Saponins from bitter melon reduce lipid accumulation via induction of autophagy in C. elegans and HepG2 cell line

The Effects of Bitter Melon ( Mormordica charantia ) on Lipid Profile: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Research indicates that bitter melon could be useful in the management of dyslipidemia. Still, there is disagreement concerning the findings. This systematic study was undertaken to clarify the impact of consuming bitter melon on lipid profile. The databases Web of Science, Cochrane Library, PubMed, and Scopus were queried from inception until February 9, 2023. The study assessed triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) levels. The effect sizes were calculated using weighted mean differences (WMDs) and 95% confidence intervals (CIs). Eight randomized controlled trials (RCTs) with a total of 423 participants were included. Bitter melon consumption resulted in a significant decrease in plasma concentrations of TC (WMD; -9.71 mg/dL; CI: -17.69 to -1.74, p = 0.01) and TG (WMD; -10.24 mg/dL; CI: -19.92 to -0.56, p = 0.03), while bitter melon did not significantly lower blood LDL-C (WMD; -8.66 mg/dL; CI: -19.83 to 2.50, p = 0.12) and HDL-C concentrations (WMD; 0.54 mg/dL; CI: -2.38 to 3.45, p = 0.71). Subgroup analysis showed a significant decrease in TC and LDL-C and an increase in HDL-C at a dose of ≤ 2000 mg/day and an intervention period of ≤ 8 weeks. Also, the greatest impact of LDL-C and HDL-C was seen in diabetic and prediabetic people. Bitter melon supplementation positively impacts TC and TG levels. The limitations of this study were short-term trials (less than 3 months).

An update on ox-LDL-inducing vascular smooth muscle cell-derived foam cells in atherosclerosis

Excess cholesterol accumulation induces the accumulation of foam cells, eventually accelerating atherosclerosis progress. Historically, the mechanisms of macrophage-derived foam cells have attracted attention because of their central role in plaque development, which was challenged by lineage tracing in union with single-cell sequencing (sc-seq). Accumulated studies have uncovered how vascular smooth muscle cells (VSMCs) proliferate and migrate to the vascular intima and accumulate, then transform into foam cells induced by surplus lipids, finally accounting for 30% to 70% of the total foam cells within the plaque of both mice and humans. Therefore, the mechanisms of VSMC-derived foam cells have received increasing attention. The review intends to summarize the transformation mechanism of VSMCs into foam cells induced by oxidized low-density lipoproteins (ox-LDL) in atherosclerosis.

Momordica charantia Bioactive Components: Hypoglycemic and Hypolipidemic Benefits Through Gut Health Modulation

Momordica charantia (MC), a member of the Cucurbitaceae family, is well known for its pharmacological activities that exhibit hypoglycemic and hypolipidemic properties. These properties are largely because of its abundant bioactive compounds and phytochemicals. Over the years, numerous studies have confirmed the regulatory effects of MC extract on glycolipid metabolism. However, there is a lack of comprehensive reviews on newly discovered MC-related components, such as insulin receptor-binding protein-19, adMc1, and MC protein-30 and triterpenoids 3β,7β,25-trihydroxycucurbita-5,23(E)-dien-19-al, and the role of MC in gut microbiota and bitter taste receptors. This review offers an up-to-date overview of the recently reported chemical compositions of MC, including polysaccharides, saponins, polyphenolics, peptides, and their beneficial effects. It also provides the latest updates on the role of MC in the regulation of gut microbiota and bitter taste receptor signaling pathways. As a result, this review will serve as a theoretical basis for potential applications in the creation or modification of MC-based nutrient supplements.

Gualou-Xiebai herb pair and its active ingredients act against atherosclerosis by suppressing VSMC-derived foam cell formation via regulating P2RY12-mediated lipophagy

BACKGROUND

Atherosclerosis (AS) is a chronic disease characterized by lipid accumulation in the aortic wall and the formation of foam cells overloaded with large lipids inclusions. Currently, Western medicine is primarily used to improve lipid metabolism disorders and reduce inflammatory reactions to delay AS progression, but these medicines come with serious side effects and drug resistance. Gualou-Xiebai (GLXB) is a renowned herb pair that has been proven effective against AS. However, the potential molecular mechanism through which GLXB exerts the anti-atherosclerotic effects of increasing lipophagy in vascular smooth muscle cells (VSMCs) remains unknown.

PURPOSE

This study aims to explore the role of lipophagy and the therapeutic mechanism of GLXB in AS.

METHODS

UPLC-Q-TOF-MS for the determination of the main components of GLXB-containing serum. An AS mouse model was established by feeding a high-fat diet (HFD) to ApoE-/- mice for 12 weeks. Ultrasonography monitoring was used to confirm the successful establishment of the AS model. Plaque areas and lipid deposition were evaluated using HE staining and aorta imagingafter GLXB treatment. Immunofluorescence staining and Western blotting were utilized to observe the P2RY12 and lipophagy levels in AS mice. VSMCs were stimulated with oxidized low-density lipoprotein (ox-LDL) to induce foam cell formation. The degree of lipophagy and the related molecular mechanisms were assessed after treating the VSMCs with GLXB-containing serum or si-P2RY12 transfection. The active components of GLXB-containing serum that act on P2RY12 were screened and verified by molecular docking and dual-luciferase reporter assays.

RESULTS

Seventeen components of GLXB were identified in rat serum by UPLC-Q-TOF-MS. GLXB significantly reduced lipid deposition in HFD-fed ApoE-/- mice and ox-LDL-induced VSMCs. GLXB strikingly increased lipophagy levels by downregulating P2RY12, p62, and plin2, upregulating LC3Ⅱ protein expression, and increasing the number of autophagosomes. Notably, the lipophagy inhibitor CQ and the P2RY12 receptor agonist ADPβ abolished the GLXB-induced increase in lipophagy. Last, we confirmed that albiflorin, apigenin, luteolin, kaempferol, 7,8-dihydroxyflavone, and hesperetin from GLXB significantly inhibited P2RY12.

CONCLUSION

GLXB activates lipophagy and inhibits lipid accumulation-associated VSMC-derived foam cell formation through suppressing P2RY12 activation, resulting in anti-atherosclerotic effects. The GLXB components albiflorin, apigenin, luteolin, kaempferol, 7,8-dihydroxyflavone, and hesperetin are the potential active effectors against P2RY12.

Indian Almond (Terminalia catappa Linn.) Leaf Extract Extends Lifespan by Improving Lipid Metabolism and Antioxidant Activity Dependent on AMPK Signaling Pathway in Caenorhabditis elegans under High-Glucose-Diet Conditions

This study aimed to evaluate the antioxidant and antiaging effects of Indian almond (Terminalia catappa Linn.) leaf extract (TCE) on high-glucose (GLU)-induced obese Caenorhabditis elegans. Since TCE contains high contents of flavonoids and phenolics, strong radical scavenging activity was confirmed in vitro. The stress-resistance effect of TCE was confirmed under thermal and oxidative stress conditions at nontoxic tested concentrations (6.25, 12.5, and 25 μg/mL). GLU at 2% caused lipid and reactive oxygen species (ROS) accumulation in C. elegans, and TCE inhibited lipid and ROS accumulation under both normal and 2% GLU conditions in a concentration-dependent manner. In addition, TCE proved to be effective in prolonging the lifespan of C. elegans under normal and 2% GLU conditions. The ROS reduction effect of TCE was abolished in mutants deficient in daf-16/FOXO and skn-1/Nrf-2. In addition, the lifespan-extending effect of TCE in these two mutants disappeared. The lifespan-extending effect was abolished even in atgl-1/ATGL-deficiency mutants. The TCE effect was reduced in aak-1/AMPK-deficient mutants and completely abolished under 2% GLU conditions. Therefore, the effect of prolonging lifespan by inhibiting lipid and ROS accumulation under the high GLU conditions of TCE is considered to be the result of atgl-1, daf-16, and skn-1 being downregulated by aak-1. These results suggest that the physiological potential of TCE contributes to antiaging under metabolic disorders.

Maackiain Mimics Caloric Restriction through aak-2-Mediated Lipid Reduction in Caenorhabditis elegans

Obesity prevalence is becoming a serious global health and economic issue and is a major risk factor for concomitant diseases that worsen the quality and duration of life. Therefore, the urgency of the development of novel therapies is of a particular importance. A previous study of ours revealed that the natural pterocarpan, maackiain (MACK), significantly inhibits adipogenic differentiation in human adipocytes through a peroxisome proliferator-activated receptor gamma (PPARγ)-dependent mechanism. Considering the observed anti-adipogenic potential of MACK, we aimed to further elucidate the molecular mechanisms that drive its biological activity in a Caenorhabditis elegans obesity model. Therefore, in the current study, the anti-obesogenic effect of MACK (25, 50, and 100 μM) was compared to orlistat (ORST, 12 μM) as a reference drug. Additionally, the hybrid combination between the ORST (12 μM) and MACK (100 μM) was assessed for suspected synergistic interaction. Mechanistically, the observed anti-obesogenic effect of MACK was mediated through the upregulation of the key metabolic regulators, namely, the nuclear hormone receptor 49 (nhr-49) that is a functional homologue of the mammalian PPARs and the AMP-activated protein kinase (aak-2/AMPK) in C. elegans. Collectively, our investigation indicates that MACK has the potential to limit lipid accumulation and control obesity that deserves future developments.

Naringin Alleviates Glucose-Induced Aging by Reducing Fat Accumulation and Promoting Autophagy in Caenorhabditis elegans

Naringin (Nar) is a dihydroflavonoid compound, widely found in citrus fruit and used in Chinese herbal medicine. As a phytochemical, it acts as a dietary supplement that can delay aging and prevent aging-related disease, such as obesity and diabetes. However, its exact mechanism remains unclear. In this study, the high-glucose-induced (HGI) Caenorhabditis elegans model was used to evaluate the anti-aging and anti-obesity effects of Nar. The mean lifespan and fast movement span of HGI worms were extended roughly 24% and 11%, respectively, by Nar treatment. Oil red O staining revealed a significant reduction in fat accumulation and dFP::LGG-labeled worms showed the promotion of autophagy. Additionally, whole transcriptome sequencing and gene set variation analysis suggested that Nar upregulated the lipid biosynthesis and metabolism pathways, as well as the TGF-β, Wnt and longevity signaling pathways. Protein-protein interaction (PPI) network analysis identified hub genes in these pathways for further analysis. Mutant worms and RNA interference were used to study mechanisms; the suppression of hlh-30, lgg-1, unc-51, pha-4, skn-1 and yap-1 disabled the fat-lowering, lifespan-prolonging, and health-promoting properties of Nar. Collectively, our findings indicate that Nar plays an important role in alleviating HGI-aging and anti-obesity effects by reducing fat accumulation and promoting autophagy.