Anti-Inflammatory Effects of Abeliophyllum distichum Nakai (Cultivar Okhwang 1) Callus through Inhibition of PI3K/Akt, NF-κB, and MAPK Signaling Pathways in Lipopolysaccharide-Induced Macrophages

One of the Korean endemic plants, Abeliophyllum distichum Nakai (Oleaceae), contains acteoside, which is a glycoside exhibiting neuroprotective, anti-inflammation effects and antibacterial capacities. We conducted an investigation on the effects of the callus of A. distichum (cultivar Okhwang 1, CAO) on pro-inflammatory mediators released following nuclear factor-кB (NF-кB), phosphatidylinositol 3-kinase/Akt (PI3K-Akt) and mitogen-activated protein kinase (MAPK) signal activation in lipopolysaccharide (LPS)-induced RAW 264.7 cells. Immunoblotting was employed to find out the expression of cyclooxygenase-2 (COX-2), inducible nitric oxide (iNOS), and activation of MAPK molecules, NF-κB and Akt. Cytokines, COX-2, and iNOS gene expression were assessed using polymerase chain reaction techniques. Cytokines, COX-2, and iNOS gene expression were assessed using polymerase chain reaction techniques. High-performance liquid chromatography revealed that CAO was rich in acteoside and isoacteoside. As a result, CAO inhibited the generation of NO, cytokines, COX-2, and iNOS expression. Further, translocation to the nuclear of NF-κB p65 and degradation of the inhibitor of NF-кB (IкB) were alleviated by suppressing phosphorylation. Additionally, CAO significantly impacted MAPK pathway activation by potentially reducing phosphorylation of MAPKs. These results indicate that the anti-inflammatory effect of CAO is mediated via the inhibition of MAPK, PI3K/Akt, and NF-κB signaling pathways, probably via glycosides, phenolics, and flavonoids bioactivity derived from plants. CAO can serve as a potential anti-inflammatory agent, which alleviates inflammation factors and act through specific cell signaling pathways.

Volatile Profiles of Five Variants of Abeliophyllum distichum Flowers Using Headspace Solid-Phase Microextraction Gas Chromatography–Mass Spectrometry (HS-SPME-GC-MS) Analysis

Abeliophyllum distichum (Oleaceae), which is the only species in the monotypic genus and is grown only on the Korean peninsula, has a high scarcity value. Its five variants (white, pink, round, blue, and ivory) have different morphological characteristics in terms of the color of petals and sepals or shape of the fruits. Despite its high value, there has been no study on variant classification except in terms of their morphological characteristics. Thus, we performed a volatile component analysis of A. distichum flowers and multivariate data analyses to reveal the relationship between fragments emitted from five variants of A. distichum flowers with their morphological characteristics. As a result, 66 volatile components of this plant were identified by headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC-MS), showing unique patterns for each set of morphological characteristics, especially the color of the petals. These results suggest that morphological characteristics of each variant are related to the volatile composition.

UPLC-ESI-Q-TOF-MS-Based Metabolite Profiling, Antioxidant and Anti-Inflammatory Properties of Different Organ Extracts of Abeliophyllum distichum

Plant extracts have gained more attention as natural therapeutic agents against inflammation characterized by an overproduction of several inflammatory mediators such as reactive oxygen species and pro-inflammatory cytokines. Although Abeliophyllum distichum Nakai is generally known for its ornamental value, recent pharmacological research has demonstrated its potential therapeutic properties. Thus, to further evaluate the applicability of A. distichum in the food, cosmetic, and medical industries, we identified the phytochemicals in three organ extracts (fruits: AF, branches: AB, leaves: AL) of A. distichum and determined their antioxidant and anti-inflammatory activities. Using UPLC-ESI-Q-TOF-MS, a total of 19 compounds, including dendromoniliside D, forsythoside B, isoacteoside, isomucronulatol 7-O-Glucoside, plantamajoside, and wighteone were identified in the A. distichum organ extracts. AB exhibited a strong reducing power, an oxygen radical antioxidant capacity, and radical scavenging values compared with other samples, whereas AL exhibited the best anti-inflammatory properties. Gene expression, western blot, and molecular docking analyses suggested that the anti-inflammatory effect of AL was mediated by its ability to suppress lipopolysaccharide (LPS)-induced production of reactive oxygen species and/or inhibit LPS-stimulated activation of extracellular signal-regulated protein kinases (ERK1/2) in RAW264.7 cells. Collectively, these results indicate that AL is a potential source of phytochemicals that could be used to treat inflammation-associated diseases.

The chemical composition and anti-inflammatory effect of the essential oil obtained from Abeliophyllum distichum flowers

In the present study, the chemical composition of the essential oil (EO) obtained from the flowers of Abeliophyllum distichum, commonly known as white forsythia, was examined by gas chromatography-mass spectrometry (GC/MS). Thirty-five components including epoxy linalool, methyl salicylate, linalool oxide (pyranoid), and L-linalool were identified in the EO of A. distichum flowers (AfEO). In addition, the AfEO exhibited a remarkable anti-inflammatory effect in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. We found that this anti-inflammatory effect was mediated by inhibiting the expression of proinflammatory mediators, including IL-1?, IL-6, and IL-18. Taken together, these results confirm the potential use of the AfEO as an anti-inflammatory agent for topical application.

Antioxidant Activity and Acteoside Analysis of Abeliophyllum distichum

This study determined acteoside and its content in Abeliophyllum distichum via HPLC/UV and LC/ESI-MS to obtain insights into the potential use of this plant as an antioxidant agent. Moreover, 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl (•OH), and O2− radical scavenging activity assays were performed to assess in vitro antioxidative activity. The DPPH, •OH, and O2− radical scavenging activities of A. distichum leaf EtOH extracts at a 250 μg/mL concentration were 88.32%, 94.48%, and 14.36%, respectively, whereas those of stem extracts at the same concentration were 88.15%, 88.99%, and 15.36%, respectively. The contents of acteoside in A. distichum leaves and stems were 162.11 and 29.68 mg/g, respectively. Acteoside was identified as the main antioxidant compound in A. distichum leaves, which resulted in DPPH, •OH, and O2− radical scavenging activities of 82.84%, 89.46%, and 30.31%, respectively, at a 25 μg/mL concentration. These results indicate that A. distichum leaves and stems containing the antioxidant acteoside can be used as natural ingredients for functional and nutritional supplements.

Abeliophyllum distichum Ameliorates High-Fat Diet-Induced Obesity in C57BL/6J Mice by Upregulating the AMPK Pathway

The use of natural compounds as anti-obesity agents has been gaining attention over the past few years. Abeliophyllum distichum Nakai is endemic to Korea. In the present study, an A. distichum leaf extract (AE) was analyzed for its anti-obesity effects in mice fed a high-fat diet. Seven-week-old male C57BL/6J mice were divided into five groups, namely, normal diet (ND), high-fat diet (HD), HD + Garcinia (GE300), HD + AE low dose (AE100), and HD + AE high dose (AE300). After 8 weeks of the experimental period, treatment with AE reduced body weight and ameliorated high-fat diet-induced changes in serum lipid levels. Histological analysis revealed that treatment with AE decreased lipid accumulation in the liver and brown adipose tissue. Also, AE reduced the adipocyte size in epididymal fat. The reduction in adipose tissue mass in the AE-treated groups was clearly visible in micro-computed tomography images. The expression levels of lipogenic genes, such as PPARγ, C/EBPα, ACC, and FAS, were significantly reduced in the AE300 group. The levels of p-AMPK and p-ACC were increased in the AE300 group compared to the HD group, indicating that the anti-obesity effect of AE was mediated through the AMPK pathway.

Verbascoside-Rich Abeliophyllum distichum Nakai Leaf Extracts Prevent LPS-Induced Preterm Birth Through Inhibiting the Expression of Proinflammatory Cytokines from Macrophages and the Cell Death of Trophoblasts Induced by TNF-α

Background: Preterm birth is a known leading cause of neonatal mortality and morbidity. The underlying causes of pregnancy-associated complications are numerous, but infection and inflammation are the essential high-risk factors. However, there are no safe and effective preventive drugs that can be applied to pregnant women. Objective: The objectives of the study were to investigate a natural product, Abeliophyllum distichum leaf (ADL) extract, to examine the possibility of preventing preterm birth caused by inflammation. Methods: We used a mouse preterm birth model by intraperitoneally injecting lipopolysaccharides (LPS). ELISA, Western blot, real-time PCR and immunofluorescence staining analyses were performed to confirm the anti-inflammatory efficacy and related mechanisms of the ADL extracts. Cytotoxicity and cell death were measured using Cell Counting Kit-8 (CCK-8) analysis and flow cytometer. Results: A daily administration of ADL extract significantly reduced preterm birth, fetal loss, and fetal growth restriction after an intraperitoneal injection of LPS in mice. The ADL extract prevented the LPS-induced expression of TNF-α in maternal serum and amniotic fluid and attenuated the LPS-induced upregulation of placental proinflammatory genes, including IL-1β, IL-6, IL-12p40, and TNF-α and the chemokine gene CXCL-1, CCL-2, CCL3, and CCL-4. LPS-treated THP-1 cell-conditioned medium accelerated trophoblast cell death, and TNF-α played an essential role in this effect. The ADL extract reduced LPS-treated THP-1 cell-conditioned medium-induced trophoblast cell death by inhibiting MAPKs and the NF-κB pathway in macrophages. ADL extract prevented exogenous TNF-α-induced increased trophoblast cell death and decreased cell viability. Conclusions: We have demonstrated that the inhibition of LPS-induced inflammation by ADL extract can prevent preterm birth, fetal loss, and fetal growth restriction.

Transcriptome Analysis Reveals That Abeliophyllum distichum Nakai Extract Inhibits RANKL-Mediated Osteoclastogenensis Mainly through Suppressing Nfatc1 Expression

Abeliophyllum distichum Nakai is known as a monotypic genus endemic to South Korea. Currently, several pharmacological studies have revealed that A. distichum extract exhibits diverse biological functions, including anti-cancer, anti-diabetic, anti-hypertensive, and anti-inflammatory activities. In this study, we present the anti-osteoporotic activity of A. distichum extract by inhibiting osteoclast formation. First, we show that the methanolic extract of the leaves of A. distichum, but not extracts of the branches or fruits, significantly inhibits receptor activator of the NF-κB ligand (RANKL)-induced osteoclast differentiation. Second, our transcriptome analysis revealed that the leaf extract (LE) blocks sets of RANKL-mediated osteoclast-related genes. Third, the LE attenuates the phosphorylation of extracellular signal-related kinase. Finally, treatment with the LE effectively prevents postmenopausal bone loss in ovariectomized mice and glucocorticoid-induced osteoporosis in zebrafish. Our findings show that the extract of A. distichum efficiently suppressed osteoclastogenesis by regulating osteoclast-related genes, thus offering a novel therapeutic strategy for osteoporosis.