Fig 1.
Structure of (−)-epicatechin-3-O-β-D-allopyranoside (BB).
Table 1.
Primers used in this study.
Fig 2.
(−)-epicatechin-3-O-β-D-allopyranoside (BB) activates Akt signaling pathways.
The cell lysates were analyzed via Western blotting for p-Akt and t-Akt. (A) representative image; Akt phosphorylation was determined from C2C12 cells, and treated with 40 μg/ mL of BB for the indicated period of time (5–60 min); (B). The ratios of phospho-Akt to total Akt forms were analyzed and presented phosphorylation of Akt.
Fig 3.
Effects of (−)-epicatechin-3-O-β-D-allopyranoside (BB) including two parts.
(A) oral glucose tolerance (OGTT). OGTT test was performed on 12 h fasted ICR mice (n = 5) that were allowed access to 40, 80, and 160 mg/kg BB or an equivalent amount of vehicle (water), which were given orally 30 min before an oral glucose load (1 g/kg body wt). The control group was given glucose, whereas the normal group was not. Blood samples were collected from the retro-orbital sinus of fasted mice at the time of the glucose administration (0) and every 30 min until 120 minutes after glucose administration and the blood glucose level was monitored. (B)~(F): Effects of BB on streptozotocin (STZ)-induced diabetic mice; (B) blood glucose levels, (C) triglycerides levels, (D) total cholesterol levels, (E) adiponectin levels, and (F) leptin levels at week 4 by oral gavage (−)-epicatechin-3-O-β-D-allopyranoside (BB: B1, B2, and B3, 10, 20 and 40 mg/kg body weight), or metformin (Metf; 300 mg/kg body weight), or fenofibrate (Feno; 250 mg/kg body weight) in streptozotocin (STZ)-induced mice. All values are means ± SE (n = 9). # P < 0.05, ## P < 0.01, and ### P < 0.001 compared with the control (CON) group; * P < 0.05, ** P < 0.01, and *** P < 0.001 compared with the streptozotocin plus vehicle (distilled water) (STZ) group by ANOVA.
Table 2.
Effects of (−)-Epicatechin-3-O-β-D-allopyranoside (BB) on absolute tissue weight, body weight, body weight gain, and food intakea in streptozotocin-induced diabetic mice.
Fig 4.
(A) liver tissue and (B) pancreatic islets of Langerhans of mice in the control (CON), streptozotocin plus vehicle (distilled water) (STZ), STZ + B1, STZ + B2, STZ + B3, STZ + metformin (Metf), or STZ + fenofibrate (Feno) groups by hematoxylin and eosin-staining. Magnification: 10 (ocular) × 20 (object lens). (−)-epicatechin-3-O-β-D-allopyranoside (BB): B1: 10, B2: 20, B3: 40 mg/kg body wt; Metf: metformin (300 mg/kg body wt); Feno: fenofibrate (250 mg/kg body wt).
Fig 5.
Semiquantative RT-PCR analysis on targeted gene mRNA levels in liver tissue of the mice by oral gavage (−)-epicatechin-3-O-β-D-allopyranoside (BB) (B1, B2, and B3, 10, 20 and 40 mg/kg body weight), or metformin (Metf; 300 mg/kg body weight), or fenofibrate (Feno; 250 mg/kg body weight).
(A) representative image; (B, C) quantification of the ratio of target gene to GAPDH mRNA expression. Total RNA (1 μg) isolated from tissue was reverse transcripted by MMLV-RT; 10 μL of RT products were used as templates for PCR. The expression levels of G6Pase, PEPCK, 11β-HSD1, PPARα, SREBP1c, CPT1a, aP2, and SREBP2 mRNA were measured and quantified by image analysis. Values were normalized to GAPDH mRNA expression. All values are means ± SE (n = 9). # P < 0.05, ## P < 0.01, and ### P < 0.001 compared with the control (CON) group; * P < 0.05, ** P < 0.01, and *** P < 0.001 compared with the streptozotocin plus vehicle (distilled water) (STZ) group.
Fig 6.
The protein contents of (A) GLUT4 in skeletal muscle, and phospho-Akt (Ser473)/total Akt, phospho-AMPK (Thr172) /total AMPK in both skeletal muscle and liver tissue of the mice by oral gavage (−)-epicatechin-3-O-β-D-allopyranoside (BB).
(A, B) representative image; (C, D) quantification of the GLUT4 expression levels and the ratio of phospho-Akt to total Akt and phospho-AMPK to total AMPK (mean ± SE, n = 9). Protein was separated by 12% SDS-PAGE detected by Western blot. # P < 0.05, ## P < 0.01, and ### P < 0.001 compared with the control (CON) group; * P < 0.05, ** P < 0.01, and *** P < 0.001 compared with the streptozotocin plus vehicle (distilled water) (STZ) group. B1, B2, and B3, (−)-epicatechin-3-O-β-D-allopyranoside (BB) (B1, B2, and B3, 10, 20, and 40 mg/kg body weight, respectively); metformin (Metf; 300 mg/kg body weight); fenofibrate (Feno, 250 mg/kg body weight).
Fig 7.
Expression levels of PPARα, FAS, and PPARγ in the liver and PPARγ and FAS in adipose tissue of mice by oral gavage (−)-epicatechin-3-O-β-D-allopyranoside (BB).
(A) representative image; (B, C) quantification of the expression levels of PPARα, FAS, and PPARγ in the liver and expression levels of FAS and PPARγ in adipose tissue. Protein was separated by 12% SDS-PAGE detected by Western blot. All values are means ± SE (n = 9). (−)-epicatechin-3-O-β-D-allopyranoside (BB): B1: 10, B2: 20, B3: 40 mg/kg body wt; Metf: metformin (300 mg/kg body wt); Feno: fenofibrate (250 mg/kg body weight). (−)-epicatechin-3-O-β-D-allopyranoside (BB): B1: 10, B2: 20, B3: 40 mg/kg body weight; Metf: metformin (300 mg/kg body wt); Feno: fenofibrate (250 mg/kg body weight).
Fig 8.
The graphic abstract of (−)-epicatechin-3-O-β-D-allopyranoside (BB) in streptozotocin-induced diabetic mice.