Estrogenic and anticarcinogenic properties of kurarinone, a lavandulyl flavanone from the roots of Sophora flavescens

Estrogenic Prenylated Flavonoids in Sophora flavescens

Sophora flavescens is a medicinal herb distributed widely in Japan and it has been used to treat various diseases and symptoms. To explore its pharmacological use, we examined the estrogenic activity of four prenylated flavonoids, namely kurarinone, kushenols A and I, and sophoraflavanone G, which are characterized by the lavandulyl group at position 8 of ring A, but have variations in the hydroxyl group at positions 3 (ring C), 5 (ring A) and 4' (ring B). These prenylated flavonoids were examined via cell proliferation assays using sulforhodamine B, Western blotting, and RT-PCR, corresponding to cell, protein, and transcription assays, respectively, based on estrogen action mechanisms. All the assays employed here found weak but clear estrogenic activities for the prenylated flavonoids examined. Furthermore, the activities were inhibited by an estrogen receptor antagonist, suggesting that the activities were likely being mediated by the estrogen receptors. However, there were differences in the activity, attributable to the hydroxyl group at position 4', which is absent in kushenol A. While the estrogenic activity of kurarinone and sophoraflavanone G has been reported before, to the best of our knowledge, there are no such reports on kushenols A and I. Therefore, this study represents the first report of their estrogenic activity.

Six undescribed lavandulylated flavonoids with PTP1B inhibition from the roots of Sophora flavescens

Six undescribed lavandulylated flavonoids (1-6) were isolated from the roots of Sophora flavescens. Remarkably, compounds 1 and 2, which were composed of a flavane unit and a phloroglucinol unit, were the first reported dimers. Compounds 3 and 4 were the first reported neoflavonoids with lavandulyl units. Compounds 5 and 6 were chalcone with oxidized lavandulyl units. Their structures were fully characterized by cumulative analyses of UV, IR, HRESIMS, NMR and ECD spectroscopic data, along with computational calculations through density functional theory. Compounds 1 and 2 showed significant protein tyrosine phosphatase-1B inhibitory activities with IC50 values of 2.669 and 3.596 μM, respectively.

Estrogenic flavonoids and their molecular mechanisms of action

Flavonoids are a major group of phytoestrogens associated with physiological effects, and ecological and social impacts. Although the estrogenic activity of flavonoids was reported by researchers in the fields of medical, environmental and food studies, their molecular mechanisms of action have not been comprehensively reviewed. The estrogenic activity of the respective classes of flavonoids, anthocyanidins/anthocyanins, 2-arylbenzofurans/3-arylcoumarins/α-methyldeoxybenzoins, aurones/chalcones/dihydrochalcones, coumaronochromones, coumestans, flavans/flavan-3-ols/flavan-4-ols, flavanones/dihydroflavonols, flavones/flavonols, homoisoflavonoids, isoflavans, isoflavanones, isoflavenes, isoflavones, neoflavonoids, oligoflavonoids, pterocarpans/pterocarpenes, and rotenone/rotenoids, was summarized through a comprehensive literature search, and their structure-activity relationship, biological activities, signaling pathways, and applications were discussed. Although the respective classes of flavonoids contained at least one chemical mimicking estrogen, the mechanisms varied, such as those with estrogenic, anti-estrogenic, non-estrogenic, and biphasic activities, and additional activities through crosstalk/bypassing, which exert biological activities through cell signaling pathways. Such mechanistic variations of estrogen action are not limited to flavonoids and are observed among other broad categories of chemicals, thus this group of chemicals can be termed as the "estrogenome". This review article focuses on the connection of estrogen action mainly between the outer and the inner environments, which represent variations of chemicals and biological activities/signaling pathways, respectively, and form the basis to understand their applications. The applications of chemicals will markedly progress due to emerging technologies, such as artificial intelligence for precision medicine, which is also true of the study of the estrogenome including estrogenic flavonoids.

Potential of natural products in the treatment of irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a kind of functional bowel disease that is characterized by bellyache, abdominal distension, and diarrhea. Although not life-threatening, IBS has a long course and recurrent attacks and seriously affects the life quality of patients. Current drugs for treating IBS possess remarkable limitations, such as limited efficacy and severe adverse reactions. Therefore, developing novel medications to treat IBS is quite essential, and natural products may be a substantial source.

PURPOSE

This is the first systematic review elaborating the recent advancement of natural products as potential drugs for the therapy of IBS.

METHODS

A comprehensive retrieval of studies was carried out in scientific databases including PubMed, Web of Science, Elsevier, and CNKI. By using ("irritable bowel syndrome" OR "IBS") AND ("natural product" OR "natural compound" OR "phytochemical") as keywords, the eligible studies were screened, and the relevant information about therapeutic action and mechanism of natural products treating IBS was extracted.

RESULTS

Natural products against IBS consisted of four categories, namely, terpenoids, flavonoids, alkaloids, and phenols. Furthermore, the underlying mechanisms for natural products treating IBS were tightly associated with increased TJs and mucus protein expression, regulation of the brain-gut axis and gut microbiota structure, and inhibition of inflammatory response and intestinal mucosal damage.

CONCLUSION

Natural products could be extremely prospective candidate drugs used to treat IBS, and further preclinical and clinical researches are needed to guarantee their efficacy and safety.

Chemical Characterization, α-Glucosidase, α-Amylase and Lipase Inhibitory Properties of the Australian Honey Bee Propolis

The use of functional foods and nutraceuticals as a complementary therapy for the prevention and management of type 2 diabetes and obesity has steadily increased over the past few decades. With the aim of exploring the therapeutic potentials of Australian propolis, this study reports the chemical and biological investigation of a propolis sample collected in the Queensland state of Australia which exhibited a potent activity in an in vitro α-glucosidase inhibitory screening. The chemical investigation of the propolis resulted in the identification of six known prenylated flavonoids including propolins C, D, F, G, H, and solophenol D. These compounds potently inhibited the α-glucosidase and two other enzymes associated with diabetes and obesity, α-amylase, and lipase on in vitro and in silico assays. These findings suggest that this propolis is a potential source for the development of a functional food to prevent type 2 diabetes and obesity. The chemical analysis revealed that this propolis possessed a chemical fingerprint relatively similar to the Pacific propolis found in Okinawa (South of Japan), Taiwan, and the Solomon Islands. This is the first time the Pacific propolis has been identified in Australia.

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

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

Five-Decade Update on Chemopreventive and Other Pharmacological Potential of Kurarinone: a Natural Flavanone

In the present article we present an update on the role of chemoprevention and other pharmacological activities reported on kurarinone, a natural flavanone (from 1970 to 2021). To the best of our knowledge this is the first and exhaustive review of kurarinone. The literature was obtained from different search engine platforms including PubMed. Kurarinone possesses anticancer potential against cervical, lung (non-small and small), hepatic, esophageal, breast, gastric, cervical, and prostate cancer cells. In vivo anticancer potential of kurarinone has been extensively studied in lungs (non-small and small) using experimental xenograft models. In in vitro anticancer studies, kurarinone showed IC₅₀ in the range of 2–62 µM while in vivo efficacy was studied in the range of 20–500 mg/kg body weight of the experimental organism. The phytochemical showed higher selectivity toward cancer cells in comparison to respective normal cells. kurarinone inhibits cell cycle progression in G2/M and Sub-G1 phase in a cancer-specific context. It induces apoptosis in cancer cells by modulating molecular players involved in apoptosis/anti-apoptotic processes such as NF-κB, caspase 3/8/9/12, Bcl2, Bcl-XL, etc. The phytochemical inhibits metastasis in cancer cells by modulating the protein expression of Vimentin, N-cadherin, E-cadherin, MMP2, MMP3, and MMP9. It produces a cytostatic effect by modulating p21, p27, Cyclin D1, and Cyclin A proteins in cancer cells. Kurarinone possesses stress-mediated anticancer activity and modulates STAT3 and Akt pathways. Besides, the literature showed that kurarinone possesses anti-inflammatory, anti-drug resistance, anti-microbial (fungal, yeast, bacteria, and Coronavirus), channel and transporter modulation, neuroprotection, and estrogenic activities as well as tyrosinase/diacylglycerol acyltransferase/glucosidase/aldose reductase/human carboxylesterases 2 inhibitory potential. Kurarinone also showed therapeutic potential in the clinical study. Further, we also discussed the isolation, bioavailability, metabolism, and toxicity of Kurarinone in experimental models.

LaPT2 Gene Encodes a Flavonoid Prenyltransferase in White Lupin

Legume plants are rich in prenylated flavonoid compounds, which play an important role in plant defense and human health. In the present study, we identified a prenyltransferase (PT) gene, named LaPT2, in white lupin (Lupinus albus), which shows a high identity and close relationship with the other known PT genes involved in flavonoid prenylation in planta. The recombinant LaPT2 protein expressed in yeast cells exhibited a relatively strong activity toward several flavonols (e.g., kaempferol, quercetin, and myricetin) and a relatively weak activity toward flavanone (naringenin). In addition, the recombinant LaPT2 protein was also active toward several other types of flavonoids, including galangin, morin, 5-deoxyquercetin, 4'-O-methylkaempferol, taxifolin, and aromadendrin, with distinct enzymatic affinities. The LaPT2 gene was preferentially expressed in the roots, which is consistent with the presence of prenylated flavonoid kaempferol in the roots. Moreover, we found that the expression level of LaPT2 paralleled with those of LaF3H1 and LaFLS2 genes that were relatively higher in roots and lower in leaves, suggesting that they were essential for the accumulation of prenylated flavonoid kaempferol in roots. The deduced full-length LaPT2 protein and its signal peptide fused with a green fluorescent protein (GFP) are targeted to plastids in the Arabidopsis thaliana protoplast. Our study demonstrated that LaPT2 from white lupin is responsible for the biosynthesis of prenylated flavonoids, in particular flavonols, which could be utilized as phytoalexin for plant defense and bioactive flavonoid compounds for human health.

Pharmacokinetic and bioavailability study of kurarinone in dog plasma by UHPLC-MS/MS

Kurarinone, a natural prenylated flavonone isolated from Sophora flavescens, has been exhibited various activities. This study aimed to establish a simple and sensitive ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for determining kurarinone in dog plasma. Acetonitrile-mediated precipitation was applied for sample pretreatment. Chromatographic separation was achieved on a Waters ACQUITY HSS T3 (100 × 2.1 mm, i. d., 1.8 μm) column with gradient elution using water containing 0.1% formic acid and acetonitrile as mobile phase. Quantitation was performed using an electrospray ionization source in negative multiple reaction monitoring mode. The linearity of this method was over the concentration range 0.1-500 ng/mL with the lowest limit of quantification (LLOQ) of 0.1 ng/mL. The intra- and inter-day precision was less than 10.51% and the accuracy ranged from 94.85% to 97.72%, respectively. The extraction recovery of kurarinone in dog plasma was more than 82.37% and no significant matrix effect was observed. The analyte was stable under tested storage conditions. The validated method was further successfully applied to a preclinical pharmacokinetic study of kurarinone in dog after a single intravenous (2 mg/kg) and oral (20 mg/kg) administration. The results revealed that kurarinone was rapidly absorbed into plasma with good bioavailability (38.19%) and low clearance.

Phytochemistry and biological properties of isoprenoid flavonoids from Sophora flavescens Ait

Sophora flavescens Ait (Ku-Shen in Chinese) is a popular traditional Chinese herbal medicine in China for a long history. It shows significant pharmacological activities in the treatment of dysentery, eczema, fever, jaundice, vulvar swelling, gastrointestinal hemorrhage and inflammatory disorders. Alkaloids and flavonoids have been identified as virtual components, especially isoprenoid flavanonols are a class of characteristic compounds for S. flavescens. However, few studies have focused on isoprenoid flavonoids analyses and no comprehensive review has yet been published. In the current review, we systematically summarized the isoprenoid flavonoids, a total of 55 compounds have been isolated from S. flavescens, particularly an isoprenyl and a lavandulyl group in backbone structures. Further pharmacological activities, qualitative and quantitative chemical analyses research will contribute to the development of natural isoprenoid flavonoid products in S. flavescens.

Antitumor effect of kurarinone and underlying mechanism in small cell lung carcinoma cells

Background

Kurarinone, a prenylated flavonone isolated from the roots of Sophora flavescens, is known to be cytotoxic against many human cancer cells but not human small cell lung carcinoma (SCLC) yet. Also, the exact molecular mechanism of kurarinone for induction cytotoxicity remains unknown.

Material and methods

We investigated the effects of kurarinone on cell proliferation, apoptosis, and migration in H1688 SCLC cells. Cell viability was determined by the MTT assay. Apoptotic indices such as cell cycle, mitochondrial membrane potential, cytochrome c release, caspase activity, and death receptors were evaluated by flow cytometry. Transwell migration and invasion assays were also included.

Results

Our results indicated that kurarinone significantly decreased H1688 cell viability and induced the accumulation of sub-G1 fractions by activating caspase-3, -9, and PARP cleavage accompanied by the elevated release of cytochrome c and mitochondrial dysfunction in H1688 cells. Additionally, kurarinone promoted Fas and TRAIL receptor-1 and -2 expression via the caspase-8/Bid pathway, suggesting that kurarinone triggered apoptosis via the mitochondria-mediated and receptor-mediated apoptotic pathways. We also observed that kurarinone repressed migration and invasion capabilities of SCLC cells by suppressing the expression of epithelial-mesenchymal transition-related proteins and matrix metalloproteinases.

Conclusion

Our findings provided evidence that kurarinone can induce apoptosis in SCLC cells via multiple mechanisms and delayed the cell migration and invasion of SCLC cells.

The flavonoid kurarinone inhibits clinical progression of EAE through inhibiting Th1 and Th17 cell differentiation and proliferation

INTRODUCTION

The flavonoid kurarinone suppresses CD4+ T-cell-mediated chronic inflammatory dermatitis. However, kurarinone's effects upon autoimmune central nervous system (CNS) disease remain unknown. We investigated the potential therapeutic effects and molecular mechanism(s) of kurarinone in an experimental autoimmune encephalomyelitis (EAE) murine model of multiple sclerosis (MS).

MATERIALS AND METHODS

Myelin oligodendrocyte glycoprotein (MOG_35-55) peptide-induced EAE was constructed in wild-type mice. Effects of kurarinone (100 mg/kg/day) upon clinical scores were assessed based on physical traits and signs. Spinal cord sections were extracted to assess inflammation, demyelination, and mRNA expression of key pro-inflammatory cytokines and chemokines. CNS-infiltrating mononuclear cells (MNCs) and splenocytes were harvested; flow cytometry was then applied to determine CD4+ and CD8+ T-cell percentages as well as Th1/Th2/Th17 subset percentages. Purified naïve CD4+ T-cells underwent in vitro T-cell polarization and proliferation to assess kurarinone's effects.

RESULTS

Prophylactic and treatment regimens of kurarinone significantly improved clinical scores in the MOG_35-55 peptide-induced EAE model (P < 0.05). Kurarinone significantly lowered CNS inflammation and demyelination (61% and 83% decreases, respectively; P < 0.05), significantly decreased MNC infiltration into CNS tissue (42% decrease; P < 0.05), and significantly inhibited levels of several pro-inflammatory cytokines and chemokines (P < 0.05). Kurarinone significantly lowered CD4+ and CD8+ CNS T-cell counts (51% and 80% decreases, respectively; P < 0.05) and significantly reduced CNS Th1 and Th17 cell percentages (24% and 44% decreases, respectively; P < 0.05). Kurarinone significantly inhibited in vitro Th1, Th2, and Th17 cell differentiation and proliferation (P < 0.05).

CONCLUSIONS

Kurarinone significantly inhibits the clinical progression of EAE through the inhibition of Th1 and Th17 cell differentiation and proliferation. Kurarinone may show promise as an immunomodulatory therapeutic agent in treating MS.

Structural Aspects of Antioxidant and Genotoxic Activities of Two Flavonoids Obtained from Ethanolic Extract of Combretum leprosum

Combretum leprosum Mart., a member of the Combretaceae family, is a traditionally used Brazilian medicinal plant, although no evidence in the literature substantiates its antioxidant action and the safety of its use. We evaluated the antioxidant properties of the ethanolic extract (EE) from flowers of C. leprosum and its isolated products 5,3′-dihydroxy-3,7,4′-trimethoxyflavone (FCL2) and 5,3′,4′-trihydroxy-3,7-dimethoxyflavone (FCL5) in Saccharomyces cerevisiae strains proficient and deficient in antioxidant defenses. Their mutagenic activity was also assayed in S. cerevisiae, whereas cytotoxic and genotoxic properties were evaluated by MTT and Comet Assays, respectively, in V79 cells. We show that the EE, FCL2, and FCL5 have a significant protective effect against H₂O₂. FCL2 showed a better antioxidant action, which can be related to the activation of the 3′-OH in the presence of a methoxyl group at 4′ position in the B-ring of the molecule, while flavonoids did not induce mutagenesis in yeast, and the EE was mutagenic at high concentrations. The toxicity of these compounds in V79 cells increases from FCL2 = FCL5 < EE; although not cytotoxic, FCL5 induced an increase in DNA damage. The antioxidant effect, along with the lower toxicity and the absence of genotoxicity, suggests that FCL2 could be suitable for pharmacological use.

Herbal Extract Incorporated Nanofiber Fabricated by an Electrospinning Technique and its Application to Antimicrobial Air Filtration

Recently, with the increased attention to indoor air quality, antimicrobial air filtration techniques have been studied widely to inactivate hazardous airborne microorganisms effectively. In this study, we demonstrate herbal extract incorporated (HEI) nanofibers synthesized by an electrospinning technique and their application to antimicrobial air filtration. As an antimicrobial herbal material, an ethanolic extract of Sophora flavescens, which exhibits great antibacterial activity against pathogens, was mixed with the polymer solution for the electrospinning process. We measured various characteristics of the synthesized HEI nanofibers, such as fiber morphology, fiber size distribution, and thermal stability. For application of the electrospun HEI nanofibers, we made highly effective air filters with 99.99% filtration efficiency and 99.98% antimicrobial activity against Staphylococcus epidermidis. The pressure drop across the HEI nanofiber air filter was 4.75 mmH2O at a face air velocity of 1.79 cm/s. These results will facilitate the implementation of electrospun HEI nanofiber techniques to control air quality and protect against hazardous airborne microorganisms.

Metabolism of kurarinone by human liver microsomes and its effect on cytotoxicity

CONTEXT

Kurarinone, the most abundant prenylated flavonoid in Sophora flavescens Aiton (Leguminosae), is a promising antitumor therapeutic. However, it shows significant hepatotoxicity. Furthermore, how kurarinone is metabolized in humans remains unclear.

OBJECTIVE

The objective of this study is to investigate kurarinone metabolism in human liver microsomes (HLMs) and the role of metabolism in kurarinone-induced cytotoxicity.

MATERIALS AND METHODS

The UDP-glucuronosyltransferase isoforms (UGTs) involved in kurarinone glucuronidation were identified using chemical inhibitors (100-1000 µM phenylbutazone; 10-100 µM β-estradiol; 10-100 µM 1-naphthol; 10-500 µM propofol; and 100-1000 µM fluconazole) and recombinant human UGTs. Kurarinone (2-500 µM) was incubated with HLMs and UGTs (0.5 mg/mL) for 15 min to determine enzyme kinetic parameters. The IC50 value of kurarinone (10-200 µM) was evaluated in a HLMs/3T3 cell co-culture system.

RESULTS

Kurarinone is extensively converted to two glucuronides (M3 and M4) in HLMs. M3 formation was catalyzed by multiple UGT1As, with UGT1A3 showing the highest intrinsic clearance (120.60 mL/min/mg). M4 formation was catalyzed by UGT1A1, UGT2B4, and UGT2B7. UGT1A1 showed the highest intrinsic clearance (60.61 mL/min/mg). The kinetic profiles of the five main UGTs and HLMs fit substrate inhibition kinetics, with Km values ranging from 5.20 to 46.52 µM, Vmax values ranging from 0.20 to 3.06 µmol/min/mg, and Ksi values ranging from 25.58 to 230.30 µM. The kurarinone IC50 value was 93 μM in the control group, 102 μM in HLMs with NADPH, and 160 μM in HLMs with UDPGA.

DISCUSSION AND CONCLUSION

Kurarinone glucuronidation is a detoxification pathway. This information may help to elucidate the risk factors regulating kurarinone toxicity.

Estrogenic activity of a hydro-alcoholic extract of Bambusa arundinaceae leaves on female wistar rats

To study the estrogenic activity of the hydro-alcoholic extract of Bambusa arundinaceae leaves (HEBA) in female Wistar rats. The dried powdered leaves were extracted with hydroalcoholic mixture (60%), and the resultant extract was subjected for phytochemical analyses to identify different phytoconstituents. HEBA were administered to ovariectomized rats for 7 days at three different doses (viz., 200, 300, 400 mg/kg body weight, p.o.) and their estrogenic activity were compared with each of daily treatment with 0.2 mg/kg body weight, i.p. conjugated equine estrogen as a positive control or olive oil as a negative control. Estrogenic activity was evaluated by doing uterotropic assay, vaginal cytology and measurement of vaginal opening in female Wistar rats. Oral administration of HEBA in ovariectomized immature and mature female Wistar rats in a dose of 400 mg/kg b.w. resulted in significant increase in the uterine wet weight (in mg) (224.82 ± 7.01) and (912.25 ± 27.22) when compared with ovariectomized control rats (111.52 ± 3.17) and (506.67 ± 21.39). HEBA (400 mg/kg b.w., p.o.) treated rats, showing only cornified epithelial cells which was an indication of the presence of the estrogen and also showed 100% vaginal opening. It was observed that HEBA possess significant estrogenic activity at 400 mg/kg b.w., p.o. which was evident by uterotropic assay, measurement of vaginal opening, and histopathological changes.

Development and evaluation of antimicrobial activated carbon fiber filters using Sophora flavescens nanoparticles

Activated carbon fiber (ACF) filters have a wide range of applications, including air purification, dehumidification, and water purification, due to their large specific surface area, high adsorption capacity and rate, and specific surface reactivity. However, when airborne microorganisms such as bacteria and fungi adhere to the carbon substrate, ACF filters can become a source of microbial contamination, and their filter efficacy declines. Antimicrobial treatments are a promising means of preventing ACF bio-contamination. In this study, we demonstrate the use of Sophora flavescens in antimicrobial nanoparticles coated onto ACF filters. The particles were prepared using an aerosol process consisting of nebulization-thermal drying and particle deposition. The extract from S. flavescens is an effective, natural antimicrobial agent that exhibits antibacterial activity against various pathogens. The efficiency of Staphylococcus epidermidis inactivation increased with the concentration of S. flavescens nanoparticles in the ACF filter coating. The gas adsorption efficiency of the coated antimicrobial ACF filters was also evaluated using toluene. The toluene-removal capacity of the ACF filters remained unchanged while the antimicrobial activity was over 90% for some nanoparticle concentrations. Our results provide a scientific basis for controlling both bioaerosol and gaseous pollutants using antimicrobial ACF filters coated with S. flavescens nanoparticles.

Estrogenic and chemopreventive activities of xanthones and flavones of Syngonanthus (Eriocaulaceae)

The possible benefits of some bioactive flavones and xanthones present in plants of the genus Syngonanthus prompted us to screen them for estrogenic activity. However, scientific research has shown that such substances may have undesirable properties, such as mutagenicity, carcinogenicity and toxicity, which restrict their use as therapeutic agents. Hence, the aim of this study was to assess the estrogenicity and mutagenic and antimutagenic properties. We used recombinant yeast assay (RYA), with the strain BY4741 of Saccharomyces cerevisiae, and Ames test, with strains TA100, TA98, TA97a and TA102 of Salmonella typhimirium, to evaluate estrogenicity, mutagenicity and antimutagenicity of methanolic extracts of Syngonanthus dealbatus (S.d.), Syngonanthus macrolepsis (S.m.), Syngonanthus nitens (S.n.) and Syngonanthus suberosus (S.s.), and of 9 compounds isolated from them (1=luteolin, 2=mix of A-1,3,6-trihydroxy-2-methoxyxanthone and B-1,3,6-trihydroxy-2,5-dimethoxyxanthone, 3=1,5,7-trihydroxy-3,6-dimethoxyxanthone, 4=1,3,6,8-tetrahydroxy-2,5-dimethoxyxanthone, 5=1,3,6,8-tetrahydroxy-5-methoxyxanthone, 6=7-methoxyluteolin-8-C-β-glucopyranoside, 7=7-methoxyluteolin-6-C-β-glucopyranoside, 8=7,3'-dimethoxyluteolin-6-C-β-glucopyranoside and 9=6-hydroxyluteolin). The results indicated the estrogenic potential of the S. nitens methanol extract and four of its isolated xanthones, which exhibited, respectively, 14.74±1.63 nM; 19.54±6.61; 7.20±0.37; 6.71±1.02 e 10.01±4.26 nM of estradiol-equivalents (EEQ). None of the extracts or isolated compounds showed mutagenicity in any of the test strains and all of them showed antimutagenic potential, in particular preventing mutations caused by aflatoxin B1 (AFB1) and benzo[a]pyrene (B[a]P). The results show that the xanthones, only isolated from the methanol extract of S. nitens capitula, probably were the responsible for its estrogenic activity and could be useful as phytoestrogens, providing a new opportunity to develop hormonal agents. In addition, flavones and xanthones could also be used as a new antimutagenic agent. Since, the mutagens are involved in the initiation and promotion of several human diseases, including cancer, the significance of novel bioactive phytocompounds in counteracting these pro-mutagenic and carcinogenic effects is now gaining credence.

Evaluation of estrogenic potential of flavonoids using a recombinant yeast strain and MCF7/BUS cell proliferation assay

Phytoestrogens are of interest because of their reported beneficial effects on many human maladies including cancer, neurodegeneration, cardiovascular disease and diabetes. Furthermore, there is a search for compounds with estrogenic activity that can replace estrogen in hormone replacement therapy during menopause, without the undesirable effects of estrogen, such as the elevation of breast cancer occurrence. Thus, the principal objective of this study was to assess the estrogenic activity of flavonoids with different hydroxylation patterns: quercetin, kaempferol, luteolin, fisetin, chrysin, galangin, flavone, 3-hydroxyflavone, 5-hydroxyflavone and 7-hydroxyflavone via two different in vitro assays, the recombinant yeast assay (RYA) and the MCF-7 proliferation assay (E-screen), since the most potent phytoestrogens are members of the flavonoid family. In these assays, kaempferol was the only compound that showed ERα-dependent transcriptional activation activity by RYA, showing 6.74±1.7 nM EEQ, besides acting as a full agonist for the stimulation of proliferation of MCF-7/BUS cells. The other compounds did not show detectable levels of interaction with ER under the conditions used in the RYA. However, in the E-screen assay, compounds such as galangin, luteolin and fisetin also stimulated the proliferation of MCF-7/BUS cells, acting as partial agonists. In the evaluation of antiestrogenicity, the compounds quercetin, chrysin and 3-hydroxyflavone significantly inhibited the cell proliferation induced by 17-β-estradiol in the E-screen assay, indicating that these compounds may act as estrogen receptor antagonists. Overall, it became clear in the assay results that the estrogenic activity of flavonoids was affected by small structural differences such as the number of hydroxyl groups, especially those on the B ring of the flavonoid.

Kurarinone promotes TRAIL-induced apoptosis by inhibiting NF-κB-dependent cFLIP expression in HeLa cells

This study was designed to investigate the effects of the prenylated flavonoid kurarinone on TNF-related apoptosis inducing ligand (TRAIL)-induced apoptosis and its underlying mechanism. A low dose of kurarinone had no significant effect on apoptosis, but this compound markedly promoted tumor cell death through elevation of Bid cleavage, cytochrome c release and caspase activation in HeLa cells treated with TRAIL. Caspase inhibitors inhibited kurarinone-mediated cell death, which indicates that the cytotoxic effect of this compound is mediated by caspase-dependent apoptosis. The cytotoxic effect of kurarinone was not associated with expression levels of Bcl-2 and IAP family proteins, such as Bcl-2, Bcl-x_L, Bid, Bad, Bax, XIAP, cIAP-1 and cIAP-2. In addition, this compound did not regulate the death-inducing receptors DR4 and DR5. On the other hand, kurarinone significantly inhibited TRAIL-induced IKK activation, IκB degradation and nuclear translocation of NF-κB, as well as effectively suppressed cellular FLICE-inhibitory protein long form (cFLIP_L) expression. The synergistic effects of kurarinone on TRAIL-induced apoptosis were mimicked when kurarinone was replaced by the NF-κB inhibitor withaferin A or following siRNA-mediated knockdown of cFLIP_L. Moreover, cFLIP overexpression effectively antagonized kurarinone-mediated TRAIL sensitization. These data suggest that kurarinone sensitizes TRAIL-induced tumor cell apoptosis via suppression of NF-κB-dependent cFLIP expression, indicating that this compound can be used as an anti-tumor agent in combination with TRAIL.

Antimicrobial durability of air filters coated with airborne Sophora flavescens nanoparticles

Airborne biological particles containing viruses, bacteria, and/or fungi can be toxic and cause infections and allergy symptoms. Recently, natural materials such as tea tree oil and Sophora flavescens have shown promising antimicrobial activity when applied as air filter media. Although many of these studies demonstrated excellent antimicrobial efficacy, only a few of them considered external environmental effects such as the surrounding humidity, temperature, and natural degradation of chemicals, all of which can affect the antimicrobial performance of these natural materials. In this study, we investigated the antimicrobial durability of air filters containing airborne nanoparticles from S. flavescens for 5 months. Antimicrobial tests and quantitative chemical analyses were performed every 30 days. Morphological changes in the nanoparticles were also evaluated by scanning electron microscopy. The major antimicrobial compounds remained stable and active for ~90 days at room temperature. After about 90 days, the quantities of major antimicrobial compounds decreased noticeably with a consequent decrease in antimicrobial activity. These results are promising for the implementation of new technologies using natural antimicrobial products and provide useful information regarding the average life expectancy of antimicrobial filters using nanoparticles of S. flavescens.

Kurarinone regulates immune responses through regulation of the JAK/STAT and TCR-mediated signaling pathways

Sophora flavescens is a medicinal herb that contains flavonoids and quinolizidine alkaloids and has a wide range of biological activities due to its anti-inflammatory, anti-bacterial and anti-cancer properties. We isolated a series of flavonoids from the roots of Sophora flavescens and examined their ability to inhibit immune responses. Among the flavonoids, kurarinone exhibited the strongest inhibitory effect on immune responses. Kurarinone suppressed the differentiation of CD4(+) T cells by inhibiting the expression and production of T-cell lineage-specific master regulators and cytokines. Our results also demonstrated that kurarinone directly suppressed the cytokine-induced Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling and T-cell receptor (TCR) pathways. In two established animal models of chronic inflammatory skin disease, one in which psoriasis-like skin disease was induced by an interleukin 23 (IL-23) injection into mouse ears and another in which 2,4,6-trinitrochlorobenzene (TNCB) application on the abdomens of mice was used to induce contact dermatitis, kurarinone repressed disease development by inhibiting the expression of pro-inflammatory mediators, including cytokines, chemokines and enzyme in murine ear skin. This study provides new evidence that kurarinone may ameliorate chronic inflammatory skin diseases through the suppression of pathogenic CD4(+) T-cell differentiation and the overall immune response.

Microbial biotransformation of kurarinone by Cunninghamella echinulata AS 3.3400

In this paper, microbial transformation of kurarinone (1) by Cunninghamella echinulata AS 3.3400 was investigated and four transformed products were isolated and identified as 6″-hydroxykurarinone (2), 4″,5″,8″-trihydroxynorkurarinone (3), norkurarinone (4), and kurarinone-7-O-β-glucoside (5), respectively. Among them, 3 and 5 are new compounds, and the rare glycosylation in microbial transformation was observed. In addition, the cytotoxicities of transformed products (2-5) were also investigated.

Involvement of Transient Receptor Potential Melastatin 7 Channels in Sophorae Radix-induced Apoptosis in Cancer Cells: Sophorae Radix and TRPM7

Sophorae Radix (SR) plays a role in a number of physiologic and pharmacologic functions in many organs.

OBJECTIVE

The aim of this study was to clarify the potential role for transient receptor potential melastatin 7 (TRPM7) channels in SR-inhibited growth and survival of AGS and MCF-7 cells, the most common human gastric and breast adenocarcinoma cell lines.

METHODS

The AGS and the MCF-7 cells were treated with varying concentrations of SR. Analyses of the caspase-3 and - 9 activity, the mitochondrial depolarization and the poly (ADPribose) polymerase (PARP) cleavage were conducted to determine if AGS and MCF-7 cell death occured by apoptosis. TRPM7 channel blockers (Gd(3+) or 2-APB) and small interfering RNA (siRNA) were used in this study to confirm the role of TRPM7 channels. Furthermore, TRPM7 channels were overexpressed in human embryonic kidney (HEK) 293 cells to identify the role of TRPM7 channels in AGS and MCF-7 cell growth and survival.

RESULTS

The addition of SR to a culture medium inhibited AGS and MCF-7 cell growth and survival. Experimental results showed that the caspase-3 and -9 activity, the mitochondrial depolarization, and the degree of PARP cleavage was increased. TRPM7 channel blockade, either by Gd(3+) or 2-APB or by suppressing TRPM7 expression with small interfering RNA, blocked the SR-induced inhibition of cell growth and survival. Furthermore, TRPM7 channel overexpression in HEK 293 cells exacerbated SR-induced cell death.

CONCLUSIONS

These findings indicate that SR inhibits the growth and survival of gastric and breast cancer cells due to a blockade of the TRPM7 channel activity. Therefore, TRPM7 channels may play an important role in the survival of patients with gastric and breast cancer.

Antibacterial activity of sophoraflavanone G isolated from the roots of Sophora flavescens against methicillin-resistant Staphylococcus aureus

In this study, sophoraflavanone G obtained from Sophora flavescens was evaluated against 10 clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA), either alone or in combination with ampicillin or oxacillin, via checkerboard assay. At the end point of an optically clear well, the minimum inhibitory concentrations (MICs) ranged from 0.5 to 8 microg/ml for sophoraflavanone G, from 64 to 1024 microg/ml for ampicillin, and from 256 to 1024 microg/ml for oxacillin. The combination of sophoraflavanone G and ampicillin or oxacillin yielded a fractional inhibitory concentration index ranging from 0.188 to 0.375, thereby indicating a principally synergistic effect. The synergistic interaction was verified by time-kill studies using sophoraflavanone G and/or antibiotics. Thirty minutes of treatment with sophoraflavanone G with ampicillin or oxacillin resulted in an increase in the rate of killing in units of CFU/ml to a greater degree than was observed with Sophoraflavanone G alone. These findings indicated that the application of the tested sophoraflavanone G alone or in combination with antibiotics might prove useful in the control and treatment of MRSA infections.

Two New Lavandulyl Flavonoids from Sophora flavescens

Two novel lavandulyl flavonoids, (2 S)-7-methoxyl-4″, 5″ -dihydroxynorkurarinone (1) and (2 S)-6″ -hydroxynorkurarinone-7- O-β-D-galactoside (2), were isolated from the rhizome of Sophora flavescens. Their structures were elucidated by spectral methods, including 2D NMR spectroscopy. Both compounds showed cytotoxic activity against Hela cells, with 2 being more active than 1.

Inhibitory activities of prenylated flavonoids from Sophora flavescens against aldose reductase and generation of advanced glycation endproducts

Important targets for the prevention and treatment of diabetic complications include aldose reductase (AR) inhibitors (ARIs) and inhibitors of advanced glycation endproduct (AGE) formation. Here we evaluate the inhibitory activities of prenylated flavonoids isolated from Sophora flavescens, a traditional herbal medicine, on rat lens AR (RLAR), human recombinant AR (HRAR) and AGE formation. Among the tested compounds, two prenylated chalcones — desmethylanhydroicaritin (1) and 8-lavandulylkaempferol (2) — along with five prenylated flavanones — kurarinol (8), kurarinone (9), (2S)-2′-methoxykurarinone (10), (2S)-3β,7,4′-trihydroxy-5-methoxy-8-(γ,γ-dimethylally)-flavanone (11), and kushenol E (13) were potent inhibitors of RLAR, with IC50 values of 0.95, 3.80, 2.13, 2.99, 3.77, 3.63 and 7.74 μM, respectively, compared with quercetin (IC50 7.73 μM). In the HRAR assay, most of the prenylated flavonoids tested showed marked inhibitory activity compared with quercetin (IC50 2.54 μM). In particular, all tested prenylated flavonols, such as desmethylanhydroicaritin (1, IC50 0.45 μM), 8-lavandulylkaempferol (2, IC50 0.79 μM) and kushenol C (3, IC50 0.85 μM), as well as a prenylated chalcone, kuraridin (5, IC50 0.27 μM), and a prenylated flavanone, (2S)-7,4′-dihydroxy-5-methoxy-8-(γ,γ-dimethylally)-flavanone (12, IC50 0.37 μM), showed significant inhibitory activities compared with the potent AR inhibitor epalrestat (IC50 0.28 μM). Interestingly, prenylated flavonoids 1 (IC50 104.3 μgmL−1), 2 (IC50 132.1 μgmL−1), 3 (IC50 84.6 μgmL−1) and 11 (IC50 261.0 μgmL−1), which harbour a 3-hydroxyl group, also possessed good inhibitory activity toward AGE formation compared with the positive control aminoguanidine (IC50 115.7 μgmL−1). Thus, S. flavescens and its prenylated flavonoids inhibit the processes that underlie diabetic complications and related diseases and may therefore have therapeutic benefit.

Differential inductive profiles of hepatic cytochrome P450s by the extracts of Sophora flavescens in male and female C57BL/6JNarl mice

AIM OF THE STUDY

Sophora flavescens has been used as an antipyretic and analgesic agent. To assess the possible herb-drug interaction, effects of S. flavescens extracts on hepatic cytochrome P450 (P450, CYP) enzymes were studied.

MATERIALS AND METHODS

Effects of the extracts prepared by three different pharmaceutical companies on P450 enzymes were investigated in male and female C57BL/6JNarl mice.

RESULTS

In male mice, extract 1 caused a dose- and time-dependent increase of 7-ethoxyresorufin O-deethylation (EROD) activity. Three-day treatment with 3g/kg extracts 1-3 elevated EROD, 7-pentoxyresorufin O-dealkylation (PROD), coumarin hydroxylation, and nifedipine oxidation (NFO) activities. In female mice, extracts 1 and 2 increased EROD and PROD activities without affecting coumarin hydroxylation and NFO activities. However, extract 3, which lacked prenylated flavonoids, caused an induction profile in females the same as in males. Treatment with extract 3 fortified with prenylated flavonoids restored the gender difference. An alkaloid, oxymatrine was present in all extracts and increased EROD and PROD activities. At a human equivalent dose (0.18 g/(kg day)), all extracts increased EROD activity.

CONCLUSIONS

These results revealed that Cyp1a had a lower induction response threshold. Oxymatrine contributed at least partly to the P450 induction by S. flavescens. At a higher dose, Cyp2a, Cyp2b, and Cyp3a could be induced and the male-specific induction of Cyp2a and Cyp3a was associated with the presence of prenylated flavonoids.

Prenylation of aromatic compounds, a key diversification of plant secondary metabolites

Prenylation plays a major role in the diversification of aromatic natural products, such as phenylpropanoids, flavonoids, and coumarins. This biosynthetic reaction represents the crucial coupling process of the shikimate or polyketide pathway providing an aromatic moiety and the isoprenoid pathway derived from the mevalonate or methyl erythritol phosphate (MEP) pathway, which provides the prenyl (isoprenoid) chain. In particular, prenylation contributes strongly to the diversification of flavonoids, due to differences in the prenylation position on the aromatic rings, various lengths of prenyl chain, and further modifications of the prenyl moiety, e.g., cyclization and hydroxylation, resulting in the occurrence of ca. 1000 prenylated flavonoids in plants. Many prenylated flavonoids have been identified as active components in medicinal plants with biological activities, such as anti-cancer, anti-androgen, anti-leishmania, and anti-nitric oxide production. Due to their beneficial effects on human health, prenylated flavonoids are of particular interest as lead compounds for producing drugs and functional foods. However, the gene coding for prenyltransferases that catalyze the key step of flavonoid prenylation have remained unidentified for more than three decades, because of the membrane-bound nature of these enzymes. Recently, we have succeeded in identifying the first prenyltransferase gene SfN8DT-1 from Sophora flavescens, which is responsible for the prenylation of the flavonoid naringenin at the 8-position, and is specific for flavanones and dimethylallyl diphosphate (DMAPP) as substrates. Phylogenetic analysis showed that SfN8DT-1 has the same evolutionary origin as prenyltransferases for vitamin E and plastoquinone. A prenyltransferase GmG4DT from soybean, which is involved in the formation of glyceollin, was also identified recently. This enzyme was specific for pterocarpan as its aromatic substrate, and (-)-glycinol was the native substrate yielding the direct precursor of glyceollin I. These enzymes are localized to plastids and the prenyl chain is derived from the MEP pathway. Further relevant genes involved in the prenylation of other types of polyphenol are expected to be cloned by utilizing the sequence information provided by the above studies.

Selective extraction of Cyclopia for enhanced in vitro phytoestrogenicity and benchmarking against commercial phytoestrogen extracts

Previous work established the phytoestrogenicity of "unfermented"Cyclopia (honeybush) extracts. The current study investigated the phytoestrogenicity of four Cyclopia harvestings (M6-9) for preparation of extracts with enhanced phytoestrogenicity for benchmarking against commercial preparations. Two extracts, from M6 (C. subternata) and M7 (C. genistoides), were identified as most phytoestrogenic using estrogen receptor binding, an estrogen receptor response element containing promoter reporter assay, alkaline phosphatase activity, and E-screen. M6 and M7 were sequentially and non-sequentially extracted with five solvents of differing polarities. Additionally, two extracts were prepared in the traditional way of preparing a cup of honeybush tea. The resultant 22 extracts were evaluated for estrogenicity. Select extracts were analysed by high-pressure liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LC-MS). The sequentially extracted M6 methanol extract (SM6Met) had the highest potency and the sequentially extracted M6 ethyl acetate extract (SM6EAc) had the highest efficacy of all the extracts. The HPLC results suggested enrichment of luteolin in SM6EAc and enrichment of an unidentified polyphenol in SM6Met. Benchmarking against four commercial phytoestrogenic preparations suggest that in terms of the assays used, Cyclopia extracts have comparable potency and efficacy to the commercial extracts and thus have potential as marketable phytoestrogenic nutraceuticals.

Re-evaluation of the antioxidant prenylated flavonoids from the roots of Sophora flavescens

The objective of this research was to re-evaluate the antioxidant effects of the prenylated flavonoids from Sophora flavescens via in vitro 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), peroxynitrite (ONOO(-)), and total reactive oxygen species (ROS) assays. In addition, a further examination of kuraridinol, kurarinol, and kurarinone, also isolated from S. flavescens, was carried out by the inhibition of tert-butylhydroperoxide (t-BHP)-induced intracellular ROS generation and t-BHP-induced activation of nuclear factor-kappaB (NF-kappaB). Upon re-examination of the ethyl acetate (EtOAc) soluble fraction of S. flavescens, two major prenylated chalcones, including kuraridin and kuraridinol, along with a minor prenylated flavonol, kushenol C, were isolated as good DPPH scavengers. This was in contrast to the prenylated flavanones, sophoraflavanone G and kurarinone, which were isolated from the methylene chloride (CH(2)Cl(2)) fraction of the same source. Five flavanones consisting of kushenol E, leachianone G, kurarinol, sophoraflavanone G, and kurarinone exhibited significant antioxidant potentials in the ABTS, ONOO(-), and total ROS assays; however, the prenylated chalcones and prenylated flavonol showed more potent scavenging/inhibitory activities than the prenylated flavanones. Therefore, the prenylated chalcones and prenylated flavonol, rather than the prenylated flavanones, may make important contributions toward the marked antioxidant capacities of S. flavescens. Furthermore, kuraridinol, kurarinol, and kurarinone showed significant inhibitory activities against intracellular ROS levels as well as NF-kappaB activation by t-BHP. Overall, the results indicate that S. flavescens and its prenylated flavonoids may possess good anti-inflammatory activity, which is implicated in their significant antioxidant activity.

Cloning and characterization of naringenin 8-prenyltransferase, a flavonoid-specific prenyltransferase of Sophora flavescens

Prenylated flavonoids are natural compounds that often represent the active components in various medicinal plants and exhibit beneficial effects on human health. Prenylated flavonoids are hybrid products composed of a flavonoid core mainly attached to either 5-carbon (dimethylallyl) or 10-carbon (geranyl) prenyl groups derived from isoprenoid (terpenoid) metabolism, and the prenyl groups are crucial for their biological activity. Prenylation reactions in vivo are crucial coupling processes of two major metabolic pathways, the shikimate-acetate and isoprenoid pathways, in which these reactions are also known as a rate-limiting step. However, none of the genes responsible for the prenylation of flavonoids has been identified despite more than 30 years of research in this field. We have isolated a prenyltransferase gene from Sophora flavescens, SfN8DT-1, responsible for the prenylation of the flavonoid naringenin at the 8-position, which is specific for flavanones and dimethylallyl diphosphate as substrates. Phylogenetic analysis shows that SfN8DT-1 has the same evolutionary origin as prenyltransferases for vitamin E and plastoquinone. The gene expression of SfN8DT-1 is strictly limited to the root bark where prenylated flavonoids are solely accumulated in planta. The ectopic expression of SfN8DT-1 in Arabidopsis thaliana resulted in the formation of prenylated apigenin, quercetin, and kaempferol, as well as 8-prenylnaringenin. SfN8DT-1 represents the first flavonoid-specific prenyltransferase identified in plants and paves the way for the identification and characterization of further genes responsible for the production of this large and important class of secondary metabolites.

Proteomic characterization of Sophoraflavone J-induced apoptosis in HepG2 cells

Chinese herb Radix sophorae is widely applied as an anticarcinogenic/antimetastatic agent against liver cancers. In the current study, Sophoraflavone J, a flavonoid constituent enriched in the root of Radix sophorae, induced apoptosis in human hepatoma HepG2 cells via the intrinsic mitochondrial death pathway. The molecular mechanism of the cytotoxic effect was further investigated by a comparative proteomic approach. Differentially expressed proteins identified included membrane proteins/antigens, structural proteins, transcriptional factors, glycolytic enzymes, heat-shock chaperon proteins, ROS-related proteins and proteosomes, etc. These findings were further validated by Western blot analysis and real-time PCR. Preliminary experiments to characterize the roles of these proteins were conducted. Our data suggested that Sophoraflavone J treatment triggered nutrient depletion and generation of ROS in cells, which subsequently led to mitochondrial dysfunction and apoptosis.

Leachianone A as a potential anti-cancer drug by induction of apoptosis in human hepatoma HepG2 cells

The Chinese herbal medicine Radix Sophorae is widely applied as an anti-carcinogenic/ anti-metastatic agent against liver cancer. In this study, Leachianone A, isolated from Radix Sophorae, possessed a profound cytotoxic activity against human hepatoma cell line HepG2 in vitro, with an IC(50) value of 3.4microg/ml post-48-h treatment. Its action mechanism via induction of apoptosis involved both extrinsic and intrinsic pathways. Its anti-tumor effect was further demonstrated in vivo by 17-54% reduction of tumor size in HepG2-bearing nude mice, in which no toxicity to the heart and liver tissues was observed. In conclusion, this is the first report describing the isolation of Leachianone A from Radix Sophorae and the molecular mechanism of its anti-proliferative effect on HepG2 cells.