Cyanidin-3-O-glucoside (C3G) is a natural anthocyanin with antioxidant, anti-inflammatory, and antitumor properties. However, as the effects of C3G on the amyloidogenic pathway, autophagy, tau phosphorylation, neuronal cell death, and synaptic plasticity in Alzheimer’s disease models have not been reported, we attempted to investigate the same in the brains of APPswe/PS1ΔE9 mice were analyzed. After oral administration of C3G (30 mg/kg/day) for 16 weeks, the cortical and hippocampal regions in the brains of APPswe/PS1ΔE9 mice were analyzed. C3G treatment reduced the levels of soluble and insoluble Aβ (Aβ40 and Aβ42) peptides and reduced the protein expression of the amyloid precursor protein, presenilin-1, and β-secretase in the cortical and hippocampal regions. And C3G treatment upregulated the expression of autophagy-related markers, LC3B-II, LAMP-1, TFEB, and PPAR-α and downregulated that of SQSTM1/p62, improving the autophagy of Aβ plaques and neurofibrillary tangles. In addition, C3G increased the protein expression of phosphorylated-AMPK/AMPK and Sirtuin 1 and decreased that of mitogen-activated protein kinases, such as phosphorylated-Akt/Akt and phosphorylated-ERK/ERK, thus demonstrating its neuroprotective effects. Furthermore, C3G regulated the PI3K/Akt/GSK3β signaling by upregulating phosphorylated-Akt/Akt and phosphorylated-GSK3β/GSK3β expression. C3G administration mitigated tau phosphorylation and improved synaptic function and plasticity by upregulating the expression of synapse-associated proteins synaptophysin and postsynaptic density protein-95. Although the potential of C3G in the APPswe/PS1ΔE9 mouse models has not yet been reported, oral administration of the C3G is shown to protect the brain and improve cognitive behavior. Graphical Abstract

Lipophagy, a type of autophagy that breaks down lipid droplets, is essential in the regulation of intracellular lipid accumulation and intracellular free fatty acid levels in numerous organisms and metabolic conditions. We investigated the effects of Stevia rebaudiana Bertoni (S), a low-calorie sweetener, and stevioside (SS) on hepatic steatosis and autophagy in hepatocytes, as well as in db/db mice. S and SS reduced the body and liver weight and levels of serum triglyceride, total cholesterol, and hepatic lipogenic proteins. In addition, S and SS increased the levels of fatty acid oxidase, peroxisome proliferator-activated receptor alpha (PPARα), and microtubule-associated protein light chain 3 B but decreased that of sequestosome 1 (p62) in the liver of db/db mice. Additionally, Beclin 1, lysosomal associated membrane protein 1, and phosphorylated adenosine monophosphate-activated protein kinase protein expression was augmented following S and SS treatment of db/db mice. Furthermore, the knockdown of PPARα blocked lipophagy in response to SS treatment in HepG2 cells. These outcomes indicate that PPARα-dependent lipophagy is involved in hepatic steatosis in the db/db mouse model and that SS, a PPARα agonist, represents a new therapeutic option for managing associated diseases.

Stevioside, the primary sweetener in stevia, is a glycoside with numerous beneficial biological activities. However, its anti-adipogenic effects on tissue differentiation and adipose tissues remain to be thoroughly investigated. In this study, the anti-adipogenic effects of stevioside during the differentiation of 3T3-L1 cells and epididymal adipose tissues of db/db mice were investigated by measuring the lipid droplets stained with Oil Red O and an immunoblot assay. Immunoblot analysis revealed that stevioside downregulated the expression of peroxisome proliferator-activated receptor-gamma (PPARγ), sterol regulatory element-binding protein-1c (SREBP-1c), CCAAT/enhancer-binding protein alpha (C/EBPα), and fatty acid synthase (FAS). Additionally, the protein expression of carnitine palmitoyltransferase 1 (CPT1), silent mating type information regulation 2 homolog 1 (SIRT1), and peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) increased following treatment with stevioside. Furthermore, stevioside increased the phosphorylation of adenosine monophosphate (AMP)-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC), both in vitro and in vivo. The activity of AMPK in stevioside-treated 3T3-L1 cells was further confirmed using agonists and antagonists of AMPK signaling. Our data indicate that stevioside ameliorates anti-adipogenic effects and promotes β-oxidation in adipocytes by activating AMPK-mediated signaling. The results of this study clearly demonstrated the inhibitory effect of stevioside on the differentiation of adipocytes and the reduction of lipid accumulation in the epididymal adipose tissues of db/db mice.

Background/Objectives: Alzheimer’s disease (AD) involves amyloid-β (Aβ) deposition, oxidative stress, and neuroinflammation, leading to cognitive decline. Nobiletin, a citrus-derived polymethoxylated flavonoid, exerts antioxidant and anti-inflammatory effects. This study explored its neuroprotective mechanisms in the 5XFAD mouse model. Methods: Male 5XFAD and C57BL/6J mice received oral nobiletin (20 or 40 mg/kg/d) for 4 weeks. Cognitive function was assessed by the Y-maze test. Amyloid-β burden was quantified by Congo red staining and ELISA. Serum cytokine levels and antioxidant enzyme activities were measured by ELISA. Western blotting and RT-PCR were used to assess proteins and genes related to amyloidogenesis, inflammation (TLR4/MyD88/NF-κB), mitochondrial biogenesis (AMPK/SIRT1/PGC-1α), and synaptic plasticity (PI3K/Akt–CREB–BDNF). Results: Nobiletin improved working memory, reduced amyloid-β40/42 deposition, and downregulated APP, BACE1, and PS1 expression, while enhancing ADAM10 expression. It lowered serum IL-6, IL-1β, and TNF-α, increased SOD, CAT, and GPx activities, and suppressed TLR4/MyD88/NF-κB signaling. Furthermore, it activated AMPK/SIRT1/PGC-1α and NRF2 pathways, enhancing antioxidant defenses, and promoted PI3K/Akt–CREB–BDNF signaling, increasing PSD95 and synaptophysin. Conclusions: Nobiletin exerts strong neuroprotective and antioxidant effects by targeting multiple signaling cascades, mitigating amyloid pathology and neuroinflammation, and improving synaptic plasticity. It represents a promising therapeutic agent against AD.

Nobiletin, a citrus-derived polymethoxylated flavone, has been reported to exert anti-obesity effects, but its molecular mechanisms remain poorly understood. This study aimed to investigate whether nobiletin suppresses adipogenesis and promotes browning in 3T3-L1 adipocytes by modulating exosomal microRNAs (miRNAs) and AMPK signaling. To this end, we treated 3T3-L1 adipocytes with various concentrations of nobiletin and evaluated gene and protein expression by RT-qPCR and Western blotting. Nobiletin significantly reduced intracellular lipid accumulation at 50 μM (p < 0.001) and downregulated key adipogenic transcription factors, PPARγ, C/EBPα, and SREBP-1c, and suppressed the lipogenic enzyme FAS, while activating the AMPK/ACC signaling pathway. Concomitantly, it enhanced the expression of thermogenic markers UCP-1, PRDM16, and PGC-1α, indicating a metabolic shift toward energy expenditure. Exosomal RNA-seq revealed 10 differentially expressed miRNAs, of which miR-181d-5p (3.1-fold) and miR-221-3p (2.4-fold) were upregulated, whereas miR-205-5p (−2.9-fold), miR-331-3p (−3.2-fold), miR-130b-3p (−2.6-fold), miR-143-5p (−2.9-fold), miR-183-3p (−2.8-fold), miR-196b-5p (−2.4-fold), miR-26b-3p (−2.2-fold), and miR-378d (−2.7-fold) were verified by RT-qPCR after nobiletin treatment (50 μM). These miRNAs are functionally associated with adipogenic and thermogenic pathways, supporting a regulatory role of the exosomal miRNA network in nobiletin’s action. Collectively, our results identify a novel exosome–miRNA–AMPK axis underlying the anti-adipogenic and browning-inducing activities of nobiletin, highlighting its potential as a therapeutic phytochemical for obesity prevention.