Evaluation of in vitro cytotoxic activity of organic and aqueous extracts of Glycyrrhiza iconica

The roots of Glycyrrhiza species (licorice) have long been utilized in different traditional systems of medicine mainly for the treatment of peptic ulcer and to relieve cough [1]. Licorice extracts and some of the isolated compounds have been shown to possess antiulcer, antimicrobial, antiviral, anti-inflammatory, hepatoprotective, cytotoxic and antitumor activities [2]. The genus Glycyrrhiza is represented by six species in the flora of Turkey including the endemic one, G. iconica [3]. In the continuation of our bioactivity and phytochemical studies on Turkish Glycyrrhiza species, we have now investigated the cytotoxic effect of G. iconica roots against three different human cancer cell lines. The roots were extracted with MeOH. The crude MeOH extract was evaluated for its cytotoxic activity against hepatocellular (HUh7), breast (MCF7) and colorectal (HCT116) cancer cell lines by Sulforhodamine B assay. The extract showed significant activity against all cell lines with IC50 values in the range of 4.3 to 12.7 µg/mL. Therefore, the crude extract was dispersed in H2O and partitioned against CHCl3, EtOAc and n-buOH respectively to obtain four subextracts which were screened in the same test. The CHCl3 subextract showed potent cytotoxic activity on all cell lines with IC50 values ranging from 0.9 – 7.0 µg/mL showing the best activity against MCF7. The EtOAc subextract displayed the most significant cytotoxic activity against HCT116 with IC50 value of less than 0.1 µg/mL, while showing activity against MCF7 and HUh7cell lines with IC50 values of 1.1 and 6.4 µg/mL, respectively. n-BuOH subextract showed inhibitory activity against all cancer cell lines with IC50 values in the range of 0.6 – 7.7 µg/mL being the most active against MCF7. H2O subextract was found to be active only on MCF7 cell line with IC50 value of 2.6 µg/mL. Based on these screening assays, EtOAc, CHCl3 and n-BuOH subextracts deserve further studies in order to isolate potent cytotoxic compounds.