Effect of flavonol glycosides from Cinnamomum osmophloeum leaves on adiponectin secretion and phosphorylation of insulin receptor-beta in 3T3-L1 adipocytes

Dietary Flavonoids and Insulin Signaling in Diabetes and Obesity

Type 2 diabetes (T2D) and obesity are relevant worldwide chronic diseases. A common complication in both pathologies is the dysregulation of the insulin-signaling pathway that is crucial to maintain an accurate glucose homeostasis. Flavonoids are naturally occurring phenolic compounds abundant in fruits, vegetables and seeds. Rising evidence supports a role for the flavonoids against T2D and obesity, and at present, these compounds are considered as important potential chemopreventive agents. This review summarizes in vitro and in vivo studies providing data related to the effects of flavonoids and flavonoid-rich foods on the modulation of the insulin route during T2D and obesity. Notably, few human studies have evaluated the regulatory effect of these phenolic compounds at molecular level on the insulin pathway. In this context, it is also important to note that the mechanism of action for the flavonoids is not fully characterized and that a proper dosage to obtain a beneficial effect on health has not been defined yet. Further investigations will contribute to solve all these critical challenges and will enable the use of flavonoids to prevent, delay or support the treatment of T2D and obesity.

Kaempferitrin-Treated HepG2 Differentially Expressed Exosomal Markers and Affect Extracellular Vesicle Sizes in the Secretome

Kaempferitrin is extracted in significantly high quantities from the leaves of Cinnamomum osmophloeum, which belongs to a group of plant species that comes under the genus Cinnamomum, well-known for its established anti-diabetic property in Chinese medicine. Oral administration of kaempferitrin and Cinnamomum osmophloeum extract reduced blood sugar in alloxan-induced diabetic rats and improved the lipid profile in hamsters respectively. In this paper we studied the differential protein expression profile using mass spectrometry approach in the kaempferitrin-treated conditioned medium of liver cancer cell line HepG2. We discovered that 33 genes were up/down-regulated consistently between two biological samples. A slightly different version of the analysis software selected 28 genes, and the final 18 genes that appeared in both lists were selected. Interestingly, 5 proteins out of 18 were either exosomal markers or reported in high frequency of occurrence in exosome/secreted vesicles. We also examined the extracellular particles with atomic force microscopy (AFM), which showed that the conditioned medium of kaempferitrin treated had larger vesicles and fewer small vesicles. Expression of some lipid-regulating genes were also altered. Our data suggested that extracellular vesicle secretions may be regulated by kaempferitrin, and regulation of lipid profile by kampeferitrin involves multiple mechanisms.

Molecular mechanism of down-regulating adipogenic transcription factors in 3T3-L1 adipocyte cells by bioactive anti-adipogenic compounds

Obesity is growing at an alarming rate, which is characterized by increased adipose tissue. It increases the probability of many health complications, such as diabetes, arthritis, cardiac disease, and cancer. In modern society, with a growing population of obese patients, several individuals have increased insulin resistance. Herbal medicines are known as the oldest method of health care treatment for obesity-related secondary health issues. Several traditional medicinal plants and their effective phytoconstituents have shown anti-diabetic and anti-adipogenic activity. Adipose tissue is a major site for lipid accumulation as well as the whole-body insulin sensitivity region. 3T3-L1 cell line model can achieve adipogenesis. Adipocyte characteristics features such as expression of adipocyte markers and aggregation of lipids are chemically induced in the 3T3-L1 fibroblast cell line. Differentiation of 3T3-L1 is an efficient and convenient way to obtain adipocyte like cells in experimental studies. Peroxisome proliferation activated receptor γ (PPARγ) and Cytosine-Cytosine-Adenosine-Adenosine-Thymidine/Enhancer-binding protein α (CCAAT/Enhancer-binding protein α or C/EBPα) are considered to be regulating adipogenesis at the early stage, while adiponectin and fatty acid synthase (FAS) is responsible for the mature adipocyte formation. Excess accumulation of these adipose tissues and lipids leads to obesity. Thus, investigating adipose tissue development and the underlying molecular mechanism is important in the therapeutical approach. This review describes the cellular mechanism of 3T3-L1 fibroblast cells on potential anti-adipogenic herbal bioactive compounds.

Traditional uses, phytochemistry and pharmacological activities of the genus Cinnamomum (Lauraceae): A review

Species of Cinnamomum exhibit excellent economic and medicinal value, and have found use in traditional medicine, are consumed as a spice, as well as being cultivated as landscape plants. Investigations into the pharmacological activities of the genus Cinnamomum revealed that it manifested a wide range of pharmacological properties including antimicrobial, antioxidant, anti-inflammatory and analgesic, antitumor, anti-diabetic and anti-obesity, immunoregulation, insecticidal and acaricidal, cardiovascular protective, cytoprotective, as well as neuroprotective properties both in vivo and in vitro. In the past five years, approximately 306 chemical constituents have been separated and identified from the genus Cinnamomum, covering 111 terpenes, 44 phenylpropanoids, 51 lignans, 17 flavonoids, 53 aromatic compounds, 17 aliphatic compounds, four coumarins, two steroids. This article highlights the traditional uses, phytochemistry and pharmacological properties of the few studied taxa of Cinnamomum through searching for the pieces of literature both at home and abroad, which would provide a reference for the pharmaceutical research and clinical application of this genus.

Beneficial Biological Activities of Cinnamomum osmophloeum and its Potential Use in the Alleviation of Oral Mucositis: A Systematic Review

The aim of this review was to provide an updated overview of studies on the medical-biological activities of Cinnamomum osmophloeum (C. osmophloeum) in vitro and in vivo and the potential therapeutic use of natural agents prepared from this plant for the alleviation of oral mucositis (OM). Reported articles were collected using web search engine tools. The systematic review was organized according to the preferred reporting items for reviews and meta-analyses (PRISMA) statement. Additional sources were identified through cross-referencing to identify the potential use of C. osmophloeum in the alleviation of OM. The results disclosed that C. osmophloeum is comprised of bioactive ingredients that could act diversely as a reagent in anti-inflammation, antibacterial, antioxidant, anti-hyperglycemic, antidyslipidemia, anti-cancer, renal disease therapy and anti-hyperuricemia capacities. Recent studies revealed that the overall effects on anti-inflammation, wound repair, and the antibacterial and antioxidant activities of its constituents would act as a potential remedy for oral mucositis. Up-to-date in vitro and in vivo studies on the medical-biological activities of C. osmophloeum suggested that C. osmophloeum and its constituents could be promising remedies as adjuvants in OM therapy and warrant further investigation.

Cinnamomum osmophloeum Kanehira ethanol extracts prevents human liver-derived HepG2 cell death from oxidation stress by induction of ghrelin gene expression

Diabetes patients associated with liver disease carry a significant risk of morbidity and mortality. Cinnamon has been reported to reduce fructose-induced oxidative stress in the rat liver. However, the mechanism by which cinnamon protects the liver in a high-saccharide environment remains to be investigated. HepG2 cells were cultured with 30 mM D-ribose to mimic the high-oxidative-stress environment, typical of a liver in a diabetic patient. Three different chemical types of C. osmophloeum ethanol extracts (CEEs) were added in HepG2 culture media and the administration of all three CEEs protected HepG2 cells from D-ribose damage and increased cell survival by approximately 20 percent. Exclusively, the transcript variant 1 of the ghrelin gene, but not variant 3, was 2-3 times induced by the addition of these CEEs. Moreover, the mRNAs of ghrelin processing enzyme, furin, and mboat4 were detected in HepG2 cells. The ghrelin hormones in the culture media were increased 4-9 times by the addition of CEEs. The protective effects of ghrelin on HepG2 cells in D-ribose environment were further confirmed by recombinant ghrelin transfection. We conclude that the CEEs induce ghrelin gene expression and protect HepG2 cells from D-ribose-induced oxidative damage through ghrelin signalling.

A comparative proteomic study of secretomes in kaempferitrin-treated CTX TNA2 astrocytic cells

ETHNOPHARMACOLOGICAL RELEVANCE

Kaempferitrin is extracted in significantly high quantities from the leaves of Cinnamomum osmophloeum (C.O) and Bauhinia forficata, and are used as an antidiabetic herbal remedy in China and Brazil. Commercial product using dry Cinnamomum osmophloeum leaves has been sold locally in Taiwan. Oral administration of kaempferitrin reduced blood sugar in diabetic rats.

AIM OF THE STUDY

Though previously demonstrated to activate the classical insulin signaling pathways, a mechanism for kaempferitrin is still not fully understood. Also, studies on kaempferitrin on immune related cells have been inconclusive, and people consuming extract containing kaempferitrin often happen to be at high risk of diabetes and neurodegenerative diseases. Therefore, for kaempferitrin to be used every day, a comprehensive study is needed.

MATERIALS AND METHODS

Astrocytic cell line was used as a model to test the differentially regulated secretomes, to test kaempferitrin effect on CNS glia, on pro-inflammatory cytokines, and to test how different the mechanism of kaempferitrin is from that of insulin. CTX TNA2 astrocytic cells were differentially treated with and without 10 µM kaempferitrin for 24 h, and the conditioned medium was collected. For the proteomic study, protein in conditioned medium was trypsin digested, and resulting peptides in kaempferitrin/non-treated sample pair were differentially dimethyl labeled. The labeled peptides were further fractionated by StageTip-based strong-exchange method before LC-MS/MS analyses. Levels of interesting proteins were verified using Western or Eliza. C.O. leaf crude extract treated samples were included for a comparison of effects of purified kaempferitrin vs. kaempferitrin containing crude extract.

RESULTS AND CONCLUSIONS

Data were obtained via ProteomeXchange with identifier PXD002814. It was found that no pro-inflammatory cytokines or inhibitory ECM were elevated upon treatment of kaempferitrin or a crude extract of C.O. leaves. This suggests that prolonged use of kaempferitrin containing herbs may not increase pro-inflammatory reaction. LDL-R trafficking between the cell membrane and the extracellular niche was regulated by kaempferitrin toward reduced secretion. Our proteomic study also demonstrated that molecules related to plasma membrane recycling were regulated by kaempferitrin. Our discoveries provide evidence that link kaempferitrin regulation for LDL-R and membrane recycling to the blood lipid regulation by the C.O. leaves extract. However, these proteins were differently regulated when cells were treated with crude extract. This demonstrates that the molecular interactions within crude extract of herbs are complex and may not act similar to the compound purified from the crude extract.

Flavonoids

Diabetes Mellitus is one of the major healthcare problems faced by the society today and has become alarmingly epidemic in many parts of the world. Despite enormous knowledge and technology advancement, available diabetes therapeutics only provide symptomatic relief by reducing blood glucose level, thereby, just slows down development and progression of diabetes and its associated complications. Thus, the need of the day is to develop alternate strategies that can not only prevent the progression but also reverse already “set-in” diabetic complications. Many flavonoids are reported, traditionally as well as experimentally, to be beneficial in averting diabetes and lowering risk of its accompanying complications. In the present chapter we have convened different flavonoids beneficial in diabetes and comorbid complications and discussed their mechanisms of action. Further, we conclude that coupling current therapeutics with flavonoids might provide exceptional advantage in the management of diabetes and its complications.

Evaluation of hypocholesterolemic effect of oleuropein in cholesterol-fed rats

Oleuropein, which is the major compound of olive leaves, has been reported to exert several pharmacological properties, including anti-cancer, antidiabetic and anti-atherosclerotic activities. The objective of this study was to evaluate the effect of oleuropein on adiponectin level in high cholesterol diet (HCD) induced obesity in rat and the molecular mechanism underlying its activation. Our results showed that orally administered oleuropein (50 mg/kg) by gavage for 8 weeks decreased the body weight, adipose tissue mass and triglyceride and attenuated steatosis in liver. Moreover, the effect of oleuropein on adiponectin, an important hormone with fatty-acid oxidation properties, was evaluated and our data illustrated that oleuropein supplementation increased serum adiponectin concentration. The effects of oleuropein on protein expression related to lipogenic genes were investigated and our results showed that its administration significantly inhibited peroxisome proliferator-activated receptor γ (PPARγ), sterol regulatory element-binding protein-1c (SREBP-1c) and fatty-acid synthase (FAS). In addition, oleuropein stimulated the HCD-induced inhibition of AMP-activated protein kinase (AMPK) in epididymal adipose tissues. These results suggest that oleuropein exerts anti-obesity effects in HCD rats by activating AMPK and suppressing PPAR γ (Peroxisome proliferator-activated receptor γ) expression in adipose tissues. These data provide that oleuropein has important implications for preventing obesity.

Antihyperglycemic and antioxidant activities of twig extract from Cinnamomum osmophloeum

This is the first report concerning the α-glucosidase, α-amylase and protein tyrosine phosphatase 1B (PTP1B) inhibitory activities of cinnamon twig extracts. Comparing the antihyperglycemic activity of renewable plant parts, indigenous cinnamon (Cinnamomum osmophloeum; tǔ ròu guì) twig extracts (CoTE) showed better α-glucosidase and α-amylase activities than leaf, 2-cm branch and 5-cm branch extracts. Chemotype of C. osmophloeum has no influence on the antihyperglycemic activities and proanthocyanidin contents of CoTE. Among four soluble fractions obtained from CoTE by following bioactivity-guided fractionation procedure, the n-butanol soluble fraction (BSF) with abundant proanthocyanidins and condensed tannins, exhibited the best antihyperglycemic and PTP1B inhibitory activities. In addition, the BSF displayed the excellent DPPH free-radical scavenging and ferrous ion-chelating activities. The antihyperglycemic and antioxidant activities of all four soluble fractions from CoTE showed high correlation coefficient with their proanthocyanidin and condensed tannin contents. Furthermore, CoTE had no toxicity on 3T3-L1 preadiocytes. Results obtained demonstrated that CoTE has excellent antihyperglycemic, antioxidant and PTP1B inhibitory activities, and thus has great potential as a source for natural health products.

Ficus deltoidea: A Potential Alternative Medicine for Diabetes Mellitus

Ficus deltoidea from the Moraceae family has been scientifically proven to reduce hyperglycemia at different prandial states. In this study, we evaluate the mechanisms that underlie antihyperglycemic action of Ficus deltoidea. The results had shown that hot aqueous extract of Ficus deltoidea stimulated insulin secretion significantly with the highest magnitude of stimulation was 7.31-fold (P < 0.001). The insulin secretory actions of the hot aqueous extract involved K⁺  _ATP channel-dependent and K⁺  _ATP-channel-independent pathway. The extract also has the ability to induce the usage of intracellular Ca²⁺ to trigger insulin release. The ethanolic and methanolic extracts enhanced basal and insulin-mediated glucose uptake into adipocytes cells. The extracts possess either insulin-mimetic or insulin-sensitizing property or combination of both properties during enhancing glucose uptake into such cells. Meanwhile, the hot aqueous and methanolic extracts augmented basal and insulin-stimulated adiponectin secretion from adipocytes cells. From this study, it is suggested that Ficus deltoidea has the potential to be developed as future oral antidiabetic agent.

A pharmacological appraisal of medicinal plants with antidiabetic potential

Diabetes mellitus is a complicated metabolic disorder that has gravely troubled the human health and quality of life. Conventional agents are being used to control diabetes along with lifestyle management. However, they are not entirely effective and no one has ever been reported to have fully recovered from diabetes. Numerous medicinal plants have been used for the management of diabetes mellitus in various traditional systems of medicine worldwide as they are a great source of biological constituents and many of them are known to be effective against diabetes. Medicinal plants with antihyperglycemic activities are being more desired, owing to lesser side-effects and low cost. This review focuses on the various plants that have been reported to be effective in diabetes. A record of various medicinal plants with their established antidiabetic and other health benefits has been reported. These include Allium sativa, Eugenia jambolana, Panax ginseng, Gymnema sylvestre, Momrodica charantia, Ocimum sanctum, Phyllanthus amarus, Pterocarpus marsupium, Trigonella foenum graecum and Tinospora cordifolia. All of them have shown a certain degree of antidiabetic activity by different mechanisms of action.

Andrographolide and 14-deoxy-11,12-didehydroandrographolide from Andrographis paniculata attenuate high glucose-induced fibrosis and apoptosis in murine renal mesangeal cell lines

ETHNOPHARMACOLOGICAL RELEVANCE

Extracts of Andrographis paniculata Nees are used for various ethnomedical conditions including hyperglycemia and hypertension complications.

AIM OF THE STUDY

The purpose of this study is to evaluate the anti-diabetic nephropathy effect of diterpene lactones andrographolide (AP1) and 14-deoxy-11,12-didehydroandrographolide (AP2) from Andrographis paniculata.

MATERIALS AND METHODS

MES-13, a SV40-transformed murine glomerular mesangial cell line, was cultured in high concentration of glucose to induce diabetic nephropathy phenotypes, which include secretion of extracellular matrix protein fibronectin, cytokine TGF-β, states of oxidative stress, and apoptosis marker caspase-3.

RESULTS

Our data suggest that addition of compounds AP1 or AP2 reduces the phenotypes indicating diabetic nephropathy in MES-13 cells. The compound AP2 showed potent activity than AP1 in the reduction of apoptosis marker caspase-3, fibrosis marker TGF-β, and PAI-1. Furthermore, AP1 and AP2 do not have antioxidant ability in acellular environment; however, addition of AP1 and AP2 reduced intracellular oxidative states in high glucose cultured MES-13 cells.

CONCLUSION

This is the first report on anti-diabetic nephropathy effect of AP1 and AP2 in part due to the regulation of intracellular signaling transduction, not mere clearance of reactive oxygen species. Thus, this study may be useful for drug development or food supplement for diabetes and nephropathy from Andrographis paniculata.

Anti-hyperglycemic activity of the leaves of Tetracera scandens Linn. Merr. (Dilleniaceae) in alloxan induced diabetic rats

AIM OF THE STUDY

The present study was aimed to investigate the anti-diabetic potential of the leaves of Tetracera scandens Linn. Merr. (Dilleniaceae) in vivo with regard to prove its efficacy by local herbalists in the treatment of diabetes frailties.

MATERIALS AND METHODS

Crude aqueous (AQ) and methanol (MEOH) extracts of the leaves of T. scandens L. were administered to both normal and alloxan induced diabetic male albino rats (Wistar strain). The blood glucose levels were measured at 0, 2, 4, 6 and 8h after oral administration of AQ and MEOH extracts.

RESULTS

Significant reduction in glucose was observed in fasting blood glucose levels in the treated diabetic rats without causing any hypoglycemic effect compared to normal rats. Both polar extracts of the leaves of T. scandens L. exhibited significant anti-hyperglycemic activity at different doses and intervals. The highest anti-hyperglycemic effect (62.5%) was observed by the AQ extract at 0.25 g/kg body weight (b.w.) and MEOH extract (36.5%) at 0.5 g/kg b.w. after 8h. The significant anti-hyperglycemic activity was found to be comparable with a known oral synthetic hypoglycemic drug, glibenclamide 0.25mg/kg b.w.

CONCLUSION

This study provides scientific evidence that the leaves of T. scandens L. have anti-diabetic efficacy and justifies its utility by local herbalists. However, more experiments at the clinical levels are required to confirm the utility of this plant by traditional practitioners in the management of diabetes mellitus.