Introduction

Benzoquinones have been reported to play important roles in bioenergetic transport, oxidative phosphorylation, electron transport processes, and the inhibition of adipogenesis [1–4]. 2,6-

Dimethoxy-1,4-benzoquinone (DMBQ) is a natural phytochemical

present in fermented wheat germ [5], and has been reported to

exhibit various biological properties including anti-inflammatory,

antitumor, and antibacterial activities [6–8]. Recent research has

shown that wheat germ extract elicits anti-adipogenic and antioxidant effects in 3T3-L1 adipocytes [9]. However, the effect of

DMBQ on adipocyte differentiation has not been previously investigated.

Obesity is a common metabolic disorder in developed countries and is associated with metabolic syndrome, which broadly includes insulin resistance, type 2 diabetes, hyperglycemia, dyslipidemia, and various types of cancer [10–13]. An imbalance of energy intake and expenditure results in the enlargement of adipocytes and their proliferation by adipogenesis, the process by

which a preadipocyte transforms into a mature adipocyte via the

alteration of cellular, morphological, and biochemical properties

within adipose tissue [14–18]. Numerous transcription factors, including CCAAT/enhancer binding protein α (C/EBP-α) and peroxisome proliferator-activated receptor-γ (PPAR-γ), play a pivotal role

in the formation of mature adipocytes [19]. Lipid synthesis proteins such as fatty acid synthase (FAS) and sterol regulatory element-binding protein (SREBP) are involved in fatty acid and cholesterol synthesis, and contribute toward lipid homeostasis.

AMP-dependent protein kinase (AMPK) is activated via elevation of the AMP/ATP ratio, and is a key regulator and energy sensor that integrates nutrients, hormones, and stress signals to

maintain whole-body energy balance [20, 21]. AMPK inhibits the

ATP consumption pathway, which includes fatty acid and cholesterol synthesis, by interfering with transcription factors and metabolic enzymes such as SREBP-1, acetyl-CoA carboxylase 1 (ACC1),

and HMG‑CoA reductase [22]. AICAR (5-Aminoimidazole-4-carboxamide ribonucleotide) is an activator of AMPK and suppresses

lipid synthesis during adipocyte differentiation by regulating β-oxidation-related proteins [23, 24]. For this reason, AMPKα-knockout mice exhibit increased body weight and fat mass due to increased lipid accumulation by adipocytes when fed a high-fat diet

[25].

The mammalian target of rapamycin complex 1 (mTORC1) is

another major nutrient sensor that regulates cell metabolism,

growth, and protein synthesis [26]. Several studies have demonstrated that the mTORC1 pathway is also involved in the regulation of lipid accumulation during the differentiation of 3T3-L1 preadipocytes [27–29]. mTORC1 enhances SREBP-1 activity, resulting in increased fatty acid and cholesterol synthesis [30]. mTORC1

activity is under the control of several upstream regulators. The

PI3K-Akt pathway regulates mTORC1 activity via TSC, and

mTORC1 activity is downregulated by AMPK activation in response to energy status [31].

The primary objective of this study was to explore the role of

DMBQ in the regulation of adipocyte generation and to investigate the molecular mechanisms of action responsible.

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