No beneficial effects of resveratrol supplementation on atherogenic risk factors in patients with nonalcoholic fatty liver disease

Unlocking Cholesterol Metabolism in Metabolic-Associated Steatotic Liver Disease: Molecular Targets and Natural Product Interventions

Metabolic-associated steatotic liver disease (MASLD), the hepatic manifestation of metabolic syndrome, represents a growing global health concern. The intricate pathogenesis of MASLD, driven by genetic, metabolic, epigenetic, and environmental factors, leads to considerable clinical variability. Dysregulation of hepatic lipid metabolism, particularly cholesterol homeostasis, is a critical factor in the progression of MASLD and its more severe form, metabolic dysfunction-associated steatohepatitis (MASH). This review elucidates the multifaceted roles of cholesterol metabolism in MASLD, focusing on its absorption, transportation, biosynthesis, efflux, and conversion. We highlight recent advancements in understanding these processes and explore the therapeutic potential of natural products such as curcumin, berberine, and resveratrol in modulating cholesterol metabolism. By targeting key molecular pathways, these natural products offer promising strategies for MASLD management. Finally, this review also covers the clinical studies of natural products in MASLD, providing new insights for future research and clinical applications.

Effects of different natural products in patients with non-alcoholic fatty liver disease-A network meta-analysis of randomized controlled trials

Due to a scarcity of appropriate therapeutic approaches capable of ameliorating or eliminating non-alcoholic fatty liver disease (NAFLD), many researchers have come to focus on natural products based on traditional medicine that can be utilized to successfully treat NAFLD. In this study, we aimed to evaluate the effects exerted by seven natural products (curcumin, silymarin, resveratrol, artichoke leaf extract, berberine, catechins, and naringenin) on patients with NAFLD. For this purpose, PubMed, Embase, Cochrane Library, and Web of Science, were searched for randomized controlled trials (RCTs) exclusively. The selected studies were evaluated for methodological quality via the Cochrane bias risk assessment tool, and data analysis software was used to analyze the data accordingly. The RCTs from the earliest available date until September 2022 were collected. This process resulted in 37 RCTs with a total sample size of 2509 patients being included. The results of the network meta-analysis showed that artichoke leaf extract confers a relative advantage in reducing the aspartate aminotransferase (AST) levels (SUCRA: 99.1%), alanine aminotransferase (ALT) levels (SUCRA: 88.2%) and low-density lipoprotein cholesterol (LDL-C) levels (SUCRA: 88.9%). Naringenin conferred an advantage in reducing triglyceride (TG) levels (SUCRA: 97.3%), total cholesterol (TC) levels (SUCRA: 73.9%), and improving high-density lipoprotein cholesterol (HDL-C) levels (SUCRA: 74.9%). High-density catechins significantly reduced body mass index (BMI) levels (SUCRA: 98.5%) compared with the placebo. The Ranking Plot of the Network indicated that artichoke leaf extract and naringenin performed better than the other natural products in facilitating patient recovery. Therefore, we propose that artichoke leaf extract and naringenin may exert a better therapeutic effect on NAFLD. This study may help guide clinicians and lead to further detailed studies.

SIRT1: Harnessing multiple pathways to hinder NAFLD

Non-alcoholic fatty liver disease (NAFLD) encompasses hepatic steatosis, non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. It is the primary cause of chronic liver disorders, with a high prevalence but no approved treatment. Therefore, it is indispensable to find a trustworthy therapy for NAFLD. Recently, mounting evidence illustrates that Sirtuin 1 (SIRT1) is strongly associated with NAFLD. SIRT1 activation or overexpression attenuate NAFLD, while SIRT1 deficiency aggravates NAFLD. Besides, an array of therapeutic agents, including natural compounds, synthetic compounds, traditional Chinese medicine formula, and stem cell transplantation, alleviates NALFD via SIRT1 activation or upregulation. Mechanically, SIRT1 alleviates NAFLD by reestablishing autophagy, enhancing mitochondrial function, suppressing oxidative stress, and coordinating lipid metabolism, as well as reducing hepatocyte apoptosis and inflammation. In this review, we introduced the structure and function of SIRT1 briefly, and summarized the effect of SIRT1 on NAFLD and its mechanism, along with the application of SIRT1 agonists in treating NAFLD.

Communication between nonalcoholic fatty liver disease and atherosclerosis: Focusing on exosomes

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic hepatic disorder on a global scale. Atherosclerosis (AS), a leading cause of cardiovascular diseases, stands as the primary contributor to mortality among patients diagnosed with NAFLD. However, the precise etiology by which NAFLD causes AS remains unclear. Exosomes are nanoscale extracellular vesicles secreted by cells, and are considered to participate in complex biological processes by promoting cell-to-cell and organ-to-organ communications. As vesicles containing protein, mRNA, non-coding RNA and other bioactive molecules, exosomes can participate in the development of NAFLD and AS respectively. Recently, studies have shown that NAFLD can also promote the development of AS via secreting exosomes. Herein, we summarized the recent advantages of exosomes in the pathogenesis of NAFLD and AS, and highlighted the role of exosomes in mediating the information exchange between NAFLD and AS. Further, we discussed how exosomes play a prominent role in enabling information exchange among diverse organs, delving into a novel avenue for investigating the link between diseases and their associated complications. The future directions and emerging challenges are also listed regarding the exosome-based therapeutic strategies for AS under NAFLD conditions.

Human diet-derived polyphenolic compounds and hepatic diseases: From therapeutic mechanisms to clinical utilization

This review focuses on the potential ameliorative effects of polyphenolic compounds derived from human diet on hepatic diseases. It discusses the molecular mechanisms and recent advancements in clinical applications. Edible polyphenols have been found to play a therapeutic role, particularly in liver injury, liver fibrosis, NAFLD/NASH, and HCC. In the regulation of liver injury, polyphenols exhibit anti-inflammatory and antioxidant effects, primarily targeting the TGF-β, NF-κB/TLR4, PI3K/AKT, and Nrf2/HO-1 signaling pathways. In the regulation of liver fibrosis, polyphenolic compounds effectively reverse the fibrotic process by inhibiting the activation of hepatic stellate cells (HSC). Furthermore, polyphenolic compounds show efficacy against NAFLD/NASH by inhibiting lipid oxidation and accumulation, mediated through the AMPK, SIRT, and PPARγ pathways. Moreover, several polyphenolic compounds exhibit anti-HCC activity by suppressing tumor cell proliferation and metastasis. This inhibition primarily involves blocking Akt and Wnt signaling, as well as inhibiting the epithelial-mesenchymal transition (EMT). Additionally, clinical trials and nutritional evidence support the notion that certain polyphenols can improve liver disease and associated metabolic disorders. However, further fundamental research and clinical trials are warranted to validate the efficacy of dietary polyphenols.

The Pharmacological Properties of Red Grape Polyphenol Resveratrol: Clinical Trials and Obstacles in Drug Development

Resveratrol is a stilbenoid from red grapes that possesses a strong antioxidant activity. Resveratrol has been shown to have anticancer activity, making it a promising drug for the treatment and prevention of numerous cancers. Several in vitro and in vivo investigations have validated resveratrol's anticancer capabilities, demonstrating its ability to block all steps of carcinogenesis (such as initiation, promotion, and progression). Additionally, resveratrol has been found to have auxiliary pharmacological effects such as anti-inflammatory, cardioprotective, and neuroprotective activity. Despite its pharmacological properties, several obstacles, such as resveratrol's poor solubility and bioavailability, as well as its adverse effects, continue to be key obstacles to drug development. This review critically evaluates the clinical trials to date and aims to develop a framework to develop resveratrol into a clinically viable drug.

Targeting Oxidative Stress with Polyphenols to Fight Liver Diseases

Reactive oxygen species (ROS) are important second messengers in many metabolic processes and signaling pathways. Disruption of the balance between ROS generation and antioxidant defenses results in the overproduction of ROS and subsequent oxidative damage to biomolecules and cellular components that disturb cellular function. Oxidative stress contributes to the initiation and progression of many liver pathologies such as ischemia-reperfusion injury (LIRI), non-alcoholic fatty liver disease (NAFLD), and hepatocellular carcinoma (HCC). Therefore, controlling ROS production is an attractive therapeutic strategy in relation to their treatment. In recent years, increasing evidence has supported the therapeutic effects of polyphenols on liver injury via the regulation of ROS levels. In the current review, we summarize the effects of polyphenols, such as quercetin, resveratrol, and curcumin, on oxidative damage during conditions that induce liver injury, such as LIRI, NAFLD, and HCC.

Progress in the Preclinical and Clinical Study of Resveratrol for Vascular Metabolic Disease

Vascular metabolic dysfunction presents in various diseases, such as atherosclerosis, hypertension, and diabetes mellitus. Due to the high prevalence of these diseases, it is important to explore treatment strategies to protect vascular function. Resveratrol (RSV), a natural polyphenolic phytochemical, is regarded as an agent to regulate metabolic pathways. Many studies have proven that RSV has beneficial effects on improving metabolism in endothelial cells (ECs) and vascular smooth muscle cells (VSMCs), which provide new directions to treat vascular metabolic diseases. Herein, we overviewed that RSV could regulate cell metabolism activity by inhibiting glucose uptake, suppressing glycolysis, preventing cells from fatty acid-related damages, reducing lipogenesis, increasing fatty acid oxidation, enhancing lipolysis, elevating uptake and synthesis of glutamine, and increasing NO release. Furthermore, in clinical trials, although the results from different studies remain controversial, we proposed that RSV had better therapeutic effects at high concentrations and for patients with metabolic disorders.

Efficacy and safety of dietary polyphenol supplementation in the treatment of non-alcoholic fatty liver disease: A systematic review and meta-analysis

Background

Dietary polyphenol treatment of non-alcoholic fatty liver disease (NAFLD) is a novel direction, and the existing clinical studies have little effective evidence for its therapeutic effect, and some studies have inconsistent results. The effectiveness of dietary polyphenols in the treatment of NAFLD is still controversial. The aim of this study was to evaluate the therapeutic efficacy of oral dietary polyphenols in patients with NAFLD.

Methods

The literature (both Chinese and English) published before 30 April 2022 in PubMed, Cochrane, Medline, CNKI, and other databases on the treatment of NAFLD with dietary polyphenols was searched. Manual screening, quality assessment, and data extraction of search results were conducted strictly according to the inclusion and exclusion criteria. RevMan 5.3 software was used to perform the meta-analysis.

Results

The RCTs included in this study involved dietary supplementation with eight polyphenols (curcumin, resveratrol, naringenin, anthocyanin, hesperidin, catechin, silymarin, and genistein) and 2,173 participants. This systematic review and meta-analysis found that 1) curcumin may decrease body mass index (BMI), Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Triglycerides (TG) total cholesterol (TC), and Homeostasis Model Assessment-Insulin Resistance (HOMA-IR) compared to placebo; and curcumin does not increase the occurrence of adverse events. 2) Although the meta-analysis results of all randomized controlled trials (RCTs) did not reveal significant positive changes, individual RCTs showed meaningful results. 3) Naringenin significantly decreased the percentage of NAFLD grade, TG, TC, and low-density lipoprotein cholesterol (LDL-C) and increased high-density lipoprotein cholesterol (HDL-C) but had no significant effect on AST and ALT, and it is a safe supplementation. 4) Only one team presents a protocol about anthocyanin (from Cornus mas L. fruit extract) in the treatment of NAFLD. 5) Hesperidin may decrease BMI, AST, ALT, TG, TC, HOMA-IR, and so on. 6) Catechin may decrease BMI, HOMA-IR, and TG level, and it was well tolerated by the patients. 7) Silymarin was effective in improving ALT and AST and reducing hepatic fat accumulation and liver stiffness in NAFLD patients.

Conclusion

Based on current evidence, curcumin can reduce BMI, TG, TC, liver enzymes, and insulin resistance; catechin can reduce BMI, insulin resistance, and TG effectively; silymarin can reduce liver enzymes. For resveratrol, naringenin, anthocyanin, hesperidin, and catechin, more RCTs are needed to further evaluate their efficacy and safety.

Atherogenic Index of Plasma in Non-Alcoholic Fatty Liver Disease: Systematic Review and Meta-Analysis

(1) Background: Approximately a billion people worldwide are affected by NAFLD, which places a high clinical burden and financial cost on society. Liver biopsy is the gold standard for diagnosing NAFLD, but its invasivity limits the early diagnosis of NAFLD. Hence, it is important to look for alternate techniques in detecting and diagnosing NAFLD. NAFLD is associated with atherosclerosis. The purpose of this study was to assess the effectiveness of the atherogenic index of plasma (AIP) as a non-invasive modality for predicting NAFLD. (2) Methods: A search using electronic databases PubMed, EMBASE, and Scopus was carried out to find observational studies, looking at research that had been published up until the date of 11 May 2022. The included studies’ quality, risk of bias, and internal validity were evaluated using the QUADAS-2 quality assessment tool. The key summary outcomes were the mean difference (MD) and area under the curve (AUC). (3) Results: A total of eight studies (81,178 participants) were included in our review, while 17% of the included participants had NAFLD. A sex distribution of 57.8% men and 42.2% women was observed. The AIP between NAFLD and the controls was not significant (MD 0.212 [95% CI 0.231–0.655]). A significant MD in AIP between the males and females with NAFLD was observed (MD 0.246 [95% CI 0.098–0.395]). The AIP predicted NAFLD with an AUC of 0.764 as well as in males (AUC 0.761) and females (AUC 0.733). (4) Conclusions: There was a substantial MD in the AIP between both sexes, but there was no significant difference in the AIP values between patients with NAFLD and the controls. The AIP is a reliable biomarker for the diagnosis of NAFLD since its ability to predict the development of NAFLD was comparable to that of the other biomarkers.

Effect of resveratrol supplementation on hepatic steatosis and cardiovascular indices in overweight subjects with type 2 diabetes: a double-blind, randomized controlled trial

BACKGROUND

Patients with type 2 diabetes mellitus (T2DM) are prone to develop non-alcoholic fatty liver disease (NAFLD) and cardiovascular diseases (CVD). We aimed to investigate whether the resveratrol supplementation improves novel hepatic and cardiovascular indices in these patients.

METHODS

We conducted a double-blind, randomized controlled trial for 8 weeks. Seventy-six patients with T2DM were randomly assigned to receive 1000 mg/day resveratrol or placebo. Levels of lipid accumulation product (LAP), visceral adiposity index (VAI), Castelli risk index I (CRI-I), CRI-II and atherogenic coefficient (AC) were measured at the beginning and after intervention.

RESULTS

A total of 71 participants completed the trial. After adjusting for confounding factors including medications, diabetes duration, energy intake and physical activity, no significant difference was found between the intervention group and the control group in LAP (mean change: - 2.46 ± 23.3 vs. 1.43 ± 14.3; P = 0.43), VAI (mean change: - 0.25 ± 1.1 vs. - 0.02 ± 0.6; P = 0.47), CRI-I (mean change: - 0.25 ± 0.9 vs. - 0.09 ± 0.5; P = 0.79), CRI-II (mean change: - 0.23 ± 0.7 vs. - 0.06 ± 0.6; P = 0.38) and AC (mean change: - 0.25 ± 0.9 vs. - 0.09 ± 0.5; P = 0.79).

CONCLUSIONS

Resveratrol supplementation had no effect on hepatic steatosis and cardiovascular indices. Further clinical trials, especially among subjects with dyslipidemia are needed to reach a firm conclusion. In addition, taking all medications should be controlled in future studies. Trial registration The protocol was registered on 29/12/2017 at the Iranian clinical trials website (IRCT20171118037528N1) with URL: https://en.irct.ir/trial/27734 .

Design of Hepatic Targeted Drug Delivery Systems for Natural Products: Insights into Nomenclature Revision of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD), recently renamed metabolic-dysfunction-associated fatty liver disease (MAFLD), affects a quarter of the worldwide population. Natural products have been extensively utilized in treating NAFLD because of their distinctive advantages over chemotherapeutic drugs, despite the fact that there are no approved drugs for therapy. Notably, the limitations of many natural products, such as poor water solubility, low bioavailability in vivo, low hepatic distribution, and lack of targeted effects, have severely restricted their clinical application. These issues could be resolved via hepatic targeted drug delivery systems (HTDDS) that boost clinical efficacy in treating NAFLD and decrease the adverse effects on other organs. Herein an overview of natural products comprising formulas, single medicinal plants, and their crude extracts has been presented to treat NAFLD. Also, the clinical efficacy and molecular mechanism of active monomer compounds against NAFLD are systematically discussed. The targeted delivery of natural products via HTDDS has been explored to provide a different nanotechnology-based NAFLD treatment strategy and to make suggestions for natural-product-based targeted nanocarrier design. Finally, the challenges and opportunities put forth by the nomenclature update of NAFLD are outlined along with insights into how to improve the NAFLD therapy and how to design more rigorous nanocarriers for the HTDDS. In brief, we summarize the up-to-date developments of the NAFLD-HTDDS based on natural products and provide viewpoints for the establishment of more stringent anti-NAFLD natural-product-targeted nanoformulations.

Effects of resveratrol supplementation on bone quality: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

The results from clinical trials have revealed that the effects of resveratrol supplementation on bone mineral density (BMD) and bone biomarkers are inconsistent. Our objective was to determine the effects of resveratrol supplementation on BMD and serum bone biomarkers.

METHODS

PubMed, Cochrane library, EMBASE, Web of science and Scopus were searched up to August 24, 2020. Two reviewers independently performed the articles search and screen according to defined selection criteria. The study quality of the randomized controlled trials (RCTs) was evaluated with the Cochrane scoring system. Heterogeneity among studies was examined by Cochrane Q test. Retrieved data were pooled after mean differences (MD) were computed between two groups for BMD and serum biomarkers. Subgroup analyses were performed to evaluate a potential difference in terms of dose of resveratrol and intervention duration. Sensitivity analysis was executed by omitting studies with imputed values in order to evaluate the influence of these studies on the overall results.

RESULTS

Ten eligible studies involving 698 subjects were included in this meta-analysis with 401 participants receiving resveratrol and 297 receiving placebo. Supplementation of resveratrol had no statistically significant effects on areal bone mineral density (aBMD) at lumbar spine (MD: -0.02, 95% CI: - 0.05, 0.01, p = 0.26, I² = 6%), total hip BMD (MD: -0.01, 95% CI: - 0.04, 0.02, p = 0.65, I² = 0%), and whole body BMD (MD: 0.00, 95% CI: - 0.02, 0.02, p = 0.74, I² = 0%). Supplementation of resveratrol also did not result in significant change in bone serum markers, including serum alkaline phosphatase (ALP), bone alkaline phosphatase (BAP), osteocalcin (OCN), procollagen I N-terminal propeptide (PINP), C-terminal telopeptide of type I collagen (CTX) and parathyroid hormone (PTH). Subgroup analysis showed the effect of resveratrol supplementation on BMD and serum bone markers were similar in trails of different doses, intervention duration, and pathological conditions of the participants.

CONCLUSION

Resveratrol supplementation did not show any significant effect on BMD or serum bone markers with the current evidence. Further investigation with more well-organized multicentre randomized trial is warranted.

Nutritional supplementation for nonalcohol-related fatty liver disease: a network meta-analysis

BACKGROUND

The prevalence of non-alcohol-related fatty liver disease (NAFLD) varies between 19% and 33% in different populations. NAFLD decreases life expectancy and increases risks of liver cirrhosis, hepatocellular carcinoma, and the requirement for liver transplantation. Uncertainty surrounds relative benefits and harms of various nutritional supplements in NAFLD. Currently no nutritional supplement is recommended for people with NAFLD.

OBJECTIVES

• To assess the benefits and harms of different nutritional supplements for treatment of NAFLD through a network meta-analysis • To generate rankings of different nutritional supplements according to their safety and efficacy SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, Science Citation Index Expanded, Conference Proceedings Citation Index-Science, the World Health Organization International Clinical Trials Registry Platform, and trials registers until February 2021 to identify randomised clinical trials in people with NAFLD.

SELECTION CRITERIA

We included only randomised clinical trials (irrespective of language, blinding, or status) for people with NAFLD, irrespective of method of diagnosis, age and diabetic status of participants, or presence of non-alcoholic steatohepatitis (NASH). We excluded randomised clinical trials in which participants had previously undergone liver transplantation.

DATA COLLECTION AND ANALYSIS

We performed a network meta-analysis with OpenBUGS using Bayesian methods whenever possible and calculated differences in treatments using hazard ratios (HRs), odds ratios (ORs), and rate ratios with 95% credible intervals (CrIs) based on an available-case analysis, according to National Institute of Health and Care Excellence Decision Support Unit guidance.

MAIN RESULTS

We included in the review a total of 202 randomised clinical trials (14,200 participants). Nineteen trials were at low risk of bias. A total of 32 different interventions were compared in these trials. A total of 115 trials (7732 participants) were included in one or more comparisons. The remaining trials did not report any of the outcomes of interest for this review. Follow-up ranged from 1 month to 28 months. The follow-up period in trials that reported clinical outcomes was 2 months to 28 months. During this follow-up period, clinical events related to NAFLD such as mortality, liver cirrhosis, liver decompensation, liver transplantation, hepatocellular carcinoma, and liver-related mortality were sparse. We did not calculate effect estimates for mortality because of sparse data (zero events for at least one of the groups in the trial). None of the trials reported that they measured overall health-related quality of life using a validated scale. The evidence is very uncertain about effects of interventions on serious adverse events (number of people or number of events). We are very uncertain about effects on adverse events of most of the supplements that we investigated, as the evidence is of very low certainty. However, people taking PUFA (polyunsaturated fatty acid) may be more likely to experience an adverse event than those not receiving an active intervention (network meta-analysis results: OR 4.44, 95% CrI 2.40 to 8.48; low-certainty evidence; 4 trials, 203 participants; direct evidence: OR 4.43, 95% CrI 2.43 to 8.42). People who take other supplements (a category that includes nutritional supplements other than vitamins, fatty acids, phospholipids, and antioxidants) had higher numbers of adverse events than those not receiving an active intervention (network meta-analysis: rate ratio 1.73, 95% CrI 1.26 to 2.41; 6 trials, 291 participants; direct evidence: rate ratio 1.72, 95% CrI 1.25 to 2.40; low-certainty evidence). Data were sparse (zero events in all groups in the trial) for liver transplantation, liver decompensation, and hepatocellular carcinoma. So, we did not perform formal analysis for these outcomes. The evidence is very uncertain about effects of other antioxidants (antioxidants other than vitamins) compared to no active intervention on liver cirrhosis (HR 1.68, 95% CrI 0.23 to 15.10; 1 trial, 99 participants; very low-certainty evidence). The evidence is very uncertain about effects of interventions in any of the remaining comparisons, or data were sparse (with zero events in at least one of the groups), precluding formal calculations of effect estimates. Data were probably because of the very short follow-up period (2 months to 28 months). It takes follow-up of 8 to 28 years to detect differences in mortality between people with NAFLD and the general population. Therefore, it is unlikely that differences in clinical outcomes are noted in trials providing less than 5 to 10 years of follow-up.

AUTHORS' CONCLUSIONS

The evidence indicates considerable uncertainty about effects of nutritional supplementation compared to no additional intervention on all clinical outcomes for people with non-alcohol-related fatty liver disease. Accordingly, high-quality randomised comparative clinical trials with adequate follow-up are needed. We propose registry-based randomised clinical trials or cohort multiple randomised clinical trials (study design in which multiple interventions are trialed within large longitudinal cohorts of patients to gain efficiencies and align trials more closely to standard clinical practice) comparing interventions such as vitamin E, prebiotics/probiotics/synbiotics, PUFAs, and no nutritional supplementation. The reason for the choice of interventions is the impact of these interventions on indirect outcomes, which may translate to clinical benefit. Outcomes in such trials should be mortality, health-related quality of life, decompensated liver cirrhosis, liver transplantation, and resource utilisation measures including costs of intervention and decreased healthcare utilisation after minimum follow-up of 8 years (to find meaningful differences in clinically important outcomes).

Natural Polyphenols in Metabolic Syndrome: Protective Mechanisms and Clinical Applications

Metabolic syndrome (MetS) is a chronic disease, including abdominal obesity, dyslipidemia, hyperglycemia, and hypertension. It should be noted that the occurrence of MetS is closely related to oxidative stress-induced mitochondrial dysfunction, ectopic fat accumulation, and the impairment of the antioxidant system, which in turn further aggravates the intracellular oxidative imbalance and inflammatory response. As enriched anti-inflammatory and antioxidant components in plants, natural polyphenols exhibit beneficial effects, including improving liver fat accumulation and dyslipidemia, reducing blood pressure. Hence, they are expected to be useful in the prevention and management of MetS. At present, epidemiological studies indicate a negative correlation between polyphenol intake and MetS incidence. In this review, we summarized and discussed the most promising natural polyphenols (including flavonoid and non-flavonoid drugs) in the precaution and treatment of MetS, including their anti-inflammatory and antioxidant properties, as well as their regulatory functions involved in glycolipid homeostasis.

Regulation of Apolipoprotein B by Natural Products and Nutraceuticals: A Comprehensive Review

Cardiovascular Disease (CVD) is the most important and the number one cause of mortality in both developing and industrialized nations. The co-morbidities associated with CVD are observed from infancy to old age. Apolipoprotein B100 (Apo B) is the primary apolipoprotein and structural protein of all major atherogenic particles derived from the liver including Very-Low- Density Lipoproteins (VLDL), Intermediate-density Lipoprotein (IDL), and Low-density Lipoprotein (LDL) particles. It has been suggested that measurement of the Apo B concentration is a superior and more reliable index for the prediction of CVD risk than is the measurement of LDL-C. Nutraceuticals and medicinal plants have attracted significant attention as it pertains to the treatment of non-communicable diseases, particularly CVD, diabetes mellitus, hypertension, and Nonalcoholic Fatty Liver Disease (NAFLD). The effect of nutraceuticals and herbal products on CVD, as well as some of its risk factors such as dyslipidemia, have been investigated previously. However, to the best of our knowledge, the effect of these natural products, including herbal supplements and functional foods (e.g. fruits and vegetables as either dry materials, or their extracts) on Apo B has not yet been investigated. Therefore, the primary objective of this paper was to review the effect of bioactive natural compounds on plasma Apo B concentrations. It is concluded that, in general, medicinal plants and nutraceuticals can be used as complementary medicine to reduce plasma Apo B levels in a safe, accessible, and inexpensive manner in an attempt to prevent and treat CVD.

Autophagy in Hepatic Steatosis: A Structured Review

Steatosis is the accumulation of neutral lipids in the cytoplasm. In the liver, it is associated with overeating and a sedentary lifestyle, but may also be a result of xenobiotic toxicity and genetics. Non-alcoholic fatty liver disease (NAFLD) defines an array of liver conditions varying from simple steatosis to inflammation and fibrosis. Over the last years, autophagic processes have been shown to be directly associated with the development and progression of these conditions. However, the precise role of autophagy in steatosis development is still unclear. Specifically, autophagy is necessary for the regulation of basic metabolism in hepatocytes, such as glycogenolysis and gluconeogenesis, response to insulin and glucagon signaling, and cellular responses to free amino acid contents. Also, genetic knockout models for autophagy-related proteins suggest a critical relationship between autophagy and hepatic lipid metabolism, but some results are still ambiguous. While autophagy may seem necessary to support lipid oxidation in some contexts, other evidence suggests that autophagic activity can lead to lipid accumulation instead. This structured literature review aims to critically discuss, compare, and organize results over the last 10 years regarding rodent steatosis models that measured several autophagy markers, with genetic and pharmacological interventions that may help elucidate the molecular mechanisms involved.

The efficacy of novel metabolic targeted agents and natural plant drugs for nonalcoholic fatty liver disease treatment: A PRISMA-compliant network meta-analysis of randomized controlled trials

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a highly prevalent chronic liver disease characterized by excess accumulation of fat in hepatocytes. Because no drug has been approved for NAFLD treatment, this work analyzed the effects of agents resulting from 2 research hotspots, metabolic target agents, and natural plant drugs, on NAFLD with network meta-analysis.

METHODS

Public databases were searched through August 14, 2020. Randomized controlled trials that compared obeticholic acid, elafibranor, cenicriviroc, selonsertib, curcumin, silymarin, and resveratrol to placebo were included. Liver pathology improvement, hepatic biochemical indicators, and lipid metabolism indicators were analyzed.

RESULTS

Thirty-five studies were included in the meta-analysis. Obeticholic acid was found to significantly increase the frequency of liver biopsy improvement compared to placebo (OR: 2.10; 95% CI: 1.60, 2.77). The ranking results among the hepatic biochemical indicators showed that obeticholic acid (94.9%) and elafibranor (86.3%) have a relative advantage in reducing alanine aminotransferase (ALT) levels, and obeticholic acid also had an advantage (95.4%) in reducing aspartate aminotransferase (AST) levels. Considering lipid metabolic indicators, elafibranor (expSMD: 0.01; 95% CI: 0.00, 0.05; SUCRA: 100%), and obeticholic acid (expSMD: 0.48; 95% CI: 0.28,0.84; SUCRA: 75.6%) significantly reduced triglyceride (TG) levels compared with placebo; moreover, obeticholic acid, but not elafibranor, caused a serious increase in total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels and a decrease in high-density lipoprotein cholesterol (HDL-C) levels.

CONCLUSIONS

Novel metabolic targeted agents generally have better effects than natural plant drugs, especially obeticholic acid, and elafibranor. However, obeticholic acid showed serious adverse effects such as increasing LDL-C levels and decreasing HDL-C levels. Curcumin showed potential advantages for NAFLD but lacked statistical significance.

Dietary Polyphenols and Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD), which is emerging as a major public health issue worldwide, is characterized by a wide spectrum of liver disorders, ranging from simple fat accumulation in hepatocytes, also known as steatosis, to non-alcoholic steatohepatitis (NASH) and cirrhosis. At present, the pharmacological treatment of NAFLD is still debated and dietary strategies for the prevention and the treatment of this condition are strongly considered. Polyphenols are a group of plant-derived compounds whose anti-inflammatory and antioxidant properties are associated with a low prevalence of metabolic diseases, including obesity, hypertension, and insulin resistance. Since inflammation and oxidative stress are the main risk factors involved in the pathogenesis of NAFLD, recent studies suggest that the consumption of polyphenol-rich diets is involved in the prevention and treatment of NAFLD. However, few clinical trials are available on human subjects with NAFLD. Here, we reviewed the emerging existing evidence on the potential use of polyphenols to treat NAFLD. After introducing the physiopathology of NAFLD, we focused on the most investigated phenolic compounds in the setting of NAFLD and described their potential benefits, starting from basic science studies to animal models and human trials.

Astragaloside IV Alleviates Liver Inflammation, Oxidative Stress and Apoptosis to Protect Against Experimental Non-Alcoholic Fatty Liver Disease

PURPOSE

Non-alcoholic fatty liver disease (NAFLD) is the main form of chronic liver disease in the world. Astragaloside IV (ASIV) has been tested in experimental models of different diseases. The purpose of this study was to evaluate the effect and protective mechanism of ASIV on NAFLD.

METHODS

Lipopolysaccharide (LPS)- and palmitate acid (PA)-induced RAW264.7 cells and LO2 cells were used as a NAFLD model. The mice NAFLD model was evaluated by hematoxylin-eosin staining (HE staining), and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. Liver lipid metabolism was evaluated by triglyceride (TG) and total cholesterol (TC) kits and oil red O staining. Oxidative stress indicators were examined through biochemical methods. Inflammatory factors were explored through enzyme-linked immuno sorbent assay (ELISA), real-time quantitative PCR and oxidative stress indicator kits. The expression levels of 5-LO (5-lipoxygenase) and leukotriene A4 hydrolase (LTA4H) were checked by real-time quantitative PCR and Western blotting. Apoptosis was detected by Annexin V-FITC/PI cell apoptosis detection kit.

RESULTS

Our results showed that in vivo ASIV significantly reduced liver tissue damage, and serum AST, ALT and serum TG levels in NAFLD mice. In vitro, ASIV reduced cell supernatant TG and TC content increased by PA treatment, and significantly decreased the accumulation of intracellular lipid droplets induced by PA treatment. Additionally, ASIV reduced reactive oxygen species (ROS) and malondialdehyde (MDA) levels, and restored glutathione peroxidase (GSH-Px) levels in PA-treated LO2 cell supernatant. Furthermore, ASIV inhibited the production of proinflammatory cytokines (IL-6 and TNF-α) in RAW264.7 cells induced by LPS. We also found that ASIV downregulated the expression of 5-LO and LTB4 (leukotriene B4) in NAFLD mice. Moreover, ASIV restored apoptotic protein (Bax and Bcl-2) expression in PA-treated LO2 cells.

CONCLUSION

ASIV may reduce liver steatosis, hepatocyte oxidative stress and apoptosis, and decrease liver inflammation, thereby attenuating the progression of NAFLD and thus might be of therapeutic interest.

Natural Product Heme Oxygenase Inducers as Treatment for Nonalcoholic Fatty Liver Disease

Heme oxygenase (HO) is a critical component of the defense mechanism to a wide variety of cellular stressors. HO induction affords cellular protection through the breakdown of toxic heme into metabolites, helping preserve cellular integrity. Nonalcoholic fatty liver disease (NAFLD) is a pathological condition by which the liver accumulates fat. The incidence of NAFLD has reached all-time high levels driven primarily by the obesity epidemic. NALFD can progress to nonalcoholic steatohepatitis (NASH), advancing further to liver cirrhosis or cancer. NAFLD is also a contributing factor to cardiovascular and metabolic diseases. There are currently no drugs to specifically treat NAFLD, with most treatments focused on lifestyle modifications. One emerging area for NAFLD treatment is the use of dietary supplements such as curcumin, pomegranate seed oil, milk thistle oil, cold-pressed Nigella Satvia oil, and resveratrol, among others. Recent studies have demonstrated that several of these natural dietary supplements attenuate hepatic lipid accumulation and fibrosis in NAFLD animal models. The beneficial actions of several of these compounds are associated with the induction of heme oxygenase-1 (HO-1). Thus, targeting HO-1 through dietary-supplements may be a useful therapeutic for NAFLD either alone or with lifestyle modifications.