Structure Modification And Antitumor Activity Studies Of Galangin

In 2008,GLOBOCAN reported that breast cancer was the sixth leading cause of death among women in China,with an ASR of 5.7 per 100,000 women after lung cancer,stomach cancer,liver cancer,esophageal cancer and colorectal cancer.Data shows that: in recent 40 years,the incidence of breast cancer at home and abroad showed an upward trend every year,particularly obvious in our country.Breast cancer has become a major problem plagued the Chinese women and the studies on the breast cancer has also become a hot topic.The majority of the existing anti-breast cancer drugs use in clinical have side effects and drug-resistance,therefore,how to find a more effective,novel anti-tumor drugs with lower toxicity,has been the target of medicinal chemists.Galangin(3,5,7-trihydroxyflavone),a naturally occurring bioflavonoid,is mainly distributed in the rhizomes of traditional Chinese medicine Alpinia officinarum Hance.It has a wide range of pharmacological activities.Modern research shows that galangin can inhibit the liver cancer,lung cancer,melanoma and other cancer cell proliferation.It is considered to be a promising chemoprophylactic medicine.However,there is litter reports about the structural modification of the galangin.We find that the chemical structure of the galangin is similar to that of Flavopiridol.Flavopiridol is one of the CDKs inhibitors,which has a wide antitumor activities.The study on structure-activity relationship showed that the presence and position of the nitrogen atom containing the nitrogen atom in the flavonoid nucleus had a great effect on the inhibitory activity of CDKs.The activity is greatly reduced when the piperidine ring was substituted by cyclohexane,the 5,7 hydroxyl group is important for CDKs inhibitory activity.Compared the structure of galangin and Flavopiridol,it was found that the galangin is lack of the D-cyclic hydroxyl piperidine nitrogen ring,which is essential to the inhibitory activity of CDKs.This phenomenon suggests that introducing the nitrogen-containing atoms D ring into the structure of the galangin is expected to enhance the inhibitory effect of galangin on CDKs,in order to find some structural optimizational products as CDKs inhibitors.Through the present research,it will make full use of Galangal plant resources and provide the possibility for the development of new anticancer drugs.In the first part of this paper,six nitrogen-containing galangin derivatives(GS-a~GS-f)were designed and synthesized by Mannich reaction.By using mass spectrometry,1H NMR and IR spectra,the structure of modified products were characterized and clarified.In addition,the antitumor activity of the modified products was measured by MTT method.The results showed that some compounds showed better anti-tumor activity than galangin,GS-a and GS-c against MGC-803,GS-d to A549 and Hela,GS-e against A875,PC-3,,GS-f against PC-3,MGC-803 activity is better than galangin.The introduced groups play a role in enhancing the activity.Previous studies have shown that galangin can induce apoptosis of MCF-7 cells and inhibit the proliferation of MCF-7 cells.However,the molecular mechanism of inducing apoptosis in MCF-7 is not clear yet.Therefore,we investigate the effects on induction apoptosis and the impact on a serial of apoptosis-related mitochondrial pathway and Caspase cascade related signal expression protein kinases in cell signal transduction pathway to explore it’s mechanism.The growth inhibition rates of of MCF-7 was measured by CCK-8 method,the results showed that galangin can significantly inhibit the proliferation of MCF-7 cells,showing a concentration dependent relationship,24 h and 48 h IC50 were 43.71 μmol/L and 20.68 μmol/L;The apoptosis of MCF-7 was detected by Hoechst 33258 staining and flow cytometry.The results showed that blue plum-like apoptotic bodies were observed under fluorescence microscope,which indicated that galangin could induce MCF-7 apoptosis,with 160 μmol/L apoptotic rate was 36.46%,and showed a concentration-dependent relationship;PI staining was used to detect the cell cycle arrest of MCF-7 cells.The results showed that the effect of galangin on MCF-7 cycle was complicated.The effects of different concentrations of galangin on the cycle were different.In the concentration of 0 ~ 40 μmol/L,the cell cycle was blocked in G2/M phase.With the increase of galangin concentration,the effect of galangin on G2/M phase arrest in the concentration of 40 ~ 160 μmol/L gradually weakened,and to strengthen the S phase arrest.The expression levels of p-PI3 K,p-Akt,Cyclin D3,Cyclin B1,cleaved-Bid,Bad,Bax,Bcl-2,cleaved-Caspase9,cleaved-Caspase-8 and cleaved-Caspase-3 were detected by Western blotting.The protein expression level of cleaved-Bid,Bad,Bax,cleaved-Caspase-9,cleaved-Caspase-8 and cleaved-Caspase-3 were increased after 12 hours of galangin treatment,the expression of Bcl-2,p-PI3 K,p-Akt,Cyclin D3,Cyclin B1 protein expression level were decreased.These results suggest that galangin can induce MCF-7 cell apoptosis through mitochondrial pathway,block MCF-7 cell cycle,inhibit PI3 K / AKT signal transduction pathway to inhibit MCF-7 cell proliferation.In conclusion,the semi-synthetic method was used to modify the structure of galangin,and six modified products were obtained,which were new compounds and enriched the compound library.Cytotoxicity test results showed four compounds with better antitumor activity.In addition,in this paper,the inhibitory effect of galangin against MCF-7 cells and its mechanism were studied.The results showed that galangin could block MCF-7 cell cycle and induce MCF-7 cell apoptosis through mitochondrial pathway,inhibition of PI3K/AKT signal transduction pathway,thereby inhibiting MCF-7 cell proliferation.