## 4 Discussion
On the HepG2 line, the dichloromethane extract proved to be more active when compared to the other extracts recording an IC\({}_{50}\) of the order of 31.54 \(\pm\) 0.242 \(\upmu\)g/mL, as for the hexanic extract, it is more active on the lines 22 Rv1 and MDA-MB-231 scoring an IC\({}_{50}\) of the order of 11.32 \(\pm\) 2.126 \(\upmu\)g/mL and 82.4 \(\pm\) 1.1243 \(\upmu\)g/mL, respectively. Our results deserve more attention since our study is the first reporting anticancer activity of leaf extracts of _C. ladanifer_ on cancer cell lines including HepG2, 22 Rv1, and MDA-MB-231. The aqueous leaf extract of Spanish _C. ladanifer_ was studied for its cytotoxic activity on cell lines of pancreas, breast and colon and showed IC\({}_{50}\) values ranging from 0.49 to 16.10 mg/mL [5]. _C. ladanifer_ extracts demonstrated antiproliferative action against two human skin cancer cells; malignant melanoma (A375) and squamous cell carcinoma (SCC-15), which, thus, confirmed our results [14]. In the case of our results, it is difficult to attribute the antiproliferative activity observed to a specific compound or group of compounds in the organic extracts of _C. ladanifer_ leaves. Several secondary metabolites may indeed be present simultaneously in the extracts [30]. However, we can advance the hypothesis that the activity of the dichloromethane extract on the HepG2 line is probably attributed to its high polyphenol content when compared to other extracts (76.066 \(\pm\) 9.978 \(\upmu\)g AGE/mg). It has been reported that phenolic compounds enhance the apoptotic action and cause cell cycle arrest in HepG2 cells by inducing inactivation of transcription factors, which in turn activate the death pathways in liver cancer cells [31]. Moreover, the high antiproliferative potential of the hexanic extract of _C. ladanifer_ leaves on the prostate and breast cancer cell lines can be explained by its high level of flavonoid compounds when compared to the other extracts (50.209 \(\pm\) 3.805 \(\upmu\)g CE/mg). Hormone-dependent cancer cell lines show a growth-inhibiting and cell death impact when exposed to flavonoids, which are found in many fruits and vegetables. Flavonoids, such as isoflavones, have been classified as phytoestrogens, which possess the ability to bind to the estrogen receptor and alter its activity, resulting in anti-estrogenic actions [6]. Several works have reported that antioxidant activity may correlate with anticancer potential. Reactive oxygen species (ROS) are involved in cancer, meanwhile, antioxidant agents are used to counteracting them. Plant extracts have been found to contain significant ROS scavenging and induce antiproliferative activities toward cancer cells through ROS-mediated activities [32]. In our case, there is no correlation between the two activities  
The phytochemical composition of the ethanolic extract was also studied and the results showed that this extract is rich in compounds that are important from pharmacological and botanical viewpoints. These compounds are mainly constituted of octacosane, heptadecanoic acid, longifolene, ledol, and bornel, which can probably be responsible for the activities of this plant. All these compounds have been demonstrated in the literature for their biological effects including antioxidant and cytotoxic properties. The Dichloromethane and the hexanic extracts with an important antiproliferative activity were also studied for their chemical composition (data not shown) showing various classes of compounds known for their pharmacological activities including bornel, ledol, camphene and alpha tocopherol. The example of bornel, one of the important compounds found in the three extracts, is a monoterenoid, which enhances antiproliferative activity by induction of apoptosis, reduces cancer cell growth through the triggering apoptotic cell death, and activates ROS-mediated DNA damage [33; 34; 35].