinensis. However, the knowledge of the secondary metabolites related to P. chinensis gender and growth season remains scant. In this study, HPLC was used to qualitatively and quantitatively determine the content of the catechin hydrate, rutin, quercetin, and kaempferol contents in male and female tree inflorescences and leaves. Total phenolics and flavonoids were also detected using a spectrophotometer. The results indicated that the contents of these compounds fluctuated with seasons and they reached the highest levels in nascent leaves. The fluctuations of these compounds followed different pathways of evolution, by increasing or decreasing in male and female trees throughout the whole growth process because they had their own biological functions. Moreover, the extracts exhibited DPPH radical scavenging bioactivity and showed no significant cytotoxicity towards 3T3-L1 preadipocytes. Together, these results demonstrated that P. chinensis has great potential as an antioxidant medicine, and the best harvest time is in the spring.