## 4 Discussion  
Bioaccessibility research of main polyphenic groups during simulated in vitro digestion included two continental samples of propolis, collected near Valpovo (Vlp) and near Zagreb (Zg). Given that the flavonoids, flavones, flavanones, and dihydroflavonols are defined by a hydrophobic benzo-\(\gamma\)-pyrone structure, they have characteristically poor solubility in water. However, the study published by [PERSON] [33] suggests that the HP-\(\beta\)-CD complexation strategy could change the physical-chemical properties of the polyphenic molecules, making them more applicable for therapeutic purposes. Therefore, the samples of raw propolis investigated in this study were prepared in the form of an oral preparation, an aqueous suspension of a lyophilized complex of an EEP and an aqueous solution of HP-\(\beta\)-CD (Table 1). Experiments were also carried out on an aqueous suspension  
Figure 2: Bioaccessibility of (**A**) total phenols (TP), (**B**) total flavones and flavonoids (TFF), (**C**) total flavanones/dihydroflavonols (TFD) after the small intestine phase performed as the centrifugation model (IF-C) and in the semipermeable dialysis membrane model (Din) in a complex: mixture of standards (std mix), ethanol extract of propolis Valpovo (Vlp) and Zagreb (Zg) with 2-hydroxypropyl-\(\beta\)-cyclodextrin(HP-\(\beta\)-CD). Statistical analysis was conducted using the Kruskal–Wallis non-parametric test and [PERSON]’s post hoc test of mutual phase, with \(p<0.05\). a,b,c—different letters indicate significant differences (\(p<0.05\)) among intestinal fractions within each complex. of a lyophilized complex of a 70% ethanolic extract of a mixture of selected polyphenol standards and an aqueous solution of HP-\(\beta\)-CD. Thus, the influence of the synergy of all analyzed polyphenols without the propolis matrix was examined. The advantage of the propolis-HP-\(\beta\)-CD complex presented in our study is that HP-\(\beta\)-CD helped to improve the solubility of the lipophilic polyphenic compounds. The propolis-HP-\(\beta\)-CD complex masked the bitter taste and intense smell of propolis, making the described processing of propolis more acceptable for oral use than the alcoholic solution. The low solubility of TFFs and TFDs of water propolis extracts in comparison to HP-\(\beta\)-CD and 70% EtOH extracts (Table 1) was also proven by our findings. As expected, the results of the TPs and TFDs contents in 70% EtOH are higher than in the propolis-HP-\(\beta\)-CD complex. However, the in vitro GID experiments were carried out with propolis-HP-\(\beta\)-CD complex in order to test an aqueous suspension of the propolis-HP-\(\beta\)-CD complex as a potential pharmaceutical form for oral administration in animals. Given that the std mix complex was prepared as a mixture of only selected standards, i.e., PC, KR, GN, CA, CAPE, and QC, the initial undigested sample (US) and the digestion fractions had significantly lower TPs and TFFs compared to Vlp and Zg propolis complexes (Tables 2-4). Considering that the previous reports on assessing the bioaccessibility and bioavailability of polyphenols in various food and plant materials confirmed very variable but also low values, from 2 to 20% [34], it was very challenging to perform this research. To the best of our knowledge, this is the first study that describes the contents of bioaccessible and dialyzable polyphenols in the complex of EEP and HP-\(\beta\)-CD. Therefore, the results were compared with similar studies of polyphenols investigated in different extracts of propolis, honey, pollen, medicinal plants, or food. The most similar research was a study conducted by [PERSON] et al. [28]; they investigated the bioaccessibility of TPs and total flavonoids (TFs) of raw propolis, and the results confirmed the increase in TPs and TFs during GF and IF. However, compared to the results of the undigested sample, their study demonstrated low bioaccessibility in GF and IF.