Swertiamarin ameliorates oleic acid induced lipid accumulation and oxidative stress by attenuating gluconeogenesis and lipogenesis in hepatic steatosis. Biomed Pharmacother. 2016;83:785-791. [PMID: 27490779 DOI: 10.1016/j.biopha.2016.07.028]

Benzoate glycosides from Gentiana scabra Bge. and their lipid-lowering activity

Seven undescribed benzoate glycosides (1-7) and five known ones (8-12) were isolated from the rhizomes of Gentiana scabra Bge. Their structures were characterized by comprehensive NMR and MS spectroscopic data analysis. The lipid-lowering effects of these compounds were evaluated by measuring the triglyceride (TG) contents and intracellular lipid droplets (LDs) in oleic acid (OA)-treated HepG2 cells. The results showed that compounds 1, 5, 7, and 11 significantly reduced the TG content at 20 μM, and the Bodipy staining displayed that OA enhanced the levels of LDs in the cell, while these compounds reversed the lipid accumulation caused by OA. These findings provide a basis for further development and utilization of G. scabra as a natural source of potential lipid-lowering agents.

Bioprotective Role of Phytocompounds Against the Pathogenesis of Non-alcoholic Fatty Liver Disease to Non-alcoholic Steatohepatitis: Unravelling Underlying Molecular Mechanisms

Non-alcoholic fatty liver disease (NAFLD), with a global prevalence of 25%, continues to escalate, creating noteworthy concerns towards the global health burden. NAFLD causes triglycerides and free fatty acids to build up in the liver. The excessive fat build-up causes inflammation and damages the healthy hepatocytes, leading to non-alcoholic steatohepatitis (NASH). Dietary habits, obesity, insulin resistance, type 2 diabetes, and dyslipidemia influence NAFLD progression. The disease burden is complicated due to the paucity of therapeutic interventions. Obeticholic acid is the only approved therapeutic agent for NAFLD. With more scientific enterprise being directed towards the understanding of the underlying mechanisms of NAFLD, novel targets like lipid synthase, farnesoid X receptor signalling, peroxisome proliferator-activated receptors associated with inflammatory signalling, and hepatocellular injury have played a crucial role in the progression of NAFLD to NASH. Phytocompounds have shown promising results in modulating hepatic lipid metabolism and de novo lipogenesis, suggesting their possible role in managing NAFLD. This review discusses the ameliorative role of different classes of phytochemicals with molecular mechanisms in different cell lines and established animal models. These compounds may lead to the development of novel therapeutic strategies for NAFLD progression to NASH. This review also deliberates on phytomolecules undergoing clinical trials for effective management of NAFLD.

Computational discovery of AKT serine/threonine kinase 1 inhibitors through shape screening for rheumatoid arthritis intervention

Rheumatoid Arthritis (RA) is a chronic, symmetrical inflammatory autoimmune disorder characterized by painful, swollen synovitis and joint erosions, which can cause damage to bone and cartilage and be associated with progressive disability. Despite expanded treatment options, some patients still experience inadequate response or intolerable adverse effects. Consequently, the treatment options for RA remain quite limited. The enzyme AKT1 is crucial in designing drugs for various human diseases, supporting cellular functions like proliferation, survival, metabolism, and angiogenesis in both normal and malignant cells. Therefore, AKT serine/threonine kinase 1 is considered crucial for targeting therapeutic strategies aimed at mitigating RA mechanisms. In this context, directing efforts toward AKT1 represents an innovative approach to developing new anti-arthritis medications. The primary objective of this research is to prioritize AKT1 inhibitors using computational techniques such as molecular modeling and dynamics simulation (MDS) and shape-based virtual screening (SBVS). A combined SBVS approach was employed to predict potent inhibitors against AKT1 by screening a pool of compounds sourced from the ChemDiv and IMPPAT databases. From the SBVS results, only the top three compounds, ChemDiv_7266, ChemDiv_2796, and ChemDiv_9468, were subjected to stability analysis based on their high binding affinity and favorable ADME/Tox properties. The SBVS findings have revealed that critical residues, including Glu17, Gly37, Glu85, and Arg273, significantly contribute to the successful binding of the highest-ranked lead compounds at the active site of AKT1. This insight helps to understand the specific binding mechanism of these leads in inhibiting RA, facilitating the rational design of more effective therapeutic agents.

A novel Alisma orientale extract alleviates non-alcoholic steatohepatitis in mice via modulation of PPARα signaling pathway

Non-alcoholic fatty liver disease (NAFLD), particularly advanced non-alcoholic steatohepatitis (NASH), leads to irreversible liver damage. This study investigated the therapeutic effects and potential mechanism of a novel extract from traditional Chinese medicine Alisma orientale (Sam.) Juzep (AE) on free fatty acid (FFA)-induced HepG2 cell model and high-fat diet (HFD) + carbon tetrachloride (CCl4)-induced mouse model of NASH. C57BL/6 J mice were fed a HFD for 10 weeks. Subsequently, the mice were injected with CCl4 to induce NASH and simultaneously treated with AE at daily doses of 50, 100, and 200 mg/kg for 4 weeks. At the end of the treatment, animals were fasted for 12 h and then sacrificed. Blood samples and liver tissues were collected for analysis. Lipid profiles, oxidative stress, and histopathology were examined. Additionally, a polymerase chain reaction (PCR) array was used to predict the molecular targets and potential mechanisms involved, which were further validated in vivo and in vitro. The results demonstrated that AE reversed liver damage (plasma levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), hepatocyte ballooning, hepatic steatosis, and NAS score), the accumulation of hepatic lipids (TG and TC), and oxidative stress (MDA and GSH). PCR array analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that AE protects against NASH by regulating the adipocytokine signaling pathway and influencing nuclear receptors such as PPARα. Furthermore, AE increased the expression of peroxisome proliferator-activated receptor gamma coactivator-1α (PPARGC1α) and reversed the decreased expression of PPARα in NASH mice. Moreover, in HepG2 cells, AE reduced FFA-induced lipid accumulation and oxidative stress, which was dependent on PPARα up-regulation. Overall, our findings suggest that AE may serve as a potential therapeutic approach for NASH by inhibiting lipid accumulation and reducing oxidative stress specifically through the PPARα pathway.

Digeda-4 decoction and its disassembled prescriptions improve dyslipidemia and apoptosis by regulating AMPK/SIRT1 pathway on tyloxapol-induced nonalcoholic fatty liver disease in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Nonalcoholic fatty liver disease (NAFLD) is a manifestation of metabolic syndrome in the liver and the leading cause of chronic liver disease worldwide. Digeda-4 decoction (DGD-4) is a commonly prescribed Mongolian herbal drug for treating acute and chronic liver injury and fatty liver. However, the mechanisms underlying the improvement of dislipidemia and liver injury via treatment with DGD-4 remain unclear. Disassembling a prescription is an effective approach to studying the effects and mechanisms underlying Mongolian medicine prescriptions. By disassembling a prescription, it is feasible to discover effective combinations of individual herbs to optimize a given prescription. Accordingly, we disassembled DGD-4 into two groups: the single Lomatogonium rotatum (L.) Fries ex Nym (LR) (DGD-1) and non-LR (DGD-3).

AIM OF THIS STUDY

To study whether DGD-4 and its disassembled prescriptions have protective effects against tyloxapol (TY)-induced NAFLD and to explore the underlying mechanisms of action and compatibility of prescriptions.

MATERIAL AND METHODS

NAFLD mice were developed by TY induction. Biochemical horizontal analyses, enzyme-linked immunosorbent assay, and liver histological staining were performed to explore the protective effects of DGD-4 and its disassembled prescriptions DGD-3 and DGD-1. Furthermore, we performed immunohistochemical analyses and Western blotting to further explore the expression of target proteins.

RESULTS

DGD-4 and its disassembled prescriptions could inhibit TY-induced dislipidemia and liver injury. In addition, DGD-4 and its disassembled prescriptions increased the levels of p-AMPKα and p-ACC, but decreased the levels of SREBP1c, SCD-1, SREBP-2, and HMGCS1 proteins. The activation of lipid metabolic pathways SIRT1, PGC-1α, and PPARα improved lipid accumulation in the liver. Moreover, DGD-4 could inhibit hepatocyte apoptosis and treat TY-induced liver injury by upregulating the Bcl-2 expression, downregulating the expression of Bax, caspase-3, caspase-8, and the ratio of Bax/Bcl-2, and positively regulating the imbalance of oxidative stress (OxS) markers (such as superoxide dismutase [SOD], catalase [CAT], malondialdehyde [MDA], and myeloperoxidase [MPO]). DGD-1 was superior to DGD-3 in regulating lipid synthesis-related proteins such as SREBP1c, SCD-1, SREBP-2, and HMGCS1. DGD-3 significantly affected the expression of lipid metabolic proteins SIRT1, PGC-1α, PPARα, apoptotic proteins Bcl-2, Bax, caspase-3, caspase-8, and the regulation of Bax/Bcl-2 ratio. However, DGD-1 showed no regulatory effects on Bax and Bcl-2 proteins.

CONCLUSION

This study demonstrates the protective effects of DGD-4 in the TY-induced NAFLD mice through a mechanism involving improvement of dyslipidemia and apoptosis by regulating the AMPK/SIRT1 pathway. Although the Monarch drug DGD-1 reduces lipid accumulation and DGD-3 inhibits apoptosis and protects the liver from injury, DGD-4 can be more effective overall as a therapy when compared to DGD-1 and DGD-3.

Enzymatic hydrolysates of κ-carrageenan by κ-carrageenase-CLEA immobilized on amine-modified ZIF-8 confer hypolipidemic activity in HepG2 cells

κ-Carrageenase can degrade κ-carrageenan to produce bioactive κ-carrageenan oligosaccharides (KCOs) that have potential applications in pharmaceutical, food, agricultural, and cosmetics industries. Immobilized enzymes gain their popularity due to their good reusability, enhanced stability, and tunability. In this study, the previously characterized catalytic domain of Pseudoalteromonas purpurea κ-carrageenase was covalently immobilized on the synthesized amine-modified zeolitic imidazolate framework-8 nanoparticles with the formation of cross-linked enzyme aggregates, and the immobilized κ-carrageenase was further characterized. The immobilized κ-carrageenase demonstrated excellent pH stability and good reusability, and exhibited higher optimal reaction temperature, better thermostability, and extended storage stability compared with the free enzyme. The KCOs produced by the immobilized κ-carrageenase could significantly decrease the TC, TG, and LDL-C levels in HepG2 cells, increase the HDL-C level in HepG2 cells, and reduce the free fatty acids level in Caco-2 cells. Biochemical assays showed that the KCOs could activate AMPK activity, increase the ratios of p-AMPK/AMPK and p-ACC/ACC, and downregulate the expression of the lipid metabolism related proteins including SREBP1 and HMGCR in the hyperlipidemic HepG2 cells. This study provides a novel and effective method for immobilization of κ-carrageenase, and the KCOs produced by the immobilized enzyme could be a potential therapeutic agent to prevent hyperlipidemia.

Use of Monoterpenes as Potential Therapeutics in Diabetes Mellitus: A Prospective Review

Monoterpenes are secondary metabolites of plants belonging to the terpenoid class of natural products. They are the most abundant components of essential oils that are generally considered to have various pharmacological properties. These compounds are reported to have antidiabetic effects in recent years. Due to nature's complex biosynthetic machinery, they also exhibit a reasonable degree of structural complexity/diversity for further analysis in structure-activity studies. Therefore, monoterpenes as antidiabetic agents have been investigated by recent in vitro and in vivo studies extensively reported in the scientific literature and claimed by patent documents. The purpose of this survey is to provide a comprehensive and prospective review concerning the potential applications of monoterpenes in the treatment of diabetes. The data for this research were collected through the specialized databases PubMed, Scopus, Web of Science, and ScienceDirect between the years 2014 and 2022, as well as the patent databases EPO, WIPO, and USPTO. The research used 76 articles published in the leading journals in the field. The main effect observed was the antidiabetic activity of monoterpenes. This review showed that monoterpenes can be considered promising agents for prevention and/or treatment of diabetes as well as have a marked pharmaceutical potential for the development of bioproducts for therapeutics applications.

Swertia bimaculata moderated liver damage in mice by regulating intestine microbiota

Swertia bimaculata (SB) is a medicinal herb in China having an array of therapeutic and biological properties. This study aimed to explore the attenuating effect of SB on carbon tetrachloride (CCl4) induced hepato-toxicity by regulation of gut microbiome in ICR mice. For this purpose, CCl4 was injected intraperitoneally in different mice groups (B, C, D and E) every 4th day for a period of 47 days. Additionally, C, D, and E groups received a daily dose (50 mg/kg, 100 mg/kg, and 200 mg/kg respectively) of Ether extract of SB via gavage for the whole study period. The results of serum biochemistry analysis, ELISA, H&E staining, and sequencing of the gut microbiome, indicated that SB significantly alleviates the CCl4-induced liver damage and hepatocyte degeneration. The serum levels of alanine transaminase, aspartate aminotransferase, malondialdehyde, interleukin 1 beta and tumor necrosis factor-alpha were significantly lower in SB treated groups compared to control while levels of glutathione peroxidase were raised. Also, the sequencing data indicate that supplementation with SB could restore the microbiome and its function in CCl4-induced variations in intestinal microbiome of mice by significantly downregulating the abundances of pathogenic intestinal bacteria species including Bacteroides, Enterococcus, Eubacterium, Bifidobacterium while upregulating the levels of beneficial bacteria like Christensenella in the gut. In conclusion, we revealed that SB depicts a beneficial effect against hepatotoxicity induced by CCl4 in mice through the remission of hepatic inflammation and injury, through regulation of oxidative stress, and by restoring gut microbiota dysbiosis.

Swertiamarin or heat-transformed products alleviated APAP-induced hepatotoxicity via modulation of apoptotic and Nrf-2/NF-κB pathways

OBJECTIVE

Swertiamarin (STM) belongs to iridoid class of compounds, and the heat-transformed products (HTPS) are produced by STM in the process of drug processing. The purpose of this study was to explore the protective effect and mechanism of STM or HTPS on acetaminophen (APAP)-induced hepatotoxicity.

METHODS

Mice and L-O2 cells were given APAP to establish the hepatotoxicity model in vivo and in vitro. The effects of STM or HTPS on oxidative stress, inflammation, and apoptosis induced by APAP were evaluated, with N-acetylcysteine (NAC) as a positive control.

RESULTS

STM or HTPS reduced the APAP-induced apoptosis of L-O2 cells and significantly alleviated the liver injury index induced by APAP (p < 0.01, 0.005) Interestingly, HTPS had better protective effect against APAP-induced hepatotoxicity than STM (p < 0.05). In addition STM or HTPS improved the histological abnormalities; inhibited lipid peroxidation and reduced the level of inflammatory mediators. They also activated the defense system of nuclear factor erythroid 2 related factor 2 (Nrf-2) and inhibited nuclear factor-κ B (NF-κB).

Mroue K, Mall R, Ullah E, S. Al-Akl N, Arredouani A. Investigation of the Effect of Exendin-4 on Oleic Acid-Induced Steatosis in HepG2 Cells Using Fourier Transform Infrared Spectroscopy

Non-alcoholic fatty liver disease (NAFLD) is a common liver lesion that is untreatable with medications. Glucagon-like peptide-1 receptor (GLP-1R) agonists have recently emerged as a potential NAFLD pharmacotherapy. However, the molecular mechanisms underlying these drugs’ beneficial effects are not fully understood. Using Fourier transform infrared (FTIR) spectroscopy, we sought to investigate the biochemical changes in a steatosis cell model treated or not with the GLP-1R agonist Exendin-4 (Ex-4). HepG2 cells were made steatotic with 400 µM of oleic acid and then treated with 200 nM Ex-4 in order to reduce lipid accumulation. We quantified steatosis using the Oil Red O staining method. We investigated the biochemical alterations induced by steatosis and Ex-4 treatment using Fourier transform infrared (FTIR) spectroscopy and chemometric analyses. Analysis of the Oil Red O staining showed that Ex-4 significantly reduces steatosis. This reduction was confirmed by FTIR analysis, as the phospholipid band (C=O) at 1740 cm⁻¹ in Ex-4 treated cells is significantly decreased compared to steatotic cells. The principal component analysis score plots for both the lipid and protein regions showed that the untreated and Ex-4-treated samples, while still separated, are clustered close to each other, far from the steatotic cells. The biochemical and structural changes induced by OA-induced lipotoxicity are at least partially reversed upon Ex-4 treatment. FTIR and chemometric analyses revealed that Ex-4 significantly reduces OA-induced lipid accumulation, and Ex-4 also restored the lipid and protein biochemical alterations caused by lipotoxicity-induced oxidative stress. In combination with chemometric analyses, FTIR spectroscopy may offer new approaches for investigating the mechanisms underpinning NAFLD.

Serum neuregulin 4 is negatively correlated with insulin sensitivity in humans and impairs mitochondrial respiration in HepG2 cells

Neuregulin 4 (NRG4) has been described to improve metabolic disturbances linked to obesity status in rodent models. The findings in humans are controversial. We aimed to investigate circulating NRG4 in association with insulin action in humans and the possible mechanisms involved. Insulin sensitivity (euglycemic hyperinsulinemic clamp) and serum NRG4 concentration (ELISA) were analysed in subjects with a wide range of adiposity (n = 89). In vitro experiments with human HepG2 cell line were also performed. Serum NRG4 was negatively correlated with insulin sensitivity (r = −0.25, p = 0.02) and positively with the inflammatory marker high-sensitivity C reative protein (hsCRP). In fact, multivariant linear regression analyses showed that insulin sensitivity contributed to BMI-, age-, sex-, and hsCRP-adjusted 7.2% of the variance in serum NRG4 (p = 0.01). No significant associations were found with adiposity measures (BMI, waist circumference or fat mass), plasma lipids (HDL-, LDL-cholesterol, or fasting triglycerides) or markers of liver injury. Cultured hepatocyte HepG2 treated with human recombinant NRG4 had an impact on hepatocyte metabolism, leading to decreased gluconeogenic- and mitochondrial biogenesis-related gene expression, and reduced mitochondrial respiration, without effects on expression of lipid metabolism-related genes. Similar but more pronounced effects were found after neuregulin 1 administration. In conclusion, sustained higher serum levels of neuregulin-4, observed in insulin resistant patients may have deleterious effects on metabolic and mitochondrial function in hepatocytes. However, findings from in vitro experiments should be confirmed in human primary hepatocytes.

Surfactin effectively improves bioavailability of curcumin by formation of nano-capsulation

To improve the bioavailability of curcumin, surfactin was used to prepare curcumin-loaded nanoemulsions (Cur-NEs). Moreover, the physicochemical properties, digestive characteristics, as well as inhibition activity to Caco-2 cells of Cur-NEs were measured. Furthermore, the morphological analysis revealed that Cur-NEs with 320 mg/L surfactin appeared spherical nanoparticale (23.23 ± 2.86 nm) and uniform distribution. The encapsulation efficiency of Cur-NEs with 320 mg/L surfactin was 97.25 ± 1.28%. Simulated gastrointestinal digestion results indicated that surfactin elevated the sustained-release characteristics and higher bioaccessibility (40.92 ± 2.84%) of curcumin. Besides, Cur-NEs with 320 mg/L surfactin exhibited excellent stability in different temperature, pH and light irradiation. In addition, the inhibition of Cur-NEs with 320 mg/L surfactin to Caco-2 cells was 71.29%. Biochemical analysis showed that Cur-NEs enhanced the activity of lactate dehydrogenase, superoxide dismutase, catalase and glutathione peroxidase, as well as the reactive oxygen species content. RT-PCR and ELISA results also revealed that Cur-NEs inhibited Caco-2 cells through the activated mitochondria-mediated pathway. This study provided a strategy to encapsulate curcumin in nanoparticles with surfactin for improving bioavailability.

Protective Effect and Mechanism of Plant-Based Monoterpenoids in Non-alcoholic Fatty Liver Diseases

The protective effect of plant active ingredients against non-alcoholic fatty liver disease (NAFLD) is becoming increasingly prominent, and the terpenoids have always been the main active compounds in Chinese herbal medicine exerting hepatoprotective effects. However, the related pharmacological effects, especially for monoterpenoids or iridoid glycosides, which have obvious effects on improvement of NAFLD, have not been systematically analyzed. The objective of this review is to systematically examine the molecular mechanisms of monoterpenoids in NAFLD. The signaling pathways of peroxisome proliferator-activated receptor, insulin, nuclear factor κB, toll-like receptor, adipocytokine, RAC-α serine/threonine protein kinase, mammalian target of rapamycin, 5'-AMP-activated protein kinase, and autophagy have been proven to mediate this protective effect. We further compared the experimental data from animal models, including the dosage of these monoterpenoids in detail, and demonstrated that they are effective and safe candidate drugs for NAFLD. This review provides a reference for the development of NAFLD drugs as well as a research guideline for the potential uses of plant monoterpenoids.

SGLT2 Inhibition for Cardiovascular Diseases, Chronic Kidney Disease, and NAFLD

Sodium glucose cotransporter 2 (SGLT-2) inhibitors are the latest class of antidiabetic medications. They prevent glucose reabsorption in the proximal convoluted tubule to decrease blood sugar. Several animal studies revealed that SGLT-2 is profoundly involved in the inflammatory response, fibrogenesis, and regulation of numerous intracellular signaling pathways. Likewise, SGLT-2 inhibitors markedly attenuated inflammation and fibrogenesis and improved the function of damaged organ in animal studies, observational studies, and clinical trials. SGLT-2 inhibitors can decrease blood pressure and ameliorate hypertriglyceridemia and obesity. Likewise, they improve the outcome of cardiovascular diseases such as heart failure, arrhythmias, and ischemic heart disease. SGLT-2 inhibitors are associated with lower cardiovascular and all-cause mortality as well. Meanwhile, they protect against nonalcoholic fatty liver disease (NAFLD), chronic kidney disease, acute kidney injury, and improve micro- and macroalbuminuria. SGLT-2 inhibitors can reprogram numerous signaling pathways to improve NAFLD, cardiovascular diseases, and renal diseases. For instance, they enhance lipolysis, ketogenesis, mitochondrial biogenesis, and autophagy while they attenuate the renin-angiotensin-aldosterone system, lipogenesis, endoplasmic reticulum stress, oxidative stress, apoptosis, and fibrogenesis. This review explains the beneficial effects of SGLT-2 inhibitors on NAFLD and cardiovascular and renal diseases and dissects the underlying molecular mechanisms in detail. This narrative review explains the beneficial effects of SGLT-2 inhibitors on NAFLD and cardiovascular and renal diseases using the results of latest observational studies, clinical trials, and meta-analyses. Thereafter, it dissects the underlying molecular mechanisms involved in the clinical effects of SGLT-2 inhibitors on these diseases.

Swertiamarin supplementation prevents obesity-related chronic inflammation and insulin resistance in mice fed a high-fat diet

Obesity is characterized by low-grade chronic inflammation, which underlies insulin resistance and non-alcoholic fatty liver disease (NAFLD). Swertiamarin is a secoiridoid glycoside that has been reported to ameliorate diabetes and NAFLD in animal models. However, the effects of swertiamarin on obesity-related inflammation and insulin resistance have not been fully elucidated. Thus, this study investigated the effects of swertiamarin on inflammation and insulin resistance in high-fat diet (HFD)-induced obese mice. C57BL/6 mice were fed a HFD or HFD containing swertiamarin for 8 weeks. Obesity-induced insulin resistance and inflammation were assessed in the epididymal white adipose tissue (eWAT) and livers of the mice. Swertiamarin attenuated HFD-induced weight gain, glucose intolerance, oxidative stress, and insulin resistance, and enhanced insulin signalling in mice. Compared to HFD-fed mice, the swertiamarin-treated mice exhibited increased lipolysis and reduced adipocyte hypertrophy and macrophage infiltration in eWAT. Moreover, swertiamarin alleviated HFD-mediated hepatic steatosis and inflammation by suppressing activation of the p38 MAPK and NF-κB pathways within the eWAT and liver of obese mice. In conclusion, supplementation with swertiamarin attenuated weight gain and hepatic steatosis, and alleviated obesity-associated inflammation and insulin resistance, in obese mice.

Chemistry, Pharmacology and Therapeutic Potential of Swertiamarin - A Promising Natural Lead for New Drug Discovery and Development

Swertiamarin, a seco-iridoid glycoside, is mainly found in Enicostemma littorale Blume (E. littorale) and exhibits therapeutic activities for various diseases. The present study aimed to provide a review of swertiamarin in terms of its phytochemistry, physicochemical properties, biosynthesis, pharmacology and therapeutic potential. Relevant literature was collected from several scientific databases, including PubMed, ScienceDirect, Scopus and Google Scholar, between 1990 and the present. This review included the distribution of swertiamarin in medicinal plants and its isolation, characterization, physicochemical properties and possible biosynthetic pathways. A comprehensive summary of the pharmacological activities, therapeutic potential and metabolic pathways of swertiamarin was also included after careful screening and tabulation. Based on the reported evidence, swertiamarin meets all five of Lipinski’s rules for drug-like properties. Thereafter, the physicochemical properties of swertiamarin were detailed and analyzed. A simple and rapid method for isolating swertiamarin from E. littorale has been described. The present review proposed that swertiamarin may be biosynthesized by the mevalonate or nonmevalonate pathways, followed by the seco-iridoid pathway. It has also been found that swertiamarin is a potent compound with diverse pharmacological activities, including hepatoprotective, analgesic, anti-inflammatory, antiarthritis, antidiabetic, antioxidant, neuroprotective and gastroprotective activities. The anticancer activity of swertiamarin against different cancer cell lines has been recently reported. The underlying mechanisms of all these pharmacological effects are diverse and seem to involve the regulation of different molecular targets, including growth factors, inflammatory cytokines, protein kinases, apoptosis-related proteins, receptors and enzymes. Swertiamarin also modulates the activity of several transcription factors, and their signaling pathways in various pathological conditions are also discussed. Moreover, we have highlighted the toxicity profile, pharmacokinetics and possible structural modifications of swertiamarin. The pharmacological activities and therapeutic potential of swertiamarin have been extensively investigated. However, more advanced studies are required including clinical trials and studies on the bioavailability, permeability and administration of safe doses to offer swertiamarin as a novel candidate for future drug development.

[Swertiamarin alleviates diabetic peripheral neuropathy in rats by suppressing NOXS/ ROS/NLRP3 signal pathway]

OBJECTIVE

To observe the therapeutic effect of swertiamarin on diabetic peripheral neuropathy (DPN) in rats and explore the molecular mechanism in light of the NOXS/ROS/NLRP3 signal pathway.

OBJECTIVE

Thirty-two SD rats were randomly divided into control group, DPN model group (treated with saline), swertiamarin (5 mg/kg) treatment group and NOXS inhibitor (10 mL/kg DPI) treatment group. Rat models of DPN were established in the latter 3 groups by intraperitoneal injections of STZ, and the treatments were administered on days 1, 7 and 14 after modeling. Tactile hypersensitivity of the rats was evaluated 30 min after the treatment. The expressions of NOXS, ROS, NLRP3 and inflammatory factors in the spinal cord tissue were detected using ELISA, and the protein expressions of NOXS, ROS, and NLRP3 were also detected with Western blotting.

OBJECTIVE

Compared with those in the control group, the rats in DPN group showed significant hyperalgesia (P < 0.001), increased expressions of TNF-α (P < 0.001) and IL-6 (P < 0.001), decreased expressions of TGF-β (P < 0.001), and increased expressions of NOXS/ROS/NLRP3 signal pathway (P < 0.001). Compared with those in DPN model group, the rats with swertiamarin treatment showed improved hyperalgesia (P < 0.001), decreased expressions of TNF-α (P=0.03) and IL-6 (P=0.002), increased expressions of TGF-β (P=0.04), and decreased expressions of NOXS (P < 0.001), ROS (P < 0.001) and NLRP3 (P=0.002). Treatment with swertiamarin and the NOXS inhibitor produced similar effects on the expressions of the inflammatory factors in the rat models (P>0.05).

OBJECTIVE

DPN effectively relieves hyperalgesia in rat models of DPN by restoring the balance in the expressions of the inflammatory factors by suppressing NOXs/ROS/NLRP3 signaling pathway.

The Impact of Anthocyanins and Iridoids on Transcription Factors Crucial for Lipid and Cholesterol Homeostasis

Nutrition determines our health, both directly and indirectly. Consumed foods affect the functioning of individual organs as well as entire systems, e.g., the cardiovascular system. There are many different diets, but universal guidelines for proper nutrition are provided in the WHO healthy eating pyramid. According to the latest version, plant products should form the basis of our diet. Many groups of plant compounds with a beneficial effect on human health have been described. Such groups include anthocyanins and iridoids, for which it has been proven that their consumption may lead to, inter alia, antioxidant, cholesterol and lipid-lowering, anti-obesity and anti-diabetic effects. Transcription factors directly affect a number of parameters of cell functions and cellular metabolism. In the context of lipid and cholesterol metabolism, five particularly important transcription factors can be distinguished: liver X receptor (LXR), peroxisome proliferator-activated receptor-α (PPAR-α), peroxisome proliferator-activated receptor-γ (PPAR-γ), CCAAT/enhancer binding protein α (C/EBPα) and sterol regulatory element-binding protein 1c (SREBP-1c). Both anthocyanins and iridoids may alter the expression of these transcription factors. The aim of this review is to collect and systematize knowledge about the impact of anthocyanins and iridoids on transcription factors crucial for lipid and cholesterol homeostasis.

Epigallocatechin-3-Gallate Alleviates High-Fat Diet-Induced Nonalcoholic Fatty Liver Disease via Inhibition of Apoptosis and Promotion of Autophagy through the ROS/MAPK Signaling Pathway

Nonalcoholic fatty liver disease (NAFLD) represents one of the most common chronic liver diseases in the world. It has been reported that epigallocatechin-3-gallate (EGCG) plays important biological and pharmacological roles in mammalian cells. Nevertheless, the mechanism underlying the beneficial effect of EGCG on the progression of NAFLD has not been fully elucidated. In the present study, the mechanisms of action of EGCG on the growth, apoptosis, and autophagy were examined using oleic acid- (OA-) treated liver cells and the high-fat diet- (HFD-) induced NAFLD mouse model. Administration of EGCG promoted the growth of OA-treated liver cells. EGCG could reduce mitochondrial-dependent apoptosis and increase autophagy possibly via the reactive oxygen species- (ROS-) mediated mitogen-activated protein kinase (MAPK) pathway in OA-treated liver cells. In line with in vitro findings, our in vivo study verified that treatment with EGCG attenuated HFD-induced NAFLD through reduction of apoptosis and promotion of autophagy. EGCG can alleviate HFD-induced NAFLD possibly by decreasing apoptosis and increasing autophagy via the ROS/MAPK pathway. EGCG may be a promising agent for the treatment of NAFLD.

Protective Effects of Iridoid Glycoside from Corni Fructus on Type 2 Diabetes with Nonalcoholic Fatty Liver in Mice

Type 2 diabetes mellitus (T2DM) is a common chronic metabolic disease. Accumulating evidence has demonstrated that nonalcoholic fatty liver disease (NAFLD) shares common typical features with T2DM, and they affect each other extensively. Thus, NAFLD has emerged as a novel target for T2DM prevention and care. Although Corni Fructus (CF) and its extracts have a therapeutic effect on T2DM, its effects and mechanisms on T2DM with NAFLD are far from elucidated. In this study, a mouse model of T2DM with NAFLD complication was established in ICR mice by feeding a high-fat, high-sugar (HFHS) diet and intraperitoneally injecting with a low dose of streptozotocin (STZ). Then, the effects of iridoid glycosides (IG) extracted from CF on this mouse model were investigated. We found that 4-week IG administration remarkably alleviated hyperglycemia and insulin resistance and significantly reduced inflammation, oxidative stress, and fat accumulation in the liver of T2DM with NAFLD mice. Further studies showed that IG inhibited the NF-κB but enhanced the PI3K-AKT signaling pathway. In summary, these results indicated that the IG from CF has potential therapeutic effects on T2DM with NAFLD.

Hydrogen Sulfide Attenuates High-Fat Diet-Induced Non-Alcoholic Fatty Liver Disease by Inhibiting Apoptosis and Promoting Autophagy via Reactive Oxygen Species/Phosphatidylinositol 3-Kinase/AKT/Mammalian Target of Rapamycin Signaling Pathway

Non-alcoholic fatty liver disease (NAFLD) is a common chronic liver disease worldwide. Hydrogen sulfide (H₂S) is involved in a wide range of physiological and pathological processes. Nevertheless, the mechanism of action of H₂S in NAFLD development has not been fully clarified. Here, the reduced level of H₂S was observed in liver cells treated with oleic acid (OA). Administration of H₂S increased the proliferation of OA-treated cells. The results showed that H₂S decreased apoptosis and promoted autophagy through reactive oxygen species (ROS)-mediated phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) cascade in OA-treated cells. In addition, administration of H₂S relieved high-fat diet (HFD)-induced NAFLD via inhibition of apoptosis and promotion of autophagy. These findings suggest that H₂S could ameliorate HFD-induced NAFLD by regulating apoptosis and autophagy through ROS/PI3K/AKT/mTOR signaling pathway. Novel H₂S-releasing donors may have therapeutic potential for the treatment of NAFLD.

Swertiamarin suppresses proliferation, migration, and invasion of hepatocellular carcinoma cells <em>via</em> negative regulation of FRAT1

Studies have shown that swertiamarin (STM) has multiple biological activities, but its anti-tumour effects and molecular mechanisms are still unclear. The present research aimed to validate the STM's impacts on the proliferation, migration, and invasion of hepatocellular carcinoma (HCC) cells, and to study its potential mechanism. Two HCC cell lines were treated with STM. Tumour growth was observed by the mouse tumour xenografts model. HCC cell lines stably expressing T-cell lymphomas 1 (FRAT1) were generated by lentivirusmediated overexpression. Cell viability, proliferation, migration, and invasion were observed using Cell Counting Kit-8 (CCK8), the xCELLigence Real-Time Cell Analyzer system (RTCA), and transwell analysis, respectively. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting were used to observe the expression of FRAT1 and proteins related to the Wnt/β-catenin signalling pathway. Tumour growth was inhibited by STM in vivo. STM suppressed the proliferation, migration, and invasion of HCC cells. STM negatively regulated FRAT1 expression, whereas overexpressed FRAT1 blocked the anti-tumour function of STM. The results revealed that STM suppressed the FRAT1/Wnt/β-catenin signalling pathway. The findings of this study provide new insights into investigation of therapeutic strategies against HCC.

Sweroside ameliorates NAFLD in high-fat diet induced obese mice through the regulation of lipid metabolism and inflammatory response

ETHNOPHARMACOLOGICAL RELEVANCE

Sweroside, an iridoid derived from Traditional Chinese Medicine, is an active component in Swertia pseudochinensis Hara. Swertia pseudochinensis Hara is first recorded in "Inner Mongolia Chinese Herb Medicine"and is considered as a folk medicine for treating hepatitis in northern China.

AIM OF THE STUDY

This study sought to elucidate the role of sweroside in high fat diet induced obesity and fatty liver by using mouse model and investigated the primary molecular mechanism via transcriptomics analysis.

MATERIALS AND METHODS

C57BL/6 mice were fed high-fat diet (HFD) for 14 weeks to induce obesity, hyperglycemia, and fatty liver. These mice were subsequently treated with HFD alone or mixed with sweroside (at a daily dosage of 60 mg per kg of BW, 120 mg per kg of BW and 240 mg per kg of BW) for 6 weeks. BW and food intake was monitored weekly. Biochemical and pathological analysis were conducted to investigate the effect of sweroside on NAFLD. RNA-sequence and RT-qPCR analysis were performed to analyze the potential mechanism.

RESULTS

The mice treated with sweroside were resistant to HFD-induced body weight gain, insulin resistance and hepatic steatosis. Ingenuity pathway analysis (IPA) demonstrated that hepatic gene networks related to lipid metabolism and inflammatory response were down-regulated in the HFD + sweroside group. PPAR-ɑ was located in the center of the hepatic gene network, and the significantly altered genes were CD36 and FGF21, which are related to hepatic inflammation and lipid metabolism. Consistently, upstream-regulators analysis revealed that the main enriched upstream-regulator was PPAR-ɑ.

CONCLUSION

Our results indicate that sweroside may ameliorate obesity with fatty liver via the regulation of lipid metabolism and inflammatory responses. The beneficial effects of sweroside might be closely associated with the regulation of PPAR-α.

Polyphenol-Rich Extracts from Toona sinensis Bark and Fruit Ameliorate Free Fatty Acid-Induced Lipogenesis through AMPK and LC3 Pathways

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease found worldwide. The present study aimed to evaluate the mechanisms of inhibiting lipid accumulation in free fatty acid (FFA)-treated HepG2 cells caused by bark and fruit extracts of Toona sinensis (TSB and TSF). FFA induced lipid and triglyceride (TG) accumulation, which was attenuated by TSB and TSF. TSB and/or TSF promoted phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-coA carboxylase and peroxisome proliferator-activated receptor alpha upregulation. Furthermore, TSB and TSF suppressed FFA-induced liver X receptor, sterol regulatory element-binding transcription protein 1, fatty acid synthase, and stearoyl-CoA desaturase 1 protein expression. Moreover, TSB and/or TSF induced phosphorylation of Unc-51 like autophagy-activating kinase and microtubule-associated protein 1A/1B-light chain 3 expressions. Therefore, TSB and TSF relieve lipid accumulation by attenuating lipogenic protein expression, activating the AMPK pathway, and upregulating the autophagic flux to enhance lipid metabolism. Moreover, TSB and TSF reduced TG contents, implying the therapeutic use of TSB and TSF in NAFLD.

Potential of Gentiana lutea for the Treatment of Obesity-associated Diseases

BACKGROUND

Obesity, diabetes, and associated diseases are increasing all over the world, and pose a great burden on public health. According to the latest reports, 440 million people are suffering from diabetes. Diabetes is caused by impaired ability to produce or respond to the hormone insulin consequently resulting in hyperglycemia.

METHODS

Data used for this review was obtained by using PUBMED/MEDLINE (1987-2018). The main data search terms were: Gentiana lutea, Gentiana lutea extract, Gentiana lutea constituents, obesity, diabetes mellitus, diabetic complications.

RESULTS

In the present review, we describe the potential of root powder of yellow gentian (Gentiana lutea) for the prevention of obesity and diabetes including complications related to this disease.

CONCLUSION

Reasonably effective, low-cost alternatives could fulfill an important role for a large part of the human population and could be of great value for the food market. Even a modest reduction of morbidity and mortality with respect to this disease translates into millions of lives saved.

Amelioration of nonalcoholic fatty liver disease by swertiamarin in fructose-fed mice

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease. Swertia bimaculata (Sieb. et Zucc.) Hook. Thoms.ex Clarke, a glabrous or procumbent perennial herb, is a traditional herb medicine. Swertiamarin, a secoiridoid glycoside, is a representative ingredient in this medical plant crude extract and shows antidiabetic and antihyperlipidaemic activities and protective effect against hepatic injury.

PURPOSE

The present study aimed to determine whether swertiamarin can attenuate NAFLD in fructose-fed mice.

METHODS

Healthy male mice freely drank water containing 10% fructose for 12 consecutive weeks, whereas animals in those swertiamarin tested groups received different doses of swertiamarin (25, 50 and 100 mg/kg) by intragastric administration once a day from the ninth week to the twelfth week.

RESULTS

At the end of the experiment, fructose-fed mice administrated with swertiamarin showed low levels of serum glucose, triglycerides, uric acid, alanine aminotransferase and aspartate transaminase. Histological examinations suggested the alleviation of hepatic ballooning degeneration and steatosis by swertiamarin treatment. Moreover, swertiamarin administration mitigated hepatic oxidative stress along with decreases of hepatic pro-inflammation cytokines, which was associated with decrease of hepatic xanthine oxidase (XO) activity and enhancements of anti-oxidant defense system enzymes, as well as activation of nuclear factor E2-related factor 2 (Nrf2) in fructose-fed mice. In addition, swertiamarin down-regulated expression of sterol-regulatory element-binding protein-1 (SREBP-1), fatty acid synthase (FAS) and acetyl-CoA carboxylase 1 (ACC1) in liver of fructose-fed mice.

CONCLUSION

The present study demonstrates that swertiamarin alleviates NAFLD and metabolic alterations in fructose-fed mice.

Alterations of Fatty Acid Profile May Contribute to Dyslipidemia in Chronic Kidney Disease by Influencing Hepatocyte Metabolism

Chronic kidney disease (CKD) is associated with atherogenic dyslipidemia. Our aim was firstly to investigate patterns of fatty acids (FA) composition through various stages of CKD, and secondly, to evaluate the effect of CKD-specific FA disturbances on the expression of genes related to lipid metabolism at a cellular level. Serum FA composition was analyzed in 191 patients with consecutive severity stages of CKD, and 30 healthy controls free from CKD. Next, HepG2 human hepatic cells were treated with major representatives of various FA groups, as well as with FA extracted from a mix of serums of controls and of CKD stage 5 patients. Across worsening stages of CKD severity, there was an increasing monounsaturated FA (MUFA) content. It was associated with a concomitant decrease in n-3 and n-6 polyunsaturated FA. The incubation of hepatocytes with FA from CKD patients (compared to that of healthy subjects), resulted in significantly higher mRNA levels of genes involved in FA synthesis (fatty acid synthase (FASN) increased 13.7 ± 3.5 times, stearoyl-CoA desaturase 1 (SCD1) increased 4.26 ± 0.36 times), and very low density lipoprotein (VLDL) formation (apolipoprotein B (ApoB) increased 7.35 ± 1.5 times, microsomal triacylglycerol transfer protein (MTTP) increased 2.74 ± 0.43 times). In conclusion, there were progressive alterations in serum FA composition of patients with CKD. These alterations may partly contribute to CKD hypertriglyceridemia by influencing hepatocyte expression of genes of lipid synthesis and release.

Ursodeoxycholic acid ameliorates hepatic lipid metabolism in LO2 cells by regulating the AKT/mTOR/SREBP-1 signaling pathway

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD), the most common chronic liver disease, can progress into nonalcoholic steatohepatitis (NASH), cirrhosis, and even hepatocellular carcinoma. Bile acids such as ursodeoxycholic acid (UDCA) play an essential role in the pathogenesis of NAFLD by regulating the level of sterol regulatory element-binding protein (SREBP) 1c, but the underlying regulatory mechanism remains elusive. Increased evidence indicates that the AKT/mTOR/SREBP-1 signaling pathway is a key pathway to regulate hepatic cellular lipid metabolism. UDCA may regulate the AKT/mTOR/SREBP-1 signaling pathway to ameliorate hepatic lipid metabolism.

AIM

To investigate the functional mechanism of UDCA in an oleic acid (OA)-induced cellular model of NAFLD.

METHODS

The cellular model of NAFLD was established using OA and treated with UDCA. First, the best concentration of UDCA was selected. For the best time-dependent assay, cells were stimulated with OA only or co-treated with OA and 2 mmol/L UDCA for 24 h, 48 h, and 72 h. Oil red O staining was used to observe the accumulation of intracellular lipids, while the intracellular contents of triglyceride, alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), and aspartate aminotransferase (AST) were detected by enzymatic methods. Meanwhile, the expression levels of AKT/mTOR/SREBP-1 signaling pathway-related proteins were detected by real-time PCR and Western blot.

RESULTS

In the NAFLD cell model established with LO2 cells induced using OA, lipid accumulation was obvious. UDCA significantly inhibited lipid accumulation at different concentrations (especially 2 mmol/L) and decreased cell growth ability at different time points. The biochemical parameters like ALT, AST, and GGT were significant improved by UDCA. UDCA treatment vividly repressed the activation of AKT, mTOR, and CRTC2 and the expression of nSREBP-1 in LO2 cells induced with OA.

CONCLUSION

Our findings demonstrate the effect of UDCA in improving NAFLD. UDCA attenuates OA-induced hepatic steatosis mainly by regulation of AKT/mTOR/SREBP-1 signal transduction.

Effect of silibinin on CFLAR-JNK pathway in oleic acid-treated HepG2 cells

AIMS

Silibinin is a flavonolignan from milk thistle with many pharmacological activities including lipid-lowering and antioxidant. Caspase 8 and Fas-associated protein with death domain-like apoptosis regulator (CFLAR) is an important target gene in regulating non-alcoholic steatohepatitis (NASH). At present, the effect of silibinin on CFLAR-JNK pathway related to NASH was unknown. Here the effect of silibinin on CFLAR-JNK pathway and its downstream target genes involved in lipid metabolism, glucose uptake, oxidative stress and inflammatory response were studied in oleic acid (OA)-treated HepG2 cells.

MAIN METHODS

OA-treated HepG2 cells were employed as a in vitro model of steatosis, insulin resistance and oxidative stress. The model cells were then treated by silibinin (5, 20, 50, and 100 μM) for 24 h and detected for the related indicators as follows: (1) cellular triglycerides (TG), nitric oxide (NO) and glucose uptake; (2) the mRNA levels of the sterol regulatory element binding protein-1C (SREBP-1C), patatin-like phospholipase domain containing 3 (PNPLA3) and peroxisome proliferator activated receptor-α (PPARα); (3) the protein levels of PPARα, SREBP-1C, PNPLA3, CFLAR, phosphorylated c-Jun N-terminal kinase (pJNK), phosphatidylinositol 3-kinase (PI3K), phosphorylated serine-threonine protein kinase (pAKT), nuclear factor E2-related factor 2 (NRF2), cytochrome P450 2E1 (CYP2E1) and 4A (CYP4A).

KEY FINDINGS

Compared to the control, OA-treatment led to a result as follows: (1) increased the intracellular levels of TG and NO; (2) up-regulated the protein expression of SREBP-1C, PNPLA3, pJNK, CYP 2E1 and CYP 4A; (3) decreased the uptake of 2-NBDG; (4) down-regulated the protein expression of CFLAR, PPARα, PI3K, pAKT and NRF2. Compared to OA-treated HepG2 cells, silibinin treatment could improve the indicators as follows: (1) decreased the intracellular levels of TG and NO; (2) down-regulated the protein expression of SREBP-1C, PNPLA3, pJNK, CYP 2E1 and CYP 4A; (3) increased the uptake of 2-NBDG; (4) up-regulated the protein expression of CFLAR, PPARα, PI3K, pAKT and NRF2.

SIGNIFICANCE

Silibinin can ameliorate some metabolic alterations and induce some molecular changes by activating the CFLAR-JNK pathway and thereby regulating its downstream target genes involved in lipid metabolism (PPARα, SREBP-1C and PNPLA3), glucose uptake (PI3K-AKT), oxidative stress (NRF2, CYP2E1, CYP4A) and inflammatory response(NO) in OA-treated HepG2 cells demonstrating its possible use in ameliorating various symptoms of NASH.

Effects of Rhizoma Alismatis extract on biochemical indices and adipose gene expression in oleic acid-induced hepatocyte injury in Jian carp (Cyprinus carpio var. Jian)

Fatty liver is an increasingly serious disease of fish in aquaculture. However, the mechanisms responsible for the occurrence of fatty liver remain unclear, and no effective methods for the prevention and treatment of this disease have yet been found. In the present study, we aimed to develop an in vitro model of hepatocyte injury using oleic acid as hepatotoxicant and evaluate the protective effects of Rhizoma Alismatis extract (RAE) in Jian carp using this model. Primary hepatocytes from Jian carp were isolated and purified and cultured in vitro. The result indicated that 0.4 mmol L^-1 oleic acid and 48 h could be the optimal conditions to induce hepatocyte injury model in cultured hepatocytes. Hepatocytes were exposed to oleic acid, followed by the addition of RAE at 0, 1, 5, 10, 20, or 50 μg mL^-1. The hepatocytes and supernatant were then analyzed. RAE suppressed oleic acid-induced elevations in aspartate aminotransferase, alanine aminotransferase, triglycerides, total cholesterol, lactate dehydrogenase, alkaline phosphatase, cholinesterase, malondialdehyde, γ-glutamyl transferase, cytochrome P450 1A, cytochrome P450 2E1, liver-type fatty acid binding protein, free fatty acid, fatty acid synthetase, and tumor necrosis factor-α (P < 0.01 or P < 0.05); reduced protein levels of cytochrome P450 1A, nuclear factor (NF)-κB p65, and NF-κB c-Rel; and inhibited cytochrome P4503A, NF-κB c-Rel, nuclear factor erythroid-related factor 2, peroxisome proliferator-activated receptor-α, and cytochrome P4501A mRNA levels. In conclusion, RAE exhibited a protective effect against hepatocyte injury in Jian carp. Further in vivo studies are needed to provide more evidence for the use of RAE as a hepatoprotective agent for the treatment of hepatocyte injury.

Antidiabetic Potential of Monoterpenes: A Case of Small Molecules Punching above Their Weight

Monoterpenes belong to the terpenoids class of natural products and are bio-synthesized through the mevalonic acid pathway. Their small molecular weight coupled with high non-polar nature make them the most abundant components of essential oils which are often considered to have some general antioxidant and antimicrobial effects at fairly high concentrations. These compounds are however reported to have antidiabetic effects in recent years. Thanks to the ingenious biosynthetic machinery of nature, they also display a fair degree of structural complexity/diversity for further consideration in structure-activity studies. In the present communication, the merit of monoterpenes as antidiabetic agents is scrutinized by assessing recent in vitro and in vivo studies reported in the scientific literature. Both the aglycones and glycosides of these compounds of rather small structural size appear to display antidiabetic along with antiobesity and lipid lowering effects. The diversity of these effects vis-à-vis their structures and mechanisms of actions are discussed. Some key pharmacological targets include the insulin signaling pathways and/or the associated PI3K-AKT (protein kinase B), peroxisome proliferator activated receptor-γ (PPARγ), glucose transporter-4 (GLUT4) and adenosine monophosphate-activated protein kinase (AMPK) pathways; proinflammatory cytokines and the NF-κB pathway; glycogenolysis and gluconeogenesis in the liver; glucagon-like-1 receptor (GLP-1R); among others.

Nimbolide attenuate the lipid accumulation, oxidative stress and antioxidant in primary hepatocytes

Nimbolide is a bioactive compound found in Azadirachta indica. This work was devised to investigate the potential effects of nimbolide on intracellular lipid deposition and its associated redox modulation in primary hepatocytes (Heps). Lipid accumulation was induced in Heps by supplementing 1 mM oleic acid for 24 h which was marked by significant accumulation of lipids. The results demonstrated that nimbolide can decrease intracellular cholesterol, free fatty acids and triglycerides. Nimbolide may also improve hepatocytes function through its antioxidant effects by inhibiting oxidative DNA damage and lipid peroxidation by curtailing the reactive oxygen species levels. Further it also restore the mitochondrial potential, improving the endogenous antioxidant levels such as GSH and antioxidant enzyme activities. Nimbolide increased (P < 0.05) liver X receptor-α (LXRα), peroxisome proliferator-activated receptor-γ (PPARγ) and sterol regulatory element-binding protein-1c (SREBP1c) gene expression in Heps. The biological significance of nimbolide may involve hypolipidemic effect, lipid peroxidation inhibition, DNA damage inhibition, ROS inhibition, restoring mitochondrial function, increases in GSH and SOD & CAT activities, and direct regulation of LXRα, PPARγ and SREBP1c gene expression. Nimbolide may be used as effective lipid lowering compound and lipid deposition-induced Heps changes.