Anti-Obesity Effect of a Tea Mixture Nano-Formulation on Rats Occurs via the Upregulation of AMP-Activated Protein Kinase/Sirtuin-1/Glucose Transporter Type 4 and Peroxisome Proliferator-Activated Receptor Gamma Pathways

Abstract

White, green, and oolong teas are produced from the tea plant (Camellia sinensis (L.) Kuntze) and are reported to have anti-obesity and hypolipidemic effects. The current study aims to investigate the anti-obesity effects of a tea mixture nano-formulation by targeting the AMPK/Sirt-1/GLUT-4 axis in rats. In vitro lipase and α-amylase inhibition assays were used to determine the active sample, which was then incorporated into a nanoparticle formulation subjected to in vivo anti-obesity testing in rats by measuring the expression level of different genes implicated in adipogenesis and inflammation using qRT-PCR. Moreover, metabolomic analysis was performed for each tea extract using LC/ESI MS/MS coupled to chemometrics in an attempt to find a correlation between the constituents of the extracts and their biological activity. The in vitro pancreatic lipase and α-amylase inhibition assays demonstrated more effective activity in the tea mixture than the standards, orlistat and acarbose, respectively, and each tea alone. Thus, the herbal tea mixture and its nanoparticle formulation were evaluated for their in vivo anti-obesity activity. Intriguingly, the tea mixture significantly decreased the serum levels of glucose and triglycerides and increased the mRNA expression of GLUT-4, P-AMPK, Sirt-1, and PPAR-γ, which induce lipolysis while also decreasing the mRNA expression of TNF-α and ADD1/SREBP-1c, thereby inhibiting the inflammation associated with obesity. Our study suggests that the tea mixture nano-formulation is a promising therapeutic agent in the treatment of obesity and may also be beneficial in other metabolic disorders by targeting the AMPK/Sirt-1/Glut-4 pathway.

Keywords: catechins; green tea; metabolomics; obesity; oolong tea; white tea.

Figure 1

Overlaid chromatograms of tea samples as analyzed using ultrahigh-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS).

Figure 2

UPLC-MS analysis of caffeoylquinic acid isomers. (A) Elution pattern of three caffeoylquinic acid isomers for the peak extracted at 355.10257 m/z. (B) Positive electrospray ionization full-scan mass spectrometry (ESI-MS) analysis (C). Positive electrospray ionization–tandem mass spectrometry (ESI-MS/MS) analysis.

Figure 3

Principal component analysis (A) and hierarchical cluster analysis (B).

Figure 4

Heatmap showing a visualization of clustering analyses of metabolites identified from the different tea samples. Each row represents a metabolite, and each column represents the average of samples from each type (n = 3). Red and blue denote high and low relative abundances of metabolites transformed into the log₁₀ scale, respectively.

Figure 5

TEM images of tea nanoparticles coated with PVA.

Figure 6

Top view AFM image of tea nanoparticles coated with PVA.

Figure 7

Three-dimensional AFM image of tea nanoparticles coated with PVA.

Figure 8

Three-dimensional DLS chart of tea nanoparticles coated with PVA.

Figure 9

Effects of conventional and nano-tea mixture extracts on (A) Wister rat weight and (B) adipose tissue deposition. Data represented as scatter plots; significant at p < 0.05.

Figure 10

Effects of conventional and nano-tea mixture extracts on lipid profiles, (A) Triglyceride, (B) Total cholesterol, (C) HDL, (D) LDL, and (E) blood glucose levels, as well as kidney and liver function represented as (F) Creatinine, (G) ALT and (H) AST. Data represented as scatter plots; significant at p < 0.05 are represented as ** (p < 0.01), *** (p < 0.001) and **** (p < 0.0001). Different colors are indicating different groups as shown at the bottom of the figure.

Figure 11

Effects of conventional and nano-tea mixture extracts on (A) leptin, (B) adiponectin, (C) vaspin, (D) omentin, (E) TNF-α, (F) GLUT-4, (G) Sirt-1, (H) PPAR-gamma, (I) P-AMPK, and (J) ADD1/SREBP-1. Data represented as scatter plots; significant at p < 0.05 are represented as **** (p < 0.0001). Different colors are indicating different groups as shown at the bottom of the figure.

Figure 12

Effects of conventional and nano-tea mixture extracts on molecular pathways in rats with high-fat-diet-induced obesity. This figure was created with BioRender.com.