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Background The Phenomenon of codon usage bias exists in the genomes of prokaryotes and eukaryotes. The codon usage pattern is affected by environmental factors, base mutation, gene flow and gene expression level, among which natural selection and mutation pressure are the main factors. The study of codon preference is an effective method to analyze the source of evolutionary driving forces in organisms. Epimedium species are perennial herbs with ornamental and medicinal value distributed worldwide. The chloroplast genome is self-replicating and maternally inherited which is usually used to study species evolution, gene expression and genetic transformation. Results The results suggested that chloroplast genomes of Epimedium species preferred to use codons ending with A/U. 17 common high-frequency codons and 2–6 optimal codons were found in the chloroplast genomes of Epimedium species, respectively. According to the ENc-plot, PR2-plot and neutrality-plot, the formation of codon preference in Epimedium was affected by multiple factors, and natural selection was the dominant factor. By comparing the codon usage frequency with 4 common model organisms, it was found that Arabidopsis thaliana, Populus trichocarpa, and Saccharomyces cerevisiae were suitable exogenous expression receptors. Conclusion The evolutionary driving force in the chloroplast genomes of 10 Epimedium species probably comes from mutation pressure. Our results provide an important theoretical basis for evolutionary analysis and transgenic research of chloroplast genes.

Baohuoside I is a flavonoid isolated from Epimedium koreanum Nakai and has many pharmacological activities. However, its role in liver cancer remains unclear. This study aimed to investigate the inhibitory effect of Baohuoside I on the Human Hepatocellular Carcinoma (HCC) cell lines QGY7703, and underlying mechanisms. QGY7703 cells were used as the model to assess the function of Baohuoside I in vitro. The effects of Baohuoside I on QGY7703 cells’ growth, proliferation, and invasiveness were confirmed by CCK‐8, lactate dehydrogenase release, and invasion assays. Cell apoptosis was analyzed by flow cytometry, and the levels of cleaved Caspase‐3, Bax, and Bcl‐2 were quantified by western blot. Western blot analysis, nuclear translocation of NF‐κB, and Q‐PCR were used to measure the expression of affected molecules. In QGY7703 cells, Baohuoside I induced the expression of molecules related to NF‐κB pathway. The toxicity of Baohuoside I on QGY7703 cells was also confirmed in vivo, in a tumor model. Baohuoside I had a significant toxic effect on QGY7703 cells from a concentration of 10 μM. This compound significantly inhibited the proliferation of QGY7703 cells by inducing apoptosis and downregulating NF‐κB signaling pathway. Thus, Baohuoside I is a novel candidate drug and opens new possibilities of clinical strategies for HCC treatment.