Cytotoxic Activities in Vitro of Flower Extracts of Three Species of Aloe Growing in Yemen: Aloe Rubroviolaceae, Aloe Vera and Aloe Sabaea, against Eleven Types of Cancer Cell Lines

Background and aims: Natural products, especially plant extracts, have opened up great opportunities in the field of drug progress due to their chemical variety. The genus Aloe has long been used for medicinal uses in countless parts of the world. This study was designed to investigate the phytochemicals and anti-cancer capabilities of Aloe rubroviolaceae, Aloe vera and Aloe sabaea flowers. Materials and Methods: The methanolic extracts of three types of plants traditionally used in Yemen to treat a variety of diseases have been tested in vitro for their potential anticancer activity on different human cancer cell lines. The cytotoxic activity of the methanolic extracts of tested plants was determined using eleven strains of human cancer cells, namely: MCF-7 (breast cancer), PC-3 (prostate cancer), HEP-2 (human epithelial carcinoma), MNFS-60 (myelogenous leukemia), CACO (intestinal cancer), A-549 (lung adenocarcinoma), HeLa (cervical cancer), RD (rhabdomyosarcoma),HepG2 (hepatocellular carcinoma), HCT-116 (colon cancer), and CHO-K1 (Chinese hamster ovary). A colorimetric sulforhodamine B assay was used to evaluate the in vitro cytotoxic activity of different extracts. Growth inhibition of 50% (IC50) for each extract was calculated from the optical density of treated and untreated cells. Doxorubicin, a broad-spectrum anticancer drug was used as a positive control. Results: More interesting cytotoxic activity was observed for Aloe vera extract more than Aloe sabaea and Aloe rubroviolaceae, extract. Conclusions: This study provides a preliminary screening for anti-proliferative activity of various Aloe species flowers extracts on different cancer cell lines. Different extracts of Aloe species significantly inhibit the growth of various cancer cell lines in a concentration-dependent manner. Further investigations are required to understand the possible mechanism(s) of action of these extract on various cancer cells and isolation of active phyto-chemicals.