Phytochemical analysis of Chinese commercial Ziziphus jujube leaf tea using high performance liquid chromatography–electrospray ionization-time of flight mass spectrometry

• Principal phytochemical components in ZJLT infusion were screened and identified.
• ZJLT infusion doesn’t contain caffeine and theophylline.
• ZJLT infusion is rich in bioactive flavonol glycosides.
• ZJLT infusion contains some antioxidant compounds.
• Based exclusively on its chemicals, ZJLT may be suitable for drinking at night.

Ziziphus jujube leaf tea (ZJLT 1) is a new type of plant tea that has recently gained popularity in China. ZJLT is often advertised by its manufacturer for its special capacity to improve sleep. However, the suitability of drinking ZJLT at night still lacks scientific basis. This work aims to identify the typical phytochemical components in ZJLT infusion and try providing a scientific basis for drinking at night. An efficient liquid chromatography–diode array detector with time-of-flight mass spectrometry (LC–DAD–TOF/MS) method and online 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay were performed to clarify the principal bioactive compounds of ZJLT. First, caffeine and theophylline, which have important functions in refreshing the human body, were not detected in the ZJLT infusion. Second, the ZJLT infusion contains rich flavonoids, mainly flavonol glycosides, with possible sedative and hypnotic activities. Finally, a number of free radical scavengers were screened out in the ZJLT infusion. In this research, the comprehensive bioactive component information showed that ZJLT does not contain refreshing components; rather, ZJLT contains rich possibly sedative flavonoids and antioxidants. Hence, based exclusively on its chemical composition, ZJLT may be suitable for drinking at night.