Study Of Antioxidant And Anti-tumor Components Of Styela Plicata

Since Hippocrates named cancer more than 2,000 years ago,cancer has been haunting humans like a nightmare.With the social changes and the transformation of human lifestyle,the incidence of cancer is also increasing.Until the development of medicine into the 21st century,cancer is still a worldwide problem that needs to be solved urgently.Anti-cancer drugs are one of the main methods for treating cancer.Naturally derived compounds are an important way to discover new drugs.According to statistics,about 50%of the drugs currently on the market come from natural products and their derivatives.Due to the high salt,high pressure,and less light in the marine environment,the natural products of marine origin are completely different from that of terrestrial environment,resulting in the natural features of the marine natural product with novel structure and strong activity.In recent years,a large number of marine natural products have been discovered,among which the anti-tumor and antioxidant activity is particularly noticeable.Oxidative free radicals play a significant role in the development of tumors in the human body,and antioxidants can eliminate free radicals and help to slow the development of cancer.As a marine tunicate animal,ascidian has unique advantages in the development of anti-tumor drugs.There have been many reports of antioxidant and anti-tumor substances isolated from ascidians.In the South China Sea,ascidians are widely distributed and Styela plicata is the dominant species.In addition,previous research often used ascidians as a whole part.In fact,there are obvious differences between the tunic and visceral mass of ascidians.Therefore,this study focuses on the anti-oxidation and anti-tumor activity in different parts of Styela plicata,and explores the antioxidant and anti-tumor mechanisms of active component.These studies laid a solid foundation for further development of marine drugs.The main findings are as follows:1.For the tunic of Styela plicata,buffer extraction and ultrafiltration were used to obtain four different molecular weight levels of tunic polypeptides and their antioxidant activity were studied respectively.At the same time,the effects on the growth of human cervical cancer HeLa cells of four molecular weight polypeptides were examined.2.Further,HPLC-based system equipped with a C18 semi-preparative column and biological activity tracking method were used to obtain a polypeptide SP336,which inhibits the growth of human cervical cancer HeLa cells.SP336 was purified from the less than 3K tunic polypeptide of Styela plicata.High-resolution mass spectrometry indicated that the molecular weight of SP336 was 336 daltons.In addition,VCEF-6,a component capable of inducing apoptosis in cancer cells,was isolated and purified from the visceral mass of Styela plicata by using methanol extraction,silica gel column chromatography with other separation methods and bioactivity-guided fractionation.The results of cell activity test showed that this component can significantly inhibit the growth of two human tumor cells in vitro,and has a dose-response relationship.However,the toxicity of VCEF-6 to human normal embryonic kidney 293FT cells is very low.3.To further study the mechanism of VCEF-6,we carried out relevant researches from morphological studies,Annexin V/FITC staining,apoptosis analysis,and cell cycle arrest.The results showed that VCEF-6 could induce apoptosis in HeLa and A549 cells,and the cell cycle of HeLa cells was arrested in G0/G1 phase,which affected cell proliferation.Based on the above results,we preliminarily concluded that VCEF-6 induces apoptosis of human cervical cancer HeLa cells by blocking the cell cycle.These results of the study indicate that Styela plicata can be used as a valuable resource for the discovery of anti-tumor compounds.With high cytotoxic activity on two human tumor cells and low cytotoxicity to human normal cells,VCEF-6,which is derived from the visceral mass of Styela plicata,is hopeful to be further developed as a new type of antitumor drug.This study conducted a preliminary exploration of the mechanism of tumor cell growth inhibition of VCEF-6.Preliminary results indicate that VCEF-6 causes the mitotic cycle of tumor cells to be arrested in the G0/G1 phase,which leads to inhibition of cell growth.However,the exact mechanism of apoptosis induced by VCEF-6 is not yet clear,and the interaction between this component and cell signaling molecules needs further research to determine.