## 4 Discussion  
Obesity is a complex multifactorial disease that is closely related to various pathological conditions. Obesity is characterized as abnormal or excessive body fat accumulation due to an energy imbalance between calorie consumption and intake [28]. Hypertrophy and hyperplasia of adipocytes are the main causes of obesity. Several signals are involved in adipogenesis both in vitro and in vivo [8]. Being overweight or obese is defined by the body mass index (BMI). A BMI below 25 is considered normal weight, a BMI of 25 to \(<\) 30 is overweight, and a BMI of 30 or higher indicates obesity [1; 29]. As the WHO declared obesity a disease, obese patients need effective treatment. The best way to treat obesity is to exercise regularly and eat healthy foods, such as a low-calorie diet. However, for severe obesity with a BMI greater than 30, anti-obesity drugs are prescribed to interfere with fat absorption or suppress appetite [30; 31; 32]. The Food and Drug Administration (FDA) has approved anti-obesity drugs, such as ilragalutide (Saxenda), orlistat (Xenical, Allii), naltrexone-bupropion (Contrave), lorcaserin (Belviq), and phentermine-topiramate (Qsymia) [29; 33; 34]. However, prescribed anti-obesity drugs have many side effects, such as xerostomia, anorexia, insomnia, and gastrointestinal distress [34; 35]. Therefore, recent research on anti-obesity drugs has focused on natural products to reduce the side effects of anti-obesity drugs [36]. _A. melanogaster_ is a rich source of anthocyanins, polyphenol compounds, and dietary fiber and is well known for its health benefits [21]. Therefore, it has traditionally been widely used as a food ingredient and for treating various diseases due to its antioxidant, anti-inflammatory, anti-diabetic, and anti-obesity effects [18; 37]. Natural products are increasingly used to prevent and treat obesity. Additionally, research on natural products is actively focused on bioactive natural compounds with anti-obesity activities [38]. Recently, various studies have been conducted to explore new anti-obesity compounds from natural products [18; 36]. Therefore, the purpose of this study was to identify whether _A. melanogaster_ fruit extract, ABF(r), has the potential to be used as an anti-obesity agent in 3T3-L1 cells. Figure 8: Effects of _Aronnia_ bioactive fraction (ABF®) on adipokine secretion in 3T3-L1 adipocytes. 3T3-L1 adipocytes were treated with ABF® (0.025 and 0.05 mg/mL). (**A**) Adiponectin significantly increased in ABF® (0.05 mg/mL). (**B**) Leptin significantly decreased in ABF® (0.025 and 0.05 mg/mL). Data represented mean \(\pm\) SEM. \({}^{*}\)\(p\)\(<\) 0.05 compared with the MDI control group. We first confirmed the cytotoxicity of ABF(r) in 3T3-L1 cells. High doses of ABF(r) (0.1, 0.2, and 0.5 mg/mL) were cytotoxic to 3T3-L1 adipocytes, and no significant cytotoxicity was detected at ABF(r) concentrations of 0.025-0.005 mg/mL. Therefore, concentrations of 0.025 and 0.05 mg/mL. ABF(r) were chosen for the following assays. The effect of ABF(r) on lipid accumulation in 3T3-L1 adipocytes was confirmed by Oil Red O staining (Figure 5). ABF(r) (0.025 and 0.05 mg/mL) significantly reduced oil droplet formation compared to that in the untreated control cells. These results suggest that adipocyte differentiation was inhibited by the regulation of lipid accumulation in adipocytes by ABF(r). Fatty acids produced by the muscles and liver are stored as triacylglycerlecrols, perform various functions, and are an important energy source [39]. Derangement of fatty acid signaling pathways causes various diseases. Molecules involved in the fatty acid synthesis pathway are targets for the development of anti-obesity drugs and chemicals. Therefore, we assayed fatty acid synthase pathways molecules that secrete LPL, C/EBP\(\alpha\), PPAR\(\gamma\), FABP2, and FAS. Lipoprotein lipase (LPL) is a member of the lipase gene family, and is usually found on the surface of small blood vessel (capillary) cells in muscle and adipose tissues [40; 41].