Anticancer activities of epigallocatechin-3-gallate against cholangiocarcinoma cells

Cancer Prevention and Treatment with Polyphenols: Type IV Collagenase-Mediated Mechanisms

Polyphenols are natural compounds found in many plants and their products. Their high structural diversity bestows upon them a range of anti-inflammatory, anti-oxidant, proapoptotic, anti-angiogenic, and anti-metastatic properties, and a growing body of research indicates that a polyphenol-rich diet can inhibit cancer development in humans. Polyphenolic compounds may modulate the expression, secretion, or activity of compounds that play a significant role in carcinogenesis, including type IV collagenases, such as matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9), by suppressing cellular signaling pathways such as nuclear factor-kappa B. These enzymes are responsible for the degradation of the extracellular matrix, thus promoting the progression of cancer. This review discusses the current state of knowledge concerning the anti-cancer activity of polyphenols, particularly curcumin, resveratrol, epigallocatechin-3-gallate, genistein, and quercetin, with a specific focus on their anti-invasive and anti-metastatic potential, based on the most recent in vitro and in vivo studies. It appears that polyphenols may be valuable options for the chemoprevention and treatment of cancer via the inhibition of MMP-2 and MMP-9 and the suppression of signaling pathways regulating their expression and activity.

Bioactive nutraceuticals as G4 stabilizers: potential cancer prevention and therapy-a critical review

G-quadruplexes (G4) are non-canonical, four-stranded, nucleic acid secondary structures formed in the guanine-rich sequences, where guanine nucleotides associate with each other via Hoogsteen hydrogen bonding. These structures are widely found near the functional regions of the mammalian genome, such as telomeres, oncogenic promoters, and replication origins, and play crucial regulatory roles in replication and transcription. Destabilization of G4 by various carcinogenic agents allows oncogene overexpression and extension of telomeric ends resulting in dysregulation of cellular growth-promoting oncogenesis. Therefore, targeting and stabilizing these G4 structures with potential ligands could aid cancer prevention and therapy. The field of G-quadruplex targeting is relatively nascent, although many articles have demonstrated the effect of G4 stabilization on oncogenic expressions; however, no previous study has provided a comprehensive analysis about the potency of a wide variety of nutraceuticals and some of their derivatives in targeting G4 and the lattice of oncogenic cell signaling cascade affected by them. In this review, we have discussed bioactive G4-stabilizing nutraceuticals, their sources, mode of action, and their influence on cellular signaling, and we believe our insight would bring new light to the current status of the field and motivate researchers to explore this relatively poorly studied arena.

EGCG Suppresses Adipogenesis and Promotes Browning of 3T3-L1 Cells by Inhibiting Notch1 Expression

BACKGROUND

With the changes in lifestyle and diet structure, the incidence of obesity has increased year by year, and obesity is one of the inducements of many chronic metabolic diseases. Epigallocatechin gallate (EGCG), which is the most abundant component of tea polyphenols, has been used for many years to improve obesity and its complications. Though it has been reported that EGCG can improve obesity through many molecular mechanisms, EGCG may have many mechanisms yet to be explored. In this study, we explored other possible mechanisms through molecular docking and in vitro experiments.

METHODS

AutoDock Vina was selected for conducting the molecular docking analysis to elucidate the interaction between EGCG and Notch1, while molecular dynamics simulations were employed to validate this interaction. Then, the new regulation mechanism of EGCG on obesity was verified with in vitro experiments, including a Western blot experiment, immunofluorescence experiment, oil red O staining, and other experiments in 3T3-L1 adipocytes.

RESULTS

The molecular docking results showed that EGCG could bind to Notch1 protein through hydrogen bonding. In vitro cell experiments demonstrated that EGCG can significantly reduce the sizes of lipid droplets of 3T3-L1 adipocytes and promote UCP-1 expression by inhibiting the expression of Notch1 in 3T3-L1 adipocytes, thus promoting mitochondrial biogenesis.

CONCLUSIONS

In this study, molecular docking and in vitro cell experiments were used to explore the possible mechanism of EGCG to improve obesity by inhibiting Notch1.

Cell Survival, Death, and Proliferation in Senescent and Cancer Cells: the Role of (Poly)phenols

Cellular senescence has long been considered a permanent state of cell cycle arrest occurring in proliferating cells subject to different stressors, used as a cellular defense mechanism from acquiring potentially harmful genetic faults. However, recent studies highlight that senescent cells might also alter the local tissue environment and concur to chronic inflammation and cancer risk by secreting inflammatory and matrix remodeling factors, acquiring a senescence-associated secretory phenotype (SASP). Indeed, during aging and age-related diseases, senescent cells amass in mammalian tissues, likely contributing to the inevitable loss of tissue function as we age. Cellular senescence has thus become one potential target to tackle age-associated diseases as well as cancer development. One important aspect characterizing senescent cells is their telomere length. Telomeres shorten as a consequence of multiple cellular replications, gradually leading to permanent cell cycle arrest, known as replicative senescence. Interestingly, in the large majority of cancer cells, a senescence escape strategy is used and telomere length is maintained by telomerase, thus favoring cancer initiation and tumor survival. There is growing evidence showing how (poly)phenols can impact telomere maintenance through different molecular mechanisms depending on dose and cell phenotypes. Although normally, (poly)phenols maintain telomere length and support telomerase activity, in cancer cells this activity is negatively modulated, thus accelerating telomere attrition and promoting cancer cell death. Some (poly)phenols have also been shown to exert senolytic activity, thus suggesting both antiaging (directly eliminating senescent cells) and anticancer (indirectly, via SASP inhibition) potentials. In this review, we analyze selective (poly)phenol mechanisms in senescent and cancer cells to discriminate between in vitro and in vivo evidence and human applications considering (poly)phenol bioavailability, the influence of the gut microbiota, and their dose-response effects.

Novel Anti-Acetylcholinesterase Effect of Euonymus laxiflorus Champ. Extracts via Experimental and In Silico Studies

Alzheimer's disease (AD) is the most common form of dementia, which is recorded as a global health issue. Natural acetylcholinesterase inhibitors (AChEIs) are considered a helpful therapy for the management of symptoms of patients with mild-to-moderate AD. This work aimed to investigate and characterize Euonymus laxiflorus Champ. (ELC) as a natural source of AChEIs compounds via in vitro and virtual studies. The screening parts used, including the leaves, heartwood, and trunk bark of ELC, revealed that the trunk bark extract possessed the highest activity, phenolics and flavonoid content. The in vitro anti-Alzheimer activity of ELC trunk bark was notably reclaimed for the first time with comparable effect (IC50 = 0.332 mg/mL) as that of a commercial AChEI, berberine chloride (IC50 = 0.314 mg/mL). Among various solvents, methanol was the most suitable to extract ELC trunk bark with the highest activity. Twenty-one secondary metabolites (1-21) were identified from ELC trunk bark extract, based on GCMS and UHPLC analyses. Of these, 10 volatile compounds were identified from this herbal extract for the first time. One phenolic (11) and seven flavonoid compounds (15-21) were also newly found in this herbal extract. Of the identified compounds, chlorogenic acid (11), epigallocatechin gallate (12), epicatechin (13), apigetrin (18), and quercetin (20) were major compounds with a significant content of 395.8-2481.5 μg/g of dried extract. According to docking-based simulation, compounds (11-19, and 21) demonstrated more effective inhibitory activity than berberine chloride, with good binding energy (DS values: -12.3 to -14.4 kcal/mol) and acceptable RMSD values (0.77-1.75 Å). In general, these identified compounds processed drug properties and were non-toxic for human use, based on Lipinski's rule of five and ADMET analyses.

Nanoparticle-mediated therapeutic management in cholangiocarcinoma drug targeting: Current progress and future prospects

Patients with cholangiocarcinoma (CCA) often have an unfavorable prognosis because of its insidious nature, low resectability rate, and poor response to anticancer drugs and radiotherapy, which makes early detection and treatment difficult. At present, CCA has a five-year overall survival rate (OS) of only 5%, despite advances in therapies. New an increasing number of evidence suggests that nanoplatforms may play a crucial role in enhancing the pharmacological effects and in reducing both short- and long-term side effects of cancer treatment. This document reviews the advantages and shortcomings of nanoparticles such as liposomes, polymeric nanoparticle，inorganic nanoparticle, nano-metals and nano-alloys, carbon dots, nano-micelles, dendrimer, nano-capsule, bio-Nanomaterials in the diagnosis and treatment of CCA and discuss the current challenges in of nanoplatforms for CCA.

Effects of Epigallocatechin-3-Gallate on Matrix Metalloproteinases in Terms of Its Anticancer Activity

Epidemiological studies have shown that the consumption of green tea has beneficial effects against cancer. Basic studies have provided evidence that epigallocatechin gallate (EGCG) is a major contributor to these effects. Matrix metalloproteinases (MMPs) are zinc-dependent metalloproteinases with the ability to degrade the extracellular matrix proteins and are involved in various diseases including cancer in which MMPs have a critical role in invasion and metastasis. In this review, we discuss the effects of EGCG on several types of MMPs in the context of its anticancer activity. In the promoter region, MMPs have binding sites for at least one transcription factor of AP-1, Sp1, and NF-κB, and EGCG can downregulate these transcription factors through signaling pathways mediated by reactive oxygen species. EGCG can also decrease nuclear ERK, p38, heat shock protein-27 (Hsp27), and β-catenin levels, leading to suppression of MMPs' expression. Other mechanisms by which EGCG inhibits MMPs include direct binding to MMPs to prevent their activation and downregulation of NF-κB to suppress the production of inflammatory cytokines such as TNFα and IL-1β. Findings from studies on EGCG presented here may be useful in the development of more effective anti-MMP agents, which would give beneficial effects on cancer and other diseases.

Epigallocatechin-3-gallate suppresses hemin-aggravated colon carcinogenesis through Nrf2-inhibited mitochondrial reactive oxygen species accumulation

BACKGROUND

Previous studies have presented evidence to support the significant association between red meat intake and colon cancer, suggesting that heme iron plays a key role in colon carcinogenesis. Epigallocatechin-3-gallate (EGCG), the major constituent of green tea, exhibits anti-oxidative and anti-cancer effects. However, the effect of EGCG on red meat-associated colon carcinogenesis is not well understood.

OBJECTIVES

We aimed to investigate the regulatory effects of hemin and EGCG on colon carcinogenesis and the underlying mechanism of action.

METHODS

Hemin and EGCG were treated in Caco2 cells to perform the water-soluble tetrazolium salt-1 assay, lactate dehydrogenase release assay, reactive oxygen species (ROS) detection assay, real-time quantitative polymerase chain reaction and western blot. We investigated the regulatory effects of hemin and EGCG on an azoxymethane (AOM) and dextran sodium sulfate (DSS)-induced colon carcinogenesis mouse model.

RESULTS

In Caco2 cells, hemin increased cell proliferation and the expression of cell cycle regulatory proteins, and ROS levels. EGCG suppressed hemin-induced cell proliferation and cell cycle regulatory protein expression as well as mitochondrial ROS accumulation. Hemin increased nuclear factor erythroid-2-related factor 2 (Nrf2) expression, but decreased Keap1 expression. EGCG enhanced hemin-induced Nrf2 and antioxidant gene expression. Nrf2 inhibitor reversed EGCG reduced cell proliferation and cell cycle regulatory protein expression. In AOM/DSS mice, hemin treatment induced hyperplastic changes in colon tissues, inhibited by EGCG supplementation. EGCG reduced the hemin-induced numbers of total aberrant crypts and malondialdehyde concentration in the AOM/DSS model.

CONCLUSIONS

We demonstrated that EGCG reduced hemin-induced proliferation and colon carcinogenesis through Nrf2-inhibited mitochondrial ROS accumulation.

Epigallocatechin-3-gallate attenuates cyclophosphamide-induced damage in mouse ovarian tissue via suppressing inflammation, apoptosis, and expression of phosphorylated Akt, FOXO3a and rpS6

This study was conducted to evaluate the protective effects of epigallocatechin-3-gallate (EGCG) against ovarian toxicity in cyclophosphamide-treated mice and to verify the possible involvement of phosphorylated Akt, FOXO3a and rpS6 in the EGCG actions. Mice received saline solution (i.p.; control) or a single dose of cyclophosphamide (200 mg/kg body weight, i.p.) or mice were pretreated with N-acetylcysteine (150 mg/kg body weight, i.p.; positive control) or with EGCG (5, 25 or 50 mg/kg body weight, i.p.) once daily for three days followed by injection with single dose of cyclophosphamide (200 mg/kg body weight, i.p.). Thereafter, the mice were euthanized, and the ovaries were harvested and destined to histological (follicular morphology and activation), immunohistochemistry (cleaved caspase-3 and TNF-α) and fluorescence (mitochondrial activity and GSH concentrations) analyses. Furthermore, we examined the participation of p-Akt, p-FOXO3a and p-rpS6 in the protective effects of EGCG in cyclophosphamide-induced ovarian damage by immunohistochemical staining. The results showed that pretreatment with N-acetylcysteine or EGCG at 25 and 50 mg/kg before cyclophosphamide administration preserved the normal follicular morphology, prevented primordial follicle loss, reduced atresia, inflammation, and mitochondrial damage, and increased GSH concentrations compared to the only cyclophosphamide treatment. Additionally, pretreatment with 25 mg/kg EGCG regulated phosphorylated Akt, FOXO3a and rpS6 after cyclophosphamide treatment. In conclusion, short-time pretreatment with 25 mg/kg EGCG can prevent follicle loss in cyclophosphamide-treated mice by reducing oxidative damage, inflammation, and apoptosis, and regulating of p-Akt, p-FOXO3a and p-rpS6.

Plants as a Source of Anticancer Agents: From Bench to Bedside

Cancer is the second leading cause of death after cardiovascular diseases. Conventional anticancer therapies are associated with lack of selectivity and serious side effects. Cancer hallmarks are biological capabilities acquired by cancer cells during neoplastic transformation. Targeting multiple cancer hallmarks is a promising strategy to treat cancer. The diversity in chemical structure and the relatively low toxicity make plant-derived natural products a promising source for the development of new and more effective anticancer therapies that have the capacity to target multiple hallmarks in cancer. In this review, we discussed the anticancer activities of ten natural products extracted from plants. The majority of these products inhibit cancer by targeting multiple cancer hallmarks, and many of these chemicals have reached clinical applications. Studies discussed in this review provide a solid ground for researchers and physicians to design more effective combination anticancer therapies using plant-derived natural products.

Chemico-biological aspects of (-)-epigallocatechin-3-gallate (EGCG) to improve its stability, bioavailability and membrane permeability: Current status and future prospects

Natural products have been a bedrock for drug discovery for decades. (-)-Epigallocatechin-3-gallate (EGCG) is one of the widely studied natural polyphenolic compounds derived from green tea. It is the key component believed to be responsible for the medicinal value of green tea. Significant studies implemented in in vitro, in cellulo, and in vivo models have suggested its anti-oxidant, anti-cancer, anti-diabetic, anti-inflammatory, anti-microbial, neuroprotective activities etc. Despite having such a wide array of therapeutic potential and promising results in preclinical studies, its applicability to humans has encountered with rather limited success largely due to the poor bioavailability, poor membrane permeability, rapid metabolic clearance and lack of stability of EGCG. Therefore, novel techniques are warranted to address those limitations so that EGCG or its modified analogs can be used in the clinical setup. This review comprehensively covers different strategies such as structural modifications, nano-carriers as efficient drug delivery systems, synergistic studies with other bioactivities to improve the chemico-biological aspects (e.g., stability, bioavailability, permeability, etc.) of EGCG for its enhanced pharmacokinetics and pharmacological properties, eventually enhancing its therapeutic potentials. We think this review article will serve as a strong platform with comprehensive literature on the development of novel techniques to improve the bioavailability of EGCG so that it can be translated to the clinical applications.

Vascular Protective Effect and Its Possible Mechanism of Action on Selected Active Phytocompounds: A Review

Vascular endothelial dysfunction is characterized by an imbalance of vasodilation and vasoconstriction, deficiency of nitric oxide (NO) bioavailability and elevated reactive oxygen species (ROS), and proinflammatory factors. This dysfunction is a key to the early pathological development of major cardiovascular diseases including hypertension, atherosclerosis, and diabetes. Therefore, modulation of the vascular endothelium is considered an important therapeutic strategy to maintain the health of the cardiovascular system. Epidemiological studies have shown that regular consumption of medicinal plants, fruits, and vegetables promotes vascular health, lowering the risk of cardiovascular diseases. This is mainly attributed to the phytochemical compounds contained in these resources. Various databases, including Google Scholar, MEDLINE, PubMed, and the Directory of Open Access Journals, were searched to identify studies demonstrating the vascular protective effects of phytochemical compounds. The literature had revealed abundant data on phytochemical compounds protecting and improving the vascular system. Of the numerous compounds reported, curcumin, resveratrol, cyanidin-3-glucoside, berberine, epigallocatechin-3-gallate, and quercetin are discussed in this review to provide recent information on their vascular protective mechanisms in vivo and in vitro. Phytochemical compounds are promising therapeutic agents for vascular dysfunction due to their antioxidative mechanisms. However, future human studies will be necessary to confirm the clinical effects of these vascular protective mechanisms.

Role of Plant-Derived Active Constituents in Cancer Treatment and Their Mechanisms of Action

Despite significant technological advancements in conventional therapies, cancer remains one of the main causes of death worldwide. Although substantial progress has been made in the control and treatment of cancer, several limitations still exist, and there is scope for further advancements. Several adverse effects are associated with modern chemotherapy that hinder cancer treatment and lead to other critical disorders. Since ancient times, plant-based medicines have been employed in clinical practice and have yielded good results with few side effects. The modern research system and advanced screening techniques for plants’ bioactive constituents have enabled phytochemical discovery for the prevention and treatment of challenging diseases such as cancer. Phytochemicals such as vincristine, vinblastine, paclitaxel, curcumin, colchicine, and lycopene have shown promising anticancer effects. Discovery of more plant-derived bioactive compounds should be encouraged via the exploitation of advanced and innovative research techniques, to prevent and treat advanced-stage cancers without causing significant adverse effects. This review highlights numerous plant-derived bioactive molecules that have shown potential as anticancer agents and their probable mechanisms of action and provides an overview of in vitro, in vivo and clinical trial studies on anticancer phytochemicals.

Modulation of Notch Signaling Pathway by Bioactive Dietary Agents

Notch signaling is often aberrantly activated in solid and hematological cancers and regulates cell fate decisions and the maintenance of cancer stem cells. In addition, increased expression of Notch pathway components is clinically associated with poorer prognosis in several types of cancer. Targeting Notch may have chemopreventive and anti-cancer effects, leading to reduced disease incidence and improved survival. While therapeutic agents are currently in development to achieve this goal, several researchers have turned their attention to dietary and natural agents for targeting Notch signaling. Given their natural abundance from food sources, the use of diet-derived agents to target Notch signaling offers the potential advantage of low toxicity to normal tissue. In this review, we discuss several dietary agents including curcumin, EGCG, resveratrol, and isothiocyanates, which modulate Notch pathway components in a context-dependent manner. Dietary agents modulate Notch signaling in several types of cancer and concurrently decrease in vitro cell viability and in vivo tumor growth, suggesting a potential role for their clinical use to target Notch pathway components, either alone or in combination with current therapeutic agents.

Preparation and Evaluation of Starch Hydrogel/Contact Lens Composites as Epigallocatechin Gallate Delivery Systems for Inhibition of Bacterial Adhesion

Microbial infections caused by wearing contact lenses has become a major health problem, so the design and development of antibacterial contact lenses has attracted widespread attention. To safely and effectively inhibit bacterial adhesion of contact lenses, we have facilely prepared epigallocatechin gallate (EGCG) loaded starch hydrogel/contact lens composites by in-situ free radical polymerization of the mixture containing 2-hydroxylethyl methacrylate, methacrylic acid and ethylene glycol dimethacrylate. The adequate transmittance of the resulting contact lenses was characterized by ultraviolet-visible spectrophotometry, and their satisfactory stability was examined using differential scanning calorimetry and thermogravimetric analysis. Whereafter, cytotoxicity and degradation experiments were performed to investigate the biocompatibility and degradability of the contact lenses. The results showed the nontoxicity and good degradability of the composites. Besides, the capacity of the contact lenses for in vitro release of EGCG was also evaluated, and the results showed that the EGCG in these contact lenses can be sustainably released for at least 14 days. Further bacterial adhesion assay suggested that the EGCG loaded starch hydrogel/contact lenses could significantly reduce the adhesion of Pseudomonas aeruginosa compared to the control. The EGCG loaded starch hydrogel/contact lens composites provide a potential intervention strategy for preventing ocular microbial infections and inhibiting bacterial keratitis.

Advanced Computational Methodologies Used in the Discovery of New Natural Anticancer Compounds

Natural chemical compounds have been widely investigated for their programmed necrosis causing characteristics. One of the conventional methods for screening such compounds is the use of concentrated plant extracts without isolation of active moieties for understanding pharmacological activity. For the last two decades, modern medicine has relied mainly on the isolation and purification of one or two complicated active and isomeric compounds. The idea of multi-target drugs has advanced rapidly and impressively from an innovative model when first proposed in the early 2000s to one of the popular trends for drug development in 2021. Alternatively, fragment-based drug discovery is also explored in identifying target-based drug discovery for potent natural anticancer agents which is based on well-defined fragments opposite to use of naturally occurring mixtures. This review summarizes the current key advancements in natural anticancer compounds; computer-assisted/fragment-based structural elucidation and a multi-target approach for the exploration of natural compounds.

Evidence of Polyphenols Efficacy against Dry Eye Disease

Dry eye disease is a multifactorial pathology compromising the quality of life of patients, resulting in significant damage of the ocular surface and discomfort. The current therapeutical strategies are not able to definitively resolve the underlying causes and stop the symptoms. Polyphenols are promising natural molecules that are receiving increasing attention for their activity/effects in counteracting the main pathologic mechanisms of dry eye disease and reducing its symptoms. In the present review, a deep literature search focusing on the main polyphenols tested against dry eye disease was conducted, analyzing related in vitro, in vivo, and clinical studies to provide a comprehensive and current review on the state of the art. Polyphenols present multiple effects against dry eye diseases-related ocular surface injury. In particular, the observed beneficial effects of polyphenols on corneal cells are the reduction of the pathological processes of inflammation, oxidative stress, and apoptosis and modulation of the tear film. Due to numerous studies reporting that polyphenols are effective and safe for treating the pathological mechanisms of this ocular surface disease, we believe that future studies should confirm and extend the evidence of polyphenols efficacy in clinical practice against dry eye disease and help to develop new ophthalmic drug(s).

Designing a high-performance smart drug delivery system for the synergetic co-absorption of DOX and EGCG on ZIF-8

Due to the extreme pore volume and valuable surface area, zeolitic imidazole frameworks (ZIFs) are promising vehicles that enhance the delivery of therapeutic agents to tissues. Furthermore, these nanoporous materials have high stability in the pH and temperature of the surrounding healthy cells (37 °C and pH = 7) and an exotic potential to deform in carcinogenic environment (T > 37 °C and pH ∼ 5.5), which make them perfect smart drug delivery vehicle candidates. In this work, a series of molecular dynamics (MD) and metadynamics simulations have been performed to gain molecular insight into the mechanisms involved in the process of co-loading of doxorubicin (DOX) and EpiGalloCatechin-3 Gallate (EGCG) on ZIF-8, which form a smart drug delivery system (SDDS). The obtained results revealed that DOX was adsorbed on the carrier mostly through electrostatic interactions (E coul = ∼-1200 kJ mol-1, E tot = -1700 kJ mol-1), and EGCG was stacked on ZIF-8 mainly via van der Waals interactions (E L-J = ∼-600 kJ mol-1, E tot = ∼-1200 kJ mol-1). It is worth mentioning that the drug-drug L-J interactions (E L-J = ∼500 kJ mol-1) were also important in the co-loading process. The insertion of DOX and EGCG as additive agents to the initial ZIF-8/EGCG and ZIF-8/DOX systems led to the enhancement of the drug-carrier pair interactions to about ∼-2300 kJ mol-1 and ∼-2000 kJ mol-1, respectively. This finding implied that the drug-drug interactions had a complementary role in the development of SDDS via ZIF-8. From the metadynamics simulation, it was found that the geometry of the drugs is a determining factor in an efficient co-loading SDDS.

The Potential Anticancer Activity of Phytoconstituents against Gastric Cancer-A Review on In Vitro, In Vivo, and Clinical Studies

Gastric cancer belongs to the heterogeneous malignancies and, according to the World Health Organization, it is the fifth most commonly diagnosed cancer in men. The aim of this review is to provide an overview on the role of natural products of plant origin in the therapy of gastric cancer and to present the potentially active metabolites which can be used in the natural therapeutical strategies as the support to the conventional treatment. Many of the naturally spread secondary metabolites have been proved to exhibit chemopreventive properties when tested on the cell lines or in vivo. This manuscript aims to discuss the pharmacological significance of both the total extracts and the single isolated metabolites in the stomach cancer prevention and to focus on their mechanisms of action. A wide variety of plant-derived anticancer metabolites from different groups presented in the manuscript that include polyphenols, terpenes, alkaloids, or sulphur-containing compounds, underlines the multidirectional nature of natural products.

Anti-Cancer Effects of Green Tea Epigallocatchin-3-Gallate and Coffee Chlorogenic Acid

Tea and coffee are consumed worldwide and epidemiological and clinical studies have shown their health beneficial effects, including anti-cancer effects. Epigallocatechin gallate (EGCG) and chlorogenic acid (CGA) are the major components of green tea polyphenols and coffee polyphenols, respectively, and believed to be responsible for most of these effects. Although a large number of cell-based and animal experiments have provided convincing evidence to support the anti-cancer effects of green tea, coffee, EGCG, and CGA, human studies are still controversial and some studies have suggested even an increased risk for certain types of cancers such as esophageal and gynecological cancers with green tea consumption and bladder and lung cancers with coffee consumption. The reason for these inconsistent results may have been arisen from various confounding factors. Cell-based and animal studies have proposed several mechanisms whereby EGCG and CGA exert their anti-cancer effects. These components appear to share the common mechanisms, among which one related to reactive oxygen species is perhaps the most attractive. Meanwhile, EGCG and CGA have also different target molecules which might explain the site-specific differences of anti-cancer effects found in human studies. Further studies will be necessary to clarify what is the mechanism to cause such differences between green tea and coffee.

Flavonoids against the Warburg phenotype-concepts of predictive, preventive and personalised medicine to cut the Gordian knot of cancer cell metabolism

The Warburg effect is characterised by increased glucose uptake and lactate secretion in cancer cells resulting from metabolic transformation in tumour tissue. The corresponding molecular pathways switch from oxidative phosphorylation to aerobic glycolysis, due to changes in glucose degradation mechanisms known as the 'Warburg reprogramming' of cancer cells. Key glycolytic enzymes, glucose transporters and transcription factors involved in the Warburg transformation are frequently dysregulated during carcinogenesis considered as promising diagnostic and prognostic markers as well as treatment targets. Flavonoids are molecules with pleiotropic activities. The metabolism-regulating anticancer effects of flavonoids are broadly demonstrated in preclinical studies. Flavonoids modulate key pathways involved in the Warburg phenotype including but not limited to PKM2, HK2, GLUT1 and HIF-1. The corresponding molecular mechanisms and clinical relevance of 'anti-Warburg' effects of flavonoids are discussed in this review article. The most prominent examples are provided for the potential application of targeted 'anti-Warburg' measures in cancer management. Individualised profiling and patient stratification are presented as powerful tools for implementing targeted 'anti-Warburg' measures in the context of predictive, preventive and personalised medicine.

Potential Therapeutic Targets of Epigallocatechin Gallate (EGCG), the Most Abundant Catechin in Green Tea, and Its Role in the Therapy of Various Types of Cancer

Epigallocatechin-3-gallate (EGCG), an active compound of green tea and its role in diseases cure and prevention has been proven. Its role in diseases management can be attributed to its antioxidant and anti-inflammatory properties. The anti-cancer role of this green tea compound has been confirmed in various types of cancer and is still being under explored. EGCG has been proven to possess a chemopreventive effect through inhibition of carcinogenesis process such as initiation, promotion, and progression. In addition, this catechin has proven its role in cancer management through modulating various cell signaling pathways such as regulating proliferation, apoptosis, angiogenesis and killing of various types of cancer cells. The additive or synergistic effect of epigallocatechin with chemopreventive agents has been verified as it reduces the toxicities and enhances the anti-cancerous effects. Despite its effectiveness and safety, the implications of EGCG in cancer prevention is certainly still discussed due to a poor bioavailability. Several studies have shown the ability to overcome poor bioavailability through nanotechnology-based strategies such as encapsulation, liposome, micelles, nanoparticles and various other formulation. In this review, we encapsulate therapeutic implication of EGCG in cancer management and the mechanisms of action are discussed with an emphasis on human clinical trials.

Epigallocatechin-3-gallate sensitises multidrug-resistant oral carcinoma xenografts to vincristine sulfate

Oral squamous cell carcinoma (OSCC) is a very aggressive malignancy, and 50% of patients who receive curative treatment die from the disease or related complications within 5 years. Epigallocatechin‐3‐gallate (EGCG) is the most abundant bioactive ingredient of tea polyphenols in green tea and has anticancer properties. Here, we evaluated the preclinical efficacy of EGCG combined with vincristine sulfate (VCR) on the growth, angiogenic activity and vascular endothelial growth factor (VEGF) expression in xenograft nude mice inoculated with KBV200 cells. Compared with VCR alone, the combined use of EGCG and VCR strongly inhibited tumour growth and angiogenesis (P < 0.01). VEGF mRNA and protein levels were lower in the KBV200 xenograft group treated with the combined regime (P < 0.01) than those in the VCR alone group. EGCG sensitises multidrug‐resistant OSCC to VCR, and this may occur through the inhibition of angiogenesis via VEGF down‐regulation.

Molecular mechanisms of action of epigallocatechin gallate in cancer: Recent trends and advancement

Epigallocatechin gallate (EGCG), also known as epigallocatechin-3-gallate, is an ester of epigallocatechin and gallic acid. EGCG, abundantly found in tea, is a polyphenolic flavonoid that has the potential to affect human health and disease. EGCG interacts with various recognized cellular targets and inhibits cancer cell proliferation by inducing apoptosis and cell cycle arrest. In addition, scientific evidence has illustrated the promising role of EGCG in inhibiting tumor cell metastasis and angiogenesis. It has also been found that EGCG may reverse drug resistance of cancer cells and could be a promising candidate for synergism studies. The prospective importance of EGCG in cancer treatment is owed to its natural origin, safety, and low cost which presents it as an attractive target for further development of novel cancer therapeutics. A major challenge with EGCG is its low bioavailability which is being targeted for improvement by encapsulating EGCG in nano-sized vehicles for further delivery. However, there are major limitations of the studies on EGCG, including study design, experimental bias, and inconsistent results and reproducibility among different study cohorts. Additionally, it is important to identify specific EGCG pharmacological targets in the tumor-specific signaling pathways for development of novel combined therapeutic treatments with EGCG. The present review highlights the ongoing development to identify cellular and molecular targets of EGCG in cancer. Furthermore, the role of nanotechnology-mediated EGCG combinations and delivery systems will also be discussed.

Nanoencapsulated dietary polyphenols for cancer prevention and treatment: successes and challenges

Many dietary polyphenols have been investigated for their therapeutic potential either as single agents or in combinations. Despite the significant anticancer potential of these polyphenols in in vitro cell culture and in vivo animal models, their clinical applications have been limited because of challenges such as ineffective systemic delivery, stability and low bioavailability. Nanoencapsulation of these polyphenols could prolong circulation, improve localization, enhance efficacy and reduce the chances of multidrug resistance. This review summarized the use of various polyphenols especially epigallocatechin gallate, quercetin, curcumin and resveratrol as nanoformulations for cancer prevention and treatment. Despite some success, more research is warranted to design a nanoencapsulated combination of polyphenols, effective in in vitro, in vivo and human systems.

EGCG Mediated Targeting of Deregulated Signaling Pathways and Non-Coding RNAs in Different Cancers: Focus on JAK/STAT, Wnt/β-Catenin, TGF/SMAD, NOTCH, SHH/GLI, and TRAIL Mediated Signaling Pathways

Decades of research have enabled us to develop a better and sharper understanding of multifaceted nature of cancer. Next-generation sequencing technologies have leveraged our existing knowledge related to intra- and inter-tumor heterogeneity to the next level. Functional genomics have opened new horizons to explore deregulated signaling pathways in different cancers. Therapeutic targeting of deregulated oncogenic signaling cascades by products obtained from natural sources has shown promising results. Epigallocatechin-3-gallate (EGCG) has emerged as a distinguished chemopreventive product because of its ability to regulate a myriad of oncogenic signaling pathways. Based on its scientifically approved anticancer activity and encouraging results obtained from preclinical trials, it is also being tested in various phases of clinical trials. A series of clinical trials associated with green tea extracts and EGCG are providing clues about significant potential of EGCG to mechanistically modulate wide ranging signal transduction cascades. In this review, we comprehensively analyzed regulation of JAK/STAT, Wnt/β-catenin, TGF/SMAD, SHH/GLI, NOTCH pathways by EGCG. We also discussed most recent evidence related to the ability of EGCG to modulate non-coding RNAs in different cancers. Methylation of the genome is also a widely studied mechanism and EGCG has been shown to modulate DNA methyltransferases (DNMTs) and protein enhancer of zeste-2 (EZH2) in multiple cancers. Moreover, the use of nanoformulations to increase the bioavailability and thus efficacy of EGCG will be also addressed. Better understanding of the pleiotropic abilities of EGCG to modulate intracellular pathways along with the development of effective EGCG delivery vehicles will be helpful in getting a step closer to individualized medicines.

Flavonoids as Anticancer Agents

Flavonoids are polyphenolic compounds subdivided into 6 groups: isoflavonoids, flavanones, flavanols, flavonols, flavones and anthocyanidins found in a variety of plants. Fruits, vegetables, plant-derived beverages such as green tea, wine and cocoa-based products are the main dietary sources of flavonoids. Flavonoids have been shown to possess a wide variety of anticancer effects: they modulate reactive oxygen species (ROS)-scavenging enzyme activities, participate in arresting the cell cycle, induce apoptosis, autophagy, and suppress cancer cell proliferation and invasiveness. Flavonoids have dual action regarding ROS homeostasis—they act as antioxidants under normal conditions and are potent pro-oxidants in cancer cells triggering the apoptotic pathways and downregulating pro-inflammatory signaling pathways. This article reviews the biochemical properties and bioavailability of flavonoids, their anticancer activity and its mechanisms of action.

Targeting the heme protein hemoglobin by (−)-epigallocatechin gallate and the study of polyphenol–protein association using multi-spectroscopic and computational methods

(−)-Epigallocatechin gallate binds to BHb and exhibits anti-glycating as well as antioxidant behaviors towards glycation and photo-oxidation of BHb.

Breaking the Barrier of Cancer through Papaya Extract and their Formulation

Background:

In the last decade, many new avenues of cancer treatment have opened up but the costs of treatment have sky-rocketed too. Hence, screening of indigenously available plant and animal resources for anti-carcinogenic potential is an important branch of anticancer research. The effort has been made through this comprehensive review to highlight the recent developments of anticancer therapies using different parts of papaya plant extract.

Methods:

In search of the naturally existing animals and plants for anticarcinogenic potential, papaya plant has been exploited by the scientist working in this research field. A widespread literature search was performed for writing this review.

Results:

Different constituents of Carica papaya responsible for anticancer activities have been discussed. Papaya extract for the treatment of breast, liver, blood, pancreas, skin, prostate, and colon cancer have also been reported. Finally, the various formulation approach using Carica papaya extract have been highlighted.

Conclusion:

The information provided in this review might be useful for researchers in designing of novel formulation of Carica papaya extract for the treatment of cancer.

Natural products as a perspective for cancer pain management: A systematic review

BACKGROUND

Cancer is the leading cause of death in the world and one of the main symptoms affecting these individuals is chronic pain, which must be evaluated and treated in its various components. Several drugs are currently used, but beyond the high cost, they have harmful side effects to patients or are transitorily effective. Ergo, there is a need to look for new options for cancer pain relief. Natural products (NPs) present themselves as strong candidates for the development of new drugs for the treatment of chronic pain, such as cancer pain.

PURPOSE

This systematic review aimed to summarize current knowledge about the analgesic profile of NPs in cancer pain.

METHODS

The search included PubMed, Scopus and Web of Science (from inception to June 2018) sought to summarize the articles studying new proposals with NPs for the management of oncological pain. Two independent reviewers extracted data on study characteristics, methods and outcomes.

RESULTS

After an extensive survey, 21 articles were selected, which described the analgesic potential of 15 natural compounds to relieve cancer pain. After analyzing the data, it can be suggested that these NPs, which have targets in central and peripheral mechanisms, are interesting candidates for the treatment of cancer pain for addressing different pharmacological mechanisms (even innovative), but ensuring the safety of these compounds is still a challenge. Likewise, the cannabinoids compounds leave the front as the most promising compounds for direct applicability due to the clinical studies that have already been developed and the background already established about these effects on chronic pain.

CONCLUSION

Regarding these findings, it can be concluded that the variability of possible biological sites of action is strategic for new perspectives in the development of therapeutic proposals different from those available in the current market.

Flavonoids in Cancer and Apoptosis

Cancer is the second leading cause of death globally. Although, there are many different approaches to cancer treatment, they are often painful due to adverse side effects and are sometimes ineffective due to increasing resistance to classical anti-cancer drugs or radiation therapy. Targeting delayed/inhibited apoptosis is a major approach in cancer treatment and a highly active area of research. Plant derived natural compounds are of major interest due to their high bioavailability, safety, minimal side effects and, most importantly, cost effectiveness. Flavonoids have gained importance as anti-cancer agents and have shown great potential as cytotoxic anti-cancer agents promoting apoptosis in cancer cells. In this review, a summary of flavonoids and their effectiveness in cancer treatment targeting apoptosis has been discussed.

Theaflavin and epigallocatechin-3-gallate synergistically induce apoptosis through inhibition of PI3K/Akt signaling upon depolymerizing microtubules in HeLa cells

Theaflavin (TF) and epigallocatechin-3-gallate (EGCG) both have been reported previously as microtubule depolymerizing agents that also have anticancer effects on various cancer cell lines and in animal models. Here, we have applied TF and EGCG in combination on HeLa cells to investigate if they can potentiate each other to improve their anticancer effect in lower doses and the underlying mechanism. We found that TF and EGCG acted synergistically, in lower doses, to inhibit the growth of HeLa cells. We found the combination of 50 µg/mL TF and 20 µg/mL EGCG to be the most effective combination with a combination index of 0.28. The same combination caused larger accumulation of cells in the G ₂ /M phase of the cell cycle, potent mitochondrial membrane potential loss, and synergistic augmentation of apoptosis. We have shown that synergistic activity might be due to stronger microtubule depolymerization by simultaneous binding of TF and EGCG at different sites on tubulin: TF binds at vinblastine binding site on tubulin, and EGCG binds near colchicines binding site on tubulin. A detailed mechanistic analysis revealed that stronger microtubule depolymerization caused effective downregulation of PI3K/Akt signaling and potently induced mitochondrial apoptotic signals, which ultimately resulted in the apoptotic death of HeLa cells in a synergistic manner.

Epigallocatechin-3-O-gallate alleviates the malignant phenotype in A-431 epidermoid and SK-BR-3 breast cancer cell lines

In this study, we evaluated the effects of epigallocatechin-3-O-gallate (EGCG) in two cancer cell lines, A-431 overexpressing ErbB1 and SK-BR-3, overexpressing ErbB2. EGCG treatment showed dose-dependent collapse of mitochondrial membrane potential (Δψ_m), increase in reactive oxygen species (ROS) production, changes in nuclear morphology and reduced viability. Flow cytometry data indicated that EGCG partially decreases the phosphorylation of several proteins involved in cell proliferation and survival: pErbB1(Y1173, Y1068), pAkt(S473) and pERK(Y204). EGCG affected the clonogenic growth in both cell lines with an EC₅₀ of 2.5 and 5.4 µM for A-431 and SK-BR-3, respectively. Wound scratch assay demonstrated that EGCG inhibited the healing in dose-dependent manner and the effect was correlated with partial reduction in phosphorylation of pFAK(S910). Our data suggest that EGCG administration might reduce the unfavourable traits, particularly associated with ErbB1/EGFR overexpression.

A Potential Role for Green Tea as a Radiation Sensitizer for Prostate Cancer

Prostate cancer (PCa) is the most common non-cutaneous cancer in the United States. There is currently a lack of safe and effective radiosensitizers that can enhance the effectiveness of radiation treatment (RT) for Pca. Clonogenic assay, PCNA staining, Quick Cell Proliferation assay, TUNEL staining and caspase-3 activity assay were used to assess proliferation and apoptosis in DU145 Pca cells. RT-PCR/IHC were used to investigate the mechanisms. We found that the percentage of colonies, PCNA staining intensity, and the optical density value of DU145 cells were decreased (RT/GT vs. RT). TUNEL + cells and the relative caspase-3 activity were increased (RT/GT vs. RT). Compared to RT, the anti-proliferative effect of RT/GT correlated with increased expression of the anti-proliferative molecule p16. Compared to RT, the pro-apoptotic effect of RT/GT correlated with decreased expression of the anti-apoptotic molecule Bcl-2. GT enhances RT sensitivity of DU145 by inhibiting proliferation and promoting apoptosis.

Litchi chinensis as a Functional Food and a Source of Antitumor Compounds: An Overview and a Description of Biochemical Pathways

Litchi is a tasty fruit that is commercially grown for food consumption and nutritional benefits in various parts of the world. Due to its biological activities, the fruit is becoming increasingly known and deserves attention not only for its edible part, the pulp, but also for its peel and seed that contain beneficial substances with antioxidant, cancer preventive, antimicrobial, and anti-inflammatory functions. Although literature demonstrates the biological activity of Litchi components in reducing tumor cell viability in in vitro or in vivo models, data about the biochemical mechanisms responsible for these effects are quite fragmentary. This review specifically describes, in a comprehensive analysis, the antitumor properties of the different parts of Litchi and highlights the main biochemical mechanisms involved.

Nutrigenomics in cancer: Revisiting the effects of natural compounds

Nutrigenomics effects have an important role in the manipulation of dietary components for human benefit, particularly in cancer prevention or treatment. The impact of dietary components, including phytochemicals, is largely studied by nutrigenomics, looking at the gene expression and molecular mechanisms interacting with bioactive compounds and nutrients, based on new 'omics' technologies. The high number of preclinical studies proves the relevant role of nutrigenomics in cancer management. By deciphering the network of nutrient-gene connections associated with cancer, relevant data will be transposed as therapeutic interventions for this devastating pathology and for fulfilling the concept of personalized nutrition. All these are presented under the nutrigenomics canopy for a better comprehension of the relation between ingested phytochemicals and chemoprevention or chemotherapy. The profits from the nutrigenomics progress, with a particular focus on the coding and noncoding genes related to the exposure of natural compounds need to be validated. A precise attention receives the evaluation of the role of natural compounds in tandem with conventional therapy using genomic approaches, with emphasis on the capacity to inhibit drug resistance mechanisms. All these relevant nutrigenomics aspects are summarized in the present review paper. It is concluded that further nutrigenomics studies are required to improve our understanding related to the complex mechanisms of action of the natural compounds and for their appropriate application as gears in cancer therapy.