Nutr Res Pract.  2025 Feb;19(1):1-13. 10.4162/nrp.2025.19.1.1.

Anti-obesity effects of ethanol extract of green Citrus junos peel enriched in naringin and hesperidin in vitro and in vivo

• Heo YJ
• Lee MK
• Im JH
• Kim BS
• Lee HI

• KMID: 2565393
• DOI: http://doi.org/10.4162/nrp.2025.19.1.1

Abstract

BACKGROUND/OBJECTIVES
Green Citrus junos (yuja) peel extract has higher naringin and hesperidin contents and antioxidant activity than yellow yuja peel extract, but its anti-obesity effects are unclear. This study examined the anti-obesity properties of green yuja peel ethanol extract (GYE) in 3T3-L1 cells and high-fat diet (HFD)-induced obese mice.
MATERIALS/METHODS
The effects of GYE on adipocyte differentiation were assessed by measuring Oil red O staining, mRNA and protein expression. The beneficial effects of GYE on HFD-induced obese mice were evaluated using the body weight, body composition, visceral fat size, and biochemical analysis.
RESULTS
GYE inhibited adipocyte differentiation and lipid accumulation compared to the control cells, as evidenced by Oil red O staining and the triglyceride level, respectively. GYE down-regulated the adipogenic genes CCAAT/enhancer binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ), and lipogenic gene diacylglycerol O-acyltransferase 2 (DGAT2). GYE at 100 μg/mL downregulated the phosphorylation levels of phosphoinositide 3-kinase (PI3K) and protein kinase B (Akt), and their downstream targets PPARγ and sterol regulatory element-binding protein-1 (SREBP-1c) compared to the control group. In obese mice, GYE (100 mg/kg/day) reduced the body weight, body weight gain, and serum lipid level compared to the control group. Analysis using dual-energy X-ray absorptiometry showed that GYE decreased the fat percentage, fat in tissue, and abdominal circumference, while it increased the lean percentage compared to control group. Furthermore, GYE significantly reduced the visceral fat weight and size compared to the control group.
CONCLUSION
GYE suppressed adipocyte differentiation by inhibiting the PI3K-Akt pathway in vitro and reduced the body fat mass and visceral adiposity in HFD-induced obese mice. These findings suggest that GYE is a viable natural option for combating obesity.

Keyword

Adipogenesis; high-fat diet; abdominal obesity; Citrus junos

Figure

• 

  Fig. 1 Effects of GYE on cell viability (B), adipocyte differentiation (A&C), and adipogenic gene (D&E) mRNA expression in 3T3-L1 cells. Quantitative analysis of Oil Red O staining and microscopic observation of lipid droplets stained with Oil Red O. Values are expressed as mean ± SE (n = 3). Values not sharing a common letter (a-d) are significantly different among the groups at P < 0.05.DMI, differentiation medium; GYE, green yuja peel ethanol extract; C/EBPα, CCAAT/enhancer-binding protein α; PPARγ, peroxisome proliferator-activated receptor γ.

• 

  Fig. 2 Effect of GYE on triglyceride content (A) and lipogenic gene (B-E) mRNA expression in 3T3-L1 cells. Values are expressed as mean ± SE (n = 3). Values not sharing a common letter (a-d) are significantly different among the groups at P < 0.05.DMI, differentiation medium; GYE, green yuja peel ethanol extract; SREBP-1c, sterol regulatory element-binding protein; FASN, fatty acid synthase; SCD1, stearoyl-coenzyme A desaturase 1; DGAT2, diacylglycerol O-acyltransferase 2.

• 

  Fig. 3 Effect of GYE on lipid metabolism related protein expression in 3T3-L1 cells. Western blot of analysis of p-PI3K and PI3K (A), p-Akt and Akt (B), PPARγ (C), and SREBP-1c (D), along with their quantitative analysis. Values are expressed as mean ± SE (n = 3). Values not sharing a common letter (a-c) are significantly different among the groups at P < 0.05.DMI, differentiation medium; GYE, green yuja peel ethanol extract; PI3K, phosphoinositide 3-kinase; Akt, protein kinase B; PPARγ, peroxisome proliferator-activated receptor γ; SREBP-1c, sterol regulatory element-binding protein.

• 

  Fig. 4 Effect of GYE on body composition and abdominal circumference in HFD induced obese mice. Dual energy X-ray absorptionmetry (DEXA) scan image (A), fat percentage, fat in tissue, lean percentage, and abdominal circumference (B) were measured by DEXA. Values are expressed as mean ± SE (n = 8). Values not sharing a common letter (a-c) are significantly different among the groups at P < 0.05.NC, normal diet fed group; HFD, high-fat diet; GYE, HFD mice supplemented with 100 mg/kg green yuja peel ethanol extract.

• 

  Fig. 5 Effect of GYE on adipocyte size (A, B) and visceral adipose tissue weights (C) in HFD induced obese mice. Epididymal adipose tissues stained with hematoxylin and eosin (200× magnification). Values are expressed as mean ± SE (n = 8). Values not sharing a common letter (a-c) are significantly different among the groups at P < 0.05.NC, normal diet fed group; HFD, high-fat diet; GYE, HFD mice supplemented with 100 mg/kg green yuja peel ethanol extract.

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