Penta- O -galloyl-beta- d -glucose suppresses tumor growth via inhibition of angiogenesis and stimulation of apoptosis: roles of cyclooxygenase-2 and mitogen-activated protein kinase pathways

Ganoderma lucidum spores-derived particulate β-glucan treatment improves antitumor response by regulating myeloid-derived suppressor cells in triple-negative breast cancer

Granular β-1,3-glucan extracted from the wall of Ganoderma lucidum spores, named GPG, is a bioregulator. In this study, we investigated the structural, thermal, and other physical properties of GPG. We determined whether GPG ameliorated immunosuppression caused by Gemcitabine (GEM) chemotherapy. Triple-negative breast cancer mice with GPG combined with GEM treatment had reduced tumor burdens. In addition, GEM treatment alone altered the tumor microenvironment(TME), including a reduction in antitumor T cells and a rise in myeloid-derived suppressor cells (MDSC) and regulatory T cells (Tregs). However, combined GPG treatment reversed the tumor immunosuppressive microenvironment induced by GEM. GPG inhibited bone marrow (BM)-derived MDSC differentiation and reversed MDSC expansion induced by conditioned medium (CM) in GEM-treated E0771 cells through a Dectin-1 pathway. In addition, GPG downgraded PD-L1 and IDO1 expression on MDSC while boosting MHC-II, CD86, TNF-α, and IL-6 expression. In conclusion, this study demonstrated that GPG could alleviate the adverse effects induced by GEM chemotherapy by regulating TME.

Pentagalloyl Glucose: A Review of Anticancer Properties, Molecular Targets, Mechanisms of Action, Pharmacokinetics, and Safety Profile

Pentagalloyl glucose (PGG) is a natural hydrolyzable gallotannin abundant in various plants and herbs. It has a broad range of biological activities, specifically anticancer activities, and numerous molecular targets. Despite multiple studies available on the pharmacological action of PGG, the molecular mechanisms underlying the anticancer effects of PGG are unclear. Here, we have critically reviewed the natural sources of PGG, its anticancer properties, and underlying mechanisms of action. We found that multiple natural sources of PGG are available, and the existing production technology is sufficient to produce large quantities of the required product. Three plants (or their parts) with maximum PGG content were Rhus chinensis Mill, Bouea macrophylla seed, and Mangifera indica kernel. PGG acts on multiple molecular targets and signaling pathways associated with the hallmarks of cancer to inhibit growth, angiogenesis, and metastasis of several cancers. Moreover, PGG can enhance the efficacy of chemotherapy and radiotherapy by modulating various cancer-associated pathways. Therefore, PGG can be used for treating different human cancers; nevertheless, the data on the pharmacokinetics and safety profile of PGG are limited, and further studies are essential to define the clinical use of PGG in cancer therapies.

Interactions of Polyphenolic Gallotannins with Amyloidogenic Polypeptides Associated with Alzheimer's Disease: From Molecular Insights to Physiological Significance

Polyphenols are natural compounds abundantly found in plants. They are known for their numerous benefits to human health, including antioxidant properties and anti-inflammatory activities. Interestingly, many studies have revealed that polyphenols can also modulate the formation of amyloid fibrils associated with disease states and can prevent the formation of cytotoxic oligomer species. In this review, we underline the numerous effects of four hydrolysable gallotannins (HGTs) with high conformational flexibility, low toxicity, and multi-targeticity, e.g., tannic acid, pentagalloyl glucose, corilagin, and 1,3,6-tri-O-galloyl-β-D-glucose, on the aggregation of amyloidogenic proteins associated with the Alzheimer's Disease (AD). These HGTs have demonstrated interesting abilities to reduce, at different levels, the formation of amyloid fibrils involved in AD, including those assembled from the amyloid β-peptide, the tubulin-associated unit, and the islet amyloid polypeptide. HGTs were also shown to disassemble pre-formed fibrils and to diminish cognitive decline in mice. Finally, this manuscript highlights the importance of further investigating these naturally occurring HGTs as promising scaffolds to design molecules that can interfere with the formation of proteotoxic oligomers and aggregates associated with AD pathogenesis.

Anti-metastatic effects of 1,2,3,4,6-Penta-O-galloyl-β-D-glucose in colorectal cancer: Regulation of cathepsin B-mediated extracellular matrix dynamics and epithelial-to-mesenchymal transition

Despite significant advances in the diagnosis and treatment of colorectal cancer (CRC), metastatic colorectal cancer still poses serious threat to CRC patients. The natural gallotannin 1,2,3,4,6-penta-O-galloyl-β-D-glucose (PGG) has been shown to possess anti-tumor effects on colon cancer cells, but its anti-metastatic effect is yet to be investigated. In this study, the effects of PGG on cell proliferation, colony formation ability, motility, migration were investigated in colon cancer cells using BrdU, colony formation, scratch, and transwell assays, respectively. Western blot assay was used for assessing protein expression. The orthotopic colon tumor-bearing mouse model and human colon cancer metastatic mouse model were employed to evaluate the anti-metastatic effects of PGG. Results showed that PGG exhibited not only anti-proliferative and colony formation inhibitory effects, but also inhibition on cell adhesion, motility, and migration in both HCT116 and colon 26-M01 cells via modulating protein expression of cathepsin B, FAK, cofilin, and epithelial-to-mesenchymal transition related proteins. In addition, PGG (10 or 15 mg/kg, i.p.) could significantly inhibit liver and lung metastasis in colon cancer metastatic mice models. Furthermore, PGG could regulate the populations of T cells, macrophages, and MDSCs, while the levels of IL-2, IL-6, IL-10, IFN-γ, and TNF-α were altered after PGG treatment in metastatic CRC mice. This is the first report of the anti-metastatic effects of PGG by regulating cathepsin B-mediated extracellular matrix dynamics and epithelial-to-mesenchymal transition process in CRC. Our findings suggested that PGG has great potential to be developed as an anti-metastatic agent for metastatic CRC.

Penta-O-Galloyl-β-D-Glucose in Pistacia integerrima Targets AMPK-ULK1 and ERK/STAT3 Signaling Axes to Induce ROS-Independent Autophagic Cell Death in Human Lung Cancer Cells

Natural molecules have promising perspectives as adjuvants to chemotherapies against cancer. Pistacia chinensis subsp. Integerrima (hereafter, Pistacia integerrima) traditionally known for medicinal values in respiratory disorders was tested for anti-lung cancer properties. The extract prepared from Pistacia integerrima (PI) selectively impaired the viability of lung cancer cells, A549 and NCI-H460, compared to non-cancer cells. At non-lethal concentrations, PI mitigated colony-forming, spheroid formations and metastatic properties of lung cancer cells. As a step toward identifying the phytomolecule that is imparting the anti-lung cancer properties in PI, we subjected the extract to extensive characterization through UPLC/QToF-MS and further validated the findings with UHPLC. The gallotannin, penta-O-galloyl-β-D-glucose (PGG), among others, was identified through UPLC/QToF-MS. PGG exhibits potential chemopreventive effects against various cancer types. However, a defined mechanism of action of PGG in restricting lung cancer progression is still unexplored. Bioactivity-guided column fractionations enabled the determination of PGG as the major phytochemical that governed PI-mediated AMPK-ULK1-dependent autophagy and apoptosis, albeit independent of intracellular ROS activation. Interestingly, the autophagy flux when inhibited restored the cell viability even in the presence of PI. The study further delineated that PI and PGG activated ERK and inhibited STAT3 to trigger apoptosis through caspase-3 and PARP 1 pathways. Collectively, the finding demonstrates that plant extract, PGG, in the PI extract effectively combats lung cancer progression through autophagic cell death by altering ERK/AMPK-ULK1/STAT3 signaling axes. The study proposes PGG as a potential AMPK activator and STAT3 inhibitor that can be exploited further in developing adjuvant chemotherapeutics against lung cancer.

The Angiogenic Balance and Its Implications in Cancer and Cardiovascular Diseases: An Overview

Angiogenesis is the process of developing new blood vessels from pre-existing ones. This review summarizes the main features of physiological and pathological angiogenesis and those of angiogenesis activation and inhibition. In healthy adults, angiogenesis is absent apart from its involvement in female reproductive functions and tissue regeneration. Angiogenesis is a complex process regulated by the action of specific activators and inhibitors. In certain diseases, modulating the angiogenic balance can be a therapeutic route, either by inhibiting angiogenesis (for example in the case of tumor angiogenesis), or by trying to activate the process of new blood vessels formation, which is the goal in case of cardiac or peripheral ischemia.

Apoptotic and DNA Damage Effect of 1,2,3,4,6-Penta-O-galloyl-beta-D-glucose in Cisplatin-Resistant Non-Small Lung Cancer Cells via Phosphorylation of H2AX, CHK2 and p53

Herein, the apoptotic mechanism of 1,2,3,4,6-penta-O-galloyl-β-D-glucopyranose (PGG) was examined in cisplatin-resistant lung cancer cells. PGG significantly reduced viability; increased sub-G1 accumulation and the number of terminal deoxynucleotidyl transferase (TdT) dUTP Nick-End Labeling (TUNEL)-positive cells; induced the cleavage of poly (ADP-ribose) polymerase (PARP), caspases (8,9,3,7), B-cell lymphoma protein 2 (Bcl-2)-associated X (Bax) and phosphatase and tensin homolog deleted on chromosome 10 (PTEN); and attenuated the expression of p-AKT, X-linked inhibitor of apoptosis protein (XIAP), Bcl-2, Bcl-XL and survivin in A549/cisplatin-resistant (CR) and H460/CR cells. Notably, PGG activated p53, p-checkpoint kinase 2 (CHK2) and p-H2A histone family member X (p-H2AX), with increased levels of DNA damage (DSBs) evaluated by highly expressed pH2AX and DNA fragmentation registered on comet assay, while p53 knockdown reduced the ability of PGG to reduce viability and cleave caspase 3 and PARP in A549/CR and H460/CR cells. Additionally, PGG treatment suppressed the growth of H460/CR cells in Balb/c athymic nude mice with increased caspase 3 expression compared with the cisplatin group. Overall, PGG induces apoptosis in cisplatin-resistant lung cancer cells via the upregulation of DNA damage proteins such as γ-H2AX, pCHK2 and p53.

Variation in Population and Solvents as Factors Determining the Chemical Composition and Antioxidant Potential of Arctostaphylos uva-ursi (L.) Spreng. Leaf Extracts

The bearberry Arctostaphylos uva-ursi (L.) Spreng. has a long history of ethnopharmacological use. This species has been used in folk medicine for centuries as a rich source of raw material abundant in secondary metabolites and is important for medicinal and pharmacological purposes. The plant is a source of herbal material—Uvae ursi folium, which is highly valued and sought by pharmaceutical and cosmetic industries. The studied bearberry leaves can be classified as a suitable herbal material for use in pharmacy; therefore, the investigated populations can be a potentially valuable source of plant material for cultivation and can be used in in vitro cultures and in biotechnological processes. The objective of this study was to characterize the variability of the phytochemical composition and antioxidant activity of water and ethanol bearberry extracts from raw material collected from different natural populations. In each of the twelve A. uva-ursi sites, three leaf samples were collected and analyzed. The water extracts from bearberry leaves were characterized by similar concentration of arbutin (77.64–105.56 mg g⁻¹) and a significantly higher concentration of hydroquinone (6.96–13.08 mg g⁻¹) and corilagin (0.83–2.12 mg g⁻¹) in comparison with the ethanol extracts −77.21–103.38 mg g⁻¹, 10.55–16.72 mg g⁻¹, 0.20–1.54 mg g⁻¹, respectively. The concentration of other metabolites in the water extracts was significantly lower in comparison with the ethanol extracts. In the case of the water extracts, a significant effect of not only total phenolic compounds, but also hydroquinone on the antioxidant parameters, was observed, which indicates the solvent-related activity of these metabolites. Therefore, it is suggested that special attention should be paid to the concentration of not only arbutin, but also hydroquinone in Uvae ursi folium. The latter metabolite serving a very important function as an active bearberry ingredient should be controlled not only in alcoholic extracts but also in water extracts, since bearberry leaves are applied as infusions and decoctions. The results presented in this paper can contribute to appropriate selection of plant material for pharmaceutical, cosmetic, and food industries, with special emphasis on the antioxidant activity of different types of extracts.

Chemical Characteristics and Antioxidant Activity of Arctostaphylos uva-ursi L. Spreng. at the Southern Border of the Geographical Range of the Species in Europe

The bearberry (Arctostaphylos uva-ursi L. Spreng.) is a source of herbal material—bearberry leaf (Uvae ursi folium), which is highly valued and sought by pharmaceutical and cosmetic industries. For many years, leaves of this plant have been used in traditional medicine as a diuretic, antimicrobial, and anti-inflammatory agent for various diseases of the urogenital tract. The bearberry has also been proposed as a natural antioxidant additive due to the high contents of phenolic compounds in its leaves. The study was focused on characterization of the basic phytochemical composition and antioxidant activity of extracts derived from bearberry leaves collected from plants located at the southern border of the geographical range of the species in Europe. The investigated herbal material is characterized by a different chemical profile compared to the chemical profiles of bearberry found in other parts of the continent. Bearberry extracts from plants growing in two different habitat types—heathlands and pine forests showed a wide range of variation, especially in the concentration of hyperoside, corilagin, and methylartutin and the total flavonoid contents. In addition to arbutin, bearberry can be a valuable source of phenolic compounds, which are mainly responsible for the antioxidant properties of extracts. The high content of phenols and high values of antioxidant parameters indicate a high potential of bearberry leaves to be used as a powerful natural source of antioxidants in herbal preparations. Therefore, the A. uva-ursi populations can be a source of plant material for pharmaceutical, cosmetic, and food industries.

Mangifera indica (Mango): A Promising Medicinal Plant for Breast Cancer Therapy and Understanding Its Potential Mechanisms of Action

Globally, breast cancer is the most common cancer type and is one of the most significant causes of deaths in women. To date, multiple clinical interventions have been applied, including surgical resection, radiotherapy, endocrine therapy, targeted therapy and chemotherapy. However, 1) the lack of therapeutic options for metastatic breast cancer, 2) resistance to drug therapy and 3) the lack of more selective therapy for triple-negative breast cancer are some of the major challenges in tackling breast cancer. Given the safe nature of natural products, numerous studies have focused on their anti-cancer potentials. Mangifera indica, commonly known as mango, represents one of the most extensively investigated natural sources. In this review, we provide a comprehensive overview of M. indica extracts (bark, kernel, leaves, peel and pulp) and phytochemicals (mangiferin, norathyriol, gallotannins, gallic acid, pyrogallol, methyl gallate and quercetin) reported for in vitro and in vivo anti-breast cancer activities and their underlying mechanisms based on relevant literature from several scientific databases, including PubMed, Scopus and Google Scholar till date. Overall, the in vitro findings suggest that M. indica extracts and/or phytochemicals inhibit breast cancer cell growth, proliferation, migration and invasion as well as trigger apoptosis and cell cycle arrest. In vivo results demonstrated that there was a reduction in breast tumor xenograft growth. Several potential mechanisms underlying the anti-breast cancer activities have been reported, which include modulation of oxidative status, receptors, signalling pathways, miRNA expression, enzymes and cell cycle regulators. To further explore this medicinal plant against breast cancer, future research directions are addressed. The outcomes of the review revealed that M. indica extracts and their phytochemicals may have potential benefits in the management of breast cancer in women. However, to validate its utility in the creation of innovative and potent therapeutic agents to treat breast cancer, more dedicated research, especially clinical studies are needed to explore the anti-breast cancer potentials of M. indica extracts and their phytochemicals.

Chitosan and Curcumin Nanoformulations against Potential Cardiac Risks Associated with Hydroxyapatite Nanoparticles in Wistar Male Rats

Nanoparticle-induced cardiovascular diseases have attracted much attention. Upon entering the blood circulation system, these particles have the potency to induce cardiomyocytes, leading to cardiac failure or myocardial ischemia, and the molecular mechanism remains to be completely clarified. In this study, the cardiac toxicity of rats orally exposed to hydroxyapatite nanoparticles (HAPNPs) has been observed through an increase in myocardial infarction serum markers including CK-MB and alterations in routine blood factors, expression of apoptosis-related protein P53, and increased levels of serum inflammatory markers represented by the tumor necrosis factor alpha and Interleukin-6, as well as a decline in heart antioxidant enzymes and reduced glutathione level, while an induction in lipid peroxidation and nitric oxide has been observed, as well as notable histological and histochemical alterations in the heart of these animals. mRNA and protein expressions of vascular endothelial growth factor (VEGF-A), cyclooxygenase-2 (COX-2), and atrial natriuretic factor (ANF) were elevated in the myocardium. However, the coadministration of chitosan nanoparticles (CsNPs) and/or curcumin nanoparticles (CurNPs) successfully modulated these alterations and induced activation in antioxidant parameters. The present data suggest that HAPNPs-induced apoptosis via the mitochondrial pathway may play a crucial role in cardiac tissue damage and the early treatment with CsNPs and CurNPs may protect the heart from infarction induced by HAPNPs toxic effect.

Phytochemical components and bioactivities of novel medicinal food - Peony roots

Peony as an important medicinal material is widely cultivated in China, which is one of the natural distribution centers of wild peony species. So far, however, there has not been a systematic study of the roots from China's wild peonies. In this study, the total phenolic (TPC), total flavonoid (TFC), other secondary metabolites, and microelement content, as well as the antioxidant, antibacterial, anticholinesterase, and antitumor activities of peony roots from 15 species and 2 subspecies were measured. Thirteen secondary metabolites were detected, with Paeoniflorin and Paeonol being the highest content bio-activities compounds. Additionally, the peony roots had a significant antioxidant activities and bacteriostatic effect against Gram-positive bacteria, with MIC varying from 0.063 to 1 mg/mL. P. anomala subsp. veitchii and P. lactiflora showed outstanding anticholinesterase capacities and cytotoxic activities. Taken together, the data presented here provide new insights into both the medicinal and edible potential of roots from wild peony species.

Profiling Anticancer and Antioxidant Activities of Phenolic Compounds Present in Black Walnuts (Juglans nigra) Using a High-Throughput Screening Approach

Our recent studies have demonstrated multiple health-promoting benefits from black walnut kernels. These biological functions of black walnuts are likely associated with their bioactive constituents. Characterization of phenolic compounds found in black walnut could point out underexplored bioactive activities of black walnut extracts and promote the development of novel applications of black walnut and its by-products. In the present study, we assessed bioactivity profiles of phenolic compounds identified in the kernels of black walnuts using a high-throughput screening (HTS) approach. Black walnut phenolic compounds were evaluated in terms of their total antioxidant capacity, antioxidant response element (ARE) induction, and anticancer activities. The anticancer activities were identified by evaluating the effects of the phenolic compounds on the growth of the tumorigenic alveolar epithelial cells (A549) and non-tumorigenic lung fibroblast cells (MRC-5). Out of 16 phenolic compounds tested, several compounds (penta-O-galloyl-β-d-glucose, epicatechin gallate, quercetin, (–)-epicatechin, rutin, quercetin 3-β-d-glucoside, gallic acid, (+)-catechin, ferulic acid, syringic acid) exerted antioxidant activities that were significantly higher compared to Trolox, which was used as a control. Two phenolic compounds, penta-O-galloyl-β-d-glucose and quercetin 3-β-d-glucoside, exhibited antiproliferative activities against both the tumorigenic alveolar epithelial cells (A549) and non-tumorigenic lung fibroblast cells (MRC-5). The antioxidant activity of black walnut is likely driven not only by penta-O-galloyl-β-d-glucose but also by a combination of multiple phenolic compounds. Our findings suggested that black walnut extracts possibly possess anticancer activities and supported that penta-O-galloyl-β-d-glucose could be a potential bioactive agent for the cosmetic and pharmaceutical industries.

Identification of functional compounds in baru (Dipteryx alata Vog.) nuts: Nutritional value, volatile and phenolic composition, antioxidant activity and antiproliferative effect

This work aimed to contribute to the nutritional and functional characterization of roasted baru nuts, a seed widely consumed and produced in Brazil. Baru nut was characterized in terms of its nutritional value and volatile composition (SPME-GC-MS analysis). The ultrasound assisted extraction was used to extract free and bound phenolic compounds that were identified by LC-DAD-ESI-MS/MS method. Bioactivity assays were carried out to evaluate the antioxidant activity (ORAC and HOSC assay) and anticancer effect (inhibition of HT29 cell growth and targeting of cancer stemness) of baru nut extracts and phenolic compounds. Results showed that baru is a good source of protein and monounsaturated fatty acids, specifically oleic acid (47.20 g/100 g). The predominant volatile compounds are hexanal (71.18%) and 2,5-dimethyl-pyrazine (9.43%). The main phenolic compounds identified were gallic acid and its derivatives, such as gallic acid esters and gallotannins. Among all, gallic acid and methyl gallate seemed to be the main compounds responsible for the high antioxidant activity. The antiproliferative effect evaluated of baru extracts in HT29 cell line showed ability to impair cell growth in both monolayer and spheroid cultures and to reduce ALDH+ population. These results supply new information about the functional compounds presents in baru nut, which are important sources of natural antioxidants and antiproliferative compounds.

Action of tannin on cellular membranes: Novel insights from concerted studies on lipid bilayers and native cells

Hydrolyzable tannin (3,6-bis-O-digalloyl-1,2,4-tri-O-galloyl-β-d-glucose) has a dual effect on the cell membrane: (1) it binds to a plasmalemmal protein of the Chara corallina cell (C₅₀ = 2.7 ± 0.3 μM) and (2) it forms ionic channels in the lipid membrane. Based on these facts, a molecular model for the interaction of tannins with the cell membrane is proposed. The model suggests that the molecules of hydrolyzable tannin bind electrostatically to the outer groups of the membrane protein responsible for the Ca²⁺-dependent chloride current and blocks it. Some tannin molecules penetrate into the hydrophobic region of the membrane, and when a particular concentration is reached, they form ion-conducting structures selective toward Cl^-.

1,2,3,4,6-Penta-O-galloyl-β-d-glucose modulates perivascular inflammation and prevents vascular dysfunction in angiotensin II-induced hypertension

Background and Purpose

Hypertension is a multifactorial disease, manifested by vascular dysfunction, increased superoxide production, and perivascular inflammation. In this study, we have hypothesized that 1,2,3,4,6‐penta‐O‐galloyl‐β‐d‐glucose (PGG) would inhibit vascular inflammation and protect from vascular dysfunction in an experimental model of hypertension.

Experimental Approach

PGG was administered to mice every 2 days at a dose of 10 mg·kg⁻¹ i.p during 14 days of Ang II infusion. It was used at a final concentration of 20 μM for in vitro studies in cultured cells.

Key Results

Ang II administration increased leukocyte and T‐cell content in perivascular adipose tissue (pVAT), and administration of PGG significantly decreased total leukocyte and T‐cell infiltration in pVAT. This effect was observed in relation to all T‐cell subsets. PGG also decreased the content of T‐cells bearing CD25, CCR5, and CD44 receptors and the expression of both monocyte chemoattractant protein 1 (CCL2) in aorta and RANTES (CCL5) in pVAT. PGG administration decreased the content of TNF⁺ and IFN‐γ⁺ CD8 T‐cells and IL‐17A⁺ CD4⁺ and CD3⁺CD4⁻CD8⁻ cells. Importantly, these effects of PGG were associated with improved vascular function and decreased ROS production in the aortas of Ang II‐infused animals independently of the BP increase. Mechanistically, PGG (20 μM) directly inhibited CD25 and CCR5 expression in cultured T‐cells. It also decreased the content of IFN‐γ⁺ CD8⁺ and CD3⁺CD4⁻CD8⁻ cells and IL‐17A⁺ CD3⁺CD4⁻CD8⁻ cells.

Conclusion and Implication

PGG may constitute an interesting immunomodulating strategy in the regulation of vascular dysfunction and hypertension.

Linked Articles

This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc

Pentagalloyl Glucose and Its Functional Role in Vascular Health: Biomechanics and Drug-Delivery Characteristics

Pentagalloyl glucose (PGG) is an elastin-stabilizing polyphenolic compound that has significant biomedical benefits, such as being a free radical sink, an anti-inflammatory agent, anti-diabetic agent, enzymatic resistant properties, etc. This review article focuses on the important benefits of PGG on vascular health, including its role in tissue mechanics, the different modes of pharmacological administration (e.g., oral, intravenous and endovascular route, intraperitoneal route, subcutaneous route, and nanoparticle based delivery and microbubble-based delivery), and its potential therapeutic role in vascular diseases such as abdominal aortic aneurysms (AAA). In particular, the use of PGG for AAA suppression and prevention has been demonstrated to be effective only in the calcium chloride rat AAA model. Therefore, in this critical review we address the challenges that lie ahead for the clinical translation of PGG as an AAA growth suppressor.

1,2,3,4,6-Penta-O-Galloyl-Beta-D-Glucopyranoside Inhibits Proliferation of Multiple Myeloma Cells Accompanied with Suppression of MYC Expression

Multiple myeloma (MM) still remains an incurable disease, therefore discovery of novel drugs boosts the therapeutics for MM. The natural compound 1,2,3,4,6-Penta-O-galloyl-beta-D-glucopyranoside (PGG) has been shown to exhibit antitumor activities against various cancer cells. Here, we aim to evaluate antitumor effects of PGG on MM cell lines. PGG inhibited the growth of three different MM cell lines in a dose- and time-dependent manner. Cell cycle analysis revealed that PGG treatment caused cell cycle arrest in G1 phase. It also induced apoptosis which was indicated by significant increases of Annexin V positive cells, caspase 3/7 activity, and cleaved caspase 3 expression in PGG treated MM cell. Since MYC is frequently hyperactivated in MM and inhibition of MYC leads to MM cell death. We further demonstrated that PGG decreased MYC expression in protein and mRNA levels and reversed the mRNA expression of MYC target genes such as p21, p27, and cyclin D2. In addition, PGG also reduced protein expression of DEPTOR which is commonly overexpressed in MM. Unexpectedly, PGG antagonized the cytotoxic effect of bortezomib in the combination treatment. However, PGG treatment sensitized MM cells to another proteasome inhibitor MG132 induced cytotoxicity. Moreover, MYC inhibitor JQ1 enhanced the cytotoxic effect of bortezomib on MM cells. Our findings raised concerns about the combinatory use of bortezomib with particular types of chemicals. The evidence also provide useful insights into the combination of MYC and proteasome-inhibitors for MM therapy. Finally, PGG has a therapeutic potential for treatment of MM and further development is mandatory.

Anti-angiogenic effect of chebulagic acid involves inhibition of the VEGFR2- and GSK-3β-dependent signaling pathways

Inhibition of angiogenesis is a useful strategy to prevent cancer growth by targeting new vessels that grow to nourish actively proliferating tumor cells. Endothelial cells can use a number of different pathways to cause angiogenesis, and each step in these pathways can be targeted. The use of multi-targeted drugs is gaining much importance in this scenario. Our previous results have shown that chebulagic acid (a benzopyran tannin present in the fruits of Terminalia chebula) has anti-angiogenic properties. Thus, this study was designed to examine the molecular mechanism for the anti-angiogenic effects of chebulagic acid. Results from our investigations using molecular docking studies and human umbilical vein endothelial cells in culture suggested that chebulagic acid inhibits both GSK-3β-dependent β-catenin phosphorylation (an important mediator of VE-cadherin–β-catenin signaling) and VEGFR2 phosphorylation, which is an important step in VEGF signaling. Chebulagic acid inhibits angiogenesis by blocking both the VEGF–VEGFR2 complex and cell–cell contact dependent downstream signaling pathways.

Water extract of Galla Rhois with steaming process enhances apoptotic cell death in human colon cancer cells

Background

Galla Rhois has been considered to have medicinal properties against diarrhea, excessive sweating, bleeding, and chronic cough in Asian countries. Gallotannins, which are Galla Rhois-derived tannins, have been reported to possess biological and pharmacological activities, especially anticancer activity. In this study, we evaluated the effect of steaming at a temperature over 120 °C on the chemical constituents and biological activities of the water extract of Galla Rhois (GRE).

Methods

GRE was steamed at a temperature over 120 °C (AGRE), and its specific constituents were analyzed; the results were validated using a high-performance liquid chromatography–diode array detector system. To evaluate the anticancer effect of GRE and AGRE, cell viability assay, cell cycle analysis, and Western blot analysis were performed in HCT116 human colon cancer cells.

Results

Steaming markedly increased the contents of gallic acid and ellagic acid in GRE, and GRE or AGRE treatment reduced the viability of HCT116 cells. Notably, the steaming process enhanced the growth inhibitory effect of GRE in cancer cells. AGRE induced apoptosis through the activation of caspase-3, caspase-8, and caspase-9. Additionally, AGRE regulated the activation of mitogen-activated protein kinases including extracellular signal-regulated kinase, p38, and c-Jun NH2-terminal kinase, whereas GRE did not. However, both GRE and AGRE inhibited the activation of AKT.

Conclusion

Compared with GRE, AGRE is more potent in its ability to induce apoptosis in HCT116 cells; therefore, we suggest that the steaming process may be useful as a feasible method for improving the anticancer effect of GRE.

Melittin suppresses cathepsin S-induced invasion and angiogenesis via blocking of the VEGF-A/VEGFR-2/MEK1/ERK1/2 pathway in human hepatocellular carcinoma

Melittin, a significant constituent of Apis mellifera (honeybee) venom, is a water-soluble toxic peptide that has traditionally been used as an antitumor agent. However, the underlying mechanisms by which it inhibits tumor cell growth and angiogenesis remain to be elucidated. In the present study, screening for increased cathepsin S (Cat S) expression levels was performed in MHCC97-H cells and various other hepatocellular carcinoma cell lines by reverse transcription-polymerase chain reaction and western blot analysis. A pcDNA3.1-small hairpin RNA (shRNA)-Cat S vector was stably transfected into MHCC97-H cells (shRNA/MHCC97-H) in order to knockdown the expression of Cat S. The effects resulting from the inhibition of Cat S-induced proliferation, invasion and angiogenesis by melittin were examined using cell proliferation, cell viability, flat plate colony formation, migration, wound healing, Transwell migration and ELISA assays. In order to substantiate the evidence for melittin-mediated inhibition of Cat S-induced angiogenesis, Cat S RNA was transfected into primary human umbilical vein endothelial cells (Cat S-HUVECs) to induce overexpression of the Cat S gene. The effects of melittin on HUVECs were examined using Transwell migration and tube formation assays. The findings demonstrated that melittin was able to significantly suppress MHCC97-H cell (Mock/MHCC97-H) proliferation, invasion and angiogenesis, as well as capillary tube formation of Cat S-HUVECs, in a dose-dependent manner. However, proliferation, invasion and angiogenesis in shRNA/MHCC97-H and in native HUVECs (Mock-HUVECs) were unaffected. In addition, melittin specifically decreased the expression of phosphorylated (activated) Cat S, and components of the vascular endothelial growth factor (VEGF)-A/VEGF receptor 2 (VEGFR-2)/mitogen-activated protein kinase kinase 1 (MEK1)/extracellular signal-regulated kinase (ERK)1/2 signaling pathway in Mock/MHCC97-H cells. In conclusion, the inhibition of tumor cell growth and anti-angiogenic activity exerted by melittin may be associated with anti-Cat S actions, via the inhibition of VEGF-A/VEGFR-2/MEK1/ERK1/2 signaling.

Antiangiogenic Effect of Ethanol Extract of Vigna angularis via Inhibition of Phosphorylation of VEGFR2, Erk, and Akt

Though dietary azuki bean (Vigna angularis) seed containing antioxidant proanthocyanidins was known to have multibiological activities including antioxidant, hypotensive, anti-inflammatory, and immunomodulatory activities, the antiangiogenic activity of ethanol extract of Vigna angularis (EVA) was never reported so far. In the present study, the antiangiogenic mechanism of EVA was examined in human umbilical vein endothelial cells (HUVECs). EVA showed weak cytotoxicity in HUVECs, while it significantly suppressed the VEGF induced proliferation of HUVECs. Consistently, wound healing assay revealed that EVA inhibited the VEGF induced migration of HUVECs. Also, EVA abrogated the VEGF induced tube formation of HUVECs in a concentration dependent fashion. Furthermore, Matrigel plug assay showed that EVA significantly reduced the hemoglobin level of Matrigel plug in mice compared to untreated control. Of note, EVA effectively attenuated the phosphorylation of VEGFR2, Erk, and Akt in VEGF-treated HUVECs. Overall, our findings suggest that EVA inhibits angiogenesis in VEGF-treated HUVECs via inhibition of phosphorylation of VEGFR2, ERK, and Akt.

Application of eupatilin in the treatment of osteosarcoma

5,7-dihydroxy-3',4',6-trimethoxyflavone, commonly known as eupatilin, is a traditional Asian medicinal plant, which is mainly used for the treatment of gastritis, as well as its use as an anti-inflammatory agent. Eupatilin is a bioactive compound; however, its effects on osteosarcoma (OS) have remained to be elucidated. Therefore, the present study aimed to investigate the effects of eupatilin on this malignant bone tumor, using the U-2 OS cell line. The experimental results revealed that eupatilin inhibited U-2 OS cell growth in a concentration-dependent manner and induced G2/M phase cell cycle arrest and apoptosis. Additionally, western blot analysis indicated that eupatilin was able to trigger the mitochondrial apoptotic pathway, demonstrated by the enhanced Bax/B cell lymphoma-2 ratio, decrease in mitochondrial membrane potential, release of cytochrome c, caspase-3 and -9 activation and poly(ADP-ribose)polymerase cleavage detected in the U-2 OS cells. These results indicated that eupatilin was able to inhibit U-2 OS cancer cell proliferation by the induction of apoptosis via the mitochondrial intrinsic pathway. Eupatilin may therefore represent a novel anticancer drug for use in the treatment of osteosarcoma.

1,2,3,4,6-Penta-O-galloylglucose within Galla Chinensis Inhibits Human LDH-A and Attenuates Cell Proliferation in MDA-MB-231 Breast Cancer Cells

A characteristic feature of aggressive malignancy is the overexpression of lactic acid dehydrogenase- (LDH-) A, concomitant to pericellular accumulation of lactate. In a recent high-throughput screening, we identified Rhus chinensis (Mill.) gallnut (RCG) (also known as Galla Chinensis) extract as a potent (IC50 < 1 µg/mL) inhibitor of human LDH-A (hLDH-A). In this study, through bioactivity guided fractionation of the crude extract, the data demonstrate that penta-1,2,3,4,6-O-galloyl-β-D-glucose (PGG) was a primary constituent responsible for hLDH-A inhibition, present at ~9.95 ± 0.34% dry weight. Theoretical molecular docking studies of hLDH-A indicate that PGG acts through competitive binding at the NADH cofactor site, effects confirmed by functional enzyme studies where the IC50 = 27.32 nM was reversed with increasing concentration of NADH. Moreover, we confirm protein expression of hLDH-A in MDA-231 human breast carcinoma cells and show that PGG was toxic (LC50 = 94.18 µM), parallel to attenuated lactic acid production (IC50 = 97.81 µM). In a 72-hour cell proliferation assay, PGG was found to be a potent cytostatic agent with ability to halt cell division (IC50 = 1.2 µM) relative to paclitaxel (IC50 < 100 nM). In summary, these findings demonstrate that PGG is a potent hLDH-A inhibitor with significant capacity to halt proliferation of human breast cancer cells.

A validated liquid chromatography-tandem mass spectrometry method for the determination of methyl gallate and pentagalloyl glucopyranose: application to pharmacokinetic studies

Methyl gallate (MG) and pentagalloyl glucopyranose (PGG) are bioactive phenolic compounds that are widely distributed in herbs and plant foods. Their potential activities include anti-oxidant, anti-inflammatory, anti-cancer, anti-bacterial and anti-viral activities. However, knowledge concerning the pharmacokinetic characteristics of MG and PGG is limited. The purpose of this study was to develop a sensitive and reproducible ultra-performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS) method to simultaneously quantify MG and PGG in rat blood samples. The linear response ranges for MG and PGG were 0.0195-20 and 0.0390-20 μM, respectively. The lower limit of quantification was 0.0195 μM for MG and 0.0390 μM for PGG. The intra- and inter-day variances were less than 15%, and accuracy was within 80-120%. This assay was successfully applied to pharmacokinetic studies in Sprague-Dawley rats after intraperitoneal administration of MG and PGG (20 mg/kg). The values of areas under the blood concentration time curves (AUC₀₋₂₄ h) for MG and PGG were 109.9 ± 73.40 and 38.78 ± 24.53 h*μM, respectively. The maximum blood concentrations (Cmax) of MG and PGG were 34.72 ± 17.32 and 6.39 ± 4.25 μM, respectively. The time required to reach the maximum concentration (Tmax) was 0.85 ± 0.70 h for both MG and PGG. The values of the elimination rate constant (Ke), elimination half-life (t1/2), volume of distribution (Vd), clearance (Cl) and mean resident time (MRTlast) were 0.056 ± 0.032 h(-1), 17.50 ± 12.25 h, 530.95 ± 247.54 L/kg, 159.91±76.05L/h/kg, 8.71 ± 2.53 h for MG and 0.023 ± 0.012 h(-1), 38.66 ± 22.89 h, 7838.89 ± 3474.72 L/kg, 30.98 ± 21.73 L/h/kg, 12.47 ± 2.77 h for PGG, respectively. In conclusion, a UPLC-MS/MS method was fully validated over a wide linear range and used to quantify the levels of MG and PGG in pharmacokinetic studies of MG and PGG in rats. The main advantages of this method are the use of small blood volumes (10 μL), rapid analysis (5 min) and excellent recoveries.

Dietary polyphenols in prevention and treatment of prostate cancer

Prostate cancer is the most prevalent disease affecting males in many Western countries, with an estimated 29,480 deaths in 2014 in the US alone. Incidence rates for prostate cancer deaths have been decreasing since the early 1990s in men of all races/ethnicities, though they remain about 60% higher in African Americans than in any other group. The relationship between dietary polyphenols and the prevention of prostate cancer has been examined previously. Although results are sometimes inconsistent and variable, there is a general agreement that polyphenols hold great promise for the future management of prostate cancer. Various dietary components, including polyphenols, have been shown to possess anti-cancer properties. Generally considered as non-toxic, dietary polyphenols act as key modulators of signaling pathways and are therefore considered ideal chemopreventive agents. Besides possessing various anti-tumor properties, dietary polyphenols also contribute to epigenetic changes associated with the fate of cancer cells and have emerged as potential drugs for therapeutic intervention. Polyphenols have also been shown to affect post-translational modifications and microRNA expressions. This article provides a systematic review of the health benefits of selected dietary polyphenols in prostate cancer, especially focusing on the subclasses of polyphenols, which have a great effect on disease prevention and treatment.

Penta-O-galloyl-β-D-glucose suppresses EGF-induced eIF3i expression through inhibition of the PI3K/AKT/mTOR pathway in prostate cancer cells

Approximately 70% of prostate cancer patients will develop bone metastasis in axial and other regions of the skeleton. Epidermal growth factor (EGF) generated from bone tissue contributes to prostate cancer metastasis. In a previous study, penta-O-galloyl-β-D-glucose (PGG) suppressed androgen-independent prostate cancer bone metastasis by transcriptionally repressing EGF-induced MMP-9 expression. This study utilized proteomics to analyze the effects of PGG in EGF-induced prostate cancer bone metastasis. This study showed that PGG suppressed EGF-induced eIF3i expression in PC-3 cells. By transfection of eIF3i shRNA, it was observed that reduced eIF3i expression suppressed the invasion of PC-3 cells in vitro. PGG reduced EGF-induced eIF3i expression through inhibition of the PI3K/AKT/mTOR pathway. Therefore, PGG may be able to be used as a potential new therapeutic drug for prostate cancer bone metastasis.

Whole-exome sequencing reveals TopBP1 as a novel gene in idiopathic pulmonary arterial hypertension

RATIONALE

Idiopathic pulmonary arterial hypertension (IPAH) is a life-threatening disorder characterized by progressive loss of pulmonary microvessels. Although mutations in the bone morphogenetic receptor 2 (BMPR2) are found in 80% of heritable and ∼15% of patients with IPAH, their low penetrance (∼20%) suggests that other unidentified genetic modifiers are required for manifestation of the disease phenotype. Use of whole-exome sequencing (WES) has recently led to the discovery of novel susceptibility genes in heritable PAH, but whether WES can also accelerate gene discovery in IPAH remains unknown.

OBJECTIVES

To determine whether WES can help identify novel gene modifiers in patients with IPAH.

METHODS

Exome capture and sequencing was performed on genomic DNA isolated from 12 unrelated patients with IPAH lacking BMPR2 mutations. Observed genetic variants were prioritized according to their pathogenic potential using ANNOVAR.

MEASUREMENTS AND MAIN RESULTS

A total of nine genes were identified as high-priority candidates. Our top hit was topoisomerase DNA binding II binding protein 1 (TopBP1), a gene involved in the response to DNA damage and replication stress. We found that TopBP1 expression was reduced in vascular lesions and pulmonary endothelial cells isolated from patients with IPAH. Although TopBP1 deficiency made endothelial cells susceptible to DNA damage and apoptosis in response to hydroxyurea, its restoration resulted in less DNA damage and improved cell survival.

CONCLUSIONS

WES led to the discovery of TopBP1, a gene whose deficiency may increase susceptibility to small vessel loss in IPAH. We predict that use of WES will help identify gene modifiers that influence an individual's risk of developing IPAH.

Assessment methods for angiogenesis and current approaches for its quantification

Angiogenesis is a physiological process which describes the development of new blood vessels from the existing vessels. It is a common and the most important process in the formation and development of blood vessels, so it is supportive in the healing of wounds and granulation of tissues. The different assays for the evaluation of angiogenesis have been described with distinct advantages and some limitations. In order to develop angiogenic and antiangiogenic techniques, continuous efforts have been resulted to give animal models for more quantitative analysis of angiogenesis. Most of the studies on angiogenic inducers and inhibitors rely on various models, both in vitro, in vivo and in ova, as indicators of efficacy. The angiogenesis assays are very much helpful to test efficacy of both pro- and anti- angiogenic agents. The development of non-invasive procedures for quantification of angiogenesis will facilitate this process significantly. The main objective of this review article is to focus on the novel and existing methods of angiogenesis and their quantification techniques. These findings will be helpful to establish the most convenient methods for the detection, quantification of angiogenesis and to develop a novel, well tolerated and cost effective anti-angiogenic treatment in the near future.

Suppression of E-cadherin mediates gallotannin induced apoptosis in Hep G2 hepatocelluar carcinoma cells

Though gallotannin was known to have anti-oxidant and antitumor activity, the underlying antitumor mechanism of gallotannin still remains unclear. Thus, in the present study, antitumor mechanism of gallotannin was elucidated in hepatocellular carcinoma cells. Gallotannin significantly exerted cytotoxicity against Hep G2 and Chang hepatocellular carcinoma cells with the accumulation of the sub-G1 population and increase of terminal deoxynucleotidyltransferasedUTP nick end labeling (TUNEL) positive cells as an apoptotic feature. Also, gallotannin attenuated the expression of pro-caspase9, pro-caspase3, Bcl2 and integrin β1 and cleaved poly(ADP)-ribose polymerase (PARP) in Hep G2 and Chang cancer cells. Furthermore, gallotannin suppressed cell repair motility by wound healing assay and also inhibited cell adhesion in Hep G2 cells. Of note, gallotannin attenuated the expression of epithelial cadherin (E-cadherin) to form cell-cell adhesion from the early stage, and also beta-catenin at late phase in Hep G2 cells. Consistently, Immunofluorescence assay showed that E-cadherin or β-catenin expression was suppressed in a time dependent manner by gallotannin. Furthermore, silencing of E-cadherin by siRNA transfection method enhanced PAPR cleavage, caspase 3 activation and sub G1 population and attenuated the cell adhesion induced by gallotannin in Hep G2 cells. Overall, our findings demonstrate that the disruption of cell adhesion junction by suppression of E-cadherin mediates gallotannin enhanced apoptosis in Hep G2 liver cancer cells.

Biological and biomedical functions of Penta-O-galloyl-D-glucose and its derivatives

Penta-O-galloyl-D-glucose (PGG) is a simple hydrolysable tannin in plants. PGG exists in two anomeric forms, α-PGG and β-PGG. While β-PGG can be found in a wide variety of plants, α-PGG is rather rare in nature. Numerous studies with β-PGG revealed a wide variety of biological activities, such as anti-microbial and anti-cancer functions. Until recently, studies with α-PGG were limited by the lack of its availability. Since the development of an efficient chemical synthesis of the compound, several investigations have revealed its anti-diabetic, anti-cancer, and anti-platelet-coagulation functions. Based on structure-activity-relationship (SAR) studies with α-PGG, a variety of α-PGG-related novel compounds were synthesized and some of them have been shown to possess promising therapeutic activities. In this review, the authors will survey and evaluate the biological functions of PGG with a focus on α-PGG and its derivatives.

Triggering of suicidal erythrocyte death by penta-O-galloyl-β-D-glucose

The polyphenolic 1,2,3,4,6-penta-O-galloyl-beta-d-glucose from several medicinal herbs triggers apoptosis and has, thus, been proposed for treatment of malignancy. The substance is at least partially effective through caspase activation. In analogy to apoptosis of nucleated cells, erythrocytes may enter suicidal death or eryptosis, which is characterized by cell shrinkage and by phosphatidylserine translocation to the erythrocyte surface. Eryptosis is triggered by increase of cytosolic Ca²⁺-activity ([Ca²⁺]i). The sensitivity to [Ca²⁺]i is enhanced by ceramide. The present study explored whether penta-O-galloyl-β-d-glucose stimulates eryptosis. Cell volume was estimated from forward scatter, phosphatidylserine exposure from annexin V binding, hemolysis from hemoglobin-release, [Ca²⁺]i from Fluo3-fluorescence and ceramide abundance from fluorescent antibodies. A 48-h exposure of human erythrocytes to penta-O-galloyl-β-d-glucose significantly decreased forward scatter (50 µM) and significantly increased annexin V binding (10 µM). Up to 50 µM penta-O-galloyl-β-d-glucose did not significantly modify [Ca²⁺]i. However, the effect of penta-O-galloyl-β-d-glucose (25 µM) induced annexin V binding was slightly, but significantly, blunted by removal of extracellular Ca²⁺, pointing to sensitization of erythrocytes to the scrambling effect of Ca²⁺. Penta-O-galloyl-β-d-glucose (25 µM) further increased ceramide formation. In conclusion, penta-O-galloyl-β-d-glucose stimulates suicidal erythrocyte death or eryptosis, an effect partially due to stimulation of ceramide formation with subsequent sensitization of erythrocytes to Ca²⁺.

Involvement of autophagy induction in penta-1,2,3,4,6-O-galloyl-β-D-glucose-induced senescence-like growth arrest in human cancer cells

Growing evidence has demonstrated that autophagy plays important and paradoxical roles in carcinogenesis, while senescence is considered to be a crucial tumor-suppressor mechanism in cancer prevention and treatment. In the present study we demonstrated that both autophagy and senescence were induced in response to penta-1,2,3,4,6-O-galloyl-β-D-glucose (PGG), a chemopreventive polyphonolic compound, in multiple types of cancer cells. Analysis of these 2 events over the experimental time course indicated that autophagy and senescence occurred in parallel early in the process and dissociated later. The long-term culture study suggested that a subpopulation of senescent cells may have the capacity to reenter the cell cycle. Inhibition of autophagy by either a chemical inhibitor or RNA interference led to a significant reduction of PGG-induced senescence, followed by induction of apoptosis. These results suggested that autophagy promoted senescence induction by PGG and that PGG might exert its anticancer activity through autophagy-mediated senescence. For the first time, these findings uncovered the relationships among autophagy, senescence, and apoptosis induced by PGG. In addition, we identified that unfolded protein response signaling played a pivotal role in the autophagy-mediated senescence phenotype. Furthermore, our data showed that activation of MAPK8/9/10 (mitogen-activated protein kinase 8/9/10/c-Jun N-terminal kinases) was an essential upstream signal for PGG-induced autophagy. Finally, the key in vitro results were validated in vivo in a xenograft mouse model of human HepG2 liver cancer. Our findings provided novel insights into understanding the mechanisms and functions of PGG-induced autophagy and senescence in human cancer cells.

1,2,3,4,6-Penta-O-galloyl-β-D-glucopyranose inhibits angiogenesis via inhibition of capillary morphogenesis gene 2

Capillary morphogenesis gene 2 (CMG2) is a transmembrane extracellular matrix binding protein that is also an anthrax toxin receptor. We have shown that high-affinity CMG2 binders can inhibit angiogenesis and tumor growth. We recently described a high-throughput FRET assay to identify CMG2 inhibitors. We now report the serendipitous discovery that PGG (1,2,3,4,6-penta-O-galloyl-β-D-glucopyranose) is a CMG2 inhibitor with antiangiogenic activity. PGG is a gallotannin produced by a variety of medicinal plants that exhibits a wide variety of antitumor and other activities. We find that PGG inhibits CMG2 with a submicromolar IC50 and it also inhibits the migration of human dermal microvascular endothelial cells at similar concentrations in vitro. Finally, oral or intraperitoneal administration of PGG inhibits angiogenesis in the mouse corneal micropocket assay in vivo. Together, these results suggest that a portion of the in vivo antitumor activity of PGG may be the result of antiangiogenic activity mediated by inhibition of CMG2.

High-Throughput Screening to Identify Plant Derived Human LDH-A Inhibitors

Aims

Lactate dehydrogenase (LDH)-A is highly expressed in diverse human malignant tumors, parallel to aggressive metastatic disease, resistance to radiation/chemotherapy and clinically poor outcome. Although this enzyme constitutes a plausible target in treatment of advanced cancer, there are few known LDH-A inhibitors.

Study Design

In this work, we utilized a high-throughput enzyme micro-array format to screen and evaluate > 900 commonly used medicinal plant extracts (0.00001-.5 mg/ml) for capacity to inhibit activity of recombinant full length human LDHA; EC .1.1.1.27.

Methodology

The protein sequence of purified enzyme was confirmed using 1D gel electrophoresis- MALDI-TOF-MS/MS, enzyme activity was validated by oxidation of NADH (500μM) and kinetic inhibition established in the presence of a known inhibitor (Oxalic Acid).

Results

Of the natural extracts tested, the lowest IC₅₀s [<0.001 mg/ml] were obtained by: Chinese Gallnut (Melaphis chinensis gallnut), Bladderwrack (Fucus vesiculosus), Kelp (Laminaria Japonica) and Babul (Acacia Arabica). Forty-six additional herbs contained significant LDH-A inhibitory properties with IC₅₀s [<0.07 mg/ml], some of which have common names of Arjun, Pipsissewa, Cinnamon, Pink Rose Buds/Petals, Wintergreen, Cat’s Claw, Witch Hazel Root and Rhodiola Root.

Conclusion

These findings reflect relative potency by rank of commonly used herbs and plants that contain human LDH-A inhibitory properties. Future research will be required to isolate chemical constituents within these plants responsible for LDH-A inhibition and investigate potential therapeutic application.