## 1 Introduction  
Tea is a traditional drink around the world, rich in various active ingredients, mainly catechins. Epigallocatechin gallate (EGCG) is a main active monomer in catechins, well-known for its anti-inflammatory, antioxidant and anti-obesity properties. [PERSON] et al. [1] found that EGCG alleviated liver lipid accumulation by regulating gut microbiota. However, these natural active nutrients seem to be difficult to absorb and utilize [2]. In fact, [PERSON] [3] stated that the probiotics in the digestive tract or in foods could enhance the bioavailability of nutrients. The roles of probiotics in the prevention and treatment of diseases, such as liver and cardiovascular disease, have been reported. In [PERSON] et al.'s study [4], the probiotics rich in selenium-glutathione alleviated carbon tetrachloride (CCI\({}_{4}\))-induced liver fibrosis by attenuating oxidative damage, endoplasmic reticulum stress and inflammation. Recently, studies have found that the natural plant ingredients worked better when combined with probiotics. For example, the combination of hull-less barley \(\beta\)-glucan and _Lactobacillus plantarum_ S58 exhibited a greater effect on ameliorating obesity by activating lipid metabolism pathway and regulating gut microbiota [5]. Therefore, we speculated that EGCG combined with probiotics would have a better bioactivity.  
The largest metabolic organ, liver, performs an antioxidant function, substance transformation and an immune function [6]. The liver shares the same embryological origin and has many anatomical and functional connections with intestine [7], and would be greatly affected by gut microbiota. Gut microbiota is an important mediator in regulating the physiological homeostasis and interacting with various organs [8]. However, the imbalance of gut microbiota promotes the occurrence and development of various diseases such as inflammatory bowel disease, obesity and liver diseases [9]. [PERSON] et al. [10] showed that the alteration of gut microbiota promoted the progression of liver diseases, and prebiotics or probiotics could prevent liver injuries through regulating gut microbiota, which served as effective therapeutics. The homeostasis of gut microbiota is of great importance for liver health.  
At present, the human liver is under great metabolic pressure from environmental pollutants. CCl\({}_{4}\), a potent industrial environmental pollutant used in detergents, is metabolized by the cytochrome P450 into trichloromethyl radical and reactive oxygen species (ROS) in the hepatocytes, which causes liver injury [11]. In recent years, CCl\({}_{4}\) has been widely used in the establishment of animal liver injury models for its clear toxicity mechanism. In this study, CCl\({}_{4}\) was chosen to induce the mice liver injury model, so as to exclude unclear mechanism interference and better demonstrate the combined bioactivity of natural plant ingredients and probiotics. Our study hypothesized that EGCG from tea and the probiotic Lactiplantiobacillus plantarum P101 (LP.P101, showed an excellent antioxidant performance, and was screened from Chinese family homemade sauerkraut) would have the best effect in alleviating liver damage caused by CCl\({}_{4}\) in mice. Moreover, we explored the effect of the altered gut microbiota through the combination of EGCG and LP.P101 in liver damage reduction. In short, there is still no great progress in improving the utilization rate and biological activity of natural plant products. The study will be beneficial in understanding the promoting effect of probiotics on natural plant products and providing a potential strategy for enhancing the utilization and biological activity of natural products. Meanwhile, the alleviating effects and mechanisms of the combination of foodborne natural plant products and probiotics on mild liver oxidative and inflammatory damage are also worthy of further study.