Dietary calamondin supplementation slows the progression of non-alcoholic fatty liver disease in C57BL/6 mice fed a high-fat diet

Research advances in citrus polyphenols: green extraction technologies, gut homeostasis regulation, and nano-targeted delivery system application

Citrus polyphenols can modulate gut microbiota and such bi-directional interaction that can yield metabolites such as short-chain fatty acids (SCFAs) to aid in gut homeostasis. Such interaction provides citrus polyphenols with powerful prebiotic potential, contributing to guts' health status and metabolic regulation. Citrus polyphenols encompass unique polymethoxy flavonoids imparting non-polar nature that improve their bioactivities and ability to penetrate the blood-brain barrier. Green extraction technology targeting recovery of these polyphenols has received increasing attention due to its advantages of high extraction yield, short extraction time, low solvent consumption, and environmental friendliness. However, the low bioavailability of citrus polyphenols limits their applications in extraction from citrus by-products. Meanwhile, nano-encapsulation technology may serve as a promising approach to improve citrus polyphenols' bioavailability. As citrus polyphenols encompass multiple hydroxyl groups, they are potential to interact with bio-macromolecules such as proteins and polysaccharides in nano-encapsulated systems that can improve their bioavailability. This multifaceted review provides a research basis for the green and efficient extraction techniques of citrus polyphenols, as well as integrated mechanisms for its anti-inflammation, alleviating metabolic syndrome, and regulating gut homeostasis, which is more capitalized upon using nano-delivery systems as discussed in that review to maximize their health and food applications.

Nobiletin promotes lipolysis of white adipose tissue in a circadian clock-dependent manner

Nobiletin has been reported to protect against obesity-related metabolic disorders by enhancing the circadian rhythm; however its effects on lipid metabolism in adipose tissue are unclear. In this study, mice were fed with high-fat diet (HFD) for four weeks firstly and gavaged with 50 or 200 mg/kg bodyweight/day nobiletin at Zeitgeber time (ZT) 4 for another four weeks while still receiving HFD. At the end of the 8-week experimental period, the mice were sacrificed at ZT4 or ZT8 on the same day. Mature 3T3-L1 adipocytes were treated with nobiletin in the presence or absence of siBmal1, siRora, siRorc, SR8278 or SR9009. Nobiletin reduced the weight of white adipose tissue (WAT) and the size of adipocytes in WAT. At ZT4, nobiletin decreased the TG, TC and LDL-c levels and increased serum FFA level and glucose tolerance. Nobiletin triggered the lipolysis of mesenteric and epididymal WAT at both ZT4 and ZT16. Nobiletin increased the level of RORγ at ZT16, that of BMAL1 and PPARγ at ZT4, and that of ATGL at both ZT4 and ZT16. Nobiletin increased lipolysis and ATGL levels in 3T3-L1 adipocytes in Bmal1- or Rora/c- dependent manner. Dual luciferase assay indicated that nobiletin enhanced the transcriptional activation of RORα/γ on Atgl promoter and decreased the repression of RORα/γ on PPARγ-binding PPRE. Promoter deletion analysis indicated that nobiletin inhibited the suppression of PPARγ-mediated Atgl transcription by RORα/γ. Taken together, nobiletin elevated lipolysis in WAT by increasing ATGL levels through activating the transcriptional activity of RORα/γ and decreasing the repression of RORα/γ on PPARγ-binding PPRE.

Chinese herbal medicines: The modulator of nonalcoholic fatty liver disease targeting oxidative stress

ETHNOPHARMACOLOGICAL RELEVANCE

Plants are a natural treasure trove; their secondary metabolites participate in several pharmacological processes, making them a crucial component in the synthesis of novel pharmaceuticals and serving as a reserve resource foundation in this process. Nonalcoholic fatty liver disease (NAFLD) is associated with the risk of progression to hepatitis and liver cancer. The "Treatise on Febrile Diseases," "Compendium of Materia Medica," and "Thousand Golden Prescriptions" have listed herbal remedies to treat liver diseases.

AIM OF THE REVIEW

Chinese herbal medicines have been widely used for the prevention and treatment of NAFLD owing to their efficacy and low side effects. The production of reactive oxygen species (ROS) during NAFLD, and the impact and potential mechanism of ROS on the pathogenesis of NAFLD are discussed in this review. Furthermore, common foods and herbs that can be used to prevent NAFLD, as well as the structure-activity relationships and potential mechanisms, are discussed.

METHODS

Web of Science, PubMed, CNKI database, Google Scholar, and WanFang database were searched for natural products that have been used to treat or prevent NAFLD in the past five years. The primary search was performed using the following keywords in different combinations in full articles: NAFLD, herb, natural products, medicine, and ROS. More than 400 research papers and review articles were found and analyzed in this review.

RESULTS

By classifying and discussing the literature, we obtained 86 herbaceous plants, 28 of which were derived from food and 58 from Chinese herbal medicines. The mechanism of NAFLD was proposed through experimental studies on thirteen natural compounds (quercetin, hesperidin, rutin, curcumin, resveratrol, epigallocatechin-3-gallate, salvianolic acid B, paeoniflorin, ginsenoside Rg1, ursolic acid, berberine, honokiol, emodin). The occurrence and progression of NAFLD could be prevented by natural antioxidants through several pathways to prevent ROS accumulation and reduce hepatic cell injuries caused by excessive ROS.

CONCLUSION

This review summarizes the natural products and routinely used herbs (prescription) in the prevention and treatment of NAFLD. Firstly, the mechanisms by which natural products improve NAFLD through antioxidant pathways are elucidated. Secondly, the potential of traditional Chinese medicine theory in improving NAFLD is discussed, highlighting the safety of food-medicine homology and the broader clinical potential of multi-component formulations in improving NAFLD. Aiming to provide theoretical basis for the prevention and treatment of NAFLD.

Development of an Improved Adenovirus Vector and Its Application to the Treatment of Lifestyle-Related Diseases

The number of patients with lifestyle-related diseases such as type 2 diabetes mellitus (T2DM) and metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD), has continued to increase worldwide. Therefore, development of innovative therapeutic methods targeting lifestyle-related diseases is required. Gene therapy has attracted considerable attention as an advanced medical treatment. Safe and high-performance vectors are essential for the practical application of gene therapy. Replication-incompetent adenovirus (Ad) vectors are widely used in clinical gene therapy and basic research. Here, we developed a novel Ad vector, named Ad-E4-122aT, exhibiting higher and longer-term transgene expression and lower hepatotoxicity than conventional Ad vectors. We also elucidated the mechanisms underlying Ad vector-induced hepatotoxicity during the early phase using Ad-E4-122aT. Next, we examined the therapeutic effects of the genes of interest, namely zinc finger AN1-type domain 3 (ZFAND3), lipoprotein lipase (LPL), and lysophospholipid acyltransferase 10 (LPLAT10), on lifestyle-related diseases using Ad-E4-122aT. We showed that the overexpression of ZFAND3 in the liver improved glucose tolerance and insulin resistance. Liver-specific LPL overexpression suppressed hepatic lipid accumulation and improved glucose metabolism. LPLAT10 overexpression in the liver suppressed postprandial hyperglycemia by increasing glucose-stimulated insulin secretion. Furthermore, we also focused on foods to advance research on the pathophysiology and treatment of lifestyle-related diseases. Cranberry and calamondin, which are promising functional foods, attenuated the progression of MASLD/NAFLD. Our findings will aid the development of new therapeutic methods, including gene therapy, for lifestyle-related diseases such as T2DM and MASLD/NAFLD.

A Lipidomic Study: Nobiletin ameliorates hepatic steatosis through regulation of lipid alternation

Hepatic lipidome has been given emphasis for years since hepatic steatosis is the most remarkable character of nonalcoholic fatty liver diseases, an increasingly serious health issue worldwide. Nobiletin (NOB), one of the citrus flavonoids, exerted outstanding effect on lipid metabolism disorder. However, the underlying mechanism of NOB exerting effect on hepatic lipid alternation remains unclear. In this study, the animal model was built by feeding APOE^-/- mice with high fat diet (HFD). The results of Oil Red O-stained liver section and the biochemical assay of lipid parameters confirmed the protective effect of NOB on hepatic steatosis and global lipid metabolism disorder in APOE^-/- mice. The hepatic lipidomic study revealed a total of 958 lipids significantly altered by HFD and a total of 86, 116, 212 lipid metabolites changed by L-NOB (50 mg/kg/d NOB), M-NOB (100 mg/kg/d NOB) and H-NOB (200 mg/kg/d NOB) respectively. In the further screening analysis, an amount of 60 lipids were identified as the potential lipid markers of NOB treatment, most of which belonged to glycerophospholipids lipid categories and exhibited obvious correlation with each other and the lipid parameters related to hepatic steatosis. Taken together, our data demonstrated that glycerophospholipids metabolism played an indispensable role in the progression of hepatic steatosis and the protective effect of NOB. Besides, the modulation towards genes involved in lipid synthesis were observed after NOB administration in this study. These finding illustrated the anti-hepatic steatosis effect of NOB based on altering hepatic lipidome, particularly the glycerophospholipids metabolism, and provided a new insight in the pathogenesis of hepatic steatosis.

Hesperetin ameliorates hepatic oxidative stress and inflammation via the PI3K/AKT-Nrf2-ARE pathway in oleic acid-induced HepG2 cells and a rat model of high-fat diet-induced NAFLD

Non-alcoholic fatty liver disease (NAFLD) is considered the most common liver disease. Dietary supplementation has become a promising strategy for managing NAFLD. Hesperetin, a citrus flavonoid, is mainly found in citrus fruits (oranges, grapefruit, and lemons) and possesses multiple pharmacological properties, including anti-cancer, anti-Alzheimer and anti-diabetic effects. However, the anti-NAFLD effect and mechanisms of hesperetin remain unclear. In this study, we investigated the therapeutic effect of hesperetin against NAFLD and the underlying mechanism in vitro and in vivo. In oleic acid (OA)-induced HepG2 cells, hesperetin upregulated antioxidant levels (SOD/GPx/GR/GCLC/HO-1) by triggering the PI3 K/AKT-Nrf2 pathway, alleviating OA-induced reactive oxygen species (ROS) overproduction and hepatotoxicity. Furthermore, hesperetin suppressed NF-κB activation and reduced inflammatory cytokine secretion (TNF-α and IL-6). More importantly, we revealed that this anti-inflammatory effect is attributed to reduced ROS overproduction by the Nrf2 pathway, as pre-treatment with Nrf2 siRNA or an inhibitor of superoxide dismutase (SOD) or/and glutathione peroxidase (GPx) abolished hesperetin-induced NF-κB inactivation and reductions in inflammatory cytokine secretion. In a rat model of high-fat diet (HFD)-induced NAFLD, we confirmed that hesperetin relieved hepatic steatosis, oxidative stress, inflammatory cell infiltration and fibrosis. Moreover, hesperetin activated the PI3 K/AKT-Nrf2 pathway in the liver, increasing antioxidant expression and inhibiting NF-κB activation and inflammatory cytokine secretion. In summary, our results demonstrate that hesperetin ameliorates hepatic oxidative stress through the PI3 K/AKT-Nrf2 pathway and that this antioxidative effect further suppresses NF-κB-mediated inflammation during NAFLD progression. Thus, our study suggests that hesperetin may be an effective dietary supplement for improving NAFLD by suppressing hepatic oxidative stress and inflammation.

ZFAND3 Overexpression in the Mouse Liver Improves Glucose Tolerance and Hepatic Insulin Resistance

Genome-wide association studies have identified more than 300 loci associated with type 2 diabetes mellitus; however, the mechanisms underlying their role in type 2 diabetes mellitus susceptibility remain largely unknown. Zinc finger AN1-type domain 3 (ZFAND3), known as testis-expressed sequence 27, is a type 2 diabetes mellitus-susceptibility gene. Limited information is available regarding the physiological role of ZFAND3 in vivo. This study aimed to investigate the association between ZFAND3 and type 2 diabetes mellitus. ZFAND3 was significantly upregulated in the liver of diabetic mice compared to wild-type mice. To overexpress ZFAND3, we generated a ZFAND3-expressing adenovirus (Ad) vector using an improved Ad vector exhibiting significantly lower hepatotoxicity (Ad-ZFAND3). Glucose tolerance was significantly improved in Ad-ZFAND3-treated mice compared to the control Ad-treated mice. ZFAND3 overexpression in the mouse liver also improved insulin resistance. Furthermore, gluconeogenic gene expression was significantly lower in primary mouse hepatocytes transduced with Ad-ZFAND3 than those transduced with the control Ad vector. The present results suggest that ZFAND3 improves glucose tolerance by improving insulin resistance and suppressing gluconeogenesis, serving as a potential novel therapeutic target for type 2 diabetes mellitus.