Tectorigenin, an isoflavone of Pueraria thunbergiana Benth., induces differentiation and apoptosis in human promyelocytic leukemia HL-60 cells

Herbal textual research of Belamcanda chinensis (L.) redouté and screening of quality-markers based on 'pharmacodynamics-substance'

ETHNOPHARMACOLOGICAL RELEVANCE

Belamcanda chinensis (L.) Redouté is widely distributed in East Asia, such as China, Russia and North Korea. Belamcandae Rhizoma is the sun-dried rhizome of B. chinensis and has a long history of traditional medicinal use. It was first recorded in the Shennong's Herbal Classic, and has the effects of clearing heat and detoxifying, eliminating phlegm and benefiting the pharynx.

AIM OF THE STUDY

To systematically study the source of Belamcandae Rhizoma, summarize the evolution of its medicinal properties, efficacy and the application history of its prescriptions, summarize its biological activity, phytochemistry, synthetic metabolic pathway and toxicology, and screen the Quality-Markers of Belamcandae Rhizoma according to the screening principle of traditional Chinese medicine Quality-Markers.

MATERIALS AND METHODS

All information available on Belamcandae Rhizoma was collected using electronic search engines, such as Pubmed, Web of Science, CNKI, WFO (www.worldfloraonline.org), MPNS (https://mpsn.kew.org), Changchun University of Traditional Chinese Medicine Library collections, Chinese Medical Classics.

RESULTS

The source of Belamcandae Rhizoma is B. chinensis of Iridaceae. It has a long history of application in China. It has the effects of clearing heat and detoxifying, eliminating phlegm and promoting pharynx. Modern pharmacological studies have shown that it has anti-inflammatory, anti-oxidation, anti-tumor and other physiological activities, and is safe and non-toxic at normal application doses. At present, tectoridin, iridin, tectorigenin, irigenin and irisflorentin are identified as the Quality-Markers of Belamcandae Rhizoma.

CONCLUSIONS

As a traditional Chinese medicine, Belamcandae Rhizoma has a long history of application, and multifaceted studies have demonstrated that Belamcandae Rhizoma is a promising Chinese medicine with good application prospects. By reviewing and identifying the Quality-Markers of Belamcandae Rhizoma, this study can help to establish the evaluation procedure of it on the one hand, and identify the shortcomings research on the other hand. Currently, there are few studies on the anabolism and toxicology of it, and future studies may focus on its in vivo processes, toxicology and adverse effects.

Tectorigenin: A Review of Its Sources, Pharmacology, Toxicity, and Pharmacokinetics

Tectorigenin is a well-known natural flavonoid aglycone and an active component that exists in numerous plants. Growing evidence suggests that tectorigenin has multiple pharmacological effects, such as anticancer, antidiabetic, hepatoprotective, anti-inflammatory, antioxidative, antimicrobial, cardioprotective, and neuroprotective. These pharmacological properties provide the basis for the treatment of many kinds of illnesses, including several types of cancer, diabetes, hepatic fibrosis, osteoarthritis, Alzheimer's disease, etc. The purpose of this paper is to provide a comprehensive summary and review of the sources, extraction and synthesis, pharmacological effects, toxicity, pharmacokinetics, and delivery strategy aspects of tectorigenin. Tectorigenin may exert certain cytotoxicity, which is related to the administration time and concentration. Pharmacokinetic studies have demonstrated that the main metabolic pathways in rats for tectorigenin are glucuronidation, sulfation, demethylation and methoxylation, but that it exhibits poor bioavailability. From our perspective, further research on tectorigenin should cover: exploring the pharmacological targets and mechanisms of action; finding an appropriate concentration to balance pharmacological effects and toxicity; attempting diversified delivery strategies to improve the bioavailability; and structural modification to obtain tectorigenin derivatives with higher pharmacological activity.

Oriental traditional herbal Medicine--Puerariae Flos: A systematic review

ETHNOPHARMACOLOGICAL RELEVANCE

Pueraria Flos (PF), a traditional herbal medicine, is botanically from the dried flowers of Pueraria lobate (Willd.) Ohwi. (Chinese: ) or Pueraria thomsonii Benth. (Chinese: ). It has a long history of thousands of years in China for awakening the spleen, clearing the lungs, relieving alcohol.

AIM OF THE REVIEW

This review aims to report the up-to-date research progress in ethnopharmacology, phytochemistry, pharmacology and toxicology, metabolism and therapeutic application of PF, so as to provide a strong basis for future clinical treatment and scientific research.

MATERIALS AND METHODS

Relevant information on PF was collected from scientific literature databases including PubMed, CNKI and other literature sources (Ph.D. and M.Sc. dissertations and Chinese herbal classic books) by using the keyword "Puerariae".

RESULTS

Briefly, phytochemical research report has isolated 39 flavonoids, 19 saponins and 25 volatile oils from PF. Flavonoids and saponins are the most important bioactive compounds, and most of the quality control studies focus on these two types of compounds. Modern pharmacological studies have revealed their significant biological activities in relieving alcoholism, hepatoprotective, anti-tumor, anti-inflammatory, and anti-oxidation, which provides theoretical support for the traditional use.

CONCLUSIONS

Comprehensive analysis showed that pharmacological activity of most purified compounds from PF had not been reported. Kakkalide, tectoridin and their deglycosylated metabolites (irisolidone and tectorigenin) has been focused on excessively due to their higher content and better activities. This leads to low development and resources waste. Interestingly, PF made a breakthrough in the field of food. Many kinds of fat-lowering foods such as PILLBOX Onaka have been popular in Japan market, which received extensive attention. Therefore, we suggest that future research can be paid attention on the development of the plant's function in the field of food and medicine, as well as the transformation from experimental to clinical.

Bioassay-Guided Characterization, Antioxidant, Anti-Melanogenic and Anti-Photoaging Activities of Pueraria thunbergiana L. Leaf Extracts in Human Epidermal Keratinocytes (HaCaT) Cells

Although the roots and flowers of P. thunbergiana are known to have various physiologically active effects, studies on the anti-melanin production and anti-photoaging effects of its leaf extracts and cellular mechanisms are still lacking. In this study, we evaluated the possibility of using Pueraria thunbergiana leaves as a natural material for skin whitening and anti-aging-related functional cosmetics. The 30% ethyl alcohol (EtOH) extract from P. thunbergiana leaves was fractionated using n-hexane, ethyl acetate (EtOAc), butanol, and aqueous solution to measure their whitening, and anti-aging effects. The EtOAc fraction contained a high content of phenolic and flavonoids and showed higher 1,1-diphenyl-2-picryhydrazyl (DPPH) and 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activities than the other fractions. It was also confirmed that the EtOAc fraction markedly inhibited α-melanocyte stimulating hormone (α-MSH)-induced melanogenesis in B16F10 melanoma cells. In addition, the EtOAc fraction showed a protective effect against ultraviolet B (UVB) in HaCaT cells and increased the collagen synthesis that was decreased due to UVB exposure. Matrix metalloproteinase-1 (MMP-1) activity and MMP-1 protein expression were reduced in human epidermal keratinocytes (HaCaT) cells. These results indicate that the EtOAc fraction has superior antioxidant activity, anti-melanogenesis, and anti-photoaging effects compared to the other fractions. Therefore, in this study, we confirmed the potential of P. thunbergiana leaf extract as a functional cosmetic ingredient, and it can be used as basic data for the physiological activity of P. thunbergiana leaf extracts.

Medicinal Importance, Pharmacological Activities and Analytical Aspects of an Isoflavone Glycoside Tectoridin

Background:

Polyphenols are a group of plant secondary metabolites that are produced in plants as a protective system against oxidative stress, UV radiation, pathogens and predator’s attack. Flavonoids are major class of plant phenolics found to be present in fruits, vegetables, tea and red wine. Tectoridin also called 40,5,7-thrihydroxy-6-methoxyisoflavone-7-Ob-D-glucopyranoside is an isoflavone glycoside found to be present in the flower of Porites lobata.

Methods:

Present work focused on the biological importance, therapeutic potential and pharmacological activities of tectoridin in medicine. Numerous scientific data has been collected from different literature databases such as Google Scholar, Science Direct, PubMed and Scopus in order to know the health beneficial potential of tectoridin. Pharmacological data have been analyzed in the present work to know the biological effectiveness of tectoridin against human disorders. Analytical data of tectoridin have been collected and analyzed in the present work in order to know the importance of modern analytical method in the isolation, separation and identification of tectoridin.

Results:

Scientific data analysis revealed the biological importance and therapeutic benefit of tectoridin in medicine, signifying the therapeutic potential of tectoridin in the healthcare systems. Biological activities of tectoridin are mainly due to its anti-inflammatory, anti-platelet, anti-angiogenic, hepatoprotective, anti-tumor, estrogenic, antioxidant and hypoglycemic activity. However effectiveness of tectoridin against rat lens aldose reductase, nitric oxide, skeletal and cardiac muscle sarcoplasmic reticulum and enzymes have been also presented in this work. Analytical data signified the importance of modern analytical techniques for the separation, identification and isolation of tectoridin.

Conclusion:

Present work signified the biological importance and therapeutic benefit of tectoridin in the medicine and other allied health sectors.

Tectoridin inhibits the progression of colon cancer through downregulating PKC/p38 MAPK pathway

Colon cancer is one of the most familiar malignancies worldwide, with high morbidity and high mortality. This study intended to explore the role and mechanism of tectoridin (TEC) in regulating the progression of colon cancer. First, colon cancer cell lines (HCT116 and SW480 cells) were treated with different doses of TEC (0-200 μM). Then, CCK8 and clone formation experiments were performed to detect cell proliferation. Flow cytometry and western blot were conducted to examine apoptosis. Subsequently, Transwell assay and wound-healing test was employed to determine the effect of TEC on colon cancer cell invasion and migration. Next, western blot was performed to monitor the PKC/p38 MAPK pathway activation. In addition, a tumor model was established in nude mice to explore the effect of TEC on tumor growth in vivo. TEC dose-dependently dampened the proliferation, migration and invasion of colon cancer cells and facilitated their apoptosis. In addition, TEC abated the tumor cell growth in vivo. Besides, TEC dose-dependently suppressed the expression of PKC and p38 MAPK. Moreover, inhibiting the PKC pathway almost cancel out the anti-tumor effects induced by TEC. TEC attenuates the colon cancer progression by inhibiting the PKC/p38 MAPK pathway.

Tectorigenin Inhibits Glioblastoma Proliferation by G0/G1 Cell Cycle Arrest

Background and objectives: Glioblastoma is one of the leading cancer-related causes of death of the brain region and has an average 5-year survival rate of less than 5%. The aim of this study was to investigate the effectiveness of tectorigenin, a naturally occurring flavonoid compound with anti-inflammatory, anti-oxidant, and anti-tumor properties, as a treatment for glioblastoma. A further goal was to use in vitro models to determine the underlying molecular mechanisms. Materials and Methods: Exposure to tectorigenin for 24 h dose-dependently reduced the viability of glioblastoma cells. Results: Significant cell cycle arrest at G0/G1 phase occurred in the presence of 200 and 300 µM tectorigenin. Treatment with tectorigenin clearly reduced the levels of phosphorylated retinoblastoma protein (p-RB) and decreased the expression of cyclin-dependent protein 4 (CDK4). Tectorigenin treatment also significantly enhanced the expression of p21, a CDK4 inhibitor. Conclusions: Collectively, our findings indicated that tectorigenin inhibited the proliferation of glioblastoma cells by cell cycle arrest at the G0/G1 phase.

Flavonoids as Multi-Target Compounds: A Special Emphasis on their Potential as Chemo-adjuvants in Cancer Therapy

Flavonoids are low molecular weight, polyphenolic phytochemicals, obtained from secondary metabolism of various plant compounds. They have a spectrum of pharmacological efficacies, including potential anticancer efficacy. Natural flavonoids are present in fruits, vegetables, grains, bark, roots, stems, flowers, tea and wine. Flavonoids can attenuate or inhibit the initiation, promotion and progression of cancer by modulating various enzymes and receptors in diverse pathways that involve cellular proliferation, differentiation, apoptosis, inflammation, angiogenesis and metastasis. Furthermore, in vitro, flavonoids have been shown to reverse multidrug resistance when used as chemo-adjuvants. Flavonoids (both natural and synthetic analogues) interact with several oncogenic targets through dependent and independent mechanisms to mediate their anticancer efficacy in different types of cancer cells.

Investigation of effect of tectorigenin (O-methylated isoflavone) on Ca2+ signal transduction and cytotoxic responses in canine renal tubular cells

Tectorigenin, a traditional Chinese medicine, is isolated from the flower of plants such as Pueraria thomsonii Benth. It is an O-methylated isoflavone, a type of flavonoid. Previous studies have shown that tectorigenin evoked various physiological responses in different models, but the effect of tectorigenin on cytosolic-free Ca²⁺ levels ([Ca²⁺]_i) and cytotoxicity in renal tubular cells is unknown. Our research explored if tectorigenin changed Ca²⁺ signal transduction and viability in Madin-Darby Canine Kidney (MDCK) renal tubular cells. [Ca²⁺]_iin suspended cells were measured by applying the fluorescent Ca²⁺-sensitive probe fura-2. Viability was explored by using water-soluble tetrazolium-1 as a fluorescent dye. Tectorigenin at concentrations of 5-50 μM induced [Ca²⁺]_irises. Ca²⁺ removal reduced the signal by approximately 20%. Tectorigenin (50 μM) induced Mn²⁺ influx suggesting of Ca²⁺ entry. Tectorigenin-induced Ca²⁺ entry was inhibited by 10% by three inhibitors of store-operated Ca²⁺ channels, namely, nifedipine, econazole, and SKF96365. In Ca²⁺-free medium, treatment with the endoplasmic reticulum Ca²⁺ pump inhibitor thapsigargin inhibited 83% of tectorigenin-evoked [Ca²⁺]_irises. Conversely, treatment with tectorigenin abolished thapsigargin-evoked [Ca²⁺]_irises. Inhibition of phospholipase C with U73122 inhibited 50% of tectorigenin-induced [Ca²⁺]_irises. Tectorigenin at concentrations between 10 and 60 μM killed cells in a concentration-dependent fashion. Chelation of cytosolic Ca²⁺ with 1,2-bis (2-aminophenoxy)ethane-N, N, N', N'-tetraacetic acid/acetoxy methyl did not reverse tectorigenin's cytotoxicity. Our data suggest that, in MDCK cells, tectorigenin evoked [Ca²⁺]_irises and induced cell death that was not associated with [Ca²⁺]_irises. Therefore, tectorigenin may be a Ca²⁺-independent cytotoxic agent for kidney cells.

Reversal of Multidrug Resistance in Cancer by Multi-Functional Flavonoids

Multidrug resistance (MDR) resulting from different defensive mechanisms in cancer is one of the major obstacles of clinical treatment. To circumvent MDR many reversal agents have been developed, but most of them fail in clinical trials due to severely adverse effects. Recently, certain natural products have been reported to overcome MDR, including flavonoids which are abundant in plants, foods, and herbs. The structure of flavonoids can be abbreviated as C6-C3-C6 (C for carbon), and further categorized into flavonoids, iso-flavonoids and neo-flavonoids, according to their structural backbones. Flavonoids possess multiple bioactivities, and a growing body of research has indicated that both flavonoids and iso-flavonoids can either kill or re-sensitize conventional chemotherapeutics to resistant cancer cells. Here, we summarize the research and discuss the underlying mechanisms, concluding that these flavonoids do not function as specific regulators of target proteins, but rather as multi-functional agents that negatively regulate the key factors contributing to MDR.

Silibinin A decreases statin‑induced PCSK9 expression in human hepatoblastoma HepG2 cells

Hypercholesterolemia is one of the major risk factors for the occurrence and development of atherosclerosis. The most common drugs used to treat hypercholesterolemia are 3‑hydroxy‑3‑methyl‑glutaryl‑CoA reductase inhibitors, known as statins. Statins induce a beneficial increase in the levels of the low density lipoprotein receptor (LDLR) and additionally upregulate proprotein convertase subtilisin/kexin type 9 (PCSK9), which leads to LDLR degradation. This process causes a negative feedback response that attenuates the lipid lowering effects of statins. Therefore, the development of PCSK9 inhibitors may increase the lipid‑lowering functions of statins. In the present study, a drug‑screening assay was developed using the human PCSK9 promoter, based on data from a dual‑luciferase reporter assay, and the efficacies of various compounds from Traditional Chinese Medicine were examined. Among the compounds examined, SIL was demonstrated to function by targeting PCSK9. It was identified that SIL treatment decreased the expression levels of PCSK9 in HepG2 cells by decreasing the activity of the PCSK9 promoter in a dose‑and time‑dependent manner. Notably, SIL antagonized the statin‑induced phosphorylation of the p38 MAPK signaling pathway. The present study suggested that SIL may be developed as a novel PCSK9 inhibitor that may increase the efficiency of statin treatment.

Tectorigenin Promotes Osteoblast Differentiation and in vivo Bone Healing, but Suppresses Osteoclast Differentiation and in vivo Bone Resorption

Although tectorigenin (TG), a major compound in the rhizome of Belamcanda chinensis, is conventionally used for the treatment of inflammatory diseases, its effects on osteogenesis and osteoclastogenesis have not been reported. The objective of this study was to investigate the effects and possible underlying mechanism of TG on in vitro osteoblastic differentiation and in vivo bone formation, as well as in vitro osteoclast differentiation and in vivo bone resorption. TG promoted the osteogenic differentiation of primary osteoblasts and periodontal ligament cells. Moreover, TG upregulated the expression of the BMP2, BMP4, and Smad-4 genes, and enhanced the expression of Runx2 and Osterix. In vivo studies involving mouse calvarial bone defects with μCT and histologic analysis revealed that TG significantly increased new bone formation. Furthermore, TG treatment inhibited osteoclast differentiation and the mRNA levels of osteoclast markers. In vivo studies of mice demonstrated that TG caused the marked attenuation of bone resorption. These results collectively demonstrated that TG stimulated osteogenic differentiation in vitro, increased in vivo bone regeneration, inhibited osteoclast differentiation in vitro, and suppressed inflammatory bone loss in vivo. These novel findings suggest that TG may be useful for bone regeneration and treatment of bone diseases.

The Anti-neuroinflammatory Activity of Tectorigenin Pretreatment via Downregulated NF-κB and ERK/JNK Pathways in BV-2 Microglial and Microglia Inactivation in Mice With Lipopolysaccharide

The activation of microglia is decisively involved with the neurodegeneration observed in many neuroinflammatory pathologies, such as multiple sclerosis, Parkinson’s disease, and Alzheimer’s disease. Tectorigenin (TEC) is an isoflavone isolated from various medicinal plants, such as Pueraria thunbergiana Benth, Belamcanda chinensis, and Iris unguicularis. In the present study, the neuroinflammatory effects of TEC were evaluated in both lipopolysaccharide (LPS)-treated BV-2 microglial and mouse models. TEC remarkably inhibited reactive oxygen species (ROS) generation. TEC also inhibits the production and expression of nitric oxide (NO), prostaglandin E₂ (PGE₂), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in LPS-stimulated BV-2 cells. In addition, TEC suppressed the LPS-induced activation of nuclear factor-κB (NF-κB), phosphorylation of extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK) to regulate the inflammatory mediators, such as inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), TNF-α, and IL-6. These results indicate that TEC may inhibit neuronal inflammation through the downregulation of inflammatory mediators, including iNOS, COX-2, TNF-α, and IL-6 by suppressing NF-κB/ERK/JNK-related signaling pathways. Furthermore, cotreatment with TEC and ERK inhibitor SCH772984 or JNK inhibitor SP600125 suppressed the overproduction of LPS-induced NO production in BV-2 cells. Consistent with the results of in vitro experiments, an LPS-induced brain inflammation mouse model, administration of TEC effectively decrease the levels of malondialdehyde, iNOS in hippocampus, and prevented increases in the levels of TNF-α and IL-6 in the serum. TEC showed marked attenuation of microglial activation. Finally, TEC inhibited protein expression of toll-like receptor 4 and myeloid differentiation factor 88 in LPS-activated BV-2 microglia and mouse models. Taken altogether, the cumulative findings suggested that TEC holds the potential to develop as a neuroprotective drug for the intervention of neuroinflammatory disorders.

Suppression of human breast cancer cells by tectorigenin through downregulation of matrix metalloproteinases and MAPK signaling in vitro

Breast cancer is a major life‑threatening malignancy and is the second highest cause of mortality. The aim of the present study was to investigate the effects of tectorigenin (Tec), a Traditional Chinese Medicine, against human breast cancer cells in vitro. MDA‑MB‑231 and MCF‑7 human breast cancer cells were treated with various concentrations of Tec. Cell proliferation was evaluated using the Cell Counting kit‑8 assay, and apoptosis and the cell cycle were examined by flow cytometry. The migratory and invasive abilities of these cells were detected by Transwell and Matrigel assays, respectively. Metastasis‑, apoptosis‑ and survival‑related gene expression levels were measured by reverse transcription‑quantitative polymerase chain reaction and western blotting. The results indicated that Tec was able to inhibit the proliferation of MDA‑MB‑231 and MCF‑7 cells in a dose‑ and time‑dependent manner. Furthermore, Tec treatment induced apoptosis and G0/G1‑phase arrest, and inhibited cell migration and invasion. Tec treatment decreased the expression of matrix metalloproteinase (MMP)‑2, MMP9, BCL‑2, phosphorylated‑AKT and components of the mitogen‑activated protein kinase (MAPK) signaling pathway, and increased the expression of BCL‑2‑associated X, cleaved poly [ADP‑ribose] polymerase and cleaved caspase‑3. In conclusion, Tec treatment suppressed human breast cancer cells through the downregulation of AKT and MAPK signaling and the upregulated expression and/or activity of the caspase family in vitro. Therefore, Tec may be a potential therapeutic drug to treat human breast cancer.

Phytochemistry and Pharmacology of Phyllanthus niruri L.: A Review

Phyllanthus niruri, a typical member of family Euphorbiaceae, is a small annual herb found throughout the tropical and subtropical regions of both hemispheres. The genus Phyllanthus has been used in traditional medicine for its wide range of pharmacological activities like antimicrobial, antioxidant, anticancer, antiinflammatory, antiplasmodial, antiviral, diuretic and hepatoprotective. This review summarizes the information about morphological, biochemical, ethanobotanical, pharmacological, biological and toxicological activities with special emphasis on mechanism of anticancer activity of P. niruri. Gaps in previous studies such as taxonomic inconsistency of P. niruri, novel phytochemicals and their therapeutic properties, especially mechanisms of anticancerous activity and market products available, have been looked into and addressed. Scientific information related to 83 phytochemicals (including many novel compounds detected recently by the authors) has been provided in a very comprehensive manner. Copyright © 2017 John Wiley & Sons, Ltd.

Anti-Endometriotic Effects of Pueraria Flower Extract in Human Endometriotic Cells and Mice

Pueraria flowers have been used as a vegetable and an ingredient for tea and jelly. In this study, we investigated the effects of Pueraria flower extract (PFE) on endometriosis, a common gynaecological disease characterised by local sterile inflammation of peritoneal cavity. PFE suppressed the adhesion of human endometriotic cells 11Z and 12Z to human mesothelial Met5A cells. In addition, PFE significantly inhibited the migration of 11Z and 12Z cells as shown by wound-healing and transwell migration assays. PFE reduced the protein and mRNA levels of matrix metalloproteinase (MMP)-2 and MMP-9 in endometriotic cells. Moreover, extracellular signal-regulated kinase (ERK)1/2 was activated by PFE treatment, and an ERK1/2 inhibitor, PD98059, significantly inhibited PFE-inhibited cell migration in endometriotic cells. Furthermore, PFE significantly suppressed endometriotic lesion formation in a mouse model. These data suggest that Pueraria flower is a potential anti-endometriotic agent for the inhibition of endometriotic cell adhesion, migration, and MMP expression.

Established Human Cell Lines as Models to Study Anti-leukemic Effects of Flavonoids

Despite the extensive work on pathological mechanisms and some recent advances in the treatment of different hematological malignancies, leukemia continues to present a significant challenge being frequently considered as incurable disease. Therefore, the development of novel therapeutic agents with high efficacy and low toxicity is urgently needed to improve the overall survival rate of patients. In this comprehensive review article, the current knowledge about the anticancer activities of flavonoids as plant secondary polyphenolic metabolites in the most commonly used human established leukemia cell lines (HL-60, NB4, KG1a, U937, THP-1, K562, Jurkat, CCRF- CEM, MOLT-3, and MOLT-4) is compiled, revealing clear anti-proliferative, pro-apoptotic, cell cycle arresting, and differentiation inducing effects for certain compounds. Considering the low toxicity of these substances in normal blood cells, the presented data show a great potential of flavonoids to be developed into novel anti-leukemia agents applicable also in the malignant cells resistant to the current conventional chemotherapeutic drugs.

Potential Skin Regeneration Activity and Chemical Composition of Absolute from Pueraria thunbergiana Flower

The flower of Pueraria thunbergiana BENTH (PTBF) contains isoflavonoids and essential oil components. It has many biological and pharmacological activities, including anti-diabetes, anti-oxidant, and weight loss. However, its effect on skin regeneration remains unknown. In the present study, we isolated the absolute from PTBF through solvent extraction and determined the role of the absolute on skin regeneration-associated responses in human epidermal-keratinocytes (HaCats). The PTBF absolute, which contained 10 compounds, stimulated migration and proliferation and increased the phosphorylation of serine/threonine-specific protein kinase and extracellular signal-regulated kinase1/2 in HaCats. It induced type I and IV collagen synthesis in HaCats. In addition, treatment with PTBF absolute resulted in increased sprout outgrowth in HaCats. These findings suggest that PTBF absolute may participate in skin regeneration, probably through promotion of migration, proliferation, and collagen synthesis.

The Antibacterial Assay of Tectorigenin with Detergents or ATPase Inhibitors against Methicillin-Resistant Staphylococcus aureus

Tectorigenin (TTR) is an O-methylated isoflavone derived from the rhizome of Belamacanda chinensis (L.) DC. It is known to perform a wide spectrum of biological activities such as antioxidant, anti-inflammatory, anti-tumor. The aim of this study is to examine the mechanism of antibacterial activity of TTR against methicillin-resistant Staphylococcus aureus (MRSA). The anti-MRSA activity of TTR was analyzed in combination assays with detergent, ATPase inhibitors, and peptidoglycan (PGN) derived from S. aureus. Transmission electron microscopy (TEM) was used to monitor survival characteristics and changes in S. aureus morphology. The MIC values of TTR against all the tested strains were 125 μg/mL. The OD(600) of each suspension treated with a combination of Triton X-100, DCCD, and NaN₃ with TTR (1/10 × MIC) had been reduced from 68% to 80%, compared to the TTR alone. At a concentration of 125 μg/mL, PGN blocked antibacterial activity of TTR. This study indicates that anti-MRSA action of TTR is closely related to cytoplasmic membrane permeability and ABC transporter, and PGN at 125 μg/mL directly bind to and inhibit TTR at 62.5 μg/mL. These results can be important indication in study on antimicrobial activity mechanism against multidrug resistant strains.

An evidence-based systematic review of kudzu (Pueraria lobata) by the Natural Standard Research Collaboration

An evidence-based systematic review of kudzu (Pueraria lobata) by the Natural Standard Research Collaboration consolidates the safety and efficacy data available in the scientific literature using a validated, reproducible grading rationale. This article includes written and statistical analysis of clinical trials, plus a compilation of expert opinion, folkloric precedent, history, pharmacology, kinetics/dynamics, interactions, adverse effects, toxicology, and dosing.

Phytoestrogens regulate the proliferation and expression of stem cell factors in cell lines of malignant testicular germ cell tumors

Phytoestrogens have been shown to exert anti-proliferative effects on different cancer cells. In addition it could be demonstrated that inhibition of proliferation is associated with downregulation of the known stem cell factors NANOG, POU5F1 and SOX2 in tumor cells. We demonstrate the potential of Belamcanda chinensis extract (BCE) and tectorigenin as anticancer drugs in cell lines of malignant testicular germ cell tumor cells (TGCT) by inhibition of proliferation and regulating the expression of stem cell factors. The TGCT cell lines TCam-2 and NTera-2 were treated with BCE or tectorigenin and MTT assay was used to measure the proliferation of tumor cells. In addition, the expression of stem cell factors was analyzed by quantitative PCR and western blot analysis. Furthermore, global expression analysis was performed by microarray technique. BCE and tectorigenin inhibited proliferation and downregulated the stem cell factors NANOG and POU5F1 in TGCT cells. In addition, gene expression profiling revealed induction of genes important for the differentiation and inhibition of oncogenes. Utilizing connectivity map in an attempt to elucidate mechanism underlying BCE treatments we found highly positive association to histone deacetylase inhibitors (HDACi) amongst others. Causing no histone deacetylase inhibition, the effects of BCE on proliferation and stem cell factors may be based on histone-independent mechanisms such as direct hyperacetylation of transcription factors. Based on these findings, phytoestrogens may be useful as new agents in the treatment of TGCT.

Tectorigenin sensitizes paclitaxel-resistant human ovarian cancer cells through downregulation of the Akt and NFκB pathway

Paclitaxel (Taxol) is currently used as the front-line chemotherapeutic agent for several cancers including ovarian carcinoma; however, the drug frequently induces drug resistance through multiple mechanisms. The new strategy of using natural compounds in combination therapies is highly attractive because those compounds may enhance the efficacy of chemotherapy. In this study, we found that tectorigenin, an isoflavonoid isolated from flower of Pueraria thunbergiana, enhanced the growth-inhibitory effect of paclitaxel in paclitaxel-resistant ovarian cancer cells (MPSC1(TR), A2780(TR) and SKOV3(TR)) as well as their naive counterparts. The combination of tectorigenin with paclitaxel resulted in a synergistic apoptosis compared with either agent alone through activation of caspases-3, -8 and -9. Treatment with tectorigenin inhibited the nuclear translocation of NFκB and the expression of NFκB-dependent genes such as FLIP, XIAP, Bcl-2, Bcl-xL and COX-2, which are known to be associated with chemoresistance. In addition, the tectorigenin-paclitaxel combination inhibited the phosphorylation of IκB and IKK and the activation of Akt in paclitaxel-resistant cancer cells. Moreover, tectorigenin-paclitaxel-induced cell growth inhibition was enhanced by pretreatment with the Akt inhibitor LY294002 or overexpression of the dominant negative Akt (Akt-DN), but reduced by overexpression of constitutively activated Akt (Akt-Myr). Furthermore, we found that Akt-Myr, at least in part, reversed tectorigenin-paclitaxel-induced nuclear translocation of NFκB and the phosphorylation of IκB and IKK. These data suggest that tectorigenin could sensitize paclitaxel-resistant human ovarian cancer cells through inactivation of the Akt/IKK/IκB/NFκB signaling pathway, and promise a new intervention to chemosensitize paclitaxel-induced cytotoxicity in ovarian cancer.

KIOM-4 Protects against Oxidative Stress-Induced Mitochondrial Damage in Pancreatic β-cells via Its Antioxidant Effects

The protective effect of KIOM-4, a mixture of plant extracts, was examined against streptozotocin (STZ)-induced mitochondrial oxidative stress in rat pancreatic β-cells (RINm5F). KIOM-4 scavenged superoxide and hydroxyl radicals generated by xanthine/xanthine oxidase and Fenton reaction (FeSO(4)/H(2)O(2)), respectively, in a cell-free chemical system. In addition, a marked increase in mitochondrial reactive oxygen species (ROS) was observed in STZ-induced diabetic cells; this increase was attenuated by KIOM-4 treatment. Mitochondrial manganese superoxide dismutase (Mn SOD) activity and protein expression were down-regulated by STZ treatment and up-regulated by KIOM-4 treatment. In addition, NF-E2 related factor 2 (Nrf2), a transcription factor for Mn SOD, was up-regulated by KIOM-4. KIOM-4 prevented STZ-induced mitochondrial lipid peroxidation, protein carbonyl and DNA modification. Moreover, KIOM-4 treatment restored the loss of mitochondrial membrane potential (Δψ) that was induced by STZ treatment, and inhibited the translocation of cytochrome c from the mitochondria to the cytosol. In addition, KIOM-4 treatment elevated the level of ATP, succinate dehydrogenase activity and insulin level, which were reduced by STZ treatment. These results suggest that KIOM-4 exhibits a protective effect through its antioxidant effect and the attenuation of mitochondrial dysfunction in STZ-induced diabetic cells.

Kudzu root: traditional uses and potential medicinal benefits in diabetes and cardiovascular diseases

Kudzu root (Gegen in Chinese) is the dried root of Pueraria lobata (Willd.) Ohwi, a semi-woody, perennial and leguminous vine native to South East Asia. It is often used interchangeably in traditional Chinese medicine with thomson kudzu root (Fengen in Chinese), the dried root of P. thomsonii, although the Chinese Pharmacopoeia has separated them into two monographs since the 2005 edition. For more than 2000 years, kudzu root has been used as a herbal medicine for the treatment of fever, acute dysentery, diarrhoea, diabetes and cardiovascular diseases. Both English and Chinese literatures on the traditional applications, phytochemistry, pharmacological activities, toxicology, quality control and potential interactions with conventional drugs of both species have been included in the present review. Over seventy phytochemicals have been identified in kudzu root, with isoflavonoids and triterpenoids as the major constituents. Isoflavonoids, in particular puerarin, have been used in most of the pharmacological studies. Animal and cellular studies have provided support for the traditional uses of kudzu root on cardiovascular, cerebrovascular and endocrine systems, including diabetes and its complications. Further studies to define the active phytochemical compositions, quality standards and clinical efficacy are warranted. Strong interdisciplinary collaboration to bridge the gap between traditional medicine and modern biomedical medicine is therefore needed for the development of kudzu root as an effective medicine for the management of diabetes and cardiovascular diseases.

Protective Mechanism of KIOM-4 in Streptozotocin-Induced Pancreatic β-Cells Damage Is Involved in the Inhibition of Endoplasmic Reticulum Stress

Endoplasmic reticulum stress-mediated apoptosis plays an important role in the destruction of pancreatic β-cells and contributes to the development of type 1 diabetes. The present study examined the effect of KIOM-4, a mixture of four plant extracts, on streptozotocin- (STZ-) induced endoplasmic reticulum (ER) stress in rat pancreatic β-cells (RINm5F). KIOM-4 was found to inhibit STZ-induced apoptotic cell death, confirmed by formation of apoptotic bodies and DNA fragmentation. STZ was found to induce the characteristics of ER stress; mitochondrial Ca(2+) overloading, enhanced ER staining, release of glucose-regulated protein 78 (GRP78), phosphorylation of RNA-dependent protein kinase (PKR) like ER kinase (PERK) and eukaryotic initiation factor-2α (eIF-2α), cleavage of activating transcription factor 6 (ATF6) and caspase 12, and upregulation of CCAAT/enhancer-binding protein-homologous protein (CHOP). However, KIOM-4 attenuated these changes induced by STZ. Furthermore, KIOM-4 suppressed apoptosis induced by STZ in CHOP downregulated cells using CHOP siRNA. These results suggest that KIOM-4 exhibits protective effects in STZ-induced pancreatic β-cell damage, by interrupting the ER stress-mediated pathway.

Tectorigenin inhibits the in vitro proliferation and enhances miR-338* expression of pulmonary fibroblasts in rats with idiopathic pulmonary fibrosis

Tectorigenin is one of the main components in rhizomes of Iris tectorum, which is traditionally used to treat disorders such as hepatic cirrhosis caused by fibrosis. Idiopathic pulmonary fibrosis (IPF), one of the most common interstitial lung diseases, is caused by accumulation of fibroblasts in lungs.

AIM OF THE STUDY

In this work we sought to examine the effects of tectorigenin on pulmonary fibroblasts in the IPF animal model and investigated the molecular mechanism (microRNA regulation) of tectorigenin treatment.

MATERIALS AND METHODS

A well-known animal disease model of pulmonary fibrosis in rat was established by intratracheally instilling of bleomycin. In vitro cultured pulmonary fibroblasts in bleomycin-treated rats and in controls were treated with or without tectorigenin. Comparative analyses of cell proliferation, apoptosis and cell cycle of pulmonary fibroblasts in bleomycin-treated rats and in controls were performed. Expression of miR-338* and its candidate gene LPA1 related to IPF of tectorigenin-treated pulmonary fibroblasts in bleomycin-treated rats were further investigated.

RESULTS

Tectorigenin significantly inhibited the proliferation of pulmonary fibroblasts in bleomycin-treated rats but not in controls. However, no altered cell cycle and apoptosis of pulmonary fibroblasts in bleomycin-treated rats and in controls was observed after tectorigenin treatment. Tectorigenin remarkably enhanced miR-338* expression of pulmonary fibroblasts in bleomycin-treated rats and downregulated LPA1 in the protein level.

CONCLUSIONS

Tectorigenin inhibits the proliferation of pulmonary fibroblasts in vitro and enhances miR-338* expression, which might in turn downregulate LPA1. This indicates a potential inhibitory role of tectorigenin on the pathogenesis of IPF.

Quantitative analysis of two isoflavones in Pueraria lobata flowers from eleven Chinese provinces using high performance liquid chromatography

Background

Pueraria lobata flower (Gehua) is a medicinal herb to treat intoxication, hepatic and gastrointestinal tract lesion induced by alcohol. This study aims to develop a new HPLC method for the determination of two major isoflavones in P. lobata flowers, namely tectoridin and 6"-O-xylosyl-tectoridin.

Methods

A high performance liquid chromatography (HPLC) method with a C₁₈ column (250 mm × 4.6 mm, 5 μm) was developed for the quantitative analysis of tectoridin and 6"-O-xylosyl-tectoridin, the main isoflavone components in P. lobata flower. A simple gradient of acetonitrile/water (0 min 15:85; 35 min 50:50; 36 min 15:85; 40 min 15:85; v/v) was used, and 265 nm was selected as detection wavelength. Tectoridin and 6"-O-xylosyl-tectoridin were used as the external standards in quality control of P. lobata flower for the first time. The method was applied to practical use in quality assessment of eleven batches of P. lobata flower samples in Chinese herbal medicine market.

Results

The peak area response was linear for tectoridin in the 11.8-236.4 μg/mL range with a correlation coefficient of 0.9996 (P < 0.001), and for 6"-O-xylosyl-tectoridin in the 10.33-185.99 μg/mL range with a correlation coefficient of 0.9984 (P < 0.001) respectively. The average recoveries were 102.7-103.7% for tectoridin and 95.7-103.2% for 6"-O-xylosyl-tectoridin (RSDs < 3%), and the intra-day and inter-day RSDs of the two components were less than 2%. This HPLC method was applied to assess the quality of P. lobata flower from eleven provinces in China. P. lobata flowers from northern China contained 26.46-43.28 mg/g of tectoridin and 30.90-48.23 mg/g of 6"-O-xylosyl-tectoridin comparing to 10.00-19.81 mg/g of tectoridin and 11.08-37.03 mg/g of 6"-O-xylosyl-tectoridin in those from southern China.

Conclusion

The results showed that P. lobata flowers from northern China contained more tectoridin and 6"-O-xylosyl-tectoridin than those from southern China.

Introducing N-glycans into natural products through a chemoenzymatic approach

The present study describes an efficient chemoenzymatic method for introducing a core N-glycan of glycoprotein origin into various lipophilic natural products. It was found that the endo-beta-N-acetylglucosaminidase from Arthrobactor protophormiae (Endo-A) had broad substrate specificity and can accommodate a wide range of glucose (Glc)- or N-acetylglucosamine (GlcNAc)-containing natural products as acceptors for transglycosylation, when an N-glycan oxazoline was used as a donor substrate. Using lithocholic acid as a model compound, we have shown that introduction of an N-glycan could be achieved by a two-step approach: chemical glycosylation to introduce a monosaccharide (Glc or GlcNAc) as a handle, and then Endo-A catalyzed transglycosylation to accomplish the site-specific N-glycan attachment. For those natural products that already carry terminal Glc or GlcNAc residues, direct enzymatic transglycosylation using sugar oxazoline as the donor substrate was achievable to introduce an N-glycan. It was also demonstrated that simultaneous double glycosylation could be fulfilled when the natural product contains two Glc residues. This chemoenzymatic method is concise, site-specific, and highly convergent. Because N-glycans of glycoprotein origin can serve as ligands for diverse lectins and cell-surface receptors, introduction of a defined N-glycan into biologically significant natural products may bestow novel properties onto these natural products for drug discovery and development.

Cytotoxic effects of compounds from Iris tectorum on human cancer cell lines

In the course of searching for novel cytotoxic compounds which can be used in chemotherapy, several Traditional Chinese Medicines (TCM) have been screened by bioassay-guided fractionation and isolation. An extract of rhizomes of Iris tectorum Maxim., a TCM used to treat cancer, exhibited highest potency and led to the isolation of two flavonoids, 7-O-methylaromadendrin and tectorigenin, and four iridal-type triterpenes, iritectols A and B, isoiridogermanal and iridobelamal A. The cytotoxicities of the isolated compounds against four human cancer cell lines were evaluated by the SRB assay. Iritectol B, isoiridogermanal and iridobelamal A showed similar cytotoxicity with IG(50) around 11 microM and 23 microM against MCF-7 and C32 cell lines, respectively. Cell cycle-specific inhibition and apoptosis induced by the isolated compounds were determined using flow cytometry with two sets of co-labelling systems: annexin V-FITC/propidium iodide and fluorescein diacetate/propidium iodide. Iritectol B demonstrated dose-dependent apoptotic effect against COR-L23 cells with an apoptotic rate of 33% at 100 microM. Tectorigenin (an analogue of genistein) showed cell cycle specific inhibition and arrested cells at G(2)/M phase up to 400 microM, but did not demonstrate apoptotic effect against COR-L23 cells up to 1 mM. The overall activities of isolated compounds observed in the present study support the traditional use of Iris tectorum Maxim. in the treatment of cancer.

Isoflavonoids of the leguminosae

Isoflavonoids are found predominantly in subfamily Papilionoideae of the Leguminosae. This review describes more than 420 new examples of Leguminosae isoflavonoids, giving details of their source, identification, biological activity, synthesis, and ecological or chemosystematic significance. Other topics addressed include the application of hyphenated analytical techniques to the characterisation of legume-derived isoflavonoids, and advances made in biosynthetic studies. A checklist of new compounds by species is given, and 404 references are cited.

Effects of dietary flavonoids on apoptotic pathways related to cancer chemoprevention

Epidemiological studies have described the beneficial effects of dietary polyphenols (flavonoids) on the reduction of the risk of chronic diseases, including cancer. Moreover, it has been shown that flavonoids, such as quercetin in apples, epigallocatechin-3-gallate in green tea and genistein in soya, induce apoptosis. This programmed cell death plays a critical role in physiological functions, but there is underlying dysregulation of apoptosis in numerous pathological situations such as Parkinson's disease, Alzheimer's disease and cancer. At the molecular level, flavonoids have been reported to modulate a number of key elements in cellular signal transduction pathways linked to the apoptotic process (caspases and bcl-2 genes), but that regulation and induction of apoptosis are unclear. The aim of this review is to provide insights into the molecular basis of the potential chemopreventive activities of representative flavonoids, with emphasis on their ability to control intracellular signaling cascades responsible for regulating apoptosis, a relevant target in cancer-preventive approach.

Rotenoids and flavonoids with anti-invasion of HT1080, anti-proliferation of U937, and differentiation-inducing activity in HL-60 from Erycibe expansa

Principal rotenoids (deguelin, tephrosin, rotenone, and 12a-hydroxyrotenone) (3-30microM) isolated from the stems of Erycibe expansa significantly inhibited invasion of human fibrosarcoma HT1080 cells through Matrigel-coated filters and release of proMMPs-2 and 9. In addition, deguelin and tephrosin showed differentiation-inducing activity in human promyelocytic leukemia HL-60 cells. Furthermore, effects of various constituents isolated from the ethyl acetate-soluble fraction on proliferation of human leukemia U937 cells were examined. As a result, most of isoflavones and several flavans as well as rotenoids showed moderate or substantial anti-proliferative activities.

Cytoprotective Effects of KIOM-79 on Streptozotocin Induced Cell Damage by Inhibiting ERK and AP-1

The present study investigated the potential cytoprotective properties of a combination of plant extracts (KIOM-79) obtained from Magnolia officinalis, Pueraria lobata, Glycyrrhiza uralensis, and Euphorbia pekinensis, against the oxidative stresses induced by streptozotocin (STZ) in a rat pancreatic beta-cells (RINm5F). KIOM-79 was found to scavenge intracellular reactive oxygen species (ROS), thereby preventing DNA damage and lipid peroxidation. The KIOM-79 inhibited apoptosis of the beta-cells exposed to STZ via radical scavenging activity and activation of antioxidant enzymes. KIOM-79 inhibited activation of extracellular regulated kinase (ERK) induced by STZ and inhibited DNA binding activity of an activator protein-1 (AP-1), a downstream transcription factor of ERK. Taken together, these findings suggest that KIOM-79 protects against STZ induced cell death in RINm5F cells by inhibiting ROS generation and the ERK pathway.

Anti-Inflammatory Mechanisms of Isoflavone Metabolites in Lipopolysaccharide-Stimulated Microglial Cells

The microglial activation plays an important role in neurodegenerative diseases by producing several proinflammatory cytokines and nitric oxide (NO). We found that three types of isoflavones and their metabolites that are transformed by the human intestinal microflora suppress lipopolysaccharide (LPS)-induced release of NO and tumor necrosis factor (TNF)-alpha in primary cultured microglia and BV2 microglial cell lines. The inhibitory effect of the isoflavone metabolites (aglycon form) was more potent than that of isoflavones (glycoside form). The RNase protection assay showed that the isoflavone metabolites regulated inducible nitric oxide synthase (iNOS) and the cytokines at either the transcriptional or post-transcriptional level. A further molecular mechanism study was performed for irisolidone, a metabolite of kakkalide, which had the most potent anti-inflammatory effect among the six isoflavones tested. Irisolidone significantly inhibited the DNA binding and transcriptional activity of nuclear factor (NF)-kappaB and activator protein-1. Moreover, it repressed the LPS-induced extracellular signal-regulated kinase (ERK) phosphorylation without affecting the activity of c-Jun N-terminal kinase or p38 mitogen-activated protein kinase. The level of NF-kappaB inhibition by irisolidone correlated with the level of iNOS, TNF-alpha, and interleukin (IL)-1beta suppression in LPS-stimulated microglia, whereas the level of ERK inhibition correlated with the level of TNF-alpha and IL-1beta repression. Overall, the repression of proinflammatory cytokines and iNOS gene expression in activated microglia by isoflavones such as irisolidone might have therapeutic potential for various neurodegenerative diseases including ischemic cerebral disease.

KIOM-79 inhibits LPS-induced iNOS gene expression by blocking NF-kappaB/Rel and p38 kinase activation in murine macrophages

We demonstrate that KIOM-79, combined extracts obtained from Magnolia officinalis, Pueraria lobata, Glycyrrhiza uralensis, and Euphorbia pekinensis, inhibits LPS-induced expression of iNOS gene in RAW 264.7 cells. Treatment of RAW 264.7 cells with KIOM-79 inhibited LPS-stimulated nitric oxide production in a dose-related manner. Immunohisto-chemical staining of iNOS and RT-PCR analysis showed that the decrease of NO was due to the inhibition of iNOS gene expression. Immunostaining of p65, EMSA, and reporter gene assay showed that KIOM-79 inhibited NF-kappa/Rel nuclear translocation, DNA binding, and transcriptional activation, respectively. Western immunoblot analysis of p38 kinase showed KIOM-79 significantly inhibited the phosphoylation of p38 kinase which is important in the regulation of iNOS gene expression. Collectively, this series of experiments indicates that KIOM inhibits iNOS gene expression by blocking NF-kappa/Rel and p38 kinase signaling. Due to the critical role that NO release plays in mediating inflammatory responses, the inhibitory effects of KIOM-79 on iNOS suggest that KIOM-79 may represent a useful anti-inflammatory agent.

Anti-angiogenic and anti-tumor activities of 2'-hydroxy-4'-methoxychalcone

In the present study, we evaluated the in vitro and in vivo anti-angiogenic and anti-tumor activities of 2'-hydroxy-4'-methoxychalcone (HMC). HMC decreased angiogenesis in both chick embryos in the chorioallantoic membrane assay and basic fibroblast growth factor (bFGF)-induced vessel formation in the mouse Matrigel plug assay. This compound also reduced the proliferation of calf pulmonary arterial endothelial cells and was found to possess relatively weak gelatinase/collagenase inhibitory activity in vitro. HMC, when administered subcutaneously at the dose of 30 mg/kg for 20 d to mice implanted with murine Lewis lung carcinoma, caused a significant inhibition of tumor volume by 27.2%. Intraperitoneal (i.p.) treatment at the same dosage for 10 d to ICR mice bearing sarcoma 180 caused a significant suppression in tumor weight by 33.7%. Taken together, out data demonstrate that the anti-angiogenic activities of HMC might be due to anti-proliferative activity under inhibition of the induction of COX-2 enzyme. Furthermore, the results suggest that the potent anti-angiogenic activity of HMC seems to be the possible mechanism of action in these animal models of solid tumors.

[Pharmacological potential of phytoestrogens in the treatment of prostate cancer]

INTRODUCTION

Phytoestrogenes are plant-derived compounds that have been shown to exert an antiproliferative potential on prostate cancer cells, although the exact mechanisms are still unclear. In prostate cancer cells proliferation is regulated by modulation of the IGF-1 receptor (IGF-R-1) by the androgen receptor (AR) and its co-activator prostate derived Ets factor (PDEF). Phytooestrogenes interact with these mechanisms as demonstrated exemplarily in the presented study with the isoflavone tectorigenin derived from Belamcanda chinensis.

MATERIAL AND METHODS

Cultured androgen-sensitive LNCaP prostate cancer cells were treated with tectorigenin of 100 microM for 24 hours. The mRNA-expression of AR, PSA, PDEF, hTERT, TIMP-3 and IGF-R-1 were quantified by real-time RT-PCR. Furthermore, the expression or activity of PSA, telomerase and IGF-R-1 was measured on the protein level. In addition, we investigated in nude mice the influence of a diet of extracts of Belamcanda chinensis on the growth of subcutaneously injected LNCaP cells versus a control group of animals fed with a soy-free diet.

RESULTS

In cultured LNCaP cells treatment with tectorigenin resulted in a significant down-regulation of the gene expression of AR, PDEF, PSA, IGF-R-1 and hTERT. On the protein level PSA secretion and the activity of telomerase and IGF-R-1 expression was also decreased. The gene expression of TIMP-3 was distinctly up-regulated by tectorigenin. Nude mice fed with Belamcanda chinensis extract showed a significantly decreased incidence and tumor growth compared to controls.

CONCLUSIONS

Tectorigenin shows an inhibition of the IGF-1-R modulated cell proliferation of PCa-Cells, due to modulation of the activity the co-activator PDEF independently from the AR. Furthermore, tectorigenin has pro-apoptotic effects and decreases tissue invasion by up-regulation of TIMP-3. Therefore, phytooestrogenes are an interesting option in the therapy of prostate especially advanced prostate cancer.

Phytoestrogens derived from Belamcanda chinensis have an antiproliferative effect on prostate cancer cells in vitro

PURPOSE

Phytoestrogens are nonsteroidal plant derived compounds with estrogenic activity that have been implicated in protecting against prostate cancer progression. We hypothesized that these compounds would alter cell number and increase the ability of antiandrogens to induce cell death in prostate cancer cells.

MATERIALS AND METHODS

RWPE-1, LNCaP and PC-3 cells were treated with or without an extract of Belamcanda chinensis, 2 purified phytoestrogens derived from this extract (irigenin and tectorigenin) and the antiandrogen bicalutamide. We assessed the effect on cell number, proliferation and apoptosis.

RESULTS

Phytoestrogens (50 to 100 microM) and bicalutamide (10 to 50 microM) alone decreased the cell number in all 3 cell lines. Phytoestrogens (50 microM) combined with bicalutamide (10 microM) further decreased the number of RWPE-1 and PC-3 cells compared to these agents alone. Tectorigenin and irigenin inhibited the proliferation of RWPE-1, LNCaP and PC-3 cells, causing G1 arrest and the induction of p21WAF1 or p27 protein expression, whereas bicalutamide induced apoptosis in a dose dependent manner in all 3 cell lines. Phytoestrogens did not have antiandrogenic activity.

CONCLUSIONS

These in vitro studies demonstrate a role for tectorigenin and irigenin in regulating prostate cancer cell number by inhibiting proliferation through cell cycle regulation.