Alisol B 23-acetate activates ABCG5/G8 in the jejunum via the LXRα/ACAT2 pathway to relieve atherosclerosis in ovariectomized ApoE-/- mice

Phytosterols have been shown to improve blood lipid levels and treat atherosclerosis. This research investigated the effects of phytosterol Alisol B 23-acetate (AB23A) on jejunum lipid metabolism and atherosclerosis. The results show that intragastric administration of AB23A can significantly reduce atherosclerotic plaque area and lipid accumulation in the jejunum of ovariectomized ApoE-/- mice fed a high-fat diet and can also improve the lipid mass spectra of the plasma and jejunum. In vitro studies have shown that AB23A can increase cholesterol outflow in Caco-2 cells exposed to high fat concentrations and increase the expression of ATP-binding cassette transfer proteins G5/G8 (ABCG5/G8), the liver X receptor α (LXRα). Furthermore, inhibition of LXRα can significantly eliminate the active effect of AB23A on decreasing intracellular lipid accumulation. We also confirmed that AB23A has a negative effect on Acyl-CoA cholesterol acyltransferase 2 (ACAT2) in Caco-2 cells cultured in the high concentrations of fat, and we found that AB23A further reduces ACAT2 expression in cells treated with the ACAT2 inhibitor pyripyropene or transfected with ACAT2 siRNA. In conclusion, we confirmed that AB23A can reduce the absorption of dietary lipids in the jejunum by affecting the LXRα-ACAT2-ABCG5/G8 pathway and ultimately exert an anti-atherosclerotic effect.

Compound K induces neurogenesis of neural stem cells in thrombin induced nerve injury through LXRα signaling in mice

Intracerebral hemorrhage (ICH) causes neurological function deficit due to the loss of neurons surrounding the hematoma. Increased neurogenesis of endogenous neural stem cells (EnNSCs) is believed to increase cell proliferation and differentiation, thereby improving the neurological deficit. However, there are still limited drugs that are effective for treating neurological deficit. So, the effects of compound K (CK) in EnNSCs were measured after thrombin-induced mice models both in vivo and in vitro, and investigated the probable mechanisms of CK during pro-neurogenesis. The results revealed that 10 μM CK promotes neurogenesis, proliferation and reduces apoptosis of EnNSCs after induction by thrombin. After that, CK treatment increased the neurogenesis of EnNSCs through liver X receptor α (LXRα) signaling pathway using adeno-associated virus knockdown and knocked out mice of LXRα gene. Finally, intraperitoneal injection of 10 mg/kg CK improved the neurogenesis of subventricular zone (SVZ), myelin repair and behavioral deficit after stereotaxic injection of thrombin in the basal ganglia of mice, and this process involved LXRα. These observations provided evidence regarding the effect of CK in pro-neurogenesis via LXRα activation, and suggested further evaluation of it due to its potential role as an effective modulator in the treatment of ICH.

Diketopiperazine-Type Alkaloids from a Deep-Sea-Derived Aspergillus puniceus Fungus and Their Effects on Liver X Receptor α

Eight new diketopiperazine-type alkaloids including four oxepin-containing diketopiperazine-type alkaloids, oxepinamides H-K (1-4), and four 4-quinazolinone alkaloids, puniceloids A-D (5-8), together with two known analogues (9 and 10), were isolated from the culture broth extracts of the deep-sea-derived fungus Aspergillus puniceus SCSIO z021. Their structures were elucidated by spectroscopic analyses, and their absolute configurations were determined by Marfey's method along with comparison of their specific rotations and ECD spectra. The absolute configurations of 4 and 5 were further confirmed by a single-crystal X-ray diffraction analysis. Compounds 1-8 showed significant transcriptional activation of liver X receptor α with EC₅₀ values of 1.7-50 μM, and 7 and 8 were the most potent agonists.

Pterosin Sesquiterpenoids from Pteris cretica as Hypolipidemic Agents via Activating Liver X Receptors

Four new pterosin sesquiterpenoids (1-4), a new ent-kaurane diterpenoid (17), and 18 known compounds were isolated from the aerial parts of Pteris cretica L. The structures of the isolates were elucidated based on spectroscopic data analysis, and their absolute configurations were determined by comparison of experimental and calculated electronic circular dichroism spectra. The compounds were evaluated for lipid-lowering effects in 3T3-L1 adipocytes. Compounds 4, 8, 17, and 22 were more potent than the positive control, berberine, in decreasing triglycerides activity, with compound 4 exerting the most potent activity. Compound 4 activated LXRα/β in a HEK 293T cell-based reporter gene assay. Molecular dynamic simulations revealed that compound 4 activates liver X receptors (LXRs) through hydrogen bonding with the residues of LXRα/β, suggesting that compound 4 reduces total triglycerides through the regulation of LXRα/β.

Saponin-enriched sea cucumber extracts exhibit an antiobesity effect through inhibition of pancreatic lipase activity and upregulation of LXR-β signaling

CONTEXT

Sea cucumbers have been consumed as tonic, food, and nutrition supplements for many years.

OBJECTIVE

The objective of this study is to investigate the antiobesity and lipid-lowering effects of sea cucumber extracts in in vitro and in vivo models and elucidate the mechanism of action of the extracts on obesity and dyslipidemia.

MATERIALS AND METHODS

The 60% ethanol extracts from the body walls of 10 different sea cucumbers were investigated for the inhibition of pancreatic lipase (PL) activity in vitro. The optimal active extract (SC-3) was further chemically analyzed by LC-MS and UV. And 0.1% and 0.2% of SC-3 was mixed with a high-fat diet to treat C57/BL6 mice for 6 weeks or 2 weeks as preventive and therapeutic study. The body weight, serum, and liver lipid profile in the mice were investigated.

RESULTS

The crude extract of Pearsonothuria graeffei Semper (Holothuriidae) inhibited the PL activity by 36.44% of control at 0.5 μg/mL. SC-3 and echinoside A inhibited PL with an IC50 value at 2.86 μg/mL and 0.76 μM. 0.1% of SC-3 reduced the body weight (23.0 ± 0.62 versus 26.3 ± 0.76 g), the serum TC (2.46 ± 0.04 versus 2.83 ± 0.12 mmol/L), TG (0.19 ± 0.08 versus 0.40 ± 0.03 mmo/L), and LDL-c (0.48 ± 0.02 versus 0.51 ± 0.02 mmol/L), and liver TC (1.19 ± 0.17 versus 1.85 ± 0.13 mmol/mg) and TG (6.18 ± 0.92 versus 10.87 ± 0.97 mmol/mg) contents of the obese C57BL/six mice on a high-fat diet.

DISCUSSION AND CONCLUSION

Sea cucumber may be used for developing antiobesity and antihyperlipidemia drugs.

Nectandrin B, a lignan isolated from nutmeg, inhibits liver X receptor-α-induced hepatic lipogenesis through AMP-activated protein kinase activation

Nonalcoholic fatty liver disease is recognized as the most commonly occurring chronic liver disease. Liver X receptor α (LXRα) and sterol regulatory element-binding protein (SREBP)-1c play a central role in de novo fatty acid synthesis. This study investigated pharmacological effects of nectandrin B, a lignan isolated from nutmeg extract, on hepatic lipogenesis stimulated by LXRα-SREBP-1c-mediated pathway and the possible molecular basis. The reporter gene assay revealed that nectandrin B completely represses LXRα activity enhanced by a synthetic LXRα ligand (T0901317) in HepG2 cells. The inhibitory effect was further supported by the suppression of mRNA expression of LXRα target genes, SREBP-1c and LXRα itself. Nectandrin B also inhibited the increase in SREBP-1c expression promoted by insulin plus high glucose, major contributors to hepatic lipid accumulation. LXRα-SREBP-1c-mediated induction of acetyl-CoA carboxylase 1 and fatty acid synthase, major genes for de novo lipogenesis, was suppressed by nectandrin B. Moreover, Oil Red O staining showed that nectandrin B notably attenuates LXRα-induced lipid accumulation. AMP-activated protein kinase (AMPK) inhibits the activities of LXRα and SREBP-1c. Nectandrin B strongly activated AMPK signaling in HepG2 cells. Taken together, the suppressive effects of nectandrin B on lipogenic gene expression and lipid accumulation in hepatocytes may be due to its inhibitory effect on the LXRα-SREBP-1c pathway presumably via AMPK activation. These results suggest the potential of nectandrin B as a therapeutic candidate for fatty liver disease.