Chinese medicine formulation Mailuoning attenuates high-fat diet-induced obesity by regulating thermogenesis through activating the peroxisome proliferator-activated receptor α/fibroblast growth factor 21 axis.

BACKGROUND

Mailuoning is a Chinese medicine formulation known for its efficacy in clearing heat, nourishing yin, activating blood circulation, and resolving blood stasis. In traditional Chinese medicine, Mailuoning is considered to have potential benefits in improving obesity. Our previous research has demonstrated that Mailuoning could effectively alleviate non-alcoholic fatty liver disease (NAFLD), a metabolic disorder with pathophysiological similarities to obesity. However, the alleviating effects of Mailuoning on obesity have yet to be fully elucidated, and further investigation is required to confirm its therapeutic effect.

PURPOSE: To assess the impact and underlying mechanisms of Mailuoning on obesity, and to investigate its potential active components.

METHODS

Mice were fed with a high-fat diet (HFD) to induce obesity. The anti-obesity effects of Mailuoning were assessed by monitoring body weight, food intake, and hepatic lipid accumulation, as well as performing insulin tolerance test (ITT) and glucose tolerance test (GTT). Real-time PCR and western-blot analyses were utilized to detect gene and protein expression, respectively. The metabolic rate of mice was assessed using metabolism cages. Ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was employed to identify compounds in inguinal white adipose tissue (iWAT). Additionally, Oil Red O staining assay was conducted on 3T3-L1 cells to detect cellular lipid accumulation and screen for active compounds.

RESULTS

Mailuoning significantly reduced the weight of mice, iWAT, and epididymis white adipose tissue (eWAT), lowered the levels of hepatic triglyceride (TG) and non-esterified fatty acid (NEFA), and improved glucose regulation and homeostasis, thereby exerting its efficacy in alleviating HFD-induced obesity. Mechanistically, Mailuoning upregulated hepatic expression of peroxisome proliferator-activated receptor α (PPARα), facilitated its nuclear translocation, and enhanced the expression of its downstream fatty acids oxidation-related genes. Moreover, Mailuoning increased the expression of hepatic fibroblast growth factor (FGF) 21 and promoted its release into the blood. In addition, Mailuoning increased the protein expression of FGF21, FGF receptor (FGFR) 1, and Klotho/β-Klotho (KLB), as well as enhanced the phosphorylation of intracellular extracellular signal-regulated kinase 1/2 (ERK1/2), consequently elevating the expression of thermogenic genes in both brown adipose tissue (BAT) and iWAT. Energy metabolism results revealed that Mailuoning increased energy expenditure in mice. Subsequent research suggested that Lonicerae Japonicae Flos and Lonicerae Flos might be the primary bioactive herbal medicines in Mailuoning for treating obesity. A total of 52 compounds were detected in iWAT, among which 18 were identified in these two herbal medicines. Among these, loganic acid, luteolin, loganin, chlorogenic acid, caffeic acid, and macranthoidin B effectively lowered intracellular lipid levels in 3T3-L1 cells.

CONCLUSION

Mailuoning improved obesity in HFD-fed mice by establishing crosstalk between the liver and adipose tissue by activating PPARα/FGF21 axis, thereby enhancing energy expenditure. Among the constituent herbs, Lonicerae Japonicae Flos and Lonicerae Flos were identified as the primary herbal medicines responsible for the anti-obesity efficacy of Mailuoning.