Tectorigenin and other phytochemicals extracted from leopard lily Belamcanda chinensis affect new and established targets for therapies in prostate cancer

Study on quality difference between Belamcanda chinensis (L.) DC and Iris tectorum Maxim. based on chemical chromatogram analysis, biological activity evaluation and in vivo distribution rule

ETHNOPHARMACOLOGICAL RELEVANCE

Belamcanda chinensis (L.) DC. (BC) and Iris tectorum Maxim. (ITM) have been widely used in recent years due to their remarkable curative effects on sore throat, cough and asthma. but they are often misused due to their similar appearance. A comprehensive comparison of the chemical composition, biological activity, pharmacokinetics and tissue distribution between the two active differential components has not been performed. Differences in their specific effects have not been fully elucidated.

AIM OF THE STUDY

This work aims at differentiating between BC and ITM in terms of appearance, chemical composition, biological activity, pharmacokinetics and tissue distribution.

MATERIALS AND METHODS

In this study, the HPLC-FP method was used to find the differences between the chemical components of BC and ITM. The pharmacological experiments were used to compare the differences in activity, including in vitro anti-inflammatory activity with LPS-induced inflammation model of RAW 264.7 cells, inhibition of AChE activity, and the regulation of isolated small intestinal smooth muscle in mice. The pharmacokinetic and tissue distribution profiles were used to analyze the differences between the two in rats.

RESULTS

The types of isoflavones in BC and ITM are basically the same, but their contents in ITM is much higher than that in BC. At the same doses, the release of TNF-α, NO, IL-1β and IL-6 from RAW 264.7 cells in the ITM group was lower than that of the BC group, and the in vitro anti-inflammatory activity of ITM was stronger than that of BC. Meanwhile, ITM had stronger inhibition ability to inhibit AChE activity than BC. The BC extract exhibited an inhibitory effect on the isolated small intestinal smooth muscle of mice, and the ITM extract showed stimulatory effect at low concentration and inhibitory effect at high concentration. There were significant differences in drug-time profiles, kinetic parameters and tissue distribution.

CONCLUSIONS

There are significant differences in the multidimensional aspects of appearance, chemical composition, biological activity, pharmacokinetics, and tissue distribution between BC and ITM. This study provides a theoretical basis for the quality control, pharmacological efficacy and clinical application of the two herbs.

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.

Long-chain fatty acid acylated derivatives of isoflavone glycosides from the rhizomes of Iris domestica

Six undescribed long-chain fatty acid esters of isoflavone glycosides were obtained from the rhizomes of Iris domestica (L.). Their structures were elucidated by comprehensive spectroscopic data, alkaline hydrolysis, and acid hydrolysis. This is the first report of the long-chain (C₁₄-C₁₈) fatty acid derivatives of isoflavone glycosides from natural products. Belamcandnoate B and D exhibited moderate cytotoxic activities against HCT-116, HepG2, and BGC823 cell lines with IC₅₀ values of 1.69-6.86 μM. Belamcandnoate B and E exhibited 72.27 and 58.98% inhibitory activities, respectively, against Fe²⁺/cysteine-induced liver microsomal lipid peroxidation at a concentration of 10 μM.

Tectorigenin attenuates the OGD/R-induced HT-22 cell damage through regulation of the PI3K/AKT and the PPARγ/NF-κB pathways

Tectorigenin (TEC) is an effective compound that derived from many plants, such as Iris unguicularis, Belamcanda chinensis and Pueraria thunbergiana Benth. Evidence suggested that TEC has anti-tumor, anti-oxidant activity, anti-bacterial and anti-inflammatory effects. In addition, there has some evidence indicated that TEC is a potential anti-stroke compound; however, its specific roles and associated mechanism have not yet been elucidated. In the present study, we aimed to investigate the anti-inflammatory, anti-oxidant activity and anti-apoptosis effects of TEC on oxygen-glucose deprivation/reperfusion (OGD/R)-induced HT-22 cells, and clarified the relevant mechanisms. Here, we observed that TEC significantly promoted cell survival, impeded cell apoptosis, inhibited ROS and inflammatory cytokines IL-1β, IL-6, TNF-α production in OGD/R-induced HT-22 cells. Moreover, TEC activated PI3K/AKT signal pathway, increased PPARγ expression and inhibited NF-κB pathway activation in OGD/R-induced HT-22 cells. Further studies indicated that PPARγ inhibitor GW9662 activated NF-κB pathway after TEC treatment in OGD/R-induced HT-22 cells. Also, PI3K/AKT inhibitor LY294002, PPARγ inhibitor GW9662 and NF-κB activator LPS both reversed the effects of TEC on OGD/R-induced HT-22 cell biology. Taken together, this research confirmed that TEC benefit to HT-22 cell survival and against OGD/R damage through the PI3K/AKT and PPARγ/NF-κB pathways. These results indicated that TEC might be an effective compound in the treatment for ischemic brain injury.

Estrogenic and antiandrogenic activities of methoxyflavans isolated from the fruit of Mauritia Flexuosa (Moriche Palm)

Moriche palm is consumed as both a fresh fruit and processed food in Peru and Brazil. Although its fruit contains phytoestrogens, the active compounds have not yet been identified. Therefore, we purified moriche palm extract (MPE) and identified compounds exhibiting estrogenic and antiandrogenic activities. Estrogenic activity was assessed by the estrogen-dependent growth of MCF-7 cells and increases in uterine weights in mice. Antiandrogenic activity was evaluated by 5α-reductase inhibitory activity and prostate-specific antigen (PSA) expression in LNCaP cells. In vivo antiestrogenic activity was also assessed based on testosterone-induced prostate growth in castrated mice. Four methoxyflavans were isolated from MPE and all, except for 7,4'-dihydroxy-5-methoxyflavan, promoted MCF-7 cell growth, indicating estrogenic activity. Uterine and ovary weights increased in mice orally administered MPE (400 mg/kg) for 2 weeks. Regarding antiandrogenic activity, among the four methoxyflavans isolated, 6,7,4'-trihydroxy-5-methoxyflavan (1 µg/ml) suppressed the mRNA and protein expression of PSA in LNCaP cells. Furthermore, prostate growth was suppressed in mice orally administered MPE (200 mg/kg) for 2 weeks. All methoxyflavans inhibited 5α-reductase activity with IC₅₀ less than 10 µg/ml. Collectively, the present results demonstrated that orally administered MPE exhibited estrogenic and antiandrogenic activities. Methoxyflavans, particularly 6,7,4'-trihydroxy-5-methoxyflavan, appear to be the active compounds for these activities. PRACTICAL APPLICATIONS: The fruit of Mauritia flexuosa (moriche palm) has been used for beverages and processed foods. Although it is said to contain phytoestrogens, the active compounds have not yet been identified. In this study, we isolated and identified methoxyflavans exhibiting estrogenic and antiandrogenic activities. Among them, 6,7,4'-trihydroxy-5-methoxyflavan appeared to be the most effective compounds for these activities.

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.

Network Pharmacology Analysis to Identify Phytochemicals in Traditional Chinese Medicines That May Regulate ACE2 for the Treatment of COVID-19

“Three formulas and three medicines,” which include Jinhua Qinggan granule, Lianhua Qingwen capsule/granule, Xuebijing injection, Qingfei Paidu decoction, HuaShiBaiDu formula, and XuanFeiBaiDu granule, have been proven to be effective in curbing coronavirus disease 2019 (COVID-19), according to the State Administration of Traditional Chinese Medicine. The aims of this study were to identify the active components of “Three formulas and three medicines” that can be used to treat COVID-19, determine their mechanism of action via angiotensin-converting enzyme 2 (ACE2) by integrating network pharmacological approaches, and confirm the most effective components for COVID-19 treatment or prevention. We investigated all the compounds present in the aforementioned herbal ingredients. Compounds that could downregulate the transcription factors (TFs) of ACE2 and upregulate miRNAs of ACE2 were screened via a network pharmacology approach. Hepatocyte nuclear factor 4 alpha (HNF4A), peroxisome proliferator-activated receptor gamma (PPARG), hsa-miR-2113, and hsa-miR-421 were found to regulate ACE2. Several compounds, such as quercetin, decreased ACE2 expression by regulating the aforementioned TFs or miRNAs. After comparison with the compounds present in Glycyrrhiza Radix et Rhizoma, quercetin, glabridin, and gallic acid present in the herbal formulas and medicines were found to alter ACE2 expression. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were used to search for possible molecular mechanisms of these compounds. In conclusion, traditional Chinese medicine (TCM) plays a pivotal role in the prevention and treatment of COVID-19. Quercetin, glabridin, and gallic acid, the active components of recommended TCM formulas and medicines, can inhibit COVID-19 by downregulating ACE2.

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.

Characterization and evaluation of a self-microemulsifying drug delivery system containing tectorigenin, an isoflavone with low aqueous solubility and poor permeability

The purpose of this study was to characterize and evaluate tectorigenin-loaded self-microemulsifying drug delivery system (TG-SMEDDS), a previously studied preparation, and further confirm the improvement of TG in solubility and bioavailability. The appearance of TG-SMEDDS was clear and transparent, with good mobility. The microemulsion formed by TG-SMEDDS was globular, edge smooth, clear-cut, and distribution homogeneous under transmission electron microscope. The stability studies revealed that TG-SMEDDS remained stable at room temperature for at least 3 months. TG-SMEDDS showed excellent dissolution behavior that more than 90% of TG was released in only 5 min. The in situ intestinal perfusion studies indicated enhancement of absorption in four tested intestinal segments, and the main absorption site of TG was changed to duodenum. In addition, TG-SMEDDS showed significantly higher Cmax and AUC values (11-fold and 5-fold higher values, respectively; P < 0.05) than TG, and the absolute oral bioavailability of TG-SMEDDS was 56.33% (5-fold higher than that of crude TG). What's more, the AUC0-t of crude TG and TG-SMEDDS in bile duct non-ligation rats were 6.05 and 2.80 times, respectively, than that in bile duct ligation rats, indicating the existence of enterohepatic circulation and the secretion of bile could significantly affect the absorption of TG. Further studies showed that even the bile duct was ligation, TG-SMEDDS can still keep a better oral bioavailability (179.67%, compared with crude TG in the bile duct non-ligation rats). Therefore, our study implies that SMEDDS containing TG could be an effective strategy for the oral administration of TG.

Prospects of estrogen receptor β activation in the treatment of castration-resistant prostate cancer

Advanced prostate cancer can develop into castration-resistant prostate cancer (CRPC). This process is mediated either by intratumoral ligand synthesis or by mutations or aberrations of the androgen receptor (AR) or its cofactors. To date, no curative therapy for CRPC is available, as AR-targeted therapies eventually result in the development of resistance. The human prostate cancer cell line VCaP (vertebral cancer of the prostate) overexpresses AR and its splice variants (ARVs) as a mechanism of resistance to androgen-deprivation therapy (ADT) of external and intratumoral origin. In the present study, we demonstrate that stimulating estrogen receptor β activity with the specific agonist 8β-VE2 in VCaP cells in successive stages of ADT induced a time- and dose-dependent decrease in cell survival and an increase in apoptosis. Furthermore, 8β-VE2 treatment reduced the overexpression of the AR as well as ARVs in VCaP cells under maximum ADT. Our results indicate that decreased survival of the androgen-dependent CRPC cells employing apoptosis together with the regulative effect on AR expression could have beneficial effects over current AR-targeting therapies.

Comprehensive assessment of estrogen receptor beta antibodies in cancer cell line models and tissue reveals critical limitations in reagent specificity

Estrogen Receptor-β (ERβ) has been implicated in many cancers. In prostate and breast cancer its function is controversial, but genetic studies implicate a role in cancer progression. Much of the confusion around ERβ stems from antibodies that are inadequately validated, yet have become standard tools for deciphering its role. Using an ERβ-inducible cell system we assessed commonly utilized ERβ antibodies and show that one of the most commonly used antibodies, NCL-ER-BETA, is non-specific for ERβ. Other antibodies have limited ERβ specificity or are only specific in one experimental modality. ERβ is commonly studied in MCF-7 (breast) and LNCaP (prostate) cancer cell lines, but we found no ERβ expression in either, using validated antibodies and independent mass spectrometry-based approaches. Our findings question conclusions made about ERβ using the NCL-ER-BETA antibody, or LNCaP and MCF-7 cell lines. We describe robust reagents, which detect ERβ across multiple experimental approaches and in clinical samples.

The unprecedented iridal lactone and adducts of spiroiridal and isoflavonoid from Belamcanda chinensis

Five novel iridal-type triterpenoid derivatives have been isolated from the rhizomes of Belamcanda chinensis, along with five known compounds. Their structures were elucidated by extensive spectroscopic analysis.

Tectorigenin inhibits osteosarcoma cell migration through downregulation of matrix metalloproteinases in vitro

Tectorigenin (Tec) is an effective component of the traditional Chinese medicine Belamcanda chinensis, which has been reported to exert beneficial effects in various types of cancer. However, the activity and mechanism of Tec in osteosarcoma (OS) have not been investigated to date. The aim of the present study was to examine the inhibitory effect of Tec on OS and its underlying mechanism of action. OS cells (Saos2 and U2OS) were treated with various concentrations of Tec for 24, 48, and 72 h. Cell proliferation was evaluated using an CCK-8 assay. Cell migration and invasion ability were measured using the Transwell assay. The expressions of MMP1, MMP2, MMP9, and cleaved caspase3 were measured using real-time PCR and/or western blot analysis. We found that Tec inhibited the proliferation of OS cells (Saos2 and U2OS) in a dose-dependent and time-dependent manner. In addition, Tec significantly inhibited migration and invasion in OS cells (P<0.05). Tec upregulated the expression of cleaved caspase3, while downregulating the expression of MMP1, MMP2, and MMP9. Taken together, the present study provided fundamental evidence for the application of Tec in chemotherapy against OS.

Belamcanda chinensis (L.) DC-An ethnopharmacological, phytochemical and pharmacological review

ETHNOPHARMACOLOGICAL RELEVANCE

Belamcanda chinensis (L.) DC is the sole species in the genus Belamcanda Adans. (Iridaceae), found mainly in Northeast Asia. Bombus chinensis has long been used in traditional Chinese medicine for its multiple therapeutic uses in the form of antipyretic agents, antidote, expectorant, antiphlogistic and analgesic.

AIM OF THE REVIEW

This manuscript comprehensively summarizes the various studies published in recent years on the botany, ethnopharmacology, phytochemistry, biological activity and toxicology of B. chinensis. We hope to provide a foundation for future studies on the mechanism of action and development of better therapeutic agents based on B. chinensis.

MATERIAL AND METHODS

All information available on B. chinensis was collected using electronic search engines, such as PubMed, SciFinder Scholar, CNKI, TPL (www.theplantlist.org), Google Scholar and Web of Science.

RESULTS

The analysis shown that ethno-medical uses of B. chinensis have been recorded in China, Japan and Korea since a long time. Based on a phytochemical investigation, this plant contains flavonoids, terpenoids, quinones, phenolic compounds, ketones, organic acids, etc. Crude extracts and pure compounds isolated from B. chinensis exhibited various biological effects.

CONCLUSIONS

In light of its long traditional use and the modern phytochemical and pharmacological studies summarized here, B. chinensis is known to be a promising medicinal plant with the isolated extracts and chemical components showing a wide range of biological activities. Thus, it is imperative that the necessary programs and value assessment of B. chinensis be established for further studies. It is also important that the synergistic or antagonistic effects of this traditional herbal medicine are investigated in depth to identify more bioactive components by bioactivity-guided isolation strategies, and to illustrate the mechanisms of action targeting on ethnomedical uses. Future clinical studies can also focus on the main therapeutic aspects, toxicity and adverse effects of B. chinensis.

Estrogen receptor beta in prostate cancer: friend or foe?

Prostate cancer is the commonest, non-cutaneous cancer in men. At present, there is no cure for the advanced, castration-resistant form of the disease. Estrogen has been shown to be important in prostate carcinogenesis, with evidence resulting from epidemiological, cancer cell line, human tissue and animal studies. The prostate expresses both estrogen receptor alpha (ERA) and estrogen receptor beta (ERB). Most evidence suggests that ERA mediates the harmful effects of estrogen in the prostate, whereas ERB is tumour suppressive, but trials of ERB-selective agents have not translated into improved clinical outcomes. The role of ERB in the prostate remains unclear and there is increasing evidence that isoforms of ERB may be oncogenic. Detailed study of ERB and ERB isoforms in the prostate is required to establish their cell-specific roles, in order to determine if therapies can be directed towards ERB-dependent pathways. In this review, we summarise evidence on the role of ERB in prostate cancer and highlight areas for future research.

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.

Tectoridin from Maackia amurensis modulates both estrogen and thyroid receptors

AIM

The stem bark of Maackia amurensis has been used as folk medicine for the treatment of cancer, cholecystitis, arthritis, and hyperthyroidism in females. In this study we examined the effects of the ethyl acetate fraction obtained from the 70% ethanol extract of M. amurensis and tectoridin, an active constituent isolated from the ethyl acetate fraction on thyroid and estrogen hormone activity.

METHODS

The effect of the ethanolic extract of M. amurensis stem bark on thyroid hormone activity was evaluated using thyroid hormone responsive-luciferase assay. We isolated tectoridin from the ethyl acetate fraction using a recrystallization method. T-screen assays were used to confirm thyroid hormone activity. The estrogenic activity of the ethyl acetate fraction of M. amurensis and tectoridin was evaluated by estrogen responsive-luciferase assay and estrogen receptor alpha regulation as compared to 17β-estradiol.

RESULTS

Both the ethyl acetate fraction and tectoridin activated thyroid-responsive reporters and increased thyroid hormone-dependent proliferation of rat pituitary GH3 cells, indicating modulation of thyroid hormone receptors. In parallel, the estrogenic activity of the fraction and tectoridin were characterized in a transient transfection system using estrogen-responsive luciferase plasmids in MCF-7 cells. The ethyl acetate fraction and tectoridin activated reporter gene expression and decreased the estrogen receptor protein level.

CONCLUSIONS

These data indicate that tectoridin acts as a weak phytoestrogen as well as a thyroid hormone-like agent by activating both estrogen and thyroid hormone receptors.

Phytoestrogens selective for the estrogen receptor beta exert anti-androgenic effects in castration resistant prostate cancer

Prostate cancer is the leading cause of cancer death in men of the Western world. A castration-resistant prostate cancer (CRPC) eventually will arise when a local restricted prostate carcinoma was not cured duly by radical prostatectomy or radiation therapy. Although androgen ablation therapies are considered the gold standard for treatments of advanced prostate cancer there is no curative therapy available at present. In previous pre-clinical and clinical trials several phytoestrogens were investigated for their anticancer potential in various models for prostate cancer. Phytoestrogens feature tumour preventive characteristics and most probably are involved in the low incidence rate of hormone related cancers in Asian countries. Phytoestrogens such as isoflavones can have a marked impact on the most essential therapy target of CRPC i.e. the androgen receptor. Furthermore, functional analyses solidified the notion of such drugs as androgen antagonistic. Phytoestrogens commonly feature low toxicity combined with a potential of targeted therapy. Thus, these drugs qualify for conceivable implementation in prostate cancer patients under active surveillance. In addition, relapse prevention with these drugs after radical prostatectomy or radiation therapy might be considered. This article is part of a Special Issue entitled 'Phytoestrogens'.

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.

The isoprenoid perillyl alcohol inhibits telomerase activity in prostate cancer cells

Isoprenoids are recognized for their ability to suppress carcinogenic processes in vivo and in vitro. We previously established that the isoprenoid, perillyl alcohol, acted mechanistically on translation of specific proteins through modulation of mechanistic target of rapamycin (mTOR) signaling. Telomerase-the enzyme responsible for immortalizing cells through the addition of telomeric repeats-is de-repressed early in an aspiring cancer cell. Here the effects of biologically-relevant concentrations and short incubations (1-16 h) of perillyl alcohol or the mTOR inhibitor, rapamycin, on telomerase activity were examined in prostate cancer cell lines. A rapid suppression of telomerase activity was observed (from ∼65% to >95%) determined by real-time quantitative telomerase repeat amplification protocol and confirmed by polyacrylamide gel-analysis. Using real-time reverse transcriptase-PCR, we demonstrated that human telomerase reverse transcriptase (hTERT) mRNA levels were unaltered. Western blot analysis revealed that hTERT protein levels decreased in response to perillyl alcohol or rapamycin. This decrease was partially blocked by pretreatment with a proteasome inhibitor MG-132, indicating that proteasomal degradation contributed to the loss of hTERT protein. No change in hTERT phosphorylation at Ser824 was observed, indicating the absence of cellular hTERT protein redistribution. These findings provide evidence for a unique link between nutrient- and macrolide-mediated regulation of mTOR and hTERT, a key enzyme that regulates DNA structure and stability.

InTERTesting association between telomerase, mTOR and phytochemicals

Telomeres are stretches of repeated DNA sequences located at the ends of chromosomes that are necessary to prevent loss of gene-coding DNA regions during replication. Telomerase – the enzyme responsible for immortalising cancer cells through the addition of telomeric repeats – is active in ~90% of human cancers. Telomerase activity is inhibited by various phytochemicals such as isoprenoids, genistein, curcumin, epigallocatechin-3-gallate, resveratrol and others. Human TERT (telomerase reverse transcriptase – the rate-limiting component of telomerase), heat shock protein 90, Akt, p70 S6 kinase (S6K) and mammalian target of rapamycin (mTOR) form a physical and functional complex with one another. The inclusion of Akt, mTOR and S6K in the TERT complex is compelling evidence to support mTOR-mediated control of telomerase activity. This review will define the role of mTOR, the master regulator of protein translation, in telomerase regulation and provide additional insights into the numerous ways in which telomerase activity is hindered by phytochemicals.

[Antiandrogen strategies in prostate cancer: reconstitution of oestrogen receptor beta]

In advanced prostate cancer, albeit castration resistant, an active androgen receptor is still pivotal for growth and cell survival. Recent therapies involving more effective antiandrogens such as MDV3100 proved to be successful. Furthermore, blocking de novo intracrine androgen synthesis, e.g. with abiraterone acetate, provides additional benefit. Besides these antiandrogen measures, compounds which enable the reconstitution of the oestrogen receptor beta as a tumour suppressor restrain aberrant androgen receptor signalling.

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.

Identification of the major metabolites of tectorigenin in rat bile by liquid chromatography combined with time-of-flight and ion trap tandem mass spectrometry

A novel methodology for the identification of tetorigenin and its metabolites in rat bile has been created using liquid chromatography (LC) combined with time-of-flight (TOF) and ion trap multiple mass spectrometry (IT-MSn). As a means to discriminate amongst unknown organic compounds in complex biological matrices, the proposed methodology relies upon the combination of LC/TOF-MS to provide accurate mass measurements in generating a molecular formula while benefiting from the complementary structural information provided by the LC/IT-MSn. In this study, the combined approach has been applied to the metabolic fingerprinting chromatograms of rat bile samples before and after tectorigenin administration. All possible metabolites are investigated based on accurate mass data and isotope function using LC/TOF-MS and structural confirmation using LC/IT-MSn. Seven phase II metabolities of tectorigenin in rat bile have been successfully elucidated using this novel LC approach and are being reported for the first time.

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.

The relevance of estrogen receptor- expression to the antiproliferative effects observed with histone deacetylase inhibitors and phytoestrogens in prostate cancer treatment

In the prostate, estrogen receptor beta (ERbeta), the preferred receptor for phytoestrogens, has features of a tumor suppressor. To investigate the mechanisms underlying the beneficial effects on prostate cancer of histone deacetylase inhibitor valproic acid (VPA) and phytoestrogen tectorigenin, we analyzed the expression of ERbeta after tectorigenin or VPA treatment. For further functional analysis, we knocked down ERbeta expression by RNA interference. LNCaP prostate cancer cells were treated with 5 mmol/L VPA or 100 micromol/L tectorigenin and transfected with small interfering RNA (siRNA) against ERbeta. Control transfections were done with luciferase (LUC) siRNA. Expression of ERbeta was assessed by Western blot. mRNA expression was quantitated by real-time reverse transcription-PCR. Expression of ERbeta mRNA and protein markedly increased after VPA or tectorigenin treatment. When ERbeta was knocked down by siRNA, the expression of prostate-derived Ets factor, prostate-specific antigen, prostate cancer-specific indicator gene DD3(PCA3), insulin-like growth factor-1 receptor, the catalytic subunit of the telomerase, and ERalpha was up-regulated and the tectorigenin effects were abrogated. ERbeta levels were diminished in prostate cancer and loss of ERbeta was associated with proliferation. Here, we show that siRNA-mediated knockdown of ERbeta increases the expression of genes highly relevant to tumor cell proliferation. In addition, we show that one prominent result of treatment with VPA or tectorigenin is the up-regulation of ERbeta resulting in antiproliferative effects. Thus, these drugs, by restoring the regulatory function of ERbeta in tumor cells, could become useful in the intervention of prostate cancer.

Phytoestrogens from Belamcanda chinensis regulate the expression of steroid receptors and related cofactors in LNCaP prostate cancer cells

OBJECTIVE

To investigate the changes in expression underlying the marked reduction of tumour growth in vivo, by analysing the effect of Belamcanda chinensis extract (BCE) on LNCaP cells in vitro, as phytoestrogens are chemopreventive in prostate cancer, and in previous studies we examined the effects of the isoflavone tectorigenin isolated from B. chinensis on LNCaP prostate cancer cells, and a BCE consisting of 13 phytoestrogenic compounds on tumour-bearing nude mice.

MATERIALS AND METHODS

LNCaP cells were treated with 100, 400 or 1400 microg/mL BCE; proliferation was assessed with an Alamar Blue assay. We used real-time reverse transcription-polymerase chain reaction to quantify mRNA expression of the androgen receptor (AR), the AR coactivator prostate derived Ets transcription factor (PDEF), NKX3.1, prostate specific antigen (PSA) and oestrogen receptor-beta (ER-beta) compared with the expression of the housekeeping gene porphobilinogen deaminase (PBGD). PSA secretion from LNCaP cells was measured and protein expression of the AR investigated by Western blot analysis.

RESULTS

Concomitant with a marked decrease of tumour cell proliferation BCE down-regulated the expression of the AR, PDEF, NKX3.1 and PSA. In the same experiments, the expression of PBGD was unaltered, whereas ER-beta expression increased. Furthermore, AR protein and PSA secretion were markedly diminished after treatments with the BCE.

CONCLUSION

BCE, comprising 13 different phytoestrogens, decreases the expression of the AR and its co-activator PDEF concomitant with diminished cell proliferation and PSA secretion. NKX3.1 expression was also reduced by BCE. We hypothesise that the positive effects of BCE are initiated by up-regulation of the ER-beta, a putative tumour-suppressor gene.

[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.