본 연구의 목적은 며느리배꼽 에탄올추출물(PPEE)을 사용하여 항산화 활성을 알아보고, 3T3-L1 지방전구세포에서 지방세포 분화와 지질대사에 미치는 효과를 알아보기 위함이다. PPEE는 kaempferol, apigenin 등을 함유하고 있으며 항산화와 항균작용 효과가 있다는 연구보고가 있지만 비만에 관련된 연구는 접할 수 없었다. 항산화 활성 실험에서 PPEE의 총 폴리페놀 함량은 149.6 mg/g, 총 플라보노이드 함량은 151.3 mg/g 이었다. PPEE는 1,000 μg/mL 농도에서 전자공여능은 89.0%, ABTS 라디칼 소거능은 87.6%, SOD 유사활성은 25% 였다. 이를 통하여 PPEE는 우수한 항산화 활성을 지님을 확인하였다. MTT assay를 이용한 3T3-L1지방전구세포에서 PPEE의 세포독성을 확인한 결과, 최대허용농도는 250 μg/mL로 확인되었다. 도립현미경으로 3T3-L1 지방전구세포의 형태를 관찰한 결과, PPEE 처치군은 250 μg/mL에서 세포독성이 관찰되지 않았고 500 μg/mL 이상에서 세포독성이 관찰되었다. 3T3-L1 지방전구세포에 분화유도배지(MDI)와 함께 62.5?250 μg/mL 농도로 PPEE를 8일간 처리한 후 Oil red O 염색하여 지질함량을 측정한 결과, 대조군에 비해 농도의존적으로 지질 축적이 억제되었으며 PPEE 250 μg/mL 처리는 27.8% 유의한(p<0.001) 억제효과가 있었다. 8일 동안 분화한 3T3-L1 지방세포에 PPEE을 24시간 처리한 후 Oil red O 염색하여 지질함량을 측정한 결과에서도, 대조군에 비해 농도 의존적으로 지질 축적이 억제되었다. 3T3-L1 지방세포의 GPDH 활성을 측정한 결과, 대조군에 비해 PPEE 250 μg/mL 처리는 24.9% 유의하게(p<0.001) 저해시켰다. PPEE 처리에 의하여 지방세포의 분화에 영향을 미치는 전사 인자인 PPARγ, C/EBPα의 발현이 농도 의존적으로 현저하게 억제되었고, SREBP-1c는 PPEE 처리 모든 농도에서 발현이 억제되었다. PPEE 처리는 지방합성 인자인 FAS, ACC, aP2 발현을 하향조절 시켰다. PPEE 처리는 지방세포 분화와 지방합성에 관련된 전사인자인 PPARγ, C/EBPα의 단백질 발현을 억제시켰으며, 이들 전사인자들의 조절을 받는 ACC의 단백질 발현 또한 억제시켰다. 따라서, PPEE의 비만억제 효과는 SREBP-1c와 C/EBPα 경로를 통한 전사인자의 발현억제와 이들 전사인자의 조절을 받는 FAS와 ACC의 발현억제로 인한 것으로 판단된다. PPEE는 에너지소비인자인 leptin과 adiponectin과 지질분해 인자인 ATGL과 HSL도 하향조절 시켰다. 이는 초기 지방합성을 억제하여 지질축적이 감소하여 지질분해 인자 또한 발현이 억제되었을 것으로 판단된다. 이상의 연구 결과를 종합해 보면, PPEE는 3T3-L1 지방전구세포에서 낮은 세포독성을 보였으며, GPDH 활성을 저해하였다. 또한, 3T3-L1 지방전구세포의 지방분화와 지방합성 인자의 mRNA와 단백질 발현을 저해시키고 에너지소비인자인 leptin과 adiponectin을 저해시킴으로써, 결과적으로 지질축적을 억제하는 것으로 나타나 항비만 천연소재로서 활용 가능성이 있을 것으로 사료된다.
Persicaria perfoliata is a traditional medicine with antioxidant and anti-inflammatory effects. However, the anti-obesity effects and mechanism of P. perfoliata ethanol extract (PPEE) remain unclear. The present study was conducted to evaluate the total polyphenol and flavonoid content and antioxidant activity of PPEE, and to investigate the effects of PPEE on adipocyte differentiation and lipid metabolism in 3T3-L1 murine fibroblast-like preadipocytes. The total polyphenol and flavonoid content of PPEE was 149.6 and 151.3 mg/g, respectively. The electron donating ability, 2,2-azino-bis(3-ethylbenzothaizoline-6-sulphonic acid) (ABTS) radical scavenging activity, and superoxide dismutase (SOD)-like activity of 1,000 μg/mL PPEE was 89.0%, 87.6%, and 25.0%, respectively. These results confirm that PPEE has strong antioxidant activity. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay demonstrated that the maximum permissible concentration of PPEE in 3T3-L1 preadipocytes was 250 μg/mL. While treatment with PPEE at 250 μg/mL did not affect the proliferation of 3T3-L1 preadipocytes, treatment with 500 μg/mL and higher PPEE had strong anti-proliferative effects. Oil red O staining analysis revealed that treatment with PPEE (62.5?250 μg/mL) inhibited lipid accumulation in a concentration-dependent manner during the differentiation of 3T3-L1 preadipocytes into adipocytes. There was 24% inhibition of lipid accumulation by PPEE treatment at 250 μg/mL, as compared to control cells. Notably, PPEE treatment for 24 h further showed a concentration-dependent inhibitory effect on lipid accumulation in differentiated 3T3-L1 adipocytes. GPDH activity in PPEE treated (250 μg/mL) cells was significantly (p<0.05) decreased by 24.9% compared to the control group during adipocyte differentiation. PPEE treatment also led to a concentration-dependent inhibition of the expression of adipogenic transcription factors, including PPARγ, C/EBPα and SREBP-1c, and fat synthesis factors, such as FAS, ACC, and aP2, at the protein and/or mRNA level, during adipocyte differentiation. Considering that SREBP-1c is an upstream regulator of FAS, and that PPARγ and C/EBPα are also responsible for the transcriptional upregulation of ACC, it is likely that PPEE inhibits lipid accumulation through downregulation of SREBP-1c and C/EBPα, subsequently leading to the suppression of FAS and ACC. In addition, PPEE treatment downregulated the expression of energy consumption factors, including leptin and adiponectin, and lipolysis enzymes, such as ATGL and HSL. It is presumed that suppression of the expression of these energy consumption factors and lipolysis enzymes by PPEE may be attributed to PPEE-mediated inhibition of adipogenesis and/or lipid accumulation at early stages of adipocyte differentiation. In conclusion, the present study demonstrated that PPEE contains high polyphenol and flavonoid levels, and had a strong anti-oxidative activity. PPEE had a low cytotoxicity in 3T3-L1 preadipocytes, but largely inhibited lipid accumulation during the differentiation of 3T3-L1 preadipocytes into adipocytes. PPEE inhibited the expression of adipogenic transcription factors (SREBP-1c, C/EBPα, PPARγ), fat synthesis factors (FAS, ACC, aP2), energy consumption factors (leptin, adiponectin), and lipolysis enzymes (ATGL, HSL) during adipocyte differentiation. These findings collectively suggest that PPEE could be a potential natural anti-obesity therapeutic.
1. INTRODUCTION 12. MATERIALS and METHODS 52.1 Reagents and apparatus 52.2 Preparation of Persicaria perfoliata ethanol extract (PPEE) 62.3 Antioxidant activity 62.3.1 Total polyphenol content 62.3.2 Total flavonoid content 62.3.3 Electron donating ability 72.3.4 ABTS radical scavenging ability 72.3.5 Superoxide dismutase (SOD)-like activity 82.4 Cell experiments 92.4.1 Cell culture and adipogenic differentiation 92.4.2 Cell viability assay 102.4.3 Oil red O staining 102.4.4 Glycerol-3-phosphate dehydrogenase (GPDH) activity assay 112.4.5 Glycerol assay 112.4.6 Reverse transcription-polymerase chain reaction (RT-PCR) 122.4.7 Protein sample preparation and Western blot analysis 152.5 Statistical analysis 163. RESULTS 173.1 Antioxidant activity of PPEE 173.1.1 Total polyphenol and flavonoid content 173.1.2 Electron donating ability 183.1.3 ABTS radical scavenging ability 193.1.4 SOD-like activity 203.2 Effects of PPEE on 3T3-L1 preadipocytes 213.2.1 Effect of PPEE on viability of 3T3-L1 preadipocytes 213.2.2 Morphological observation of 3T3-L1 preadipocytes 223.2.3 Effect of PPEE on lipid accumulation during the differentiation of 3T3-L1 preadipocyte 233.2.4 Effect of PPEE on GPDH activity 263.2.5 Effect of PPEE on adipogenic gene expression 273.2.6 Effect of PPEE on PPARγ protein expression 283.2.7 Effect of PPEE on C/EBPα protein expression 293.2.8 Effect of PPEE on lipogenic gene expression 303.2.9 Effect of PPEE on ACC and FAS protein expression 313.2.10 Effect of PPEE on energy consumption gene expression 323.2.11 Effect of PPEE on lipolytic gene expression 333.2.12 Effect of PPEE on ATGL and HSL protein expression 343.3 Effects of PPEE on differentiated 3T3-L1 adipocytes 353.3.1 Effect of PPEE on lipid accumulation in differentiated 3T3-L1 adipocytes 353.3.2 Effect of PPEE on glycerol release from differentiated 3T3-L1 adipocytes 383.3.3 Effect of PPEE on mRNA expression of adipogenic, lipogenic, and lipolytic genes in differentiated 3T3-L 1 adipocytes 393.3.4 Effect of PPEE on PPARγ protein expression 403.3.5 Effect of PPEE on ACC and FAS protein expression 413.3.6 Effect of PPEE on ATGL and HSL protein expression 424. DISCUSSION 43REFERENCES 48ENGLISH ABSTRACT 59KOREAN ABSTRACT 63