Phloroglucinol inhibits the bioactivities of endothelial progenitor cells and suppresses tumor angiogenesis in LLC-tumor-bearing mice

Antioxidant and Anti-inflammatory Effects of Marine Phlorotannins and Bromophenols Supportive of Their Anticancer Potential

Following the goal of optimizing nutrition, the food industry has been continuously working on food reformulation, nutritional patterns, functional foods development, and the general promotion of a healthy lifestyle. To this end, the scientific community has been increasingly investigating natural compounds that could prevent or treat chronic diseases. Phlorotannins and bromophenols are phenolic compounds particularly present in marine organisms. There is extensive evidence that shows their potential in the prevention of noncommunicable diseases, including cancer, the second cause of mortality worldwide. Numerous studies have demonstrated the anticarcinogenic activity of polyphenolic algae compounds both in cell culture and experimental animal models. Although recent reviews are also available, the present update focuses on the most recent findings related to the antioxidant/anti-inflammatory effect of seaweed phenolics, as well as their regulatory capacity for new molecular targets. Additionally, the review addresses and discusses the close link between inflammation and oxidative stress, along with their relationship with tumor onset and progression, including the most recent findings supporting this correlation. Although clinical studies are still needed to support this evidence, phlorotannins and bromophenols constitute an emerging bioactive group with high potential as chemopreventive agents and/or potential adjuvants for existing cancer therapies.

Low Phosphatidylserine+ Cells Within the CD34+/CD45dim/CD117(c-kit)+ Subpopulation Are Associated with Poor Outcomes in Metastatic Colorectal Cancer

BACKGROUND

Colorectal cancer is among the most prevalent causes of tumor-related deaths worldwide. Antiangiogenic therapy represents a cornerstone of metastatic CRC treatment, and biomarkers are advocated for the optimization of this therapeutic strategy.

METHODS

In this observational prospective study, we employed an optimized flow cytometry protocol to investigate the prognostic and predictive potential of blood circulating endothelial cells (CECs), circulating endothelial progenitor cells (CEPCs), and related subsets in a cohort of patients with metastatic colorectal cancer (n = 40).

RESULTS

Computational FC analysis revealed a differential enrichment of blood cell clusters with a CD34+/CD45dim/CD117(c-kit)+ phenotype between responders and non-responders both to antiangiogenic and non-antiangiogenic treatments. Intriguingly, our results show that a high percentage of annexin V-negative cells in a putative circulating progenitor population with a CD34+/CD45dim/CD117+ phenotype was correlated with a reduced response to systemic anticancer treatments (p = 0.015) and worse overall survival (log-rank p = 0.03). In addition, we observed increased blood concentrations of CD34+/CD45dim/CD117+/annexin V- cells in patients with a higher number of metastatic sites (p = 0.03).

CONCLUSIONS

Overall, these findings hold promise for the identification of novel circulating biomarkers to develop more personalized treatment approaches in patients with metastatic colorectal cancer.

Anticancer Activities of Marine-Derived Phenolic Compounds and Their Derivatives

Since the middle of the last century, marine organisms have been identified as producers of chemically and biologically diverse secondary metabolites which have exerted various biological activities including anticancer, anti-inflammatory, antioxidant, antimicrobial, antifouling and others. This review primarily focuses on the marine phenolic compounds and their derivatives with potent anticancer activity, isolated and/or modified in the last decade. Reports on the elucidation of their structures as well as biosynthetic studies and total synthesis are also covered. Presented phenolic compounds inhibited cancer cells proliferation or migration, at sub-micromolar or nanomolar concentrations (lamellarins D (37), M (38), K (39), aspergiolide B (41), fradimycin B (62), makulavamine J (66), mayamycin (69), N-acetyl-N-demethylmayamycin (70) or norhierridin B (75)). In addition, they exhibited anticancer properties by a diverse biological mechanism including induction of apoptosis or inhibition of cell migration and invasive potential. Finally, phlorotannins 1–7 and bromophenols 12–29 represent the most researched phenolic compounds, of which the former are recognized as protective agents against UVB or gamma radiation-induced skin damages. Finally, phenolic metabolites were assorted into six main classes: phlorotannins, bromophenols, flavonoids, coumarins, terpenophenolics, quinones and hydroquinones. The derivatives that could not be attributed to any of the above-mentioned classes were grouped in a separate class named miscellaneous compounds.

Biochemistry of Amaranthus polyphenols and their potential benefits on gut ecosystem: A comprehensive review of the literature

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Amaranthus is phytonutrients-rich plant distributed worldwide and has been recognized as having medicinal value in traditional use against several diseases and conditions. There are a large amount of research data on the polyphenol profiles of Amaranthus plants and their links with potential benefits against gastrointestinal disorders.

AIM OF THE REVIEW

This review article aims to provide a comprehensive review of Amaranthus phenolic compounds and their microbial metabolites, as well as the biological and/or pharmacological effects of those compounds/metabolites.

METHODOLOGY

The relevant information about the genus Amaranthus was collected from various sources and databases, including Google Scholar, Google Books, PubMed, Web of Science, Scopus, Science Direct, and other internet sources. The World Flora Online (2021) database was used to verify the scientific names of the plants.

RESULTS

Comprehensive review of identified compounds in Amaranthus plants revealed the presence of phenolic acids, flavonoids, and coumarins in each part of the plants. The biotransformation by gut microbiota enzymes prominently produces diverse bioactive metabolites that are potentially active than their precursors. Lines of the evidence support the beneficial roles of Amaranthus extracts in several gastrointestinal diseases, particularly with the polar extracts of several plant parts. Dietary fibers in Amaranthus plants also coordinate the alteration of gut microbiota-related metabolisms and may be beneficial to certain gastrointestinal disorders in particular, such as constipation.

CONCLUSIONS

Amaranthus plants are rich in polyphenols and dietary fibers. Several microbial metabolites are biologically active, so alteration of gut microbiota is largely linked to the metabolic feature of the plants. Based on the evidence available to date, several Amaranthus plants containing a combination of phytonutrients, particularly polyphenols and dietary fibers, may be a promising candidate that is of interest to be further developed for use in the treatment of certain gastrointestinal conditions/disorders.

Chemerin regulates normal angiogenesis and hypoxia-driven neovascularization

Chemerin is a multifunctional protein initially characterized in our laboratory as a chemoattractant factor for leukocyte populations. Its main functional receptor is CMKLR1. We identified previously chemerin as an anti-tumoral factor inhibiting the vascularization of tumor grafts. We show here that overexpression of bioactive chemerin in mice results in a reduction of the density of the retinal vascular network during its development and in adults. Chemerin did not affect vascular sprouting during the post-natal development of the network, but rather promoted endothelial cell apoptosis and vessel pruning. This phenotype was reversed to normal in CMKLR1-deficient mice, demonstrating the role of this receptor. Chemerin inhibited also neoangiogenesis in a model of pathological proliferative retinopathy, and in response to hind-limb ischemia. Mechanistically, PTEN and FOXO1 antagonists could almost completely restore the density of the retinal vasculature, suggesting the involvement of the PI3-kinase/AKT pathway in the chemerin-induced vessel regression process.

Wnt/β-catenin Antagonists: Exploring New Avenues to Trigger Old Drugs in Alleviating Glioblastoma Multiforme

BACKGROUND

Glioblastoma multiforme is one of the most heterogenous primary brain tumor with high mortality. Nevertheless, of the current therapeutic approaches, survival rate remains poor with 12 to 15 months following preliminary diagnosis, this warrants the need for effective treatment modality. Wnt/β-catenin pathway is presumably the most noteworthy pathway up-regulated in almost 80% GBM cases contributing to tumor-initiation, progression and survival. Therefore, therapeutic strategies targeting key components of Wnt/β-catenin cascade using established genotoxic agents like temozolomide and pharmacological inhibitors would be an effective approach to modulate Wnt/β-catenin pathway. Recently, drug repurposing by means of effective combination therapy has gained importance in various solid tumors including GBM, by targeting two or more proteins in a single pathway, thereby possessing the ability to overcome the hurdle implicated by chemo-resistance in GBM.

OBJECTIVE

In this context, by employing computational tools, an attempt has been carried out to speculate the novel combinations against Wnt/β-catenin signaling pathway.

METHODS

We have explored the binding interactions of three conventional drugs namely temozolomide, metformin, chloroquine along with three natural compounds viz., epigallocatechin gallate, naringenin and phloroglucinol on the major receptors of Wnt/β-catenin signaling.

RESULTS

It was noted that all the experimental compounds possessed profound interaction with the two major receptors of Wnt/β-catenin pathway.

CONCLUSION

To the best of our knowledge, this study is the first of its kind to characterize the combined interactions of the afore-mentioned drugs on Wnt/β-catenin signaling in silico and this will putatively open up new avenues for combination therapies in GBM treatment.

Phlorotannins: From isolation and structural characterization, to the evaluation of their antidiabetic and anticancer potential

Phlorotannins are phenolic characteristic compounds of brown seaweeds that are only constituted by phloroglucinol (1,3,5-trihydroxybenzene). They are chain- and net-like structures of diverse molecular weights and have been widely identified in Ecklonia, Eisenia, and Ishige species. Since the time they were discovered in the '70 s, phlorotannins have been suggested as a main factor responsible for the antimicrobial activities attributed to algae extracts. Currently, cumulative in vitro and in vivo research evidence the diverse bioactivities of phlorotannin extracts -such as antidiabetic, anticancer, and antibacterial- pointing out their potential pharmacological and food applications. However, metabolomic studies and clinical trials are scarce, and thus many phlorotannins health-beneficial effects in humans are not yet confirmed. This article reviews recent studies assessing the antidiabetic and anticancer activities of phlorotannins. Particularly, their potential to prevent and control the progression of these non-communicable diseases is discussed, considering in vitro and animal studies, as well as clinical interventions. In contrast to other approaches, we only included investigations with isolated phlorotannins or phlorotannin-rich extracts. Thus, phlorotannin extraction, purification and characterization procedures are briefly addressed. Overall, although considerable research showing the antidiabetic and anticancer potential of phlorotannins is now available, further clinical trials are still necessary to conclusively demonstrate the efficacy of these compounds as adjuvants for diabetes and cancer prevention or treatment.

Exploitation of Drosophila Choriogenesis Process as a Model Cellular System for Assessment of Compound Toxicity: the Phloroglucinol Paradigm

Phloroglucinol (1,3,5 tri-hydroxy-benzene) (PGL), a natural phenolic substance, is a peroxidase inhibitor and has anti-oxidant, anti-diabetic, anti-inflammatory, anti-thrombotic, radio-protective, spasmolytic and anti-cancer activities. PGL, as a medicine, is administered to patients to control the symptoms of irritable bowel syndrome and acute renal colic, in clinical trials. PGL, as a phenolic substance, can cause cytotoxic effects. Administration of PGL up to 300 mg/kg (bw) is well tolerated by animals, while in cell lines its toxicity is developed at concentrations above the dose of 10 μg/ml. Furthermore, it seems that tumor or immortalized cells are more susceptible to the toxic power of PGL, than normal cells. However, studies of its cytotoxic potency, at the cellular level, in complex, differentiated and meta-mitotic biological systems, are still missing. In the present work, we have investigated the toxic activity of PGL in somatic epithelial cells, constituting the follicular compartment of a developing egg-chamber (or, follicle), which directs the choriogenesis (i.e. chorion assembly) process, during late oogenesis of Drosophila melanogaster. Our results reveal that treatment of in vitro growing Drosophila follicles with PGL, at a concentration of 0.2 mM (or, 25.2 μg/ml), does not lead to follicle-cell toxicity, since the protein-synthesis program and developmental pattern of choriogenesis are normally completed. Likewise, the 1 mM dose of PGL was also characterized by lack of toxicity, since the chorionic proteins were physiologically synthesized and the chorion structure appeared unaffected, except for a short developmental delay, being observed. In contrast, concentrations of 10, 20 or 40 mM of PGL unveiled a dose-dependent, increasing, toxic effect, being initiated by interruption of protein synthesis and disassembly of cell-secretory machinery, and, next, followed by fragmentation of the granular endoplasmic reticulum (ER) into vesicles, and formation of autophagic vacuoles. Follicle cells enter into an apoptotic process, with autophagosomes and large vacuoles being formed in the cytoplasm, and nucleus showing protrusions, granular nucleolus and condensed chromatin. PGL, also, proved able to induce disruption of nuclear envelope, activation of nucleus autophagy (nucleophagy) and formation of a syncytium-like pattern being produced by fusion of plasma membranes of two or more individual follicle cells. Altogether, follicle cell-dependent choriogenesis in Drosophila has been herein presented as an excellent, powerful and reliable multi-cellular, differentiated, model biological (animal) system for drug-cytotoxicity assessment, with the versatile compound PGL serving as a characteristic paradigm. In conclusion, PGL is a substance that may act beneficially for a variety of pathological conditions and can be safely used for differentiated somatic -epithelial- cells at clinically low concentrations. At relatively high doses, it could potentially induce apoptotic and autophagic cell death, thus being likely exploited as a therapeutic agent against a number of pathologies, including human malignancies.

Biomarkers of seaweed intake

Seaweeds are marine macroalgae, some of which are edible. They are rich in specific dietary fibers and also contain other characteristic biological constituents. Biological activities have been investigated mainly in animal studies, while very few results are available from human studies. Biomarkers of food intake (BFIs) specific to seaweed could play an important role as objective measurements in observational studies and dietary intervention studies. Thus, the health effects of seaweeds can be explored and understood by discovering and applying BFIs. This review summarizes studies to identify candidate BFIs of seaweed intake. These BFIs are evaluated by a structured validation scheme. Hydroxytrifuhalol A, 7-hydroxyeckol, C-O-C dimer of phloroglucinol, diphloroethol, fucophloroethol, dioxinodehydroeckol, and/or their glucuronides or sulfate esters which all belong to the phlorotannins are considered candidate biomarkers for brown seaweed. Fucoxanthinol, the main metabolite of fucoxanthin, is also regarded as a candidate biomarker for brown seaweed. Further validation will be needed due to the very limited number of human studies. Further studies are also needed to identify additional candidate biomarkers, relevant specifically for the red and green seaweeds, for which no candidate biomarkers emerged from the literature search. Reliable BFIs should also ideally be found for the whole seaweed food group.

Algae metabolites: from in vitro growth inhibitory effects to promising anticancer activity

Covering: 1957 to 2017 Algae constitute a heterogeneous group of eukaryotic photosynthetic organisms, mainly found in the marine environment. Algae produce numerous metabolites that help them cope with the harsh conditions of the marine environment. Because of their structural diversity and uniqueness, these molecules have recently gained a lot of interest for the identification of medicinally useful agents, including those with potential anticancer activities. In the current review, which is not a catalogue-based one, we first highlight the major biological events that lead to various types of cancer, including metastatic ones, to chemoresistance, thus to any types of current anticancer treatment relating to the use of chemotherapeutics. We then review algal metabolites for which scientific literature reports anticancer activity. Lastly, we focus on algal metabolites with promising anticancer activity based on their ability to target biological characteristics of cancer cells responsible for poor treatment outcomes. Thus, we highlight compounds that have, among others, one or more of the following characteristics: selectivity in reducing the proliferation of cancer cells over normal ones, potential for killing cancer cells through non-apoptotic signaling pathways, ability to circumvent MDR-related efflux pumps, and activity in vivo in relevant pre-clinical models.

Streptomyces nigra sp. nov. Is a Novel Actinobacterium Isolated From Mangrove Soil and Exerts a Potent Antitumor Activity in Vitro

A new bacterial strain, designated 452^T, was isolated from the rhizosphere soil of the mangrove Avicennia marina in China. As determined, its cell wall peptidoglycan contained LL-diaminopimelic acid; MK-9(H8) and MK-9(H6) were the major isoprenoid quinones; and iso-C_16:0 (31.3%), anteiso-C_15:0 (16.9%), and iso-C_15:0 (12.5%) were the major cellular fatty acids (>10.0%). Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain 452^T formed a distinct lineage in the clade of the genus Streptomyces, and was closely related to S. coerulescens DSM 40146^T (99.6% sequence identity), S. bellus DSM 40185^T (99.5%), and S. coeruleorubidus DSM 41172^T (99.3%). The DNA-DNA relatedness between strain 452^T and these type strains ranged between 29.3 and 42.3%. Based on the phenotypic, chemotaxonomic, and phylogenetic features, the strain 452^T is considered to represent a novel species of the genus Streptomyces, for which the name Streptomyces nigra sp. nov. is proposed. The type strain is 452^T (=KCTC 39960^T = MCCC 1K03346^T). Further, strain 452^T extracts exhibited a pronounced antitumor activity against human cancer cell lines A549, HCT-116, and HepG2, but not against normal human colon cells CCD-18Co. Active substances in the fermentation broth of strain 452^T were isolated by bioassay-guided analysis, and then purified using a macroporous resin, silica gel, sephadex LX-20 column, and semi-preparative high-performance liquid chromatography (HPLC). Eight proline-containing diketopiperazines, namely, cyclo(Pro-Ala), cyclo(Pro-Gly), cyclo(Pro-Phe), cyclo(Pro-Met), cyclo(Pro-Val), cyclo(Pro-Leu), cyclo(Pro-Tyr), and cyclo(L-Leu-trans-4-hydroxy-L-Pro), were identified by electrospray ionization mass spectrometry (MS) and nuclear magnetic resonance (NMR). The compounds displayed different levels of cytotoxicity. The highest cytotoxicity was exhibited by cyclo(Pro-Ala) and cyclo(Pro-Met) against A549 cells, and cyclo(Phe-Pro) and cyclo(Pro-Ala) against HCT-116 cells, with average IC₅₀ values equal to 18.5, 27.3, 32.3, and 47.6 μg/mL, respectively. The diversity of diketopiperazines and other chemicals produced by 452^T was further investigated using gas chromatography (GC)-MS and liquid chromatography (LC)-MS. The analysis revealed 16 types of metabolites with antitumor activity and 16 other types of diketopiperazines. Hence, extracts of the newly identified strain may be used a starting material for the development of antitumor agents.

Deguelin inhibits vasculogenic function of endothelial progenitor cells in tumor progression and metastasis via suppression of focal adhesion

Deguelin is a nature-derived chemopreventive drug. Endothelial progenitor cells (EPCs) are bone-marrow (BM)-derived key components to induce new blood vessels in early tumorigenesis and metastasis. Here we determined whether deguelin inhibits EPC function in vitro and in vivo at doses not affecting cancer cell apoptosis. Deguelin significantly reduced the number of EPC colony forming units of BM-derived c-kit+/sca-1+ mononuclear cells (MNCs), proliferation, migration, and adhesion to endothelial cell monolayers, and suppressed incorporation of EPC into tube-like vessel networks when co-cultured with endothelial cells. Deguelin caused cell cycle arrest at G1 without induction of apoptosis in EPC. In a mouse tumor xenograft model, tumor growth, lung metastasis and tumor-induced circulating EPCs were supressed by deguelin treatment (2 mg/kg). In mice tranplanted with GFP-expressing BM-MNCs, deguelin reduced the co-localization of CD31 and GFP, suggesting suppression of BM-derived EPC incoporation into tumor vessels. Interestingly, focal adhesion kinase (FAK)-integrin-linked kinase (ILK) activation and actin polymerization were repressed by deguelin. Decreased number of focal adhesions and a depolarized morphology was found in deguelin-treated EPCs. Taken together, our results suggest that the deguelin inhibits tumorigenesis and metastasis via EPC suppression and that suppression of focal adhesion by FAK-integrin-ILK-dependent actin remodeling is a key underlying molecular mechanism.

Brown algae phlorotannins enhance the tumoricidal effect of cisplatin and ameliorate cisplatin nephrotoxicity

OBJECTIVE

The clinical application of cisplatin is limited due to its drug resistance and side effects. We investigated the effect of a phlorotannin-rich extract from the edible brown alga Ecklonia cava (PREC) and its major phlorotannin (dieckol) on cisplatin responsiveness and side effects.

METHODS

The A2780 and SKOV3 ovarian cancer cell lines and the SKOV3-bearing mouse model were used. The MTT assay was applied to assess cell viability, and the annexin V assay was employed for apoptosis analysis. Reactive oxygen species (ROS) production and protein expression were assessed by H2DCFDA staining and Western blotting, respectively.

RESULTS

We found that PREC enhanced the tumor growth-inhibitory effect of cisplatin and diminished cisplatin-induced nephrotoxicity and weight loss in SKOV3-bearing mice. PREC augmented cisplatin-induced apoptosis by activating caspases in SKOV3 and A2780 ovarian cancer cells. In addition, a combination of PREC and cisplatin-induced ovarian cancer cell apoptosis by downregulating the Akt and NFκB pathways. We further demonstrated that PREC increased intracellular ROS and that antioxidants significantly attenuated Akt-NFκB activation and apoptosis in ovarian cancer cells. In contrast, PREC inhibited cisplatin-induced ROS production and cell death in normal HEK293 kidney cells. Dieckol, a major compound in PREC, significantly enhanced the inhibition of tumor growth by cisplatin with less weight loss and kidney damage in a mouse model.

CONCLUSION

These data suggest that brown algae phlorotannins may improve the efficacy of platinum drugs for ovarian cancer by enhancing cancer cell apoptosis via the ROS/Akt/NFκB pathway and reduce nephrotoxicity by protecting against normal kidney cell damage.

Endothelial progenitor cells--potential new avenues to improve neoangiogenesis and reendothelialization

The term endothelial progenitor cell (EPC) was established more than 10 years ago and is used to refer to a group of circulating cells that display endothelial lineage qualities and are able to home to areas of ischemia or vascular injury and to facilitate the repair of damaged blood vessels or develop new vessels as needed. This chapter reviews the current lineage relationships among all the cells called EPC and will clear the terminology used in EPC research. Furthermore, an overview of the clinical and in vitro research, as well as cytokine and drug interactions and potential EPC applications, is given.

Pyrostegia venusta heptane extract containing saturated aliphatic hydrocarbons induces apoptosis on B16F10-Nex2 melanoma cells and displays antitumor activity in vivo

Background:

Pyrostegia venusta (Ker. Gawl.) Miers (Bignoniacea) is a medicinal plant from the Brazilian Cerrado used to treat leucoderma and common diseases of the respiratory system.

Objective:

To investigate the antitumor activity of P.venusta extracts against melanoma.

Materials and Methods:

The cytotoxic activity and tumor induced cell death of heptane extract (HE) from P. venusta flowers was evaluated against murine melanoma B16F10-Nex2 cells in vitro and in a syngeneic model in vivo.

Results:

We found that HE induced apoptosis in melanoma cells by disruption of the mitochondrial membrane potential, induction of reactive oxygen species and late apoptosis evidenced by plasma membrane blebbing, cell shrinkage, chromatin condensation and DNA fragmentation, exposure of phosphatidylserine on the cell surface and activation of caspase-2,-3,-8,-9. HE was also protective against singeneyc subcutaneous melanoma HE compounds were also able to induce cell cycle arrest at G2/M phases on tumor cells. On fractionation of HE in silica gel we isolated a cytotoxic fraction that contained a mixture of saturated hydrocarbons identified by ¹H NMR and GC-MS analyses. Predominant species were octacosane (C₂₈H₅₈-36%) and triacontane (C₃₀H₆₂-13%), which individually showed significant cytotoxic activity against murine melanoma B16F10-Nex2 cells in vitro and a very promising antitumor protection against subcutaneous melanoma in vivo.

Conclusion:

The results suggest that the components of the heptane extract, mainly octasane and triacontane, which showed antitumor properties in experimental melanoma upon regional administration, might also be therapeutic in human cancer, such as in the mostly epidermal and slowly invasive melanomas, such as acral lentiginous melanoma, as an adjuvant treatment to surgical excision.

Regular exercise training increases the number of endothelial progenitor cells and decreases homocysteine levels in healthy peripheral blood

Endothelial progenitor cells (EPCs) are known to play an important role in the repair of damaged blood vessels. We used an endothelial progenitor cell colony-forming assay (EPC-CFA) to determine whether EPC numbers could be increased in healthy individuals through regular exercise training. The number of functional EPCs obtained from human peripheral blood-derived AC133 stem cells was measured after a 28-day regular exercise training program. The number of total endothelial progenitor cell colony-forming units (EPC-CFU) was significantly increased compared to that in the control group (p=0.02, n=5). In addition, we observed a significant decrease in homocysteine levels followed by an increase in the number of EPC-CFUs (p=0.04, n=5), indicating that the 28-day regular exercise training could increase the number of EPC colonies and decrease homocysteine levels. Moreover, an inverse correlation was observed between small-endothelial progenitor cell colony-forming units (small-EPC-CFUs) and plasma homocysteine levels in healthy men (r=-0.8125, p=0.047). We found that regular exercise training could increase the number of EPC-CFUs and decrease homocysteine levels, thus decreasing the cardiovascular disease risk in men.

Isolation and structural determination of two novel phlorotannins from the brown alga Ecklonia kurome Okamura, and their radical scavenging activities

Two novel phlorotannins with a molecular weight of 974, temporarily named 974-A and 974-B, were isolated from the polyphenol powder prepared from the edible marine brown alga Ecklonia kurome Okamura, and their chemical structures were determined by spectroscopic method. The isolated yield of the total of 974-A and 974-B was approximately 4% (w/w) from the polyphenol powder. In 974-A, the carbon at the C2' position in the A ring of phlorofucofuroeckol-A forms a C-C bond with the carbon at the C2″ position of the C ring of triphloretol-B, while in 974-B, phlorofucofuroeckol-B and triphloretol-B form a C-C bond in the same manner as in 974-A. These structures were supported by high resolution-MS/MS data. To evaluate the antioxidant activities, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and intracellular radical scavenging assay, using 2',7'-dichlorofluorescin diacetate (DCFH-DA), were performed for 974-A, 974-B, and four known phlorotannins. The results of the DPPH assay showed that the IC(50) values of 974-A, 974-B, phlorofucofuroeckol-A, and dieckol were significantly smaller than those of phlorofucofuroeckol-B, phloroglucinol, α-tocopherol, and ascorbic acid. Furthermore, the DCFH-DA assay suggested that 974-A, 974-B, and dieckol reduce intracellular reactive oxygen species most strongly among the tested compounds.

Zoledronate attenuates angiogenic effects of angiotensin II-stimulated endothelial progenitor cells via RhoA and MAPK signaling

BACKGROUND

New vessel formation plays a pivotal role in the pathogenesis of neovascular-related diseases. Endothelial progenitor cells (EPCs) were found to contribute to neovascular-related diseases and interference with EPC neovascularization may be a novel target for these diseases. Zoledronate (Zol) was reported to exhibit anti-angiogenic effect. Basing on these evidences, we proposed that Zol may affect EPC function to exert novel anti-angiogenic effect. In this study, we therefore investigated the effects of Zol on multiple aspects of EPC function and explored the underlying mechanisms involved.

METHODOLOGY/PRINCIPAL FINDINGS

EPCs were cultured from bone marrow derived mononuclear cells. The potential effects of Zol on Angiotensin II (Ang II)-stimulated EPC proliferation, migration, adhesion, in vitro tube formation were investigated. The results showed that Ang II (1 µM) enhanced EPC migration, adhesion, in vitro tube formation but had no effect on cell proliferation. Zol (75 and 100 µM) inhibited proliferation of EPCs and 50 µM geranylgeranyol (GGOH) could reverse the decrease of EPC proliferation. We found for the first time that Zol (50-100 µM) dose dependently attenuated migration, adhesion, and in vitro tube formation of EPCs stimulated by Ang II. GGOH could reverse the attenuation of EPC function induced by Zol. However, Zol did not induce EPC apoptosis. In addition, the underlying mechanisms were determined. The results revealed that Zol markedly down-regulated active RhoA stimulated by Ang II and inhibited the phosphorylation of Erk1/2 and JNK. Moreover, RhoA silencing resulted in a notable inhibition of EPC in vitro tube formation, suggesting that RhoA suppression played a pivotal role in Zol antiangiogenic effect.

CONCLUSIONS/SIGNIFICANCE

These findings suggested that Zol attenuated the promotion of EPC function stimulated by Ang II and exhibited novel antiangiogenic effect via RhoA and MAPK signaling. Thus, Zol may be served as a novel therapeutic agent for neovascular-related diseases treatment.