BackgroundXeniji, produced by fermenting various types of foods with lactic acid bacteria and yeast, has been commonly consumed as functional food. However, nutrition value, bioactivities and safety of different fermented products maybe varies.MethodsOrganic acid and antioxidant profiles of Xeniji fermented foods were evaluated. Moreover, oral acute (5 g/kg body weight) and subchronic toxicity (0.1, 1 and 2 g/kg body weight) of Xeniji were tested on mice for 14 days and 30 days, respectively. Mortality, changes of body weight, organ weight and serum liver enzyme level were measured. Liver and spleen of mice from subchronic toxicity study were subjected to antioxidant and immunomodulation quantification.ResultsXeniji was rich in β-carotene, phytonadione, polyphenol, citric acid and essential amino acids. No mortality and significant changes of body weight and serum liver enzyme level were recorded for both oral acute and subchronic toxicity studies. Antioxidant level in the liver and immunity of Xeniji treated mice were significantly upregulated in dosage dependent manner.ConclusionXeniji is a fermented functional food that rich in nutrients that enhanced antioxidant and immunity of mice.Graphical abstractXeniji that rich in β-carotene, phytonadione, polyphenol, citric acid and essential amino acids promote antioxidant and immunity in mice without causing toxic effect. Electronic supplementary materialThe online version of this article (doi:10.1186/s12906-017-1845-6) contains supplementary material, which is available to authorized users.

Xeniji is a health food product produced by bacterial lactic acid fermentation. Although fermented foods, including Xeniji, have been widely consumed for various health purposes, including as an antioxidant to improve liver disease, their polyphenol content and in vivo hepato-recovery effects have yet to be evaluated. This study aims to evaluate the polyphenol content of Xeniji and its in vivo hepato-recovery effect on ethanol-induced liver damage. In this study, the polyphenolic acids of Xeniji are quantified by liquid chromatography-mass spectrometry (LCMS). In addition, the recovery effect of Xeniji on ethanolinduced liver damage in mice is evaluated by assessing the serum liver enzyme profile, liver inflammation, liver oxidative stress, and the level of CYP2E1. Xeniji is recorded to contain a high concentration of caffeoylquinic acid and sakuranetin, based on the LCMS-MS quantification results. In terms of the in vivo hepato-recovery study, intake of ethanol induces substantial liver damage indicated by an increase of the serum liver enzyme profile, liver inflammation, liver oxidative stress and the level of CYP2E1. On the other hand, Xeniji promotes recovery from ethanol-induced liver damage by restoring antioxidant levels, enhancing the metabolism of ethanol in the liver and suppressing inflammation in a dosage-dependent manner. Xeniji is a fermented functional food that possesses hepato-recovery effects on ethanol-induced liver damage.