### Cytotoxic Screening Activity  
Squill is recognized for its anticancer effect against various cancer cells and for its antioxidant and cytotoxic properties [58]. Consequently, a comparative cytotoxic assay of both WS and RS was evaluated on the different cell lines to include breast adenocarcinoma (MCF-7), lung (A-549) and ovarian cancer (SKOV-3) cell lines using Sulforhodamine B assay (SRB). The results revealed the potential cytotoxic activity of both varieties, with WS found to be more active against both cell lines A-549 and SKOV-3 than RS, as evidenced by its lower IC\({}_{50}\) values. The recorded IC\({}_{50}\) values of WS against A-549 and SKOV-3 cell lines were at 0.108 \(\pm\) 0.003 and 0.690 \(\pm\) 0.018 \(\mathrm{\SIUnitSymbolMicro g}\)/mL versus RS's IC\({}_{50}\) values at 0.271 \(\pm\) 0.005 and 0.912 \(\pm\) 0.021 \(\mathrm{\SIUnitSymbolMicro g}\)/mL, respectively. In contrast, the RS extract showed a more potent effect than WS on the MCF-7 cell line, with IC\({}_{50}\) values of 0.165 \(\pm\) 0.007 and 0.326 \(\pm\) 0.005 \(\mathrm{\SIUnitSymbolMicro g}\)/mL, respectively. The doxorubicin \"positive control\" IC\({}_{50}\) values recorded on MCF7, A-549, and SKOV-3 cancer cell lines were 0.2 \(\pm\) 0.004, 0.56 \(\pm\) 0.003 and 0.2 \(\pm\) 0.01 \(\mathrm{\SIUnitSymbolMicro g}\)/mL, respectively (Table 4 and Figure 8). The potential cytotoxicity of WS compared to RS could be attributed to its abundance of bufadienolides, as revealed from both LC/MS and NMR reported for its cytotoxic action, and suggests that bufadeinolides are more determinant than flavonoids regarding cytotoxic action in squill, at least in case of A-549 and SKOV-3 cell lines. Previous reports of helebrigenin and bufatalin isolated from squill showed potential cytotoxic activity against leukemia, human colon carcinoma, human glioblastoma melanoma, and human liver carcinoma cells with IC\({}_{50}\) values ranging from 0.0007 to 0.16 \(\mathrm{\SIUnitSymbolMicro g}\)[59]. Moreover, bufatalin induced apoptosis in human leukemia cells [60]. Sillarenin exhibited stronger cytotoxic action in the nanomolar range in comparison with bufatalin [61]. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**RS (MCF7)** & **WS (MCF7)** & **Dox.(MCF7)** & **RS (A-549)** & **WS (A-549)** & **Dox. (A-549)** & **RS (SKOV-3)** & **WS (SKOV-3)** & **Dox.** \\
**ICS0** & **ICS0** & **ICS0** & **ICS0** & **ICS0** & **ICS0** & **ICS0** & **ICS0** & **ICS0** & **(SKOV-3)IC0** \\ \hline
0.165 \(\pm\) 0.007 * & 0.326 \(\pm\) 0.005 & 0.2 \(\pm\) 0.004 * & 0.271 \(\pm\) 0.005 * & 0.108 \(\pm\) 0.003 * & 0.56 \(\pm\) 0.003 * & 0.912 \(\pm\) 0.021 & 0.690 \(\pm\) 0.018 & 0.2 \(\pm\) 0.01 \\ \hline \end{tabular}
* \(p<\) 0.05 comparing dox. positive control with each treatment group of RS and WS extracts on different cancer cell lines using one way ANOVA followed by Dunnett’s test.  
\end{table} 
Table 4: The IC\({}_{50}\) values (mean \(\pm\) SD) of RS and WS extract against different cancer cell lines measured by SRB assay versus dox. (doxorubicin) positive control. Proscillaridin A, a cardiac glycoside isolated from _U. martiima_, was reported to exert an cytotoxic and/or antiproliferative effect against human breast cancer. proscillaridin A anticancer properties are mediated via its ability to block Na+/K+ ATPase, leading to increase in Ca\({}^{2+}\) levels, activating the AMPK pathway. Interestingly, on the opposite, the Ca\({}^{2+}\) level was reduced by ca. 30% after an 18 h administration of proscillaridin A to the normal lung fibroblast cell line CCD19-LU, which suggests differential action mechanisms against normal and cancer cells [62]. In a previous report, bufadienolides recorded effective cytotoxic action on human cancer cells [63]. Although in WS, the most abundant bufadienolide glycoside \"scillioside\" is suggested to mediate the observed toxic action of _Urginea_ sp. The lethal dose (LD\({}_{50}\)) of scillioside was 0.7 and 0.43 mg/kg for male and female rats in vivo, respectively.