Role of ellagic acid in regulation of apoptosis by modulating novel and atypical PKC in lymphoma bearing mice

Advanced Strategies in Enhancing the Hepatoprotective Efficacy of Natural Products: Integrating Nanotechnology, Genomics, and Mechanistic Insights

Liver disorders like hepatitis, cirrhosis, and hepatocellular carcinoma present a significant global health challenge, with high morbidity and mortality rates. Key factors contributing to liver disorders include inflammation, oxidative stress, and apoptosis. Due to their multifaceted action, natural compounds are promising candidates for mitigating liver-related disorders. Research studies revealed the antioxidant, anti-inflammatory, and detoxifying properties of natural compounds like curcumin, glycyrrhizin, and silymarin and their potential for liver detoxification and protection. With advancements in nanotechnology in drug delivery, natural compounds have improved stability and targetability, thereby enhancing their bioavailability and therapeutic efficiency. Further, recent advancements in genomics and an increased understanding of genetic factors influencing liver disorders and the hepatoprotective effects of natural agents made way for personalized medicine. Moreover, combinatorial therapy with natural products, synthetic drugs, or other natural agents has improved therapeutic outcomes. Even though clinical trials have confirmed the efficiency of natural compounds as hepatoprotective agents, several challenges remain unanswered in their translation to clinical practice. Therefore, it is logical to integrate natural compounds with nanotechnology and genomics to further advance hepatoprotection. This review gives an overview of the substantial progress made in the field of hepatoprotection, with specific emphasis on natural compounds and their integration with nanotechnology and genomics. This provides valuable insights for future research and innovations in developing therapeutic strategies for liver disorders.

The multifaceted mechanisms of ellagic acid in the treatment of tumors: State-of-the-art

Ellagic acid (EA) is a kind of polyphenol compound extracted from a variety of herbs, such as paeoniae paeoniae, raspberry, Chebule, walnut kernel, myrrh, loquat leaf, pomegranate bark, quisquite, and fairy herb. It has anti-tumor, anti-oxidation, anti-inflammatory, anti-mutation, anti-bacterial, anti-allergic and multiple pharmacological properties. Studies have shown its anti-tumor effect in gastric cancer, liver cancer, pancreatic cancer, breast cancer, colorectal cancer, lung cancer and other malignant tumors, mainly through inducing tumor cell apoptosis, inhibiting tumor cell proliferation, inhibiting tumor cell metastasis and invasion, inducing autophagy, affecting tumor metabolic reprogramming and other forms of anti-tumor efficacy. Its molecular mechanism is mainly reflected in inhibiting the proliferation of tumor cells through VEGFR-2 signaling pathway, Notch signaling pathway, PKC signaling pathway and COX-2 signaling pathway. PI3K/Akt signaling pathway, JNK (cJun) signaling pathway, mitochondrial pathway, Bcl-2 / Bax signaling pathway, TGF-β/Smad3 signaling pathway induced apoptosis of tumor cells and blocked EMT process and MMP SDF1α/CXCR4 signaling pathway inhibits the metastasis and invasion of tumor cells, induces autophagy and affects tumor metabolic reprogramming to produce anti-tumor effects. At present, the analysis of the anti-tumor mechanism of ellagic acid is slightly lacking, so this study comprehensively searched the literature on the anti-tumor mechanism of ellagic acid in various databases, reviewed the research progress of the anti-tumor effect and mechanism of ellagic acid, in order to provide reference and theoretical basis for the further development and application of ellagic acid.

Protein Kinase C (PKC) Isozymes as Diagnostic and Prognostic Biomarkers and Therapeutic Targets for Cancer

Protein kinase C (PKC) is a large family of calcium- and phospholipid-dependent serine/threonine kinases that consists of at least 11 isozymes. Based on their structural characteristics and mode of activation, the PKC family is classified into three subfamilies: conventional or classic (cPKCs; α, βI, βII, and γ), novel or non-classic (nPKCs; δ, ε, η, and θ), and atypical (aPKCs; ζ, ι, and λ) (PKCλ is the mouse homolog of PKCι) PKC isozymes. PKC isozymes play important roles in proliferation, differentiation, survival, migration, invasion, apoptosis, and anticancer drug resistance in cancer cells. Several studies have shown a positive relationship between PKC isozymes and poor disease-free survival, poor survival following anticancer drug treatment, and increased recurrence. Furthermore, a higher level of PKC activation has been reported in cancer tissues compared to that in normal tissues. These data suggest that PKC isozymes represent potential diagnostic and prognostic biomarkers and therapeutic targets for cancer. This review summarizes the current knowledge and discusses the potential of PKC isozymes as biomarkers in the diagnosis, prognosis, and treatment of cancers.

Synergism of ellagic acid in combination with radiotherapy and chemotherapy for cancer treatment

BACKGROUND

Ellagic acid (EA) is a polyphenol compound abundant in berries, walnuts, pecans, pomegranate, cranberries, and other plant foods and exerts a wide array of biological properties. In particular, EA has received considerable research attention in anti-cancer therapy. EA administered alone has been shown to exert effects against human cancers through multiple pathways. In addition, EA may increase tumor sensitivity to chemotherapy and radiotherapy. Namely, EA combination with a relatively low dosage of therapeutic drugs or optimized radiation dose could improve the treatment outcome. More importantly, EA could counteract chemotherapy-related adverse reactions.

PURPOSE

This review aims to summarize the in vitro and in vivo experimental evidence of synergism of EA in radiotherapy/chemotherapy for the treatment of cancers. In addition, the preventive effect of EA to counteract chemotherapy-induced toxicity is also discussed.

METHODS

The searches were performed in the PubMed, Web of Science and Google scholar and introduced the information about the role of EA in cancer treatment.

RESULTS

EA exhibits synergistic effects in radiotherapy/chemotherapy for the treatment of cancers and exerts a great potential in reducing the side effects of chemotherapy and radiotherapy due to its biological activities, such as antioxidant and anti-inflammatory activities.

CONCLUSION

EA could be a promising drug adjuvant for cancer treatment. In the near future, novel strategies for EA delivery systems that overcome the low EA solubility and bioavailability should be studied further to fully exploit the therapeutic potential of EA.

Putative role of natural products as Protein Kinase C modulator in different disease conditions

INTRODUCTION

Protein kinase C (PKC) is a promising drug target for various therapeutic areas. Natural products derived from plants, animals, microorganisms, and marine organisms have been used by humans as medicine from prehistoric times. Recently, several compounds derived from plants have been found to modulate PKC activities through competitive binding with ATP binding site, and other allosteric regions of PKC. As a result fresh race has been started in academia and pharmaceutical companies to develop an effective naturally derived small-molecule inhibitor to target PKC activities. Herein, in this review, we have discussed several natural products and their derivatives, which are reported to have an impact on PKC signaling cascade.

METHODS

All information presented in this review article regarding the regulation of PKC by natural products has been acquired by a systematic search of various electronic databases, including ScienceDirect, Scopus, Google Scholar, Web of science, ResearchGate, and PubMed. The keywords PKC, natural products, curcumin, rottlerin, quercetin, ellagic acid, epigallocatechin-3 gallate, ingenol 3 angelate, resveratrol, protocatechuic acid, tannic acid, PKC modulators from marine organism, bryostatin, staurosporine, midostaurin, sangivamycin, and other relevant key words were explored.

RESULTS

The natural products and their derivatives including curcumin, rottlerin, quercetin, ellagic acid, epigallocatechin-3 gallate, ingenol 3 angelate, resveratrol, bryostatin, staurosporine, and midostaurin play a major role in the management of PKC activity during various disease progression.

CONCLUSION

Based on the comprehensive literature survey, it could be concluded that various natural products can regulate PKC activity during disease progression. However, extensive research is needed to circumvent the challenge of isoform specific regulation of PKC by natural products.

Role of ellagic acid for the prevention and treatment of liver diseases

Globally, one of the alarming problems is the prevalence and burden of liver diseases, which accounts for 2 million cases per year. Chronic liver aetiologies such as hepatitis infections, alcoholic or non-alcoholic liver disease, environmental agents, and drug-induced toxicity are invariably responsible for liver fibrosis progression to finally hepatocellular carcinoma. Current treatment options are unable to overwhelm and cure liver diseases. Emerging findings suggest researchers' interest in using evidence-based complementary medicine such as ellagic acid with extensive pharmacological properties. They include antioxidant, anti-inflammatory, anti-hyperlipidaemic, anti-viral, anti-angiogenic, and anticancer activity. The molecular functions elicited by ellagic acid include scavenging of free radicals, regulation of lipid metabolism, the prohibition of fibrogenesis response-mediating proteins, inhibits hepatic stellate cells and myofibroblasts, restrains hepatic viral replication, facilitates suppression of growth factors, regulates transcription factors, proinflammatory cytokines, augments the liver immune response, fosters apoptosis and inhibits cell proliferation in tumorigenic cells. This review will most notably focus on preclinical and clinical information based on currently available evidence to warrant ellagic acid's prospective role in preventing liver diseases.

CYP2C9, a Metabolic CYP450s Enzyme, Plays Critical Roles in Activating Ellagic Acid in Human Intestinal Epithelial Cells

Background

The metabolic processing of ellagic acid (EA) by cytochrome P450s (CYP450s) expressed in the intestines is unclear. This study aimed to investigate the effects of CYP450s that are highly expressed in HIEC cells on metabolic activity of EA.

Material/Methods

HIEC cell models expressing 2B6, 2C9, 2D6, and 3A4 were generated by stably transfecting with CYP450 genes using a lentivirus system. PCR and Western blot assay were used to detect expression of CYP450s. Cell Counting Kit-8 (CCK-8) assay was used to examine the cytotoxic effect of EA on CYP450s-expressing HIEC cells. Flow cytometry was employed to evaluate apoptosis of CYP450s-expressing HIEC cells after addition of EA. Metabolic clearance rate of EA in vitro by the constructed HIEC cell models was measured using UPLC-MS method.

Results

CYP450s expression HIEC cell models, including CYP2B6, CYP2C9, CYP2D6, and CYP3A4, were successfully established. EA treatment at different concentrations (10 μg/mL and 50 μg/mL) remarkably decreased cell viability of HIEC cells expressing CYP2C9 compared to the untreated control (p<0.01), in a concentration-dependent and time-dependent manner. Expression of CYP2C9 significantly increased the apoptosis rate of HIEC cells treated with EA compared to that in HIEC cells without any CYP450s expression (p<0.01). The clearance rate of EA in CYP2B6-expressing (p<0.05) and CYP2C9-expressing (p<0.001) HIEC cell models was remarkably reduced after 120 min.

Conclusions

Ellagic acid was effectively activated by CYP2C9 in HIEC cells and caused cytotoxicity and apoptosis of HIEC cells. Therefore, CYP2C9 is main metabolic enzyme of EA when compared to other CYP450 HIEC cell models.

Antinociceptive and anti-inflammatory effect of Poincianella pyramidalis (Tul.) L.P. Queiroz

ETHNOPHARMACOLOGY RELEVANCE

Poncianella pyramidalis (Leguminosae) is a Caatinga plant used in folk medicine because of its pharmacological properties, which include anti-inflammatory action. However, chemical compounds responsible for this effect have not yet been identified.

AIM OF THE STUDY

This study aimed to evaluate the antioxidant, antinociceptive and anti-inflammatory effects of the ethyl acetate fraction from the inner bark of P. pyramidalis.

MATERIAL AND METHODS

Total phenol content (TP) was estimated using the Folin-Ciocalteu reagent, while in vitro antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay. Chemical identification was done using LC-PDA/MS and LC-ESI/MS/MS. In vivo antinociceptive and anti-inflammatory properties were investigated using formalin, mechanical hypernociception and carrageenan-induced pleurisy assays in mice.

RESULTS

TP was 525.08 ± 17.49 μg mg^-1 gallic acid equivalent. The ethyl acetate fraction (EAF) inhibited 87.76% of the DPPH radical with an EC₅₀ of 22.94 μg mL^-1 and Antioxidant Activity Index of 1.74. LC-PDA/MS and LC-ESI/MS/MS identified 15 compounds that are mostly derived from gallic and ellagic acids. Regarding in vivo antinociceptive and anti-inflammatory activity, EAF (100 mg kg-1) significantly reduced the nociceptive response in the second phase of the formalin assay by 50% (p < 0.01) compared with the control group. In the hypernociception test, a significant (p < 0.001) anti-hyperalgesic effect of EAF (100 mg kg-1) was observed up to the third hour of evaluation (p < 0.001). In the carrageenan assay, EAF (100 mg kg-1) was shown to inhibit protein extravasation, increase total leukocytes and neutrophils, and inhibit mononuclear cells.

CONCLUSION

These results demonstrate EAF from the inner bark of P. pyramidalis has strong in vitro antioxidant effect as well as in vivo antinociceptive and anti-inflammatory activities, which may be attributed to the bark being rich in phenolic compounds derived from gallic acid.

Organic Extract of Justicia pectoralis Jacq. Leaf Inhibits Interferon-γ Secretion and Has Bacteriostatic Activity against Acinetobacter baumannii and Klebsiella pneumoniae

Justicia pectoralis Jacq. (Acanthaceae) leaves currently found in the Brazilian north-east are widely used to treat diabetes, menstrual pains, asthma, and other disorders. This work aimed to identify the phytochemical characterization and biological activities of J. pectoralis leaf extracts. The plant material was ground and the crude extracts were obtained with water or acetone: water (7:3 v/v), yielding aqueous (JPA), and organic (JPO) extracts. Phytochemical characterization was performed by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). Cytotoxicity was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay and trypan blue (TB) exclusion assay in peripheral blood mononuclear cells (PBMCs), BALB/c splenocytes, and neoplastic cells (TOLEDO, K562, DU-145, and PANC-1) at 1, 10, and 100 μg/mL. Antibacterial activity was evaluated using the microdilution test to obtain the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Cytokines, IFN-γ, and IL-17A from culture supernatants of BALB/c mice splenocytes were measured by sandwich ELISA. In the TLC analysis, both JPA and JPO extracts presented coumarin and flavonoids. In addition, HPLC was able to identify coumarin, apigenin, and ellagic acid in both extracts. JPO IC₅₀ was 57.59 ± 1.03 μg/mL (MTT) and 69.44 ± 8.08 μg/mL (TB) in TOLEDO. MIC value of JPO against Acinetobacter baumannii and Klebsiella pneumoniae was 500 μg/mL. JPO (100 μg/mL) significantly inhibited IFN-γ levels (p=0.03). J. pectoralis is a potential candidate to be further investigated as an IFN-γ inhibitory agent and against Acinetobacter baumannii and Klebsiella pneumoniae.

Cell type-dependent effects of ellagic acid on cellular metabolism

Ellagic acid is a botanical polyphenol which has been shown to have numerous effects on cellular function. Ellagic acid can induce apoptosis and inhibit the proliferation of various cancer cell types in vitro and in vivo. As such, ellagic acid has attracted significant interest as a potential chemotherapeutic compound. One mechanism by which ellagic acid has been proposed to affect cellular physiology is by regulating metabolic pathways. Here we show the dose-dependent effects of ellagic acid on cellular energy production and downstream induction of the apoptotic program in HEK293, HeLa, MCF7, and HepG2 cells. At physiologically relevant doses, ellagic acid has pleiotropic and cell-type specific effects on mitochondrial function. At high doses ellagic acid can also influence glycolytic pathways and induce cell death. Our results demonstrate that ellagic acid can influence mitochondrial function at therapeutically relevant concentrations. The observed effects of ellagic acid on cellular respiration are complex and cell type-specific, which may limit the chemotherapeutic utility of this compound.

Gallnuts: A Potential Treasure in Anticancer Drug Discovery

Introduction. In the discovery of more potent and selective anticancer drugs, the research continually expands and explores new bioactive metabolites coming from different natural sources. Gallnuts are a group of very special natural products formed through parasitic interaction between plants and insects. Though it has been traditionally used as a source of drugs for the treatment of cancerous diseases in traditional and folk medicinal systems through centuries, the anticancer properties of gallnuts are barely systematically reviewed. Objective. To evidence the traditional uses and phytochemicals and pharmacological mechanisms in anticancer aspects of gallnuts, a literature review was performed. Materials and Methods. The systematic review approach consisted of searching web-based scientific databases including PubMed, Web of Science, and Science Direct. The keywords for searching include gallnut, Galla Chinensis, Rhus chinensis, Rhus potaninii, Rhus punjabensis, nutgall, gall oak, Quercus infectoria, Quercus lusitanica, and galla turcica. Two reviewers extracted papers independently to remove the papers unrelated to the anticancer properties of gallnuts. Patents, abstracts, case reports, and abstracts in symposium and congress were excluded. Results and Conclusion. As a result, 14 articles were eligible to be evaluated. It is primarily evident that gallnuts contain a number of bioactive metabolites, which account for anticancer activities. The phytochemical and pharmacological studies reviewed strongly underpin a fundamental understanding of anticancer properties for gallnuts (Galla Chinensis and Galla Turcica) and support their ongoing clinical uses in China. The further bioactive compounds screening and evaluation, pharmacological investigation, and clinical trials are expected to progress gallnut-based development to finally transform the wild medicinal gallnuts to the valuable authorized anticancer drugs.

Ellagic acid in suppressing in vivo and in vitro oxidative stresses

Oxidative stress is a biological condition produced by a variety of factors, causing several chronic diseases. Oxidative stress was, therefore, treated with natural antioxidants, such as ellagic acid (EA). EA has a major role in protecting against different diseases associated with oxidative stress. This review critically discussed the antioxidant role of EA in biological systems. The in vitro and in vivo studies have confirmed the protective role of EA in suppressing oxidative stress. The review also discussed the mechanism of EA in suppressing of oxidative stress, which showed that EA activates specific endogenous antioxidant enzymes and suppresses specific genes responsible for inflammation, diseases, or disturbance of biochemical systems. The amount of EA used and duration, which plays a significant role in the treatment of oxidative stress has been discussed. In conclusion, EA is a strong natural antioxidant, which possesses the suppressing power of oxidative stress in biological systems.

The methanol-ethyl acetate partitioned fraction from Chinese olive fruits inhibits cancer cell proliferation and tumor growth by promoting apoptosis through the suppression of the NF-κB signaling pathway

Chinese olives (Canarium album L.) have historically been used for medicinal purposes rather than commercially for oil. In this report, we reveal that the methanol-ethyl acetate partitioned fraction from Chinese olive fruits (MEO), of which ellagic acid accounted for 12%, exhibited profound anti-proliferative activities in the human colon cancer cell line, HCT116. Additionally, oral administration of MEO remarkably inhibited the tumor growth of subcutaneously implanted CT26 cells, a mouse colon carcinoma cell line, in BALB/c mice. Treatment with MEO induced a significant increase in the percentage of apoptotic cells and resulted in poly(ADP-ribose) polymerase (PARP) cleavage, suggesting that MEO inhibits cancer cell proliferation by promoting apoptosis. Our study also showed that MEO exerted the most potent effect on the inhibition of NF-κB-mediated signaling among the partitioned fractions from Chinese olives. This process employed the use of reporter-based bio-platforms that are capable of detecting the activation of NF-κB. In addition, phosphorylation of NF-κB signaling-associated proteins, IKKα/β, IκBα, and p65, was reduced in MEO-incubated cancer cells, indicating that MEO suppresses NF-κB activation. Moreover, MEO treatment significantly suppressed lipopolysaccharide (LPS)-induced cancer cell proliferation, demonstrating that MEO promotes cancer cell apoptosis through the inhibition of the NF-κB signaling pathway. In summary, our findings demonstrate that the methanol-ethyl acetate partitioned fraction from Chinese olive fruits inhibits cancer cell proliferation and tumor growth by promoting apoptosis through the suppression of NF-κB signaling. Therefore, the Chinese olive fruit has promising potential in cancer treatment.

Neuroprotective effects of ellagic acid on cuprizone-induced acute demyelination through limitation of microgliosis, adjustment of CXCL12/IL-17/IL-11 axis and restriction of mature oligodendrocytes apoptosis

CONTEXT

Ellagic acid (EA) is a natural phenol antioxidant with various therapeutic activities. However, the efficacy of EA has not been examined in neuropathologic conditions.

OBJECTIVE

In vivo neuroprotective effects of EA on cuprizone (cup)-induced demyelination were evaluated.

MATERIAL AND METHODS

C57BL/6 J mice were fed with chow containing 0.2% cup for 4 weeks to induce oligodendrocytes (OLGs) depletion predominantly in the corpus callosum (CC). EA was administered at different doses (40 or 80 mg/kg body weight/day/i.p.) from the first day of cup diet. Oligodendrocytes apoptosis [TUNEL assay and myelin oligodendrocyte glycoprotein (MOG+)/caspase-3+ cells), gliosis (H&E staining, glial fibrillary acidic protein (GFAP+) and macrophage-3 (Mac-3+) cells) and inflammatory markers (interleukin 17 (IL-17), interleukin 11 (IL-11) and stromal cell-derived factor 1 α (SDF-1α) or CXCL12] during cup intoxication were examined.

RESULTS

High dose of EA (EA-80) increased mature oligodendrocytes population (MOG+ cells, p < 0.001), and decreased apoptosis (p < 0.05) compared with the cup mice. Treatment with both EA doses did not show any considerable effects on the expression of CXCL12, but significantly down-regulated the expression of IL-17 and up-regulated the expression of IL-11 in mRNA levels compared with the cup mice. Only treatment with EA-80 significantly decreased the population of active macrophage (MAC-3+ cells, p < 0.001) but not reactive astrocytes (GFAP+ cells) compared with the cup mice.

DISCUSSION AND CONCLUSION

In this model, EA-80 effectively reduces lesions via reduction of neuroinflammation and toxic effects of cup on mature OLGs. EA is a suitable therapeutic agent for moderate brain damage in neurodegenerative diseases such as multiple sclerosis.

Protective effects of ellagic acid against tetrachloride-induced cirrhosis in mice through the inhibition of reactive oxygen species formation and angiogenesis

Ellagic acid has been proven to have anticancer, antimutation, antimicrobial and antiviral functions. The present study investigated whether treatment with ellagic acid was able to prevent tetrachloride (CCl4)-induced cirrhosis through the inhibition of reactive oxygen species (ROS) formation and angiogenesis. CCl₄ diluted in olive oil at a final concentration of 10% was used to induce a cirrhosis model. A total of 40 mice were random allocated into four groups, as follows: Control, cirrhosis model, 7.5 mg/kg ellagic acid and 15 mg/kg ellagic acid groups. In the control group, mice were given normal saline. The results indicated that ellagic acid exerted a protective effect, evidently preventing CCl₄-induced cirrhosis. In addition, treatment with ellagic acid significantly inhibited collagen I and inducible nitric oxide synthase protein expression levels in CCl₄-induced cirrhosis mice. Oxidative stress and ROS formation were also significantly reduced by ellagic acid treatment. The protein expression levels of vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2), and the caspase-3 activity were significantly inhibited by treatment with ellagic acid. In conclusions, these results suggest that ellagic acid exerted protective effects against CCl₄-induced cirrhosis through the inhibition of ROS formation and angiogenesis.

Polyphenol compounds and PKC signaling

BACKGROUND

Naturally occurring polyphenols found in food sources provide huge health benefits. Several polyphenolic compounds are implicated in the prevention of disease states, such as cancer. One of the mechanisms by which polyphenols exert their biological actions is by interfering in the protein kinase C (PKC) signaling pathways. PKC belongs to a superfamily of serine-threonine kinase and are primarily involved in phosphorylation of target proteins controlling activation and inhibition of many cellular processes directly or indirectly.

SCOPE OF REVIEW

Despite the availability of substantial literature data on polyphenols' regulation of PKC, no comprehensive review article is currently available on this subject. This article reviews PKC-polyphenol interactions and its relevance to various disease states. In particular, salient features of polyphenols, PKC, interactions of naturally occurring polyphenols with PKC, and future perspective of research on this subject are discussed.

MAJOR CONCLUSIONS

Some polyphenols exert their antioxidant properties by regulating the transcription of the antioxidant enzyme genes through PKC signaling. Regulation of PKC by polyphenols is isoform dependent. The activation or inhibition of PKC by polyphenols has been found to be dependent on the presence of membrane, Ca(2+) ion, cofactors, cell and tissue types etc. Two polyphenols, curcumin and resveratrol are in clinical trials for the treatment of colon cancer.

GENERAL SIGNIFICANCE

The fact that 74% of the cancer drugs are derived from natural sources, naturally occurring polyphenols or its simple analogs with improved bioavailability may have the potential to be cancer drugs in the future.