Research on the Chemical Components and Antitumor Activity of Hedyotis diffusa
Hedyotis diffusa Willd is a dried whole plant of the Rubiaceae family, belonging to the genus Hedyotis diffusa Willd. It is cold in nature, bitter in taste, and sweet in taste. It is suitable for the heart, liver, spleen, and large intestine meridians. The whole plant is used as medicine and is mainly distributed in Guangxi, Fujian, Anhui, Yunnan, and other regions of China. Research reports that Hedyotis diffusa contains dozens of compounds including iridoids, acid compounds, anthraquinone compounds, volatile components, phenylpropanoids, coumarins, and polysaccharides, as well as various trace elements. It has various pharmacological activities such as anti-tumor, anti-inflammatory, antibacterial, antioxidant, and immune enhancement. Hedyotis diffusa is a common medicinal herb in traditional Chinese medicine anti-tumor compound therapy. Its anti-tumor activities include inhibiting tumor cell proliferation, inducing tumor cell apoptosis and tumor angiogenesis, regulating host immune response, and protective autophagy. It is widely used in various anti-cancer treatments such as digestive system tumors, reproductive system tumors, respiratory system tumors, and myeloma. The main anti-tumor components in Hedyotis diffusa are ursolic acid and oleanolic acid. The anti-tumor mechanism of ursolic acid is to inhibit the growth of breast cancer and colon cancer cell lines by triggering cell apoptosis, cell cycle arrest, and playing anti metastasis and anti angiogenesis characteristics through various molecular targets and signal pathways. Oleanolic acid induces cell apoptosis by simultaneously regulating different signal pathways and biological processes through multiple action targets, including intracellular calcium level, NF – κ B signal pathway, Notch signal pathway, JAK/STAT3 signal pathway, and the expression of ribose polymerase. In recent years, many scholars have conducted extensive research on the chemical composition and pharmacological effects of Hedyotis diffusa, and have continuously isolated new compounds based on the pharmacological substances of different parts of Hedyotis diffusa. Up to now, 171 compounds have been isolated from Hedyotis diffusa, including 32 cyclohexene ether terpenes, 26 flavonoids, 24 anthraquinones, 26 phenolic compounds and their derivatives, and 50 volatile oil compounds. These plant chemicals and extracts have various pharmacological activities, such as anti-tumor, antioxidant, anti-inflammatory, fibroblast proliferation inhibition, immune function regulation, and nervous system protection. This experiment isolated and purified the chloroform and ethyl acetate parts of Hedyotis diffusa, and detected the anti-tumor activity of different polar parts of Hedyotis diffusa through in vitro cell experiments.

 

This experiment systematically isolated the chemical components from the chloroform and ethyl acetate parts of Hedyotis diffusa, and obtained 13 compounds. Among them, compounds heptadecanoate, 7-hydroxytectoquinone, and 2-butyl-1-hydroxyanthra-9,10-quinone were first isolated from this plant. The inhibitory effect of different polar parts and monomeric compounds of Hedyotis diffusa on A549 cell proliferation was detected through CCK8 experiment. The results showed that both the chloroform and ethyl acetate parts of Hedyotis diffusa had good inhibitory effects on A549 cell proliferation, and there was a significant dose-response relationship. The effect of different polar parts of Hedyotis diffusa on the proliferation of A549 cells was compared with cisplatin. When the drug concentration reached 200 μ g/mL, only chloroform extract was more effective than cisplatin. When the drug concentration reached 400 μ g/mL, both chloroform extract and ethyl acetate extract were more effective than cisplatin. From this, it can be determined that the chloroform and ethyl acetate parts of Hedyotis diffusa are the active sites for anti lung cancer A549 cells, and these two parts will be the targets for isolating active substances. Through screening experiments on the inhibitory proliferation activity of compounds on A549 cells, it was found that betulinic acid, oleanolic acid, and ursolic acid have good inhibitory effects on A549 cells at the same concentration. The inhibition rates of betulinic acid and oleanolic acid significantly increased with the increase of drug concentration, and both tended to stabilize at 16-20 μ mol/L. The inhibition rate of ursolic acid remained relatively stable within the range of 1-8 μ mol/L, and then increased with increasing concentration, reaching 68.45% at 20 μ mol/L. In the concentration range of 1-20 μ mol/L, compared with the positive control cisplatin, the inhibition rate of betulinic acid was higher at concentrations of 16 μ mol/L and 20 μ mol/L than cisplatin; The inhibition rate of ursolic acid is higher than that of cisplatin when the concentration exceeds 16 μ mol/L; The inhibition rate of oleanolic acid is comparable to cisplatin at 4-12 μ mol/L, but higher than cisplatin at concentrations exceeding 12 μ mol/L. In previous studies, it has been found that the chemical components of Hedyotis diffusa, such as terpenes, anthraquinones, sterols, flavonoids, and polysaccharides, have prominent anti-cancer effects. Research on the anti-tumor therapeutic effect and mechanism often uses water extracts or alcohol extracts of Hedyotis diffusa to act on different tumor cells to observe in vitro anti-tumor effects. The results of this experiment provide a theoretical basis for the basic research on the anti-tumor active substances of Hedyotis diffusa.