## 3 Discussion  
Obesity is a chronic metabolic disorder that threatens the health of people in developed and developing countries due to excessive body fat accumulation [30]. Obesity is related to various diseases, such as diabetes, hypertension, hyperlipidemia, stroke, and angina, and is known to be a major cause of aging [31]. Accordingly, prevention and treatment of obesity are important. To treat obesity, a combination of diet and drug approaches has been used. However, orlistat and rimonabant, commercially available drugs to treat obesity, have limitations in their use in children, patients with myocardial infarction, liver disease, and kidney disease, as well as various side effects, such as headache, abdominal pain, and panic disorder [32; 33]. In this context, interest in food products based on natural substances, \begin{table}
\begin{tabular}{c c c c} \hline
**Extracts** & **RT** & **Name of Compounds (Molecular Formula)** & **Area (\%)** \\ \hline \multirow{4}{*}{_S. horneri_} & 22.8 & Neophytadiene (C\({}_{20}\)H\({}_{38}\)) & 25.3 \\ \cline{2-3}  & 23.1 & 3,7,11,15-Tetramethyl-2-hexadecen-1-ol (C\({}_{20}\)H\({}_{40}\)O) & 14.0 \\ \cline{2-3}  & 24.4 & Hexadecanoic acid, ethyl ester (C\({}_{18}\)H\({}_{36}\)O\({}_{2}\)) & 24.6 \\ \hline \multirow{2}{*}{_U. australis_} & 23.3 & 2-Hexadecen-1-ol, 3,7,11,15-tetramethyl-acetate, [R-[R*,R*-(E)]]-(C\({}_{22}\)H\({}_{42}\)O\({}_{2}\)) & 40.4 \\ \hline \end{tabular}
\end{table} 
Table 6: Compounds isolated from _S. horneri_ and _U. australis_ extracts. Figure 7: Microphotographs of the adipose tissue in HFD-fed C57 BL/6 mice showing the effect of treatment with _S. horneri_ and _U. australis_. Representative sections of adipose tissue stained for H&E (magnification \(\times\) 200). (**A**) ND; (**B**) HFD; (**C**) HFD+SH; and (**D**) HFD+UA. such as anti-obesity substances, oriental medicines, and medicinal plants, has been steadily growing [34]. Seaweed has been widely used as diet food due to its low fat and calorie content and the presence of various essential nutrients, such as protein, vitamins, and minerals whose deficiency is commonly noted during dieting [13]. Most seaweeds have been used as food and functional additives; however, SH and UA are not consumed in Korea and have been classified as marine organic waste resources causing coastal pollution on Jeju Island [35]. In the present study, extracts were prepared using 80% ethanol to upcycle these two seaweed waste resources into functional materials. Their antioxidant effect was then identified, and anti-obesity effects were confirmed in vitro and in vivo. The antioxidant activities of SH and UA extracts were analyzed based on their DPPH radical scavenging activity. DPPH radical scavenging activity measures antioxidant activity via a reduction process in amines and aromatic compounds due to the electron-donating ability of antioxidants, and the degree of purple discoloration has previously been used as an indicator [36]. Using this method, we confirmed that the SH and UA extracts show free radical scavenging activity in a concentration-dependent manner. Additionally, the SH extract was found to have a higher scavenging activity than the UA extract. Phenolic compounds play an essential role as antioxidants, possess phenolic hydroxyl groups, which are collectively referred to as flavonoids, anthocyanins, tannins, and catechins, and are widely distributed in the plant kingdom [37]. Flavonoids are pigments in various plants that have been reported to have antioxidant, UV-blocking, anti-mutagenic, antiviral, and anti-inflammatory effects [38]. In the present study, the total polyphenol contents in the SH and UA extracts were compared, and SH was found to have a higher content than UA (95.5 and 62.4 mg GAE/g, respectively). This finding is consistent with previous research showing that brown algae have a higher polyphenol content than green and red algae [39].