Antiangiogenic Activity of Acer tegmentosum Maxim Water Extract in Vitro and in Vivo

Acer tegmentosum Maxim and Bacillus subtilis-fermented products inhibit TNF-α-induced endothelial inflammation and vascular dysfunction of the retina: the role of tyrosol moiety in active compounds targeting Glu230 in SIRT1

Acer tegmentosum Maxim (AT) is a medicinal plant used to treat hepatic, neurological diseases, and cancer. However, the beneficial effects of AT on endothelial dysfunction have not been reported yet. In this study, we evaluated the effects of AT and the main compounds against TNF-α-mediated inflammatory responses and their possible mechanism of action. The anti-inflammatory effect and its molecular mechanism were analyzed by adhesion assay, immunoblotting, promoter-luciferase assay, ELISA, RT-PCR, immunocytochemistry, immunoprecipitation, siRNA gene knockdown, docking, and molecular dynamics simulation. AT and its compounds salidroside and tyrosol reduced TNF-α-induced adhesion between monocytes and endothelial cells. Fermentation of AT with Bacillus subtilis converted salidroside to tyrosol, which is salidroside's aglycone. The fermented AT product (ATF) potently inhibited TNF-α-mediated monocyte adhesion with higher potency than AT. AT or ATF abrogated TNF-α-induced expression of adhesion molecules (VCAM-1 and ICAM-1) and production of MCP-1 with the inhibition of phosphorylated MAP kinases. TNF-α-mediated NF-κB transactivation and RelA/p65 acetylation were suppressed by AT and ATF through the interaction of NF-κB with sirtuin-1 (SIRT1), an NAD+-dependent histone deacetylase. Sirt1 gene knockdown diminished the protective effects of AT and ATF against TNF-α-mediated signaling and inflammatory response. Interestingly, SIRT1 protein expression was significantly increased by ATF and tyrosol rather than by AT and salidroside, respectively. Molecular docking showed that the tyrosol moiety is critical for the interaction with Glu230 of SIRT1 (PDB ID: 4ZZH and 4ZZJ) for the deacetylase activity. Molecular dynamics revealed that tyrosol can induce the movement of the N-terminal domain toward the catalytic domain of SIRT1. This study demonstrates the potential of AT and ATF to prevent endothelial inflammation and vascular dysfunction of the retina by the MAPK/NF-κB/SIRT1 signaling pathways and targeting of the tyrosol moiety to Glu230 in SIRT1.

Therapeutic Effect of Acer tegmentosum Maxim Twig Extract in Bile Duct Ligation-Induced Acute Cholestasis in Mice

Cholestatic liver disease, or cholestasis, is a condition characterized by liver inflammation and fibrosis following a bile duct obstruction and an intrahepatic accumulation of bile acids. Inhibiting inflammation is a promising therapeutic strategy for cholestatic liver diseases. Acer tegmentosum Maxim extract (ATE) is best known for its anti-inflammatory and antioxidative properties. In this study, we investigated the effects of ATE on liver injury and fibrosis in mice with bile duct ligation (BDL)-induced cholestasis through analysis of gene expression, cytokines, and histological examination. Oral administration of ATE (20 or 50 mg/kg) for 14 days significantly attenuated hepatocellular necrosis compared to vehicle-treated BDL mice, which was accompanied by the reduced level of serum bile acids and bilirubin. We determined that ATE treatment reduced liver inflammation, oxidative stress, and fibrosis. These beneficial effects of ATE were concurrent with the decreased expression of genes involved in the NF-κB pathway, suggesting that the anti-inflammatory effect of ATE could be a possible mechanism against cholestasis-associated liver injury. Our findings substantiate ATE's role as an alternative therapeutic agent for cholestasis-induced liver injury and fibrosis.

Acer tegmentosum Maxim Inhibits Adipogenesis in 3t3-l1 Adipocytes and Attenuates Lipid Accumulation in Obese Rats Fed a High-Fat Diet

We investigated the effect of Acer tegmentosum Maxim (ATM) on adipocyte differentiation in 3T3-L1 cells and anti-obesity properties in obese rats fed a high-fat diet (HFD). Cellular lipid content in DMI (dexamethasone, 3–isobutyl–1–methylxanthine, and insulin mixture)-treated cells increased, while ATM treatment caused a significant reduction in lipid accumulation in differentiated 3T3-L1 cells. ATM (60 ug/mL) caused inhibition of adipogenesis via down-regulation of the CCAAT/enhancer binding protein β (C/EBPβ) (48%), C/EBPα (66%), and peroxisome proliferator-activated receptor γ (PPARγ) (64%) expressions in 3T3-L1 cells. Moreover, ATM induced a decrease in the expressions of adipocyte-specific genes, such as adipocyte fatty acid-binding protein-2 (aP2), fatty acid synthase (FAS), and lipoprotein lipase (LPL). Protein kinase B (Akt) and glycogen synthase kinase 3β (GSK3β) phosphorylation was also decreased by ATM treatment of 3T3-L1 adipocytes. We investigated the anti-obesity effects of ATM on HFD-induced obese rats. Rats fed with an HFD demonstrated elevations in body weight gain, while the administration of ATM reversed body weight (BW) gains and adipose tissue weights in rats fed an HFD. ATM supplementation caused a decrease in the circulating triglyceride and total cholesterol levels and led to inhibition of lipid accumulation in the adipose tissues in HFD-induced obese rats. Epididymal fat exhibited significantly larger adipocytes in the HFD group than it did in the ATM-treated group. These results demonstrate that ATM administration caused a reduction in adiposity via attenuation in adipose tissue mass and adipocyte size.

Antiangiogenic activity of terpenoids from Euphorbia neriifolia Linn

Angiogenesis is known to serve an important role in embryonic development, wound healing, tissue regeneration, and growth. Two new abietane-type diterpenoids (3, 5), a new lanosterol triterpenoid (8) and seven known compounds haven been isolated from the Euphorbia neriifolia Linn. The structures of all compounds were elucidated by spectroscopic analysis and comparing their NMR data with reported data. Furthermore, we found that compounds 6 and 9 had the antiangiogenic effects in vitro. They could inhibit HUVEC migration and microvessel sprouting in rat aortic rings. Moreover, compound 6 inhibited VEGFR and phosphorylation of Akt, but compound 9 only shown inhibitory effect on phosphorylation of Akt. Taken together, these results suggest that inhibition of VEGF signaling and downstream pathways may be responsible for the antiangiogenic activity of compounds 6 and 9.

Hepatoprotective effects of an Acer tegmentosum Maxim extract through antioxidant activity and the regulation of autophagy

ETHNOPHARMACOLOGICAL RELEVANCE

Acer tegmentosum Maxim (AT), the East Asian stripe maple, is an herb used to treat liver disease and is approved as a functional food in Korea. AT protects against hepatic disorders, atopic dermatitis, and diabetes mellitus.

AIM OF THE STUDY

We explored the mechanism of the hepatoprotective effects of AT extract in in vitro and in vivo levels.

MATERIALS AND METHODS

AT extract from Acer tegmentosum Maxim was extracted by hot water. Hepatoprotective effects of AT extract were confirmed using carbon tetrachloride (CCl₄)- or alcohol-induced mouse model, and H₂O₂- or alcohol-induced HepG2 (liver hepatocellular carcinoma cell line) cells by measuring GOT, GPT, TG, and MDA levels. Hematoxylin and eosin (H&E) staining was used to observe the pathological analysis. Cytotoxicity or protective effect of AT extract was confirmed using MTT assay in HepG2 cells. Antioxidant effect of AT extract was measured using DPPH or H₂DCFDA assay. Mechanism study of antioxidant and autophagy was carried out using western blotting and immunofluorescence analysis.

RESULTS

AT extract increased the viability of HepG2 cells treated with H₂O₂ and ethanol, and protected the liver against damage induced by CCl₄ and alcohol. The AT extract increased the levels of nuclear respiratory factor 2 (Nrf2) and heme oxygenase-1 (HO-1). The level of microtubule-associated protein light chain 3 (LC3)-Ⅱ, beclin-1, autophagy-related genes (Atg) such as Atg3 and Atg12-5 as markers of autophagy activation was also increased. Moreover, the AT extract increased activation of mitogen-activated protein kinase (MAPK), which regulated autophagy and HO-1.

CONCLUSION

Therefore, these results indicate that the AT extract has a hepatoprotective effect by increasing antioxidant activity and inducing autophagy.

Natural products against cancer angiogenesis

The process of angiogenesis is quite well-known nowadays. Some medicines and extracts affecting this process are already used routinely in supporting the conventional treatment of many diseases that are considered angiogenic such as cancer. However, we must be aware that the area of currently used drugs of this type is much narrower than the theoretical possibilities existing in therapeutic angiogenesis. Plant substances are a large and diverse group of compounds that are found naturally in fruits, vegetables, spices, and medicinal plants. They also have different anticancer properties. The aim of this literature review article is to present the current state of knowledge concerning the molecular targets of tumor angiogenesis and the active substances (polyphenols, alkaloids, phytohormones, carbohydrates, and terpenes) derived from natural sources, whose activity against cancer angiogenesis has been confirmed.