Rhamnetin-induced suppression of clonal expansion during early stage of adipogenesis

Adipose and non-adipose perspectives of plant derived natural compounds for mitigation of obesity

ETHNOPHARMACOLOGICAL RELEVANCE

Phyto-preparations and phyto-compounds, by their natural origin, easy availability, cost-effectiveness, and fruitful traditional uses based on accumulated experiences, have been extensively explored to mitigate the global burden of obesity.

AIM OF THIS REVIEW

The review aimed to analyse and critically summarize the prospect of future anti-obesity drug leads from the extant array of phytochemicals for mitigation of obesity, using adipose related targets (adipocyte formation, lipid metabolism, and thermogenesis) and non-adipose targets (hepatic lipid metabolism, appetite, satiety, and pancreatic lipase activity). Phytochemicals as inhibitors of adipocyte differentiation, modulators of lipid metabolism, and thermogenic activators of adipocytes are specifically discussed with their non-adipose anti-obesogenic targets.

MATERIALS AND METHODS

PubMed, Google Scholar, Scopus, and SciFinder were accessed to collect data on traditional medicinal plants, compounds derived from plants, their reported anti-obesity mechanisms, and therapeutic targets. The taxonomically accepted name of each plant in this review has been vetted from "The Plant List" (www.theplantlist.org) or MPNS (http://mpns.kew.org).

RESULTS

Available knowledge of a large number of phytochemicals, across a range of adipose and non-adipose targets, has been critically analysed and delineated by graphical and tabular depictions, towards mitigation of obesity. Neuro-endocrinal modulation in non-adipose targets brought into sharp dual focus, both non-adipose and adipose targets as the future of anti-obesity research. Numerous phytochemicals (Berberine, Xanthohumol, Ursolic acid, Guggulsterone, Tannic acid, etc.) have been found to be effectively reducing weight through lowered adipocyte formation, increased lipolysis, decreased lipogenesis, and enhanced thermogenesis. They have been affirmed as potential anti-obesity drugs of future because of their effectiveness yet having no threat to adipose or systemic insulin sensitivity.

CONCLUSION

Due to high molecular diversity and a greater ratio of benefit to risk, plant derived compounds hold high therapeutic potential to tackle obesity and associated risks. This review has been able to generate fresh perspectives on the anti-diabetic/anti-hyperglycemic/anti-obesity effect of phytochemicals. It has also brought into the focus that many phytochemicals demonstrating in vitro anti-obesogenic effects are yet to undergo in vivo investigation which could lead to potential phyto-molecules for dedicated anti-obesity action.

Adipogenesis as a Potential Anti-Obesity Target: A Review of Pharmacological Treatment and Natural Products

Obesity is recognized as a severe threat to overall human health and is associated with type 2 diabetes mellitus, dyslipidemia, hypertension, and cardiovascular diseases. Abnormal expansion of white adipose tissue involves increasing the existing adipocytes' cell size or increasing the number through the differentiation of new adipocytes. Adipogenesis is a process of proliferation and differentiation of adipocyte precursor cells in mature adipocytes. As a key process in determining the number of adipocytes, it is a possible therapeutic approach for obesity. Therefore, it is necessary to identify the molecular mechanisms involved in adipogenesis that could serve as suitable therapeutic targets. Reducing bodyweight is regarded as a major health benefit. Limited efficacy and possible side effects and drug interactions of available anti-obesity treatment highlight a constant need for finding novel efficient and safe anti-obesity ingredients. Numerous studies have recently investigated the inhibitory effects of natural products on adipocyte differentiation and lipid accumulation. Possible anti-obesity effects of natural products include the induction of apoptosis, cell-cycle arrest or delayed progression, and interference with transcription factor cascade or intracellular signaling pathways during the early phase of adipogenesis.

Ginsenoside Rk1 inhibits cell proliferation and promotes apoptosis in lung squamous cell carcinoma by calcium signaling pathway

Ginsenoside Rk1 (Rk1) is a rare saponin extracted from Sun Ginseng (SG) and has been shown to have an anti-tumor effect; however, the potential role of its in lung squamous cell carcinoma remains elusive. In this study, we investigated the anti-proliferative activity and involved mechanism of Rk1 against lung squamous cell carcinoma in vitro and in vivo. First, MTT assay, cell colony formation assay and cell cycle assay showed that Rk1 effectively inhibited cell proliferation and colony formation, and induced cell arrest at G1 phase. Following AV/PI staining, JC-10 staining, Western blot and immunohistochemistry indicated that Rk1 induced caspase-dependent apoptosis. In addition, Rk1 induced ER stress, causing the release of Ca2+, resulting in intracellular calcium and mitochondrial calcium overload. Intracellular calcium overload activated the calpain-caspase-12 and calpain-caspase-7-PARP pathways, while mitochondrial calcium overload caused mitochondrial membrane potential reduced, and the release of cytochrome c. BAPTA-AM (Ca2+ scavengers) and calpeptin (calpain inhibitors) significantly attenuated Rk1-induced apoptosis. Moreover, Rk1 significantly inhibited the growth of SK-MES-1 xenograft tumors with low toxic side effects. In summary, this study for the first time demonstrated that Rk1 had significant antitumor effects against lung squamous cell carcinoma and great potential to serve as a novel anticancer agent.

Natural Products and Obesity: A Focus on the Regulation of Mitotic Clonal Expansion during Adipogenesis

Obesity is recognized as a worldwide health crisis. Obesity and its associated health complications such as diabetes, dyslipidemia, hypertension, and cardiovascular diseases impose a big social and economic burden. In an effort to identify safe, efficient, and long-term effective methods to treat obesity, various natural products with potential for inhibiting adipogenesis were revealed. This review aimed to discuss the molecular mechanisms underlying adipogenesis and the inhibitory effects of various phytochemicals, including those from natural sources, on the early stage of adipogenesis. We discuss key steps (proliferation and cell cycle) and their regulators (cell-cycle regulator, transcription factors, and intracellular signaling pathways) at the early stage of adipocyte differentiation as the mechanisms responsible for obesity.

Rhamnetin induces apoptosis in human breast cancer cells via the miR-34a/Notch-1 signaling pathway

The present study aimed to investigate whether rhamnetin induced apoptosis in human breast cancer cells and the underlying molecular mechanism of this anti cancer effect. The treatment of MCF-7 cells with rhamnetin was able to significantly inhibit cell proliferation and induce caspase-3/9 activity in a dose- and time-dependent manner, compared with untreated cells. In addition, treatment with rhamnetin was able to significantly promote the expression of p53 protein and microRNA (miR-)34a compared with untreated cells. The treatment with rhamnetin also suppressed the expression of Notch1 protein in MCF-7 cells compared with untreated cells. Subsequently, miR-24a expression was promoted in rhamnetin-treated MCF-7 cells using a miR-34a plasmid. The overexpression of miR-34a was able to significantly inhibit cell viability and induce caspase-3/9 activity in MCF-7 cells following treatment with rhamnetin. Furthermore, the overexpression of miR-34a was able to significantly promote the expression of p53 protein and miR-34a, and suppress the expression of Notch1 protein in rhamnetin-treated MCF-7 cells. Therefore, the results of the present study demonstrated that rhamnetin induced apoptosis in human breast cancer cells via the miR-34a/Notch-1 signaling pathway.

Antihyperlipidemic effect of a Rhamnus alaternus leaf extract in Triton-induced hyperlipidemic rats and human HepG2 cells

The Mediterranean buckthorn, Rhamnus alaternus L., is a plant used in traditional medicine in Mediterranean countries. We aimed at characterizing its phenolic compounds and explore potential antihyperlipidemic activity of this plant. The profile of phenolic compounds in R. alaternus leaf crude methanolic extract (CME) and its liquid-liquid extraction-derived fractions were analyzed by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS²). Effects of CME on: circulating lipids in rats with Triton WR-1339-induced hyperlipidemia, intracellular lipid accumulation and expression of genes of fatty acid metabolism in human hepatoma HepG2 cells, and adipogenesis in the 3T3-L1 murine adipocyte cell model were assessed. The HPLC/ESI-MS² analytical profile revealed a total of fifteen compounds, of which eleven were identified. Oral CME administration decreased blood levels of cholesterol and triacylglycerols in hyperlipidemic rats (by 60% and 70%, respectively, at 200 mg CME/kg). In HepG2 cells, CME exposure dose-dependently decreased intracellular lipids and up-regulated gene expression of carnitine palmitoyltransferase 1 involved in fatty acid oxidation. In the 3T3-L1 model, CME favored preadipocyte proliferation and adipogenesis, pointing to positive effects on adipose tissue expandability. These results suggest novel uses of R. alaternus by showing that its leaves are rich in flavonoids and flavonoid derivatives with an antihyperlipidemic effect in vivo and in hepatic cells.

Differential effects of dietary flavonoids on adipogenesis

Propose

Obesity is a fast growing epidemic worldwide. During obesity, the increase in adipose tissue mass arise from two different mechanisms, namely, hyperplasia and hypertrophy. Hyperplasia which is the increase in adipocyte number is characteristic of severe obese patients. Recently, there has been much interest in targeting adipogenesis as therapeutic strategy against obesity. Flavonoids have been shown to regulate several pathways and affect a number of molecular targets during specific stages of adipocyte development.

Methods

Presently, we provide a review of key studies evaluating the effects of dietary flavonoids in different stages of adipocyte development with a particular emphasis on the investigations that explore the underlying mechanisms of action of these compounds in human or animal cell lines as well as animal models.

Results

Flavonoids have been shown to regulate several pathways and affect a number of molecular targets during specific stages of adipocyte development. Although most of the studies reveal anti-adipogenic effect of flavonoids, some flavonoids demonstrated proadipogenic effect in mesenchymal stem cells or preadipocytes.

Conclusion

The anti-adipogenic effect of flavonoids is mainly via their effect on regulation of several pathways such as induction of apoptosis, suppression of key adipogenic transcription factors, activation of AMPK and Wnt pathways, inhibition of clonal expansion, and cell-cycle arrest.