## 4 Discussion
prausnitzii_ is considered a key player in the gut, with significant effects on host health and immunity, as it produces anti-inflammatory molecules such as butyrate [63]. The role of _A. muciniphila_ in treating intestinal inflammatory diseases, especially inflammatory bowel disease, has been widely recognized [64]. Lactobacillus species are representative probiotic strains in adjunctive IBD treatment. Multiple lactobacillus strains have been proven to reduce intestinal damage and enhance the intestinal immune barrier [65]. The Firmicutes/Bacteroidetes ratio is widely considered as crucial for maintaining normal intestinal homeostasis. Dysbiosis is often associated with an increase or decrease in this ratio. In the DSS group, the ratio significantly increased, whereas it significantly decreased after treatments. In summary, this study found that the co-administration of TA and LC significantly increased the content of various probiotics capable of treating colitis and adjusting the intestinal flora environment. This supports the notion that phlorotannin metabolites can maintain intestinal homeostasis and reduce inflammation by increasing the abundance of probiotic bacteria. In this study, TA was administered to animals at a concentration of 50 mg/kg bw/day. A previous study administered dieckol at 5-15 mg/kg bw in DSS-induced colitis animal experiments, revealing efficacy against inflammation even at lower concentrations [11; 66]. Additionally, another DSS mouse model using a phlorotannin-rich _Eckolonia cava_ extract demonstrated anti-inflammatory effects ranging from 50 mg/kg bw up to 200 mg/kg bw [30]. In this study, the concentration of lactic acid bacteria was determined based on previous research, where a notable anti-inflammatory effect was observed after feeding _Lactobacillus plantarum_ at a concentration of 1 \(\times\) 10\({}^{9}\) CFU/mL for 10 days [67; 68]. In an effort to establish optimal conditions, we administered approximately 1/10 th of the amount used in the earlier experiment for a duration of approximately 7 days. Our selection of 50 mg/kg for this study is based on the preventive effects of phlorotannin on colitis. After converting the mouse doses to human-equivalent doses based on body surface area, to achieve similar effects, a 60 kg human would need to take 8 mg/kg bw, totaling 480 mg/day [69]. In studies involving other insomniacs and obese individuals, doses ranging from 100 mg to 500 mg per day were administered, with no reported toxic effects [70]. Therefore, it is unlikely that the 480 mg/day dose would lead to any adverse effects. Understanding the dose-response relationship is crucial for optimizing therapeutic applications. While in vitro results showed that different doses of TA and LC led to varying effects on inflammatory markers, our in vivo experiments were limited to testing only one concentration. Therefore, conducting additional dose-response studies is necessary to fully explore the potential for enhancing the anti-inflammatory effects of symbiotics. Future research avenues may include investigating the synergistic effects between different doses of TA and LC, as well as exploring the impact of different dosing on treatment outcomes. Our study's limitation lies in the low efficiency of extraction. Preliminary tests suggested higher efficiency when extracting _E. bicyclis_ with 70% ethanol, contrasting with our primary objective to extract dieckol using the established method with 80% MeOH and 100% ethyl acetate [38; 71]. Moreover, we solely monitored phlorotannin derivatives in the extract to evaluate the impact of probiotics on phlorotannin metabolism. While _E. bicyclis_ is rich in phlorotannin, it also contains other bioactive compounds such as carotenoids, fucoxanthin, quercetin, and caffe acid [72]. Further efforts are needed to investigate the amounts and effects of these other compounds, improve extraction efficiency, and enhance the purity of phlorotannin fractions.