Platycodin D inhibits adipogenesis of 3T3-L1 cells by modulating Kruppel-like factor 2 and peroxisome proliferator-activated receptor gamma

Medicinal Plant Extracts against Cardiometabolic Risk Factors Associated with Obesity: Molecular Mechanisms and Therapeutic Targets

Obesity has increasingly become a worldwide epidemic, as demonstrated by epidemiological and clinical studies. Obesity may lead to the development of a broad spectrum of cardiovascular diseases (CVDs), such as coronary heart disease, hypertension, heart failure, cerebrovascular disease, atrial fibrillation, ventricular arrhythmias, and sudden cardiac death. In addition to hypertension, there are other cardiometabolic risk factors (CRFs) such as visceral adiposity, dyslipidemia, insulin resistance, diabetes, elevated levels of fibrinogen and C-reactive protein, and others, all of which increase the risk of CVD events. The mechanisms involved between obesity and CVD mainly include insulin resistance, oxidative stress, inflammation, and adipokine dysregulation, which cause maladaptive structural and functional alterations of the heart, particularly left-ventricular remodeling and diastolic dysfunction. Natural products of plants provide a diversity of nutrients and different bioactive compounds, including phenolics, flavonoids, terpenoids, carotenoids, anthocyanins, vitamins, minerals, fibers, and others, which possess a wide range of biological activities including antihypertensive, antilipidemic, antidiabetic, and other activities, thus conferring cardiometabolic benefits. In this review, we discuss the main therapeutic interventions using extracts from herbs and plants in preclinical and clinical trials with protective properties targeting CRFs. Molecular mechanisms and therapeutic targets of herb and plant extracts for the prevention and treatment of CRFs are also reviewed.

Recent Advances of Natural Pentacyclic Triterpenoids as Bioactive Delivery System for Synergetic Biological Applications

Bioactive compounds have drawn much attention according to their various health benefits. However, poor dissolvability, low stability and limited bioavailability largely narrow their applications. Although a variety of nontoxic ingredients have been rapidly developed as vehicles to deliver bioactive compounds in the last few years, most of them are non-bioactive. Pentacyclic triterpenoids, owing to their unique self-assembly and co-assembly behaviors and different physiological functions, can construct bioactive carriers due to their higher biodegradability, biocompatibility and lower toxicity. In this paper, the basic classification, biological activities and physicochemical properties of pentacyclic triterpenoids were summarized. Additionally, applications of self-assembled and co-assembled pentacyclic triterpenoids as bioactive delivery systems to load bioactive components and future research directions were discussed. This study emphasizes the potential of pentacyclic triterpenoids as bioactive delivery systems, offering a new perspective for constructing self- or co-assemblies for further synergetic biological applications.

Platycodin D induces apoptosis via regulating MAPK pathway and promotes autophagy in colon cancer cell

Platycodin D (PD) is the main component of triterpene saponins found in Platycodi radix. In this study, we observed a decrease in cell viability, an increase in apoptotic bodies, and an increase in the rate of apoptosis. Also, we observed an increase in cleaved PARP and Bax, a decrease in Bcl-2, and p-ERK, and an increase in p-p38 and p-JNK. Furthermore, a change in cell viability and the expression of p-p38, Bax, and Bcl-2 using the p38 inhibitor revealed a decrease in p-p38 and Bax and an increase in Bcl-2 in the inhibitor treatment group. In addition, we observed an increase in vacuole formation through morphological changes and an increase in acidic vesicular organelles (AVOs). We also observed an increase in the expression of beclin 1, LC 3-I, and -II. There was no significant decrease in cell viability in the group treated with 3-MA, but a decrease in cell viability was noted in the group treated with HCQ. HCQ treatment resulted in an increase in Bax and a decrease in Bcl-2. These findings reveal that in HT-29 colon cancer cells, PD induces apoptosis through the MAPK pathway, thereby exerting anticancer effects. Moreover, autophagy caused by PD inhibits apoptosis by protecting the cells.

New insights into anti-diabetes effects and molecular mechanisms of dietary saponins

Diabetes mellitus (DM) is a long-term metabolic disorder that manifests as chronic hyperglycemia and impaired insulin, bringing a heavy load on the global health care system. Considering the inevitable side effects of conventional anti-diabetic drugs, saponins-rich natural products exert promising therapeutic properties to serve as safer and more cost-effective alternatives for DM management. Herein, this review systematically summarized the research progress on the anti-diabetic properties of dietary saponins and their underlying molecular mechanisms in the past 20 years. Dietary saponins possessed the multidirectional anti-diabetic capabilities by concurrent regulation of various signaling pathways, such as IRS-1/PI3K/Akt, AMPK, Nrf2/ARE, NF-κB-NLRP3, SREBP-1c, and PPARγ, in liver, pancreas, gut, and skeletal muscle. However, the industrialization and commercialization of dietary saponin-based drugs are confronted with a significant challenge due to the low bioavailability and lack of the standardization. Hence, in-depth evaluations in pharmacological profile, function-structure interaction, drug-signal pathway interrelation are essential for developing dietary saponins-based anti-diabetic treatments in the future.

The pharmacology and mechanisms of platycodin D, an active triterpenoid saponin from Platycodon grandiflorus

Chinese doctors widely prescribed Platycodon grandiflorus A. DC. (PG) to treat lung carbuncles in ancient China. Modern clinical experiences have demonstrated that PG plays a crucial role in treating chronic pharyngitis, plum pneumonia, pneumoconiosis, acute and chronic laryngitis, and so forth. Additionally, PG is a food with a long history in China, Japan, and Korea. Furthermore, Platycodin D (PLD), an oleanane-type triterpenoid saponin, is one of the active substances in PG. PLD has been revealed to have anti-inflammatory, anti-viral, anti-oxidation, anti-obesity, anticoagulant, spermicidal, anti-tumor etc., activities. And the mechanism of the effects draws lots of attention, with various signaling pathways involved in these processes. Additionally, research on PLD's pharmacokinetics and extraction processes is under study. The bioavailability of PLD could be improved by being prescribed with Glycyrrhiza uralensis Fisch. or by creating a new dosage form. PLD has been recently considered to have the potential to be a solubilizer or an immunologic adjuvant. Meanwhile, PLD was discovered to have hemolytic activity correlated. PLD has broad application prospects and reveals practical pharmacological activities in pre-clinical research. The authors believe that these activities of PLD contribute to the efficacy of PG. What is apparent is that the clinical translation of PLD still has a long way to go. With the help of modern technology, the scope of clinical applications of PLD is probable to be expanded from traditional applications to new fields.

Traditional Chinese medicine for colorectal cancer treatment: potential targets and mechanisms of action

Colorectal cancer (CRC) is a disease with complex pathogenesis, it is prone to metastasis, and its development involves abnormalities in multiple signaling pathways. Surgery, chemotherapy, radiotherapy, target therapy, and immunotherapy remain the main treatments for CRC, but improvement in the overall survival rate and quality of life is urgently needed. Traditional Chinese medicine (TCM) has a long history of preventing and treating CRC. It could affect CRC cell proliferation, apoptosis, cell cycle, migration, invasion, autophagy, epithelial-mesenchymal transition, angiogenesis, and chemoresistance by regulating multiple signaling pathways, such as PI3K/Akt, NF-κB, MAPK, Wnt/β-catenin, epidermal growth factor receptors, p53, TGF-β, mTOR, Hedgehog, and immunomodulatory signaling pathways. In this paper, the main signaling pathways and potential targets of TCM and its active ingredients in the treatment of CRC were systematically summarized, providing a theoretical basis for treating CRC with TCM and new ideas for further exploring the pathogenesis of CRC and developing new anti-CRC drugs.

Platycodin D induces neutrophil apoptosis by downregulating PD-L1 expression to inhibit breast cancer pulmonary metastasis

During breast cancer development, programmed cell death 1 ligand 1 (PD-L1) overexpression in neutrophils leads to delayed apoptosis and promotes neutrophil hyperproliferation in the lung to form a premetastatic niche, which is beneficial for pulmonary metastasis. Platycodin D (PlaD), a triterpenoid saponin with known anti-inflammatory and antitumor effects, has been reported to downregulate PD-L1 expression. This study aimed to investigate the inhibitory effect of PlaD on neutrophil PD-L1 in 4 T1 tumor-bearing mice and the potential mechanism of breast cancer pulmonary metastasis. In this study, the orthotopic 4 T1 murine mammary carcinoma model was administered 10 and 20 mg/kg PlaD by gavage. PlaD reduced the excess neutrophils and decreased their high migratory capacity in bone marrow, peripheral blood and lung tissue in the premetastatic period, thereby effectively inhibiting tumor growth and pulmonary metastasis. Moreover, PlaD inhibited the phosphatidylinositol-3-kinase (PI3K)/Akt pathway by decreasing the expression of PD-L1 in neutrophils and promoted neutrophil apoptosis. In vitro, PlaD treatment decreased the viability and inhibited migration of neutrophil-like dHL-60 in a dose-dependent manner. Similarly, PlaD inhibited the increase in PD-L1 induced by IFN-γ stimulation and subsequently induced apoptosis in dHL-60 cells. In conclusion, the administration of PlaD inhibited the PI3K/Akt signaling pathway by reducing the expression of PD-L1 in neutrophils. PlaD promoted neutrophil apoptosis, thereby inhibiting the establishment of a premetastatic niche and ultimately blocking the development of pulmonary metastasis.

Platycodin D sensitizes KRAS-mutant colorectal cancer cells to cetuximab by inhibiting the PI3K/Akt signaling pathway

Cetuximab is a monoclonal antibody against epidermal growth factor receptor that blocks downstream signaling pathways of receptor tyrosine kinases, including Ras/Raf/MAPK and PI3K/Akt, thereby inhibiting tumor cell proliferation and inducing cancer cell apoptosis. Owing to KRAS mutations, the effectiveness of cetuximab is usually limited by intrinsic drug resistance. Continuous activation of the PI3K/Akt signaling pathway is another reason for cetuximab resistance. Platycodin-D, a bioactive compound isolated from the Chinese herb Platycodon grandiflorum, regulates Akt in different trends based on tissue types. To investigate whether platycodin-D can sensitize KRAS-mutant colorectal cancer cells to cetuximab by inhibiting the PI3K/Akt signaling pathway, HCT116 and LoVo cells were treated with cetuximab and platycodin-D. LY294002 and SC79 were used to regulate Akt to further evaluate whether platycodin-D sensitizes cells to cetuximab by inhibiting Akt. Our results confirmed that platycodin-D increased the cytotoxic effects of cetuximab, including inhibition of growth, migration, and invasion, via downregulation of PI3K and Akt phosphorylation in HCT116 and LoVo cells both in vitro and in vivo. Given these data, platycodin-D may sensitize KRAS-mutant colorectal cancer cells to cetuximab via inhibition of the PI3K/Akt signaling pathway.

Terpenoids' anti-cancer effects: focus on autophagy

Terpenoids are the largest class of natural products, most of which are derived from plants. Amongst their numerous biological properties, their anti-tumor effects are of interest for they are extremely diverse which include anti-proliferative, apoptotic, anti-angiogenic, and anti-metastatic activities. Recently, several in vitro and in vivo studies have been dedicated to understanding the 'terpenoid induced autophagy' phenomenon in cancer cells. Light has already been shed on the intricacy of apoptosis and autophagy relationship. This latter crosstalk is driven by the delicate balance between activating or silencing of certain proteins whereby the outcome is expressed via interrelated signaling pathways. In this review, we focus on nine of the most studied terpenoids and on their cell death and autophagic activity. These terpenoids are grouped in three classes: sesquiterpenoid (artemisinin, parthenolide), diterpenoids (oridonin, triptolide), and triterpenoids (alisol, betulinic acid, oleanolic acid, platycodin D, and ursolic acid). We have selected these nine terpenoids among others as they belong to the different major classes of terpenoids and our extensive search of the literature indicated that they were the most studied in terms of autophagy in cancer. These terpenoids alone demonstrate the complexity by which these secondary metabolites induce autophagy via complex signaling pathways such as MAPK/ERK/JNK, PI3K/AKT/mTOR, AMPK, NF-kB, and reactive oxygen species. Moreover, induction of autophagy can be either destructive or protective in tumor cells. Nevertheless, should this phenomenon be well understood, we ought to be able to exploit it to create novel therapies and design more effective regimens in the management and treatment of cancer.

Transcription Factor KLF14 and Metabolic Syndrome

Metabolic syndrome (MetSyn) is a combination of metabolic abnormalities that lead to the development of cardiovascular disease (CVD) and Type 2 Diabetes (T2D). Although various criteria for defining MetSyn exist, common abnormalities include abdominal obesity, elevated serum triglyceride, insulin resistance, and blood glucose, decreased high-density lipoprotein cholesterol (HDL-C), and hypertension. MetSyn prevalence has been increasing with the rise of obesity worldwide, with significantly higher prevalence in women compared with men and in Hispanics compared with Whites. Affected individuals are at a higher risk of developing T2D (5-fold) and CVD (2-fold). Heritability estimates for individual components of MetSyn vary between 40 and 70%, suggesting a strong contribution of an individual's genetic makeup to disease pathology. The advent of next-generation sequencing technologies has enabled large-scale genome-wide association studies (GWAS) into the genetics underlying MetSyn pathogenesis. Several such studies have implicated the transcription factor KLF14, a member of the Krüpple-like factor family (KLF), in the development of metabolic diseases, including obesity, insulin resistance, and T2D. How KLF14 regulates these metabolic traits and increases the risk of developing T2D, atherosclerosis, and liver dysfunction is still unknown. There have been some debate and controversial results with regards to its expression profile and functionality in various tissues, and a systematic review of current knowledge on KLF14 is lacking. Here, we summarize the research progress made in understanding the function of KLF14 and describe common attributes of its biochemical, physiological, and pathophysiological roles. We also discuss the current challenges in understanding the role of KLF14 in metabolism and provide suggestions for future directions.

Bioactive platycodins from Platycodonis Radix: Phytochemistry, pharmacological activities, toxicology and pharmacokinetics

Platycodonis Radix, the root of Platycodon grandiflorum (Jacq.) A. DC., is a well-known edible herbal medicine. It is a common vegetable used for the preparation of side dish, kimchi, dessert, and tea. Besides, it has been used to treat respiratory disease including cough, excessive phlegm, and sore throat for a long history. In the past decades, the bioactive components and the pharmacological activities of Platycodonis Radix have been widely investigated. Thereinto, platycodins, the oleanane-type triterpenoid saponins were demonstrated to be the main bioactive components in Platycodonis Radix, and more than 70 platycodins have been identified up to date. This paper mainly reviewed the phytochemistry, pharmacological activities (apophlegmatic, anti-tussive, anti-inflammatory, anti-cancer, anti-obesity, anti-diabetic, immunomodulatory, cardiovascular protective, and hepatoprotective activities, etc.), toxicology and pharmacokinetics of platycodins isolated from Platycodonis Radix, aiming to promote further investigation on therapeutic potential of these platycodins.

Platycodin D, a bioactive component of Platycodon grandiflorum, induces cancer cell death associated with extreme vacuolation

Platycodin D (PD) is a major active component of the roots of Platycodon grandiflorum (Jacq.) A.DC. and possesses multiple biological and pharmacological properties, including anti-cancer activity. The aim of this study was to characterize PD-induced cytoplasmic vacuolation in human cancer cells and investigate the underlying mechanisms. PD-induced cancer cell death was associated with cytoplasmic pinocytic and autophagic vacuolation. Cellular energy levels were decreased by this compound, leading to the activation of AMP-activated protein kinase (AMPK). Additionally, compound C, an inhibitor of AMPK, completely prevented PD-induced vacuolation. These results suggest that PD induces cancer cell death, associated with excessive vacuolation through AMPK activation when cellular energy levels are low. Therefore, our findings provide a mechanistic rationale for a novel combinatorial approach using PD to treat cancer.

Chitosan Oligosaccharides Improve Glucolipid Metabolism Disorder in Liver by Suppression of Obesity-Related Inflammation and Restoration of Peroxisome Proliferator-Activated Receptor Gamma (PPARγ)

Chitosan oligosaccharides (COS) display various biological activities. In this study, we aimed to explore the preventive effects of COS on glucolipid metabolism disorder using palmitic acid (PA)-induced HepG2 cells and high-fat diet (HFD)-fed C57BL/6J mice as experimental models in vitro and in vivo, respectively. The results showed that COS pretreatment for 12 h significantly ameliorated lipid accumulation in HepG2 cells exposed to PA for 24 h, accompanied by a reversing of the upregulated mRNA expression of proinflammatory cytokines (IL-6, MCP-1, TNF-α) and glucolipid metabolism-related regulators (SCD-1, ACC1, PCK1-α). In addition, COS treatment alleviated glucolipid metabolism disorder in mice fed with HFD for five months, including reduction in body weight and fasting glucose, restoration of intraperitoneal glucose tolerance, and suppression of overexpression of proinflammatory cytokines and glucolipid metabolism-related regulators. Furthermore, our study found that COS pretreatment significantly reversed the downregulation of PPARγ at transcriptional and translational levels in both PA-induced HepG2 cells and liver tissues of HFD-fed mice. In summary, the study suggests that COS can improve glucolipid metabolism disorder by suppressing inflammation and upregulating PPARγ expression. This indicates a novel application of COS in preventing and treating glucolipid metabolism-related diseases.

Bioinformatics Analysis and Competitive Regulation by Transcription Factors of SIRT5 at the Core Promoter Region Using Bovine Adipocytes

Sirtuin 5 (SIRT5) belongs to the mitochondrial sirtuin family, which constitutes a highly conserved family of nicotinamide adenine dinucleotide NAD⁺-dependent deacetylases and ADP-ribosyltransferases that play an important regulatory role in stress resistance and metabolic homeostasis. SIRT5, a member of the mitochondrial sirtuins, has been confirmed to exhibit deacetylase, desuccinylase, and demalonylase enzymatic activities. First, we showed that SIRT5 was expressed at the highest level in the bovine testis, followed by longissimus thoracis and subcutaneous adipose tissue, using real-time quantitative PCR and mRNA levels of SIRT5 during adipocyte differentiation, which increased before the first day and then decreased rapidly. To explore the molecular regulation of bovine SIRT5 expression, we cloned a 2-kb fragment of the 5'-regulatory region and the functional proximal minimal promoter of bovine SIRT5. Electrophoretic mobility shift assays and luciferase reporter assays identified Kruppel-like factor 2 (KLF2), CCAAT enhancer binding protein beta (CEBPβ), peroxisome proliferator-activated receptor alpha (PPARα), myogenic differentiation 1 (MYOD), and nuclear respiratory factor 1 (NRF1) binding sites as transcriptional activators or repressors in the core promoter region of SIRT5. In brief, our study focused on the mechanism underlying the transcriptional regulation of SIRT5 expression in bovine adipocytes.

Differential Tissue-specific and Pathway-specific Anti-obesity Effects of Green Tea and Taeumjowitang, a Traditional Korean Medicine, in Mice

Background

Traditional medicines have been leveraged for the treatment and prevention of obesity, one of the fastest growing diseases in the world. However, the exact mechanisms underlying the effects of traditional medicine on obesity are not yet fully understood.

Methods

We produced the transcriptomes of epididymal white adipose tissue (eWAT), liver, muscle, and hypothalamus harvested from mice fed a normal diet, high-fat-diet alone, high-fat-diet together with green tea, or a high-fat-diet together with Taeumjowitang, a traditional Korean medicine.

Results

We found tissue-specific gene expression patterns as follows: (i) the eWAT transcriptome was more significantly altered by Taeumjowitang than by green tea, (ii) the liver transcriptome was similarly altered by Taeumjowitang and green tea, and (iii) both the muscle and hypothalamus transcriptomes were more significantly altered by green tea than Taeumjowitang. We then applied integrated network analyses, which revealed that functional networks associated with lymphocyte activation were more effectively regulated by Taeumjowitang than by green tea in the eWAT. In contrast, green tea was a more effective regulator of functional networks associated with glucose metabolic processes in the eWAT.

Conclusions

Taeumjowitang and green tea have a differential tissue-specific and pathway-specific therapeutic effect on obesity.

Effects of Flavonoids and Triterpene Analogues from Leaves of Eleutherococcus sieboldianus (Makino) Koidz. 'Himeukogi' in 3T3-L1 Preadipocytes

Eleutherococcus sieboldianus (Makino) Koidz. is a local product from the area in and around Yonezawa City in Yamagata Prefecture, Japan. It has been used as a medicinal plant for a long time. We isolated and identified four types of flavonoid glycosides [astragalin (1), isoquercetin (2), rhamnocitrin 3-O-glucoside (3), and nicotiflorin (4)], a triterpene [methyl hederagenin (5)], and three types of triterpene glycosides [δ-hederin (6), echinocystic acid 3-O-arabinoside (7), and cauloside B (8)] from the methanol extract of E. sieboldianus, which regulates lipid accumulation in 3T3-L1 preadipocytes. Among the compounds isolated, 2 and 8 up- and down-regulated lipid accumulation and insulin induced adipocyte differentiation in 3T3-L1 preadipocytes. Compound 2 induced up-regulation of lipid accumulation and decreased adipocyte size, while 8 down-regulated lipid accumulations without decreasing cell size. Additionally, 2 increased adipogenic proteins [peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), and fatty-acid-binding protein 4 (FABP4)]. In contrast, 8 decreased the levels of all adipogenic proteins and glucose transporter type 4 (GLUT4), but increased adiponectin.

Proteomic analysis of hepatocellular carcinoma HepG2 cells treated with platycodin D

Platycodin D (PD), a triterpenoid saponin isolated from Platycodonis Radix, is a famous Chinese herbal medicine that has been shown to have anti-proliferative effects in several cancer cell lines. The aim of this study was to determine the changes in cellular proteins after the treatment of hepatocellular carcinoma HepG2 cells with PD using proteomics approaches. The cell viability was determined using the MTT assay. The proteome was analyzed by two-dimensional difference gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Western blot analysis was used to confirm the expression of changed proteins. Our results showed that PD inhibited the proliferation of HepG2 cells in concentration- and time-dependent manners. Sixteen proteins were identified to be up-regulated in PD-treated HepG2 cells, including ATP5H, OXCT1, KRT9, CCDC40, ERP29, RCN1, ZNF175, HNRNPH1, HSP27, PA2G4, PHB, BANF1, TPM3, ECH1, LGALS1, and MYL6. Three proteins (i.e., RPS12, EMG1, and KRT1) decreased in HepG2 cells after treatment with PD. The changes in HSP27 and PHB were further confirmed by Western blotting. In conclusion, our results shed new lights on the mechanisms of action for the anti-cancer activity of PD.

Lipin1-Mediated Repression of Adipogenesis by Rutin

Rutin, also called rutoside or quercetin-3-O-rutinoside and sophorin, is a glycoside between the flavonol quercetin and the disaccharide rutinose. Although many effects of rutin have been reported in vitro and in vivo, the anti-adipogenic effects of rutin have not been fully reported. The aim of this study was to confirm how rutin regulates adipocyte related factors. In this study, rutin decreased the expressions of adipogenesis-related genes, including peroxisome proliferators, activated receptor [Formula: see text] (PPAR[Formula: see text], CCAAT/enhancer-binding protein [Formula: see text] (C/EBP[Formula: see text], fatty acid synthase, adipocyte fatty acid-binding protein, and lipoprotein lipase in 3T3-L1 cells. Rutin also repressed the expression of lipin1, which is an upstream regulator that controls PPAR[Formula: see text] and C/EBP[Formula: see text]. In addition, when 3T3-L1 was transfected with lipin1 siRNA to block lipin1 function, rutin did not affect the expressions of PPAR[Formula: see text] and C/EBP[Formula: see text]. These results suggest that rutin has an anti-adipogenic effect that acts through the suppression of lipin1, as well as PPAR[Formula: see text] and C/EBP[Formula: see text].

Platycodin D induces apoptosis and triggers ERK- and JNK-mediated autophagy in human hepatocellular carcinoma BEL-7402 cells

AIM

Platycodin D, the main saponin isolated from Chinese herb Platycodonis Radix, exhibits anticancer activities against various cancer cell lines. Here we evaluated its anticancer action against human hepatocellular carcinoma cells in vitro and in vivo, and elucidated the relationship between platycodin D-induced apoptosis and autophagy.

METHODS

The viability of human hepatocellular carcinoma BEL-7402 cells was evaluated with MTT assay, and the apoptosis was examined using Annexin V/PI and Hoechst 33342 staining assays. Monodansylcadaverine (MDC) staining was used to label autophagic vacuoles. The proteins were detected using Western blot analysis. For studying its anticancer action in vivo, platycodin D (5 and 10 mg· kg(-1)·d(-1)) was intraperitoneally injected to BEL-7402-bearing mice for 21 days.

RESULTS

Platycodin D (5-40 μmol/L) inhibited the cell proliferation in vitro with IC50 values of 37.70±3.99, 24.30±2.30 and 19.70±2.36 μmol/L at 24, 48 and 72 h, respectively. Platycodin D (5-20 μmol/L) dose-dependently increased BEL-7402 cell apoptosis, increased the Bax/Bcl-2 ratio and the levels of cleaved PARP and cleaved caspase-3, and decreased the level of Bcl-2. Furthermore, platycodin D (5-20 μmol/L) induced autophagy in BEL-7402 cells, as evidenced by formation of cytoplasmic vacuoles, increased amounts of LC3-II, and increased numbers of MDC-positive cells. Pretreatment with the autophagy inhibitor chloroquine (5 μmol/L) or BAF (50 nmol/L) significantly enhanced platycodin D-induced proliferation inhibition and apoptosis. Moreover, platycodin D (20 μmol/L) activated the ERK and JNK pathways in BEL-7402 cells, and simultaneous blockage of the two pathways effectively suppressed platycodin D-induced autophagy and enhanced platycodin D-induced apoptosis. In BEL-7402-bearing mice, platycodin D (10 mg·kg(-1)•d(-1)) significantly reduced relative tumor volume with decreased body weight.

CONCLUSION

Platycodin D not only inhibits the proliferation of BEL-7402 cells but also suppresses BEL-7402 xenograft tumor growth. Platycodin D-induced cell proliferation inhibition and apoptosis are amplified by co-treatment with autophagy inhibitors.

Platycodon grandiflorum A. De Candolle Ethanolic Extract Inhibits Adipogenic Regulators in 3T3-L1 Cells and Induces Mitochondrial Biogenesis in Primary Brown Preadipocytes

This study was designed to evaluate the effects of Platycodon grandiflorum A. DC. ethanolic extract (PG) on obesity in brown/white preadipocytes. The effect of PG on the differentiation and mitochondrial biogenesis of brown adipocytes is still not examined. An in vivo study showed that PG induced weight loss in mice with high-fat-diet-induced obesity. PG successfully suppressed the differentiation of 3T3-L1 cells by down-regulating cellular induction of the peroxisome proliferators activated receptor γ (PPARγ), CCAAT enhancer binding protein α (C/EBPα), lipin-1, and adiponectin but increasing expression of silent mating type information regulation 2 homologue 1 (SIRT1) and the phosphorylation of AMP-activated protein kinase α (AMPKα). The effect of PG on the adipogenic factors was compared with that of its bioactive compound platycodin D. In addition, PG increased expressions of mitochondria-related genes, including uncoupling protein 1 (UCP1), peroxisome proliferator activated receptor-coactivator 1 α (PGC1α), PR domain containing 16 (PRDM16), SIRT3, nuclear respiratory factor (NRF), and cytochrome C (CytC) in primary brown adipocytes. These results indicate that PG stimulates the differentiation of brown adipocytes through modulation of mitochondria-related genes and could offer clinical benefits as a supplement to treat obesity.

The AMPK pathway mediates an anti-adipogenic effect of fruits of Hovenia dulcis Thunb

Hovenia dulcis Thunb. is well known as a treatment for liver disease. Several studies have demonstrated that extracts of Hovenia dulcis Thunb. or its purified compounds can serve as detoxifying agents for alcohol poisoning. However, its anti-obesity effect has not been reported thus far. In this study, the anti-obesity effect of water extracts from the fruits or stems of Hovenia dulcis Thunb. was examined in 3T3-L1 preadipocytes. The cellular lipid contents in 3T3-L1 adipocytes were assessed by Oil Red O staining. Fruits of Hovenia dulcis Thunb. (FHD) significantly inhibit lipid accumulation during adipogenesis in a dose-dependent manner, but not stems of Hovenia dulcis Thunb. FHD (100 μg ml(-1)) significantly down-regulates the expression of the peroxisome proliferator-activated receptor-γ, CCAAT/enhancer-binding protein-α, adipocyte fatty acid-binding protein 2, adiponectin, and resistin, and the inhibition rates were 29.33%, 54.36%, 34.5%, 55.69%, and 60.39%, respectively. In addition, FHD (100 μg ml(-1)) also up-regulates the phosphorylation of AMP-activated protein kinase (AMPK)-α, liver kinase B1 as a major AMPK kinase, and the downstream substrate acetyl-CoA carboxylase, and the inhibition rates were 43.52%, 38.25%, and 20.39%, respectively. These results indicate that FHD has a significant anti-obesity effect through the modulation of the AMPK pathway, suggesting that FHD has a potential benefit in preventing obesity.

Cineromycin B isolated from Streptomyces cinerochromogenes inhibits adipocyte differentiation of 3T3-L1 cells via Krüppel-like factors 2 and 3

AIMS

3T3-L1 cells are preadipocytes and often used as a model for cellular differentiation to adipocytes; however, the mechanism of this differentiation is not completely understood even in these model cells. In this study, we sought to identify a unique anti-adipogenesis agent from microorganisms and to examine its mechanism of action to gain knowledge and create a tool and/or seed compound for anti-obesity drug discovery research.

MAIN METHOD

Screening for anti-adipogenesis agents from microorganisms was performed using a 3T3-L1 cell differentiation system, and an active compound was isolated. The inhibitory mechanism of the compound was investigated by measuring the expression of key regulators using quantitative real-time PCR and Western blot analysis.

KEY FINDINGS

The compound with anti-adipogenic activity in 3T3-L1 cells was identified as cineromycin B. Cineromycin B at 50 μg/mL suppressed intracellular lipid accumulation and the expression of peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer binding protein alpha (C/EBPα), which are master regulators of adipocyte differentiation. Further investigations showed that cineromycin B increased significantly the mRNA expression of two negative regulators of adipocyte differentiation, Krüppel-like factor (KLF) 2 and KLF3, at an early stage of the differentiation. The results of siRNA transfection experiments indicated that cineromycin B is a unique adipocyte differentiation inhibitor, acting mainly via upregulation of KLF2 and KLF3, and these KLFs may play a role in the early stage of differentiation.

SIGNIFICANCE

Cineromycin B inhibited adipocyte differentiation in 3T3-L1 cells mainly via upregulation of KLF2 and KLF3 mRNA expression at an early stage of the differentiation.

Platycodon grandiflorus - an ethnopharmacological, phytochemical and pharmacological review

ETHNOPHARMACOLOGICAL RELEVANCE

Platycodon grandiflorus (Jacq.) A. DC., the sole species in genus Platycodon A. DC. (Campanulaceae) has a long history of use as a traditional herbal medicine for the treatments of cough, phlegm, sore throat, lung abscess, chest pain, dysuria, and dysentery. As a legal medicine and dietary supplement, it is also frequently used as an ingredient in health foods and vegetable dishes. The aim of this review is to provide up-to-date information on the botanical characterization and distribution, ethnopharmacology, phytochemistry, pharmacology, and toxicity of Platycodon grandiflorus based on literature published in recent years. It will build a foundation for further study of the mechanism of action and the development of better therapeutic agents and healthy products from Platycodon grandiflorus.

MATERIAL AND METHODS

All of the available information on Platycodon grandiflorus was collected via electronic search (using PubMed, SciFinder Scholar, CNKI, TPL (www.theplantlist.org), Google Scholar, Baidu Scholar, and Web of Science).

RESULTS

A comprehensive analysis of the literature obtained through the above-mentioned sources confirmed that ethno-medical uses of Platycodon grandiflorus have been recorded in China, Japan, Mongolia, and Korea for thousands of years. A phytochemical investigation revealed that this product contains steroidal saponins, flavonoids, polyacetylenes, sterols, phenolics, and other bioactive compounds. Crude extracts and pure compounds isolated from Platycodon grandiflorus exhibited significant anti-inflammatory and immunostimulatory effects. They also showed valuable bioactive effects, such as anti-tumor, anti-oxidant, anti-diabetic, anti-obesity, hepatoprotective and cardiovascular system effects, among others.

CONCLUSIONS

In light of its long traditional use and the modern phytochemical and pharmacological studies summarized here, Platycodon grandiflorus has been demonstrated to show a strong potential for therapeutic and health-maintaining uses. Both the extracts and chemical components isolated from the plant showed a wide range of biological activities. Thus, more studies on the pharmacological mechanisms of its main active compounds (e.g., platycodin D, D2) need to be conducted. In addition, as one of the most popular traditional herbal medicines, clinical studies of the main therapeutic aspects, toxicity and adverse effects of Platycodon grandiflorus will also undoubtedly be the focus of future investigation.

Suppressive effects of saponin-enriched extracts from quinoa on 3T3-L1 adipocyte differentiation

This study was performed to investigate the effect of quinoa saponins (QS) on the differentiation of 3T3-L1 preadipocytes.

An HPLC-MS/MS method for the quantitative determination of platycodin D in rat plasma and its application to the pharmacokinetics of Platycodi Radix extract

AIMS

To develop an HPLC-MS/MS method for the quantification of platycodin D (PD) in rat plasma, and to acquire the main pharmacokinetic parameters of PD after oral administration of pure PD or of Platycodi Radix extract (PRE) containing PD.

METHOD

Plasma samples were pretreated with solid-phase extraction using an Oasis® HLB SPE cartridge. Madecassoside was used as the internal standard (IS). Chromatographic separation was achieved on an ODS column (100 mm × 2.1 mm i.d., 3.5 μm) with a mobile phase consisting of acetonitrile/water (30 : 70, V/V) containing 0.1 mmol·L(-1) ammonium acetate at a flow rate of 0.25 mL·min(-1). The detection was performed on a triple quadruple tandem mass spectrometer using an electrospray ionization (ESI) source with a chromatographic run time of 3.0 min. The detection was operated by multiple reaction monitoring (MRM) of the transitions of m/z 1 223.6→469.2 for PD and of m/z 973.6→469.2 for madecassoside (IS), respectively.

RESULTS

The calibration curve was linear from 5 to 2 000 ng·mL(-1) (r(2) >0.99) with a lower limit of quantification (LLOQ) of 5 ng·mL(-1). The intra- and inter-day precision (relative standard deviation, RSD) values were below 15% and the accuracy (relative error, RE) was from -15% to +15% at three quality control (QC) levels. Plasma concentrations of PD were determined for 24 h after i.v. administration of PD, and oral administration of PD and PRE, respectively. The absolute oral bioavailability of PD in rats was found to be (0.48 ± 0.19)% when administered PD, and to be (1.81 ± 0.89)% when administered PRE.

CONCLUSION

The developed HPLC-MS/MS method was successfully applied to assess the pharmacokinetic parameters and oral bioavailability of PD in rats after administration of PD and Platycodi Radix extract.

Effects of phytoestrogens and other plant-derived compounds on mesenchymal stem cells, bone maintenance and regeneration

Phytoestrogens and other plant-derived compounds and extracts have been developed for the treatment of menopause-related complaints and disorders, e.g. hot flushes and osteoporosis. Since estrogens have been discussed to enhance the risk for hormone-sensitive cancers, research activities try to find alternatives. Phytoestrogens like genistein and resveratrol as well as other plant-derived compounds are capable of substituting for estrogens to some extent. Their effects on mesenchymal stem cells and the tissues derived therefrom have been investigated in vitro and in preclinical settings. Besides their well-known estrogenic, i.e. mainly antiresorptive effects on bone via estrogen receptor (ER) signalling, they also directly or indirectly affect osteogenic and adipogenic pathways. As a novel mechanism, phytoestrogens and plant-derived saponins and flavonoids like kaempferol and xanthohumol have been described to reciprocally affect the osteogenic versus the adipogenic differentiation pathway. Both, ER-mediated and other pathways mediate a shift towards osteogenesis by inhibiting PPARγ and C/EBPα, the key adipogenic transcription factors (TFs), while stimulating the key osteogenic TFs Runx2 and Sp7. Besides ER signalling, the broad spectrum of molecular mechanisms supporting osteogenesis comprises the modulation of PPARγ, Wnt/β-catenin, and Sirt1 signalling, which inversely influence the transcription or transactivation of osteogenic versus adipogenic TFs. Preventing the age- and hormone deficiency-related shift towards adipogenesis without provoking adverse estrogenic effects represents a very promising strategy for treating bone loss and other metabolic diseases beyond bone. Research on plant-derived compounds will have to be pursued in vitro as well as in preclinical studies and controlled clinical trials in humans are urgently needed. This article is part of a Special Issue entitled 'Phytoestrogens'.

The Evaluation of the Body Weight Lowering Effects of Herbal Extract THI on Exercising Healthy Overweight Humans: A Randomized Double-Blind, Placebo-Controlled Trial

We investigated the effects of herbal extracts, a mixture of Scutellariae Radix and Platycodi Radix containing the active ingredients Baicalin and Saponin (target herbal ingredient (THI)), on lowering body weight. The present study was a prospective, randomized, double-blind, and placebo-controlled trial carried out at the outpatient department of a hospital over a period of 2 months. Group 1 patients (n = 30) received THI, and group 2 patients (n = 23) received placebo three times a day before meals. Weight, waist circumference, BMI, total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol, and glucose were measured at baseline and again at the 2nd month. For safety evaluation, various hematological and biochemical parameters were assessed. Values of mean change of weight in the THI-treated group were -1.16 ± 1.41 kg and in the placebo-treated group were -0.24 ± 1.70 kg, respectively. The difference in mean change of weight in the THI-treated group compared with that in the placebo-treated group was statistically significant (P < 0.05). The incidence of subjective and objective adverse drug reactions was insignificant (P > 0.05). THI was statistically significant in its effectiveness on the weight loss.

Role of kruppel-like transcription factors in adipogenesis

The zinc-finger transcription factors of the kruppel-like factor family (KLF) are critical in many physiological and pathological processes including cell proliferation, differentiation, inflammation, and apoptosis. Recently, there is increasing evidence that suggests these KLFs have an important role in fat biology. This review summarizes the role of KLFs in lipid metabolism, especially in adipogenesis, and reveals the relationship networks among members of KLF family in differentiation.

Long-Term Consumption of Platycodi Radix Ameliorates Obesity and Insulin Resistance via the Activation of AMPK Pathways

This study was designed to evaluate the effects and mechanism of Platycodi radix, having white balloon flower (Platycodon grandiflorum for. albiflorum (Honda) H. Hara) on obesity and insulin resistance. The extracts of Platycodi radix with white balloon flower were tested in cultured cells and administered into mice on a high-fat diet. The Platycodi radix activated the AMPK/ACC phosphorylation in C2C12 myotubes and also suppressed adipocyte differentiation in 3T3-L1 cells. In experimental animal, it suppressed the weight gain of obese mice and ameliorated obesity-induced insulin resistance. It also reduced the elevated circulating mediators, including triglyceride (TG), T-CHO, leptin, resistin, and monocyte chemotactic protein (MCP)-1 in obesity. As shown in C2C12 myotubes, the administration of Platycodi radix extracts also recovered the AMPK/ACC phosphorylation in the muscle of obese mice. These results suggest that Platycodi radix with white balloon flower ameliorates obesity and insulin resistance in obese mice via the activation of AMPK/ACC pathways and reductions of adipocyte differentiation.

Platyconic acid, a saponin from Platycodi radix, improves glucose homeostasis by enhancing insulin sensitivity in vitro and in vivo

BACKGROUND

Previous research demonstrated that the crude saponins of Platycodi radix improve glucose metabolism by enhancing insulin sensitivity in type 2 diabetic animals; however, which individual saponins are the most potent insulin sensitizers is unknown.

OBJECTIVES

This study investigated which saponin(s) have anti-diabetic action in vitro and in vivo.

METHODS

The insulin-stimulated glucose uptake and PPAR-γ agonistic actions of six saponins from Platycodi radix were investigated in 3T3-L1 adipocytes, and glucose-stimulated insulin secretion was determined in Min6 cells. Four individual saponins (20 mg/kg body weight) were orally administered to low-dose streptozotocin-injected diabetic mice fed a high-fat diet for 8 weeks to evaluate glucose tolerance by oral glucose tolerance testing (OGTT), insulin sensitivity by insulin tolerance testing, and insulin signaling in the liver and adipose tissues.

RESULTS

Platyconic acid (PA) most effectively increased insulin-stimulated glucose uptake in 3T3-L1 adipocytes, possibly in part by working as a peroxisome proliferator-activated receptors (PPAR)-γ activator; however, none of the saponins improved glucose-stimulated insulin secretion in insulinoma cells. PA-treated diabetic mice exhibited the lowest peak serum glucose levels and highest serum insulin levels during the first part of OGTT. PA also improved insulin sensitivity: PA increased glycogen accumulation and decreased triacylglycerol storage in liver, which was associated with enhanced hepatic insulin signaling, while PA potentiated the expression of adiponectin and PPAR-γ in adipose tissue, and improved insulin signaling and increased GLUT4 translocation into the membranes.

CONCLUSIONS

PA improves glucose homeostasis in type 2 diabetic mice, partly by enhancing hepatic and adipocyte insulin sensitivity, possibly by activating PPAR-γ.

Herbal extract THI improves metabolic abnormality in mice fed a high-fat diet

Target herbal ingredient (THI) is an extract made from two herbs, Scutellariae Radix and Platycodi Radix. It has been developed as a treatment for metabolic diseases such as hyperlipidemia, atherosclerosis, and hypertension. One component of these two herbs has been reported to have anti-inflammatory, anti-hyperlipidemic, and anti-obesity activities. However, there have been no reports about the effects of the mixed extract of these two herbs on metabolic diseases. In this study, we investigated the metabolic effects of THI using a diet-induced obesity (DIO) mouse model. High-fat diet (HFD) mice were orally administered daily with 250 mg/kg of THI. After 10 weeks of treatment, the THI-administered HFD mice showed reduction of body weights and epididymal white adipose tissue weights as well as improved glucose tolerance. In addition, the level of total cholesterol in the serum was markedly reduced. To elucidate the molecular mechanism of the metabolic effects of THI in vitro, 3T3-L1 cells were treated with THI, after which the mRNA levels of adipogenic transcription factors, including C/EBPα and PPARγ, were measured. The results show that the expression of these two transcription factors was down regulated by THI in a dose-dependent manner. We also examined the combinatorial effects of THI and swimming exercise on metabolic status. THI administration simultaneously accompanied by swimming exercise had a synergistic effect on serum cholesterol levels. These findings suggest that THI could be developed as a supplement for improving metabolic status.

Platycoside N: a new oleanane-type triterpenoid saponin from the roots of Platycodon grandiflorum

A new oleanane-type triterpenoid saponin, named platycoside N (1), together with six known saponins, was isolated from the roots of Platycodon grandiflorum. On the basis of acid hydrolysis, comprehensive spectroscopic data analyses and comparison with the spectral data of the known compounds, its structure was elucidated as 3-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl-2β,3β,16α,23-tetrahydroxyolean-12-en-28-oic acid 28-O-β-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranoside. The six known compounds were platycodin D (2), deapioplatycodin D (3), platycodin D₃ (4), deapio- platycodin D₃ (5), platycoside E (6) and deapioplatycoside E (7).