Ethanol extract of Pinus koraiensis leaves containing lambertianic acid exerts anti-obesity and hypolipidemic effects by activating adenosine monophosphate-activated protein kinase (AMPK)

Myoung-Sun Lee,Min-Ho Lee,Hyo-Jeong Lee,Eun-Ok Lee,Sung-Hoon Kim,Sun-Mi Cho

doi:10.1186/s12906-016-1031-2

Abstract

BackgroundIn this study, we investigated the anti-obesity and anti-hyperlipidemic mechanisms of lambertianic acid (LA) isolated from Pinus koraiensis leaves and the ethanol extract of Pinus koraiensis leaves (EPK), both in vitro and in vivo.MethodsDifferentiated 3T3L-1 cells were treated with EPK (25 or 50 μg/mL) or LA (200 μM) and analyzed by western blotting or RT-PCR. In vitro, lipid accumulation of adipocytes was observed using Oil-Red-O staining and triglyceride analysis. The contribution of AMPK to anti-obesity activity was assessed by siRNA-mediated AMPK knockdown. After AMPK silencing, expression of AMPK was observed by western blotting. To confirm the in vitro activity, an animal study was conducted by administering a normal diet, HFD, and EPK for 6 weeks. Obesity-related physiological parameters and protein levels were measured.ResultsLA induced the expression of p-AMPK and inhibited PPARγ, C/EBP α, adiponectin, FAS, SREBP-1, and HMGCR expression. EPK containing LA significantly decreased lipid accumulation and triglyceride levels in the differentiated 3 T3-L1 cells. EPK treatment suppressed the expression of adipogenic transcription factors, FABP, GPDH, and cholesterol-synthesis-related factors in the differentiated 3 T3-L1 cells. EPK increased the expression of p-AMPK. The effects of EPK were reversed on inhibiting AMPK by using AMPK siRNA and compound C. In vivo analysis showed that body weight gain, serum triglyceride, total cholesterol, LDL cholesterol and AI value in the EPK treatment group were lower than those in the HFD control group. EPK induced the expression of p-AMPK and inhibited PPARγ in liver and adipose tissue.ConclusionsOverall, the results suggest that EPK containing LA exerts significant anti-obesity and cholesterol-lowering effects by activating AMPK.Electronic supplementary materialThe online version of this article (doi:10.1186/s12906-016-1031-2) contains supplementary material, which is available to authorized users.

Highlights

In this study, we investigated the anti-obesity and anti-hyperlipidemic mechanisms of lambertianic acid (LA) isolated from Pinus koraiensis leaves and the ethanol extract of Pinus koraiensis leaves (EPK), both in vitro and in vivo
Several studies have reported that Sterol regulatory element-binding protein 1 (SREBP-1) is a transcription factor that regulates adipogenesis, cellular cholesterol, and cholesterol synthesis proteins, such as 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), in 3 T3-L1 adipocytes [8,9,10]
LA as an active ingredient in EPK Through activity-guided fractionation (Additional file 1: Figure S1), we identified LA (Fig. 1a) from P. koraiensis needles as a novel anti-hyperlipidemic compound for use in increasing LDLR

Summary

Introduction

We investigated the anti-obesity and anti-hyperlipidemic mechanisms of lambertianic acid (LA) isolated from Pinus koraiensis leaves and the ethanol extract of Pinus koraiensis leaves (EPK), both in vitro and in vivo. Adipocyte differentiation is regulated by crucial transcription factors such as peroxisome proliferator-activated receptor-γ (PPARγ) and CCAAT/enhancer-binding proteins α (C/EBPα). These transcription factors control the expression of many adipogenic proteins [4,5,6,7]. The identification of a natural compound that can exert anti-obesity effects with fewer side effects than currently available prescription medications is attracting attention [4]. One such compound is P. koraiensis (Korean nut pine), which is native to Korea, Japan, China, and Eastern Russia. The purpose of this study is to investigate the anti-adipogenic effect of EPK on 3T3L-1 cells and the anti-obesity activity of EPK on high fat diet (HFD)-fed rats

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