## 3 Results and Discussion
### In Vitro Cytotoxic Effect on Cancerous Cell Lines Using Synthesized AgNPs
Significant cytotoxic levels (IC\({}_{50}\) 16.11 and 27.23 \(\upmu\)g/mL) were observed for the MCF-7 cell line upon exposure to the methanolic leaf and stem AgNPs. Moderate cytotoxic levels were observed in the fresh leaf and stem AgNPs (47.86 and 41.30 \(\upmu\)g/mL), and lower levels in the powdered leaf and stem AgNPs (74.13 and 100 \(\upmu\)g/mL) (Table 6). [PERSON] and [PERSON] [125] have proposed that AgNPs interact with the thiol groups of the inner membrane of the mitochondria, inhibiting the antioxidant defense mechanism, leading to the formation of reactive oxygen species (ROS). The accumulation of ROS results in an inflammatory response that initiates the destruction of the mitochondria, triggering the release of apoptotic factors leading to cell death. NPs are small in size, allowing them to easily enter and interact with cancer cells, and ultimately disturb cellular functions [126]. Additionally, [PERSON] et al. [127] have proposed that AgNPs have the potential to interfere with genes associated with cell cycle progression, thus inducing DNA damage and apoptosis in cancerous cells. Furthermore, [PERSON] et al. [128] have suggested that there are different mechanisms for the cytotoxicity of AgNPs, which include the induction of ROS, apoptosis, and Ag ion release. [PERSON] et al. [129] have observed an increase in the generation of ROS as NP concentrations are increased. Therefore, it can be expected that any cytotoxic effects induced in the cancer cells may be due to the active bound compounds capping the AgNPs. Biosynthetic methods using plant extracts act as reducing and capping agents [14; 19; 20; 21]. Using various microscopic techniques, AgNPs of similar shapes and sizes found in _B. albostellata_ were noted in other species of _Barleria_[15; 80]. The biosynthesized AgNPs from the leaves and stem extracts exhibited antibacterial activity against both Gram-positive and Gram-negative bacteria; this was also noted in several species of _Barleria_[80; 86; 90]. The precise mechanism for synthesizing NPs using plant extracts is unclear. It has been shown that biomolecules such as alkaloids, phenols, and flavonoids found in these extracts play an important role in reducing the metal ions and capping the biosynthesized NPs [26; 27]. Synthesized AgNPs exhibited selective in vitro cytotoxicity against HEK293, HeLa, and \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Cell Lines**} & \multirow{2}{*}{**Extracts**} & \multicolumn{2}{c}{**Cytotoxicity (\(\upmu\)g/mL)**} \\ \cline{3-4}  & & **Leaves** & **Stems** \\ \hline \multirow{4}{*}{HEK293} & Methanol & 9.02 & 61.66 \\  & Fresh & 47.86 & 33.04 \\  & Powder & 100.00 & 61.24 \\ \hline \multirow{4}{*}{HeLa} & Methanol & 5.87 & 12.58 \\  & Fresh & 29.64 & 32.14 \\  & Powder & 69.18 & 54.70 \\ \hline \multirow{4}{*}{MCF-7} & Methanol & 16.11 & 27.23 \\  & Fresh & 47.86 & 41.30 \\ \cline{1-1}  & Powder & 74.13 & 100.00 \\ \hline \hline \end{tabular} Data are presented as mean. \(n=3\).  
\end{table} 
Table 6: IC\({}_{50}\) values of the cytotoxicity activity of methanol, powder and fresh leaf and stem extracts of _B. albostellata_. MCF-7 cell lines. The size of the NPs allow them to easily enter and interact with cancer cells, ultimately enabling them to disturb cellular functions [66]. AgNPs possess the capability to disrupt genes linked to the advancement of the cell cycle, consequently initiating DNA damage and apoptosis in cancerous cells. The cytotoxic consequences observed in the cancer cells might be attributed to the bioactive molecules capping the AgNPs [67].