## 3 Results
### Cytotoxic Activity against Cancer Cells  
The cytotoxic activity of the extracts and microcapsules was assessed against four colon cancer cell lines (Caco-2, Ht-29, Ls180, and Dld-1). In the first part of the assay, the cytotoxic activity of CE and PE alone was assessed. As can be seen in Figure 3, only PE was capable of inhibiting cancer cell viability. The estimated cytotoxicity was significantly (\(p\) < 0.05) dose-dependent. At the highest administered PE concentration of 500 ug/mL, the cell viability of Caco-2, Ht-29, Ls180, and Dld-1 was 3.62, 14.56, 2.50, and 5.84%, respectively, compared to the control. The highest sensitivity to the extract assessed was characteristic of Caco-2 and Ls180 lines. The obtained values are consistent with the previous results regarding the anticancer activity of blueberry fruit extracts [16; 17; 18]. The lack of cytotoxic effect of CE is probably due to the presence of ballast substances in the extract, which could stimulate the growth of cancer cells, as well as the low concentration of bioactive compounds compared to PE. Figure 2: Biocompatibility of microcapsules with crude extract (CE), purified extract (PE), and control samples against normal colon epithelial cells (CCD841 CoN). Abbreviations: A, microcapsules Alg + CE; B, microcapsules Alg + Pect + CE; C, microcapsules Alg + WPI + CE; D, microcapsules Alg + Pect + WPI + CE; E, microcapsules Alg + PE; F, microcapsules Alg + Pect + PE; G, microcapsules Alg + WPI + PE; H, microcapsules Alg + Pect + WPI + PE; I, microcapsules Alg; J, microcapsules Alg + Pect; K, microcapsules Alg + WPI; L, microcapsules Alg + Pect + WPI. Results are expressed as mean (n = 4) and SD. Significant differences (* < 0.05) were assessed using the t-student’s test. Due to the demonstration of anticancer activity only for PE, microcapsules with this core were selected for the evaluation of cytotoxic activity against four colon cancer cell lines. All of the tested microcapsules caused a dose-dependent decrease in cancer cell viability (Figure 4). Analyzing the types of carrier materials, the highest cytotoxic activity against Caco-2, Ht-29, Ls180, and Dld-1 lines was demonstrated for G microcapsules (Alg + WPI). At the highest concentration, cell viability was inhibited by 51.8% (for Caco-2 line), 77.1% (Ht-29), 75.2% (Ls180), and 57.5% (Dld-1). On the other hand, the lowest cell sensitivity was demonstrated after their treatment with H microcapsules (Alg + Pect + WPI) despite the demonstrated highest content of phenolic compounds. Therefore, just like in the biocompatibility test, it can be seen that the simultaneous enrichment of Alg with polysaccharides and proteins has a beneficial effect on the growth of both normal and cancer cells. The incidence of colorectal cancer creates a need for developing therapies that can play a significant role in the prevention and/or treatment of these diseases. There is a lot of scientific evidence emphasizing the effectiveness and practical use of microcapsules loaded with an active substance targeted for release in the large intestine in the treatment of cancer. Such a procedure ensures reduced release of the active substance outside the target site, and thus a reduction in side effects, as well as a reduction in the therapeutic dose required to achieve the intended effects [54; 55; 56]. It has been shown that over 60% of curcumin in Alg microcapsules is released in the colon, demonstrating cytotoxicity towards cancer cells (Ht-29 line) [54]. Gastrosistant properties and effective release of the active substance in the large intestine were also confirmed for Alg microcapsules containing the drug cetuximab (CTX), which ensured higher cytotoxic activity towards cancer cells than in the case of administration of the free drug [55]. Anticancer activity is also noted for plant phytochemicals bound in microcapsules. [PERSON] et al. [57] showed greater efficacy against lung cancer cells (A549) for the extract of olive tree leaves (_Olea europaea_) in microcapsules of Alg coated with chitosan than for the free extract.