Advances in the research on anticancer active ingredients and their anticancer mechanisms in litchi fruits

Currently, the global cancer burden continues to increase. Existing cancer treatments face bottlenecks such as drug resistance and toxic side effects, and scientists are looking for natural products that can effectively prevent and treat cancer. litchi fruit as a kind of food with medicine effect is rich in polyphenols (proanthocyanidins, phenolic acid, flavonoids), vitamin C, dietary fiber, polysaccharides and saponins and other active ingredients. Research has shown that litchi fruit has a certain preventive and inhibitory effect on the occurrence of breast cancer, colon cancer, prostate cancer and liver cancer, etc. due to the active ingredients. The total phenolic content of nine Litchi varieties, including Feizixiao, Heiye and Nuomici, ranged from 9.39 to 30.16 mg·g-1 , with an average of 16.27 mg·g-1 , which showed potent antioxidant properties and reduced the risk of cancerous lesions. The Litchi proanthocyanidins could inhibit the metastasis of colon cancer by triggering the intestinal-lung axis to influence the immune response of T-cells, and the total flavonoids from Litchi kernel could inhibit the development of breast cancer, prostate cancer and liver cancer. The total flavonoids from Litchi Semen (TFLS) could inhibit the growth of prostate cancer in bone by inhibiting the HGFR/NF- κB signaling pathway, and TFLS could reduce the expression level of phosphorylated JAK2 and STAT3 by activating SHP-1 to block the JAK2/STAT3 signaling pathway. The TFLS could inhibit the proliferation of HepG2 cells by activating SHP-1 to block the JAK2/STAT3 signaling pathway, and also inhibit the migration and invasion ability of HepG2 cells by reversing the EMT process of the cells, thus exerting anti-tumor effects. In addition, the TFLS could inhibit the proliferation and metastasis of non- small cell lung cancer (NSCLC) through regulating the Skp2-p21/p53 signaling axis. The vitamin and dietary fiber contents of litchi also differed from each other. The Vitamin C content ranked in the forefront of common fruits, the black leaves contained about 32 mg of vitamin per 100 g, while toffee contained about 56 mg of vitamin C per 100 g; the content of dietary fiber in the pulp of white wax, toffee and wyche wass 0.77 g·100 g-1 , 0.75 g · 100 g-1 and 1.16 g · 100 g-1 , respectively, which built an intestinal defense barrier for the organism. The litchi dietary fiber could play a role in preventing colon cancer through regulating intestinal function and strong antioxidant function dual pathway. Studies showed that the intake of dietary fiber was negatively correlated with the incidence of colon cancer; litchi polysaccharides could also inhibit the proliferation of human hepatocellular carcinoma cells HepG2, human cervical cancer cells Hela, human lung cancer cells A549 three kinds of tumor cell lines in a concentration- dependent manner, and the degree of inhibition and litchi fresh and dried also had a certain relationship; the use of litchi kernels and nuclei of litchi could help to build a defense barrier for the body. The use of litchi nuclear saponin for endocrine treatment of breast cancer could also delay the progression and recurrence of breast cancer. In addition to these anti-cancer mechanisms, the anti-cancer active ingredients in litchi could also produce synergistic effects with drugs, reducing the adverse effects of anti-tumor drugs. The litchi nuclear flavonoids and paclitaxel combined with the proliferation of drug-resistant cells of prostate cancer inhibition, so that the two could be used in conjunction with synergistic inhibitory effects. The rich anticancer active ingredients of litchi fruit and its potential shown in the prevention and treatment of many kinds of cancers have opened up a new dimension for the development of multi-targeted and synergistic anticancer drugs. Existing studies have not only systematically identified a variety of anticancer active ingredients, but also elucidated the anticancer efficacy of these ingredients through multiple pathways, but the studies are generally conducted on a single active ingredient, and the studies on the specific mechanism of action of the anticancer active ingredients in litchi fruits are relatively dispersed. Therefore, this paper summarized the anticancer active ingredients in Litchi chinensis fruit and their mechanisms of action in the stages of cancer proliferation and metastasis, with the aim of providing reference for the subsequent drug development and comprehensive utilization of L. chinensis fruit.