## 4 Discussion  
Due to the high death rate associated with BC and the limitations of standard therapies, it is vital to develop innovative methods for treating this illness [27]. The anticancer properties of the natural plant extract CV in several cancer types have recently been assessed. CV's limited solubility and bioavailability, however, may limit its anti-cancer effect [28,29]. Combination therapy using nanotechnology is currently a compelling argument for cancer therapy because of its greater efficacy and fewer adverse effects. In this regard, this study postulated that SeNPs green-synthesized using CV would synergize and increase the anticancer effect of CV. In the current study, the cytotoxic activities of CP, CV, SeNPs, and SeNPs-CV were evaluated in MCF-7 cells. The IC\({}_{50}\) of CP was found to be 1.9 \(\upmu\)g/mL, while the IC\({}_{50}\) of CV and SeNPs alone was 32.1 \(\upmu\)g/mL and 41.6 \(\upmu\)g/mL, respectively, whereas the IC\({}_{50}\) of the SeNPs-CV was 8.3 \(\upmu\)g/mL, approximately four times lower than that of CV, indicating a synergetic potential between CV and SeNPs. These results also indicated the marked cytotoxic effects of CV and SeNPs-CV in MCF-7 cell lines. Additionally, the study's findings revealed that cells exposed to either CV or SeNPs-CV had a much higher percentage of cells in the early and late phases of apoptosis as contrasted to the vehicle cells, as shown in Figure 3.  
These results are in line with those of previous studies that have confirmed the anti-proliferative effects of CV in many types of cancer cell lines [30,31]. Moreover, CV dramatically increased apoptosis in several BC cell lines, with MDA-MB-231 cells being the most susceptible and MCF-7 cells being the least sensitive, suggesting that the efficacy of CV may vary depending on the type of BC [5]. Numerous studies have confirmed that green-synthesized SeNPs are highly effective in the treatment of various forms of cancer [32,33]. In a recent study, SeNPs showed stronger anti-proliferative activities in MCF-7 cells, with an IC\({}_{50}\) value of 25 \(\upmu\)g. Similarly, [PERSON] and [PERSON] [34] reported that SeNPs decreased MCF-7 cell proliferation in a dose-dependent manner owing to their cytotoxicity and apoptotic potential. One of the most intriguing findings of this study was that the conjugation of CV with SeNPs led to an increase in anti-proliferative and anti-apoptotic effects when compared with CV alone, as evidenced by the decrease in IC\({}_{50}\) to 8.3 \(\upmu\)g/mL. Our results also revealed a marked elevation in the percentage of apoptotic cells in the SeNPs-CV group in contrast to that in the CV group. These findings agree with those of a previous report [1], in which the coupling of SeNPs with the natural flavonoid apigenin demonstrated significantly greater cytotoxic potential in BC therapy than either component alone. In another study, conjugation of SeNPs with berberine, a natural alkaloid extract, demonstrated greater cytotoxic efficacy than that of each agent alone [32]. Due to their propensity to induce apoptosis and autophagy, reactive oxygen species (ROS) have recently received interest for their therapeutic utility. Previous studies have revealed that ROS may chemically bind to nucleic acids and proteins by interacting with the nucleophilic center of the cell, which can damage DNA. To enhance clinical outcomes for cancer patients, novel methods that increase ROS levels have been included in cancer therapy [5]. The formation of ROS in cells is modulated by a number of anticancer drugs by triggering various regulatory systems. For instance, doxorubicin increases ROS production by causing electron leakage and the Fenton reaction, whereas gamitrinib boosts ROS generation by causing malignant cells' mitochondria to collapse [16]. Moreover, the identification of intracellular ROS generation is a key marker for early cellular reactions with NPs and the initial step in the cytotoxicity cascade.