# Natural Extracts from White Common Bean
## 3 Results and Discussion
### mRNA and Protein Expression of PPAR\(\gamma\), C/EBP\(\alpha\), and SREBP-1c  
The PPAR\(\gamma\), C/EBP\(\alpha\), and SREBP1c are sequentially and cooperatively expressed during 3T3-L1 adipocyte differentiation [42]. PPAR\(\gamma\) is an essential factor in adipocyte differentiation, which is involved in the regulation of adipocyte biogenesis. C/EBP\(\alpha\) triggers the expression of adipocyte-specific genes together with PPAR\(\gamma\). SREBP1c controls fatty acids synthesis during 3T3-L1 adipocytes differentiation [34,35]. In the present study, we investigated whether the reduced intracellular lipid contents were related to the decreased expression of these transcription factors. The results of the RT-PCR analysis and Western blot analysis demonstrated that CBP and \(\alpha\)-AIE suppress the mRNA expression level and protein expression level of PPAR\(\gamma\), C/EBP\(\alpha\), and SREBP-1c, in a dose-dependent manner (Figures 3 and 4). No statistical significances (\(p<0.05\)) are found in a low dose of \(\alpha\)-AIE (2 mg/mL). PPAR\(\gamma\), C/EBP\(\alpha\), and SREBP1c are early expressed in adipocyte differentiation. Our results suggest that CBP and \(\alpha\)-AIE inhibit the adipogenesis of 3T3-L1 adipocytes at an early stage of adipogenesis, and CBP exhibits stronger effects than \(\alpha\)-AIE.  
LPL and ap2 are the downstream regulatory factors of DNA in the process of adipogenesis and are specific genes in adipose tissue that are jointly activated by PPAR\(\gamma\) and C/EBP\(\alpha\) during fatty acid metabolism [43]. Since the inhibitory effects of CBP and \(\alpha\)-AIE on the mRNA and protein expression of PPAR\(\gamma\) and C/EBP\(\alpha\) were demonstrated, we next evaluated their effects on the expression of ap2 and LPL. Excess aP2 secreted from adipose tissue acts as a hormone, supporting inter-organ communication and resulting in lipid derangement [44]. As shown (Figure 3), mRNA expression levels of ap2 are significantly (\(p<0.05\)) downregulated to 82.69% and 66.52% by different doses of CBP (150 mg/mL and 300 mg/mL). However, the obvious inhibition in the expression of ap2 was only observed for a high dose of \(\alpha\)-AIE (4 mg/mL). Excess fatty acids can enter into white fat cells under the action of LPL and be stored after esterification, and it may tend to obese [37]. Results showed that CBP also significantly (\(p<0.05\)) reduces the mRNA expression levels of LPL to 87.57% and 72.77%, while \(\alpha\)-AIE has no statistically effect on it. The Western blot results show that the LPL and ap2 protein expression levels are consistent with mRNA expression and show a similar trend (Figure 4). These results further demonstrate that CBP showed better inhibitory effects on adipocyte differentiation than \(\alpha\)-AIE.  
Figure 4: _Cont_.  
Figure 3: Effects of CBP and \(\alpha\)-AIE on the mRNA expression level of peroxisome-proliferative-activated receptor families (PPAR\(\gamma\)), CCAAT/enhancer binding protein (C/EBP\(\omega\)), sterol-regulatory element binding proteins 1 c (SREBP1c), lipoprotein lipase (LPL), and astragalus polysaccharides (ap2). The data were expressed as mean \(\pm\) SD. Different letters mean significantly different (\(p<0.05\)).