## 1 Introduction  
Saponins are found in a variety of higher plants, and display a wide range of pharmacological activities, including expectorant, anti-inflammatory, vasoprotective, gastoprotective, antihelmmitic, antileishman, antifungal, and antimicrobial properties [1; 2; 3; 4]. Potential anticancer activity of saponins has been suggested by their antiproliferative, cytotoxic, cytostatic, pro-apoptotic, and anti-invasive effects [5; 6; 7; 8]. Structurally, saponins are amphiphilic compounds composed of one or more hydrophilic sugar parts and a lipophilic steroidal or triterpene part (sapogenin). Saponins can be classified into monodesmoxidic, bidesmoxidic, or polydesmoxidic saponins, having one, two, or more sugar chains. A large structural variety can be found in nature, due to the presence of different sugars, sugar branchings, and sapogenins [9; 10; 11]. The interesting properties of saponins have led us to investigate the monodesmoxidic saponin \(\alpha\)-hederin, which has shown activities towards cancer cells [12]. \(\alpha\)-Hederin, or Kalopanax saponin A, was first isolated from the leaves of common ivy or _Hedera helix_ L. (Araliaceae) [13; 14], along with aglycone hederagenin, a triterpenic acid, by [PERSON] in 1912. Hederagenin is the aglycon part of numerous saponins found in _Hedera helix_,with the most prevalent being hederacoside C, a triterpene saponin with three sugar chains in its structure [15; 16; 17]. Triterpene saponins (hederacoside B, C, and D) and monodesmosides (\(\alpha\)-, \(\beta\)-, \(\delta\)-hederin, and hederagenin) were tested in vitro on four cell strains, mouse B16 tumor cells, 3T3 mouse normal fibroblasts, and HeLa human tumor cells, and presented about 5 times less antiproliferative activity compared to the reference compound strychnopentamine [18]. The most active compounds were \(\alpha\)- and \(\beta\)-hederins, which were cytotoxic at concentrations greater than or equal to 10 \(\mu\)g/mL. Bidesmostic hederacosides C, B, and D and hederagenin were inactive at concentrations up to 200 \(\mu\)g/mL. In another study, \(\alpha\)-hederin extracted from _Clematis ganpiiniana_ was tested in two human breast cancer cell lines, MCF-7 and MDA-MB-231, inducing apoptosis in both types of cultures [19]. The researchers determined the strong inhibitory activity of \(\alpha\)-hederin on breast tumor cells growth by apoptosis evaluation. Most  antitumor therapies result in tumor inhibition by triggering cell apoptosis. Mitochondria play an important role in the survival of tumor cells; therefore, they are one of the main targets on which antitumor drugs work [20]. Apoptotic mitochondrial pathways have often been approached to highlight the activity of triterpene saponins in other human cancers, such as liver, gastric, esophagus, and colorectal cancer [21; 22]. \(\alpha\)-Hederin from _Nigella sativa_ has been reported to induce apoptosis by mitochondrial perturbation in mouse P388 leukemia cells [23]. _In vitro_ studies on the action mechanism of saponins had shown that saponins reacted and destroyed the lipids of the cell membrane [24; 25]. In addition, \(\alpha\)-hederin from _Hedera helix_ L. presented anti-inflammatory and antileishmanial activities [26; 27]. The aim of this study was to evaluate the in vitro cytotoxic and antiproliferative activity induced by the three triterpene saponins, i.e., \(\alpha\)-hederin, hederagenin, and hederacoside C, and to optimize a mixture of the three standard saponins for a maximal antiproliferative effect. For this purpose, the three standard saponins were tested for cytotoxicity in normal mouse fibroblasts (NCTC cells) and antiproliferative activity in human epithelial cervix tumor cells (Hep-2). The obtained experimental results were analyzed using the Response Surface Method (RSM) provided by the Design Expert 11 software (Version: 11.1.0.1 64 bit, Stat-Ease Inc., Minneapolis, MN, USA, 2018 [28], correlating the concentration of studied saponins with the antiproliferative activity.