Antioxidant and antibiofilm activities of secondary metabolites from Ziziphus jujuba leaves used for infusion preparation

- Extracts obtained from jujube leaves showed high antioxidant activity.
- The main antioxidant polyphenols of jujube leaves have been identified.
- Jujube leaf extracts showed antibiofilm activity against Streptococcus mutans.
- Alphitolic acid was identified as the antibiofilm agent of jujube leaf extract.
- Jujube leaf extracts could be natural remedies for prevention of dental caries.

Ziziphus jujuba Mill., jujube, leaf infusions are popular bedtime beverages as they improve sleep by soothing the nerves. With the aim of providing further insights into the polyphenol content of jujube leaf infusion and their antioxidant activities, a 2,2-diphenyl-1-picrylhydrazyl (DPPH)-guided purification of the aqueous extract of Z. jujuba Mill. leaves was conducted. Three major antioxidant polyphenols (i.e. quercitrin, catechin and gallocatechin) of the leaves were identified. In addition, a significant antibiofilm bioactivity against Streptococcus mutans, a causative agent of human dental caries, was detected for the aqueous leaf extract and its bio-guided separation resulted in the identification of the lupane triterpenoid alphitolic acid as the main antibiofilm metabolite. The results herein presented further promote the consumption of jujube leaf infusion as a healthy antioxidant bedtime beverage, and associate it to an unreported anti-caries activity.