Human breast tumour cells viability effect of African Dioscorea Rotundata Tuber extracts in MCF-7 and MDA-MB231 cell lines

Abstract

Background : Several Dioscorea species are used in Chinese medicine for tumours and Dioscorea species grown in Africa are yet to be tested to the best of knowledge for efficacy as cytotoxic agents. In Nigeria, the greatest producer of edible yams in the world, Dioscorea is the king of plants. Its tubers feeds millions of people and also function as ethnomedicine for diverse diseases. We aim to test the efficacy of edible Dioscorea species grown and consumed in Nigeria on two breast cancer cell lines; MCF-7 and MDA-MB231 derived from a luminal and a triple-negative breast cancer (TNBC) respectively and to confirm safety in non-tumour cells MCF-10A (normal breast cell lines) using a well established cytotoxic compound paclitaxel as a standard. Metastatic breast cancer is a prevalent cause of mortality in women around the world. Breast cancer therapies have greatly advanced in recent years, leading to the statement that cancer is not a death sentence but many patients develop cancer re-occurrence and metastasis and subsequently yield to the disease because of chemoresistance. Methods : Ethanolic extracts of Dioscorea rotundata boiled and raw (DiosB and DiosR) respectively were chemically analysed for the presence of diosgenin using HPLC and their cytotoxic activity was tested on MCF-7, MDA-MB-231 and MCF-10A cells I n vitro by MTT assay.Results : DiosB and DiosR extracts were more effective on MCF-7 than on MDA-MB231 cells showing a higher maximal effect on MCF-7 cells than on MDA-MB231 after 24 h and 48 h treatments (p<0.0001 and p<0.05 respectively). DiosR, if applied at a range between 50-70 g/ml, can be effective to reduce breast tumor cell viability without affecting non tumorigenic MCF-10A cells either at 24 h or at 48 h. African yams contain cytotoxic principles. DiosB showed an IC 50 of 38.83µg/ml while DiosR showed an IC 50 of 41.80µg/ml. Discussion : The results have shown that Dioscorea rotundata tubers could be used effectively to treat breast cancer tumors and this is in sync with its diosgenin content, a known cytotoxic compound and the use of other Dioscorea species for similar treatments in Asia etc. A major limitation will be in creating higher demand for the tuber which is consumed as a staple and at the moment affordable to all.Conclusion : There will be need to make consumers aware of the significant anticancer importance of D. rotundat a and a great need to increase its cultivation in order to make it sufficient as food and as medicine.