# Natural Extracts from White Common Bean
## 1 Introduction  
In recent years, obesity has dramatically increased and become a worldwide public health concern [1]. To date, more than 30% of adults across the world are overweight, and almost 10% of adults are obese [2]. In China, it is reported that the rates of overweight and obesity have reached 23.7% among Chinese children and 17.6% among Chinese adolescents in 2015 [3]. Obesity is related with an increased occurrence of various chronic metabolic diseases, such as cancer, type 2 diabetes, and cardiovascular disease, which even decreases 5-20 years of life depending on the severity of the condition and comorbid disorder [4]. A major and direct characteristic involved in obesity is the hypertrophy of pre-existing adipocytes and an increased deposition of cytoplasmic triglycerides during pre-adipocyte differentiation into mature adipocytes [5, 6]. Previous studies suggested that several transcription factors, mainly peroxisome-proliferator-activated receptor families (PPAR) and CCAAT/enhancer binding protein (C/EBP) families, will promote adipocyte differentiation [7, 8, 9]. Accordingly, it is helpful to understand the mechanisms of specific nutrients that affect adipocyte differentiation in the prevention of obesity and treatment of the associated diseases.  
Increasing interests have focused on the use of natural extracts from plants as an alternative approach for the treatment of obesity. It is reported that many natural agents, such as polyphenol, glycoprotein, plant-derived peptides, and polysaccharides, exert anti-obesity effects by inhibiting adipocyte differentiation [10; 11; 12; 13]. Common beam (_Phaseolus vulgaris L._) is one of the traditional food legumes in Africa and South America, and it has attracted worldwide attention owing to its well-documented anti-obesity activity [14; 15; 16]. A series of bioactive compounds that include \(\alpha\)-amylase inhibitor glycinin (\(\alpha\)-Al), polyphenol, flavonoid, and dietary fiber (resistant starch, non-starch polysaccharide) has been discovered as the bioactive components in common bean [17; 18]. At present, \(\alpha\)-Al is the mostly focused component responsible for the anti-obesity effects of common bean foods. \(\alpha\)-Al is able to inhibit saliva and pancreatic amylase, hinder the hydrolysis of starch in food, decrease the digestion of major carbohydrates, and modulate the gut microbiota composition in vivo, so it can be used to restrain fat synthesis without side effects [19; 20]. However, as a glycoprotein, limited research studies have focused on the effects of \(\alpha\)-Al on the adipocyte differentiation. Additionally, polyphenols from various plants and non-starch polysaccharides-rich extract (NSP) from cereals have been confirmed to inhibit adipocyte differentiation in vitro by the downregulation of three key transcription factors which include PPAR\(\gamma\), C/EBP\(\alpha\), and sterol-regulatory element binding proteins 1 c ( SREBP-1c) [13; 21; 22; 23]. Whether the NSP and polyphenol extracted from common bean could suppress the differentiation of adipocyte remains to be studied. 3T3-L1 cells are well-known models for evaluating the inhibition effect of bioactivity compounds on preadipocyte differentiation or lipid metabolism [13; 24; 25].  
Consequently, in the present study, we aimed to compare the inhibitory effects of different natural extracts from white common bean on 3T3-L1 adipocyte differentiation, thus providing a new insight into the anti-obesity effects of common bean foods. Based on this purpose, we firstly isolated different natural extracts, including polyphenols-rich extract (CBP), \(\alpha\)-amylase inhibitor (AI)-rich extract (\(\alpha\)-AIE), and NSP from white common bean seeds. Then, their suppressive effects on 3T3-L1 adipocyte differentiation were evaluated. At last, the effects on the PPAR\(\gamma\) signaling pathway were further investigated.