A novel anticancer agent, icaritin, induced cell growth inhibition, G1 arrest and mitochondrial transmembrane potential drop in human prostate carcinoma PC-3 cells

Estrogen receptor-α36 is involved in icaritin induced growth inhibition of triple-negative breast cancer cells

A sub-class of ER-negative breast cancer that is negative for ER, PR and HER2 expression known as triple-negative breast cancer (TNBC) is highly malignant and lacks effective treatment. Recently, it has been reported that an isoform of estrogen receptor-alpha ER-α36 is expressed and plays a critical role in development of TNBC. ER-α36 forms a positive regulatory loop with epidermal growth factor receptor (EGFR), which promotes malignant growth of TNBC cells. Thus, ER-α36 has been proposed as an important target for development of novel drugs for TNBC. In this study, we evaluated the effects of icaritin, a prenylflavonoid derivant purified from Epimedium Genus, on growth of TNBC cells and examined the possible underlying mechanisms. Our study demonstrated that icartin decreased both ER-α36 and EGFR protein expression, and induced apoptosis in TNBC MDA-MB-231 and MDA-MB-453 cells. We also found that icaritin inhibited ER-α36-mediated MAPK/ERK pathway and cyclin D1 induction by estrogen. Our results thus indicated that icaritin has a potential to be developed into a novel therapeutic agent for human TNBC.

Potential of Icariin Metabolites from Epimedium koreanum Nakai as Antidiabetic Therapeutic Agents

The therapeutic properties of Epimedium koreanum are presumed to be due to the flavonoid component icariin, which has been reported to have broad pharmacological potential and has demonstrated anti-diabetic, anti-Alzheimer’s disease, anti-tumor, and hepatoprotective activities. Considering these therapeutic properties of icariin, its deglycosylated icaritin and glycosylated flavonoids (icaeriside II, epimedin A, epimedin B, and epimedin C) were evaluated for their ability to inhibit protein tyrosine phosphatase 1B (PTP1B) and α-glucosidase. The results show that icaritin and icariside II exhibit potent inhibitory activities, with 50% inhibition concentration (IC₅₀) values of 11.59 ± 1.39 μM and 9.94 ± 0.15 μM against PTP1B and 74.42 ± 0.01 and 106.59 ± 0.44 μM against α-glucosidase, respectively. With the exceptions of icaritin and icariside II, glycosylated flavonoids did not exhibit any inhibitory effects in the two assays. Enzyme kinetics analyses revealed that icaritin and icariside II demonstrated noncompetitive-type inhibition against PTP1B, with inhibition constant (K_i) values of 11.41 and 11.66 μM, respectively. Moreover, molecular docking analysis confirmed that icaritin and icariside II both occupy the same site as allosteric ligand. Thus, the molecular docking simulation results were in close agreement with the experimental data with respect to inhibition activity. In conclusion, deglycosylated metabolites of icariin from E. koreanum might offer therapeutic potential for the treatment of type 2 diabetes mellitus.

Oridonin induces G2/M cell cycle arrest and apoptosis via the PI3K/Akt signaling pathway in hormone-independent prostate cancer cells

Oridonin is an active constituent isolated from the traditional Chinese herb Rabdosia rubescens, which exerts antitumor effects in experimental and clinical settings. However, its antitumor effects and underlying mechanisms on prostate cancer cells have not yet been clearly identified. In the present study, the androgen-independent prostate cancer PC3 and DU145 cell lines were used as models to investigate the effects and possible mechanisms of oridonin on cellular proliferation and apoptosis. Results demonstrated that oridonin inhibited cellular proliferation, and was able to significantly induce G₂/M cell cycle arrest and apoptosis. Detailed signaling pathway analysis by western blotting demonstrated that the expression levels of p53 and p21 were upregulated, whereas the expression of cyclin-dependent kinase 1 was downregulated following oridonin treatment, which led to cell cycle arrest in the G₂/M phase. Oridonin also upregulated the proteolytic cleaved forms of caspase-3, caspase-9 and poly (ADP-ribose) polymerase. Furthermore, the protein expression levels of B-cell lymphoma 2 were decreased and those of Bcl-2-associated X protein were increased following oridonin treatment. In addition, oridonin treatment significantly inhibited the expression of phosphoiniositide-3 kinase (PI3K) p85 subunit and the phosphorylation of Akt. The downstream gene murine double minute 2 was also downregulated, which may contribute to the elevated expression of p53 following oridonin treatment. In conclusion, the results of the present study suggested that oridonin is able to inactivate the PI3K/Akt pathway and activate p53 pathways in prostate cancer cells, resulting in the suppression of proliferation and the induction of caspase-mediated apoptosis.

Arsenic Trioxide and Icariin Show Synergistic Anti-leukemic Activity

Although As2O3 (ATO) has been recommended as the front-line agent for treatment of acute promyelocytic leukemia (APL), particularly for relapsed or refractory APL, it has been associated with profound toxicity. Icariin is a natural compound with activity against a variety of cancers. This study was designed to investigate the effect of Icariin on APL cells and to determine whether Icariin can potentiate the antitumor activity of ATO in APL cells. Cell proliferation and apoptosis were measured using MTT assay and flow cytometry, respectively. The expression of apoptosis and proliferation-related molecules was detected by Western blotting. Reactive oxygen species (ROS) and mitochondrial membrane potential were determined with florescence staining. Icariin inhibited proliferation in a dose-dependent manner and induced apoptosis in both of the tested APL cell lines. Icariin enhanced the in vitro antitumor activity of ATO against APL. The antitumor activity of Icariin and its enhancement of the antitumor activity of ATO correlated with the increase in accumulation of intracellular ROS. Our results showed that Icariin, by increasing intracellular ROS, exhibited antitumor activity and potentiated the antitumor activity of ATO against APL. Therefore, combination treatment with Icariin and ATO might offer a novel therapeutic option for patients with APL, although further studies are needed.

Icaritin Reduces Oral Squamous Cell Carcinoma Progression via the Inhibition of STAT3 Signaling

Icaritin, a traditional Chinese medicine, possesses antitumor activity. The current study aimed to investigate icaritin effect and potential mechanism on oral squamous cell carcinoma (OSCC) development. OSCC cells proliferation, apoptosis, and autophagy were analyzed after incubation with icaritin at different concentrations and incubation times. The expressions of proteins related to proliferation, apoptosis, and autophagy, as well as signal transducer and activator of transcription 3 (STAT3) signal network, were also evaluated by western blot. Furthermore, STAT3 was knocked down by siRNA transfection to determine STAT3 role in OSCC cell proliferation and apoptosis. An oral specific carcinogenesis mouse model was used to explore icaritin effect on OSCC in vivo. Icaritin significantly inhibited OSCC proliferation in vitro and reduced the expression of both the cell-cycle progression proteins cyclin A2 and cyclin D1. Besides, icaritin increased cleaved caspase 3 and cleaved poly-(ADP-ribose) polymerase expression leading to apoptosis, and it activated autophagy. Icaritin significantly inhibited the expression of phospho-STAT3 (p-STAT3) in a dose- and time-dependent manner. In the in vivo experiment, the number of malignant tumors in the icaritin-treated group was significantly lower than the control. Overall, icaritin suppressed proliferation, promoted apoptosis and autophagy, and inhibited STAT3 signaling in OSCC in vitro and in vivo. In conclusion, icaritin might be a potential therapeutic agent against OSCC development.

Icaritin induces mitochondrial apoptosis by up-regulating miR-124 in human oral squamous cell carcinoma cells

AIM OF THE STUDY

The present study is aimed to investigate the apoptosis-inducing effect of icaritin in human oral squamous cell carcinoma (OSCC) cells and the associated mechanisms.

MATERIALS AND METHODS

KB and SCC9 cell lines were used as model cell lines. Effect of icaritin on apoptosis was analyzed by flow cytometry. The effect of icaritin on mitochondrial apoptotic pathway was demonstrated by loss of mitochondrial membrane potential and release of cytocrome C from mitochondria. MiR-124 mimic and miR-124 inhibitor were used to manipulate the expression of miR-124 in OSCC cells. SiRNA targeting Sp1 and DNMT1 as well as Sp1 and DNMT1 overexpressing vector were utilized to confirm their roles in the apoptosis-inducing effect of icaritin in OSCC cells. Activation of relevant signaling pathway by icaritin and effect of icaritin on expression of targeting molecules were determined by western blots or qRT-PCR.

RESULTS

Our results showed that icaritin inhibited tumor cell viability in a dose- and time-dependent manner, and induced cell apoptosis via intrinsic mitochondrial pathway by upregulating miR-124. Moreover, our results showed that the icaritin exerted regulatory effect on miR-124 through suppressing Sp1/DNMT1 signaling.

CONCLUSION

Our data provide the first experimental evidence that icaritin induces mitochondrial apoptosis in OSCC cells by upregulating miR-124 and suggest a new mechanism to explain its anti-tumor effects.

Synergistic Anti-Cancer Effects of Icariin and Temozolomide in Glioblastoma

Glioblastoma is an aggressive malignancy, which is associated with poor prognosis. Temozolomide (TMZ) has been showed to be an effective chemotherapeutic agent for glioblastoma treatment; however, the response rate is not satisfactory. Icariin is a natural compound with anti-cancer activity against a variety of cancers. This study is designed to determine whether icariin could potentiate the antitumor activity of TMZ in glioblastoma. Cell proliferation and apoptosis were measured using MTT assay and flow cytometry, respectively. Expression of apoptosis and proliferation-related molecules was detected by Western blotting while NF-κB activity was detected by ELISA. Icariin dose-dependently inhibited proliferation and induced apoptosis in tested glioblastoma cell lines. Icariin enhanced the anti-tumor activity of TMZ in vitro. The anti-tumor activity of icariin and the enhanced anti-tumor activity of TMZ by icariin correlated with suppression of NF-κB activity. Our results showed that icariin exhibited anti-tumor activity and potentiated the anti-tumor activity of TMZ in glioblastoma, at least in part, by inhibiting NF-κB activity. Although more studies including clinical trials are needed, this study provides insight for using icariin as a chemosensitizing agent in clinic settings.

The Anticancer Properties of Herba Epimedii and Its Main Bioactive Componentsicariin and Icariside II

Cancer is one of the leading causes of deaths worldwide. Compounds derived from traditional Chinese medicines have been an important source of anticancer drugs and adjuvant agents to potentiate the efficacy of chemotherapeutic drugs and improve the side effects of chemotherapy. HerbaEpimedii is one of most popular herbs used in China traditionally for the treatment of multiple diseases, including osteoporosis, sexual dysfunction, hypertension and common inflammatory diseases. Studies show HerbaEpimedii also possesses anticancer activity. Flavonol glycosides icariin and icariside II are the main bioactive components of HerbaEpimedii. They have been found to possess anticancer activities against various human cancer cell lines in vitro and mouse tumor models in vivo via their effects on multiple biological pathways, including cell cycle regulation, apoptosis, angiogenesis, and metastasis, and a variety of signaling pathways including JAK2-STAT3, MAPK-ERK, and PI3k-Akt-mTOR. The review is aimed to provide an overview of the current research results supporting their therapeutic effects and to highlight the molecular targets and action mechanisms.

Three New Isoprenylated Flavonoids from the Root Bark of Morus alba

Phytochemical investigation of the root bark of Morus alba has led to the isolation and identification of three new isoprenylated flavonoids, namely sanggenon U (1), sanggenon V (2), and sanggenon W (3), along with four known isoprenylated flavonoids: euchrenone a₇ (4), sanggenon J (5), kuwanon E (6), and kuwanon S (7). All compounds were isolated by repeated silica gel (SiO₂), octadecyl SiO₂ (ODS), and Sephadex LH-20 open column chromatography. The structure of the compounds were determined based on spectroscopic analyses, including nuclear magnetic resonance (NMR), mass spectrometry (MS), circular dichroism (CD), and infrared (IR). In addition, compounds 1-4 were isolated for the first time from the root bark of M. alba in this study.

Anti-Cancer Properties of the Naturally Occurring Aphrodisiacs: Icariin and Its Derivatives

Epimedium (family Berberidaceae), commonly known as Horny Goat Weed or Yin Yang Huo, is commonly used as a tonic, aphrodisiac, anti-rheumatic and anti-cancer agent in traditional herbal formulations in Asian countries such as China, Japan, and Korea. The major bioactive compounds present within this plant include icariin, icaritin and icariside II. Although it is best known for its aphrodisiac properties, scientific and pharmacological studies suggest it possesses broad therapeutic capabilities, especially for enhancing reproductive function and osteoprotective, neuroprotective, cardioprotective, anti-inflammatory and immunoprotective effects. In recent years, there has been great interest in scientific investigation of the purported anti-cancer properties of icariin and its derivatives. Data from in vitro and in vivo studies suggests these compounds demonstrate anti-cancer activity against a wide range of cancer cells which occurs through various mechanisms such as apoptosis, cell cycle modulation, anti-angiogenesis, anti-metastasis and immunomodulation. Of note, they are efficient at targeting cancer stem cells and drug-resistant cancer cells. These are highly desirable properties to be emulated in the development of novel anti-cancer drugs in combatting the emergence of drug resistance and overcoming the limited efficacy of current standard treatment. This review aims to summarize the anti-cancer mechanisms of icariin and its derivatives with reference to the published literature. The currently utilized applications of icariin and its derivatives in cancer treatment are explored with reference to existing patents. Based on the data compiled, icariin and its derivatives are shown to be compounds with tremendous potential for the development of new anti-cancer drugs.

A novel anticancer agent icaritin inhibited proinflammatory cytokines in TRAMP mice

PURPOSE

We aimed to investigate whether icaritin (ICT) would inhibit serum proinflammatory cytokines and postpone prostate cancer (PCa) development and progression in both normal diet and high-fat diet (HFD) transgenic adenocarcinoma mouse prostate (TRAMP) mice.

METHODS

TRAMP mice were randomly divided into four groups: normal diet with/without ICT group and HFD with/without ICT group. Each TRAMP mouse received intraperitoneal injection of ICT solution at the dose of 30 mg/kg 5 times per week.

RESULTS

ICT treatment could significantly increase the survival when compared with those in normal diet group (P = 0.015, log-rank test) and HFD group (P = 0.009, log-rank test). Proinflammatory cytokine levels, including IL-1α, IL-1β, IL-6, and TNF-α, were decreased more or less in ICT-treated TRAMP mice. Moreover, significant higher inflammation scores were detected in normal diet group and HFD group compared with their relevant ICT treatment groups (P = 0.026 and P = 0.006, respectively). Meanwhile, the incidences of well-differentiated tumor tissue in two ICT treatment groups (39.13 and 31.82 %) were moderately higher than control groups (29.41 and 20.00 %, respectively), though no significant difference was observed.

CONCLUSIONS

Taken together, our findings indicate that ICT could inhibit the development and progression of PCa in TRAMP mice via inhibiting proinflammatory cytokines.

Icaritin suppresses multiple myeloma, by inhibiting IL-6/JAK2/STAT3

Icaritin is an active prenylflavonoid derived from Epimedium genus, a traditional Chinese medicine. Icaritin has a wide range of pharmacological and biological activities, including cardiovascular function improvement, hormone regulation and antitumor activity. Here, we investigated the effect of icaritin on multiple myeloma (MM) in vitro and in vivo. Icaritin inhibited cell growth of MM cell line and primary MM cells. In contrast, icaritin had low or no cytotoxic effect on normal hematopoiesis. We also demonstrated that in MM xenograft mouse models, icaritin suppressed tumor growth and decreased serum IL-6 and IgE levels, but did not show adverse reactions such as body weight loss. The anti-MM activity of icaritin was mainly mediated by inhibiting IL-6/JAK2/STAT3 signaling. We suggest that icaritin can be further tested in clinical trials in MM.

Knockdown of GPR137,G Protein-coupled receptor 137, Inhibits the Proliferation and Migration of Human Prostate Cancer Cells

GPR137 belongs to the G protein-coupled receptor family involving the regulation of transmembrane signal transduction that launches pivotal cellular functions. However, its function in prostate cancer (PCa) has been rarely reported. It was found in this study that GPR137 was upregulated in PCa tissues as compared with that in paracancerous tissues. To see whether GPR137 could serve as a potential therapeutic target for PCa, GPR137 was knocked down to verify its biological function in PCa cells. Lentivirus-introduced short hairpin RNA (shRNA) was designed to silence GPR137 gene. It was found that silencing of GPR137 gene suppressed the proliferation and colony formation of PCa cell lines PC-3 and DU145. Further study indicated that growth inhibition by GPR137 knockdown was associated with cell cycle arrest at G0/G1 phase. Furthermore, silencing of GPR137 repressed the invasion and migration abilities of PC-3 cells via downregulating slug and snail and upregulating E-cadherin. Collectively, these findings imply that GPR137 plays an important role in the occurrence and progression of PCa and may prove to be a potential therapeutic target for the treatment of advanced PCa.

Icariin enhances cytotoxicity of doxorubicin in human multidrug-resistant osteosarcoma cells by inhibition of ABCB1 and down-regulation of the PI3K/Akt pathway

Multidrug resistance is one of the major causes limiting the efficacy of chemotherapeutic agents used to control osteosarcoma. Multidrug resistance protein 1 (MDR1 or ABCB1) was considered to play a critical role in multidrug resistance. Agents from traditional Chinese medicines (TCMs) have great potential to prevent the onset or delay the progression of the carcinogenic process, and also to enhance the efficacy of mainstream antitumor agents. Herein, we investigated the effect and mechanism of icariin in the human osteosarcoma doxorubicin (DOX)-resistant cell line MG-63/DOX. In this study, icariin exhibited significant effects in sensitization of the resistant cancer cells at a concentration non-toxic to doxorubicin. It also increased the intracellular doxorubicin accumulation and retention in MG-63/DOX cells. In addition, an increase in Rh123 accumulation and a decrease in Rh123 efflux were observed in MG-63/DOX cells treated with icariin, indicating a blockage of the activity of MDR1. Furthermore, icariin enhanced the apoptosis induced by doxorubicin and down-regulated the expression of MDR1. The mechanism involves the inhibition of phosphatidyl inositol 3-kinase (PI3K)/Akt signaling. In conclusion, icariin possesses a reversal effect on multidrug resistance in MG-63/DOX cells through down-regulation of the MDR1 and the PI3K/Akt pathway, and has the potential to be an adjunct to chemotherapy for osteosarcoma.

Icaritin acts synergistically with epirubicin to suppress bladder cancer growth through inhibition of autophagy

Bladder cancer is one of the most commonly diagnosed urological malignancies. Acquired resistance to chemotherapy is a great barrier for achieving successful treatment of bladder cancer. In the present study, we investigated the effect and mechanisms of icaritin, a flavonol glycoside derived from genus Epimedium, against human bladder cancer cells. It was found that despite the low cytotoxicity in normal human HEK293 cells, icaritin significantly inhibited the proliferation and colony formation of BT5637 and T24 bladder cancer cells time- and dose-dependently compared to the DMSO vehicle control. Moreover, cell viability monitored through mitochondrial membrane potential was inhibited markedly after icaritin treatment. Further investigation indicated that icaritin may inhibit epirubicin (EPI)-induced autophagy, and acted synergistically with EPI to suppress the proliferation of BT5637 and T24 cells. These findings suggest that icaritin may prove to be a novel potent therapeutic agent for the treatment of bladder cancer.

Icaritin activates JNK-dependent mPTP necrosis pathway in colorectal cancer cells

The colorectal cancer (CRC) is one leading contributor of cancer-related mortality worldwide. The search for effective anti-CRC agents is valuable. In the current study, we showed that icaritin (ICT), an active natural ingredient from the Chinese plant Epimedium, potently inhibited proliferation and survival of established (HT-29, HCT-116, DLD-1, and SW-620) and primary (patient-derived) CRC cells. Significantly, ICT mainly induced necrosis, but not apoptosis, in CRC cells. The necrosis inhibitor necrostatin-1 attenuated ICT-mediated cytotoxicity in CRC cells. We showed that ICT treatment in CRC cells induced mitochondrial permeability transition pore (mPTP) opening, which was evidenced by mitochondrial membrane potential (MMP) decrease and mitochondrial adenine nucleotide translocator-1 (ANT-1)-cyclophilin-D (CyPD) association. On the other hand, mPTP blockers, including sanglifehrin A, cyclosporin A, and bongkrekic acid, as well as siRNA-mediated knockdown of mPTP component (CyPD or ANT-1), significantly alleviated ICT-mediated cytotoxicity against CRC cells. We suggested that Jun-N-terminal kinase (JNK) activation by ICT mediated mPTP opening and subsequent CRC cell necrosis. JNK pharmacological inhibition, dominant negative mutation, or shRNA downregulation suppressed ICT-induced MMP reduction and subsequent HT-29 cell necrosis. In vivo, oral gavage of ICT dramatically inhibited HT-29 xenograft growth in nude mice. The in vivo activity by ICT was largely attenuated by co-administration with the mPTP blocker CsA. Collectively, our results showed that ICT exerts potent inhibitory effect against CRC cells in vitro and in vivo. JNK-dependent mPTP necrosis pathway could be key mechanism responsible for ICT's actions.

Icariin-mediated inhibition of NF-κB activity enhances the in vitro and in vivo antitumour effect of 5-fluorouracil in colorectal cancer

Colorectal cancer (CRC) is an aggressive malignancy that has a poor prognosis. 5-Fluorouracil (5-FU) is a first line chemotherapeutic medication used in the treatment of gallbladder cancer; however, the efficacy is below satisfactory. Icariin is a natural compound that is conventionally reported to have activity against a variety of cancers. This study was carried out to investigate the anti-cancer effect of icariin in CRC cells and to determine whether the compound can enhance the antitumour activity of 5-FU. Cell proliferation and apoptosis were measured using an MTT assay and flow cytometry, respectively. The activity of transcription factor NF-κB was determined by EMSA method. The expression of apoptosis- and proliferation-related proteins was determined by western blotting. The in vivo antitumour effect of combination treatment with icariin and 5-FU on CRC was also assessed using a murine model of CRC. Icariin sensitized the CRC cells to 5-FU both in vitro and in vivo. The antitumour activity of icariin and its potentiating effect on the antitumour activity of 5-FU implicated the suppression of NF-κB activity and consequent down-regulation of the gene products regulated by NF-κB. Our results showed that icariin, suppressed tumour growth and enhanced the antitumour activity of 5-FU in CRC by inhibiting NF-κB activity. Therefore, we suggest that combination of icariin with 5-FU might offer a therapeutic benefit to the patients with CRC; however, further studies are required to ascertain this proposition.

Chemical Constituents, Quality Control, and Bioactivity of Epimedii Folium (Yinyanghuo)

Epimedii Folium (Yinyanghuo in Chinese) is one of the most commonly used traditional Chinese medicines. Its main active components are flavonoids, which exhibit multiple biological activities, such as promotion of bone formation and sexual function, protection of the nervous system, and prevention of cardiovascular diseases. Flavonoids also show anti-inflammatory and anticancer effects. Various effective methods, including genetic and chemical approaches, have been developed for the quality control of Yinyanghuo. In this review, the studies conducted in the last decade about the chemical constituents, quality control, and bioactivity of Yinyanghuo are summarized and discussed.

Synthesis and cancer cell growth inhibitory activity of icaritin derivatives

A series of icaritin derivatives bearing carboxylic acid or carboxylic ester groups are synthesized, and their in vitro cytotoxic activity against three cancer cell lines, MCF-7, MDA-MB-435s, and A549, are evaluated by MTT assay. Several derivatives including 2h, 2j, 5b and 5d show higher cytotoxic activity than the parent compound icaritin against these cancer cell lines. Compounds 5b and 5d are even more cytotoxic to MCF-7 cells than the clinic drug tamoxifen. Moreover, compound 5b is found to be non-toxic to normal cells (Vero) and both 5b and 5d exhibit good selectivity towards estrogen receptor positive MCF-7 breast cancer cells over estrogen receptor negative MDA-MB-435s breast cancer cells. The structure activity relationship analysis has revealed that mono-substitution at either C-3 or C-7 hydroxyl group of icaritin could improve the cytotoxicity of icaritin, and the C-3 hydroxyl group may be a preferable site for chemical modification. In addition, the length, the flexibility and the additional branching substituent group of the substitution chain(s) at both C-3 and C-7 hydroxyl groups can all affect the anti-cancer activity of these derivatives.

A novel prostate cancer therapeutic strategy using icaritin-activated arylhydrocarbon-receptor to co-target androgen receptor and its splice variants

Persistent androgen receptor (AR) signaling is the key driving force behind progression and development of castration-resistant prostate cancer (CRPC). In many patients, AR COOH-terminal truncated splice variants (ARvs) play a critical role in contributing to the resistance against androgen depletion therapy. Unfortunately, clinically used antiandrogens like bicalutamide (BIC) and enzalutamide (MDV), which target the ligand binding domain, have failed to suppress these AR variants. Here, we report for the first time that a natural prenylflavonoid, icaritin (ICT), can co-target both persistent AR and ARvs. ICT was found to inhibit transcription of key AR-regulated genes, such as KLK3 [prostate-specific antigen (PSA)] and ARvs-regulated genes, such as UBE2C and induce apoptosis in AR-positive prostate cancer (PC) cells. Mechanistically, ICT promoted the degradation of both AR and ARvs by binding to arylhydrocarbon-receptor (AhR) to mediate ubiquitin-proteasomal degradation. Therefore, ICT impaired AR transactivation in PC cells. Knockdown of AhR gene restored AR stability and partially prevented ICT-induced growth suppression. In clinically relevant murine models orthotopically implanted with androgen-sensitive and CRPC cells, ICT was able to target AR and ARvs, to inhibit AR signaling and tumor growth with no apparent toxicity. Our results provide a mechanistic framework for the development of ICT, as a novel lead compound for AR-positive PC therapeutics, especially for those bearing AR splice variants.

Systematic considerations for a multicomponent pharmacokinetic study of Epimedii wushanensis herba: From method establishment to pharmacokinetic marker selection

BACKGROUND

Prenylflavonoids are major active components of Epimedii wushanensis herba (EWH). The global pharmacokinetics of prenylflavonoids are unclear, as these compounds yield multiple, often unidentified metabolites.

PURPOSE

This study successfully elucidated the pharmacokinetic profiles of EWH extract and five EWH-derived prenylflavonoid monomers in rats.

STUDY DESIGN

The study was a comprehensive analysis of metabolic pathways and pharmacokinetic markers.

METHODS

Major plasma compounds identified after oral administration of EWH-derived prototypes or extract included: (1) prenylflavonoid prototypes, (2) deglycosylated products, and (3) glucuronide conjugates. To select appropriate EWH-derived pharmacokinetic markers, a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was established to simultaneously monitor 14 major compounds in unhydrolyzed plasma and 10 potential pharmacokinetic markers in hydrolyzed plasma.

RESULTS

The pharmacokinetic profiles indicated that the glucuronide conjugates of icaritin were the principle circulating metabolites and that total icaritin accounted for ∼99% of prenylflavonoid exposure after administration of EWH-derived materials to rats. To further investigate icaritin as a prospective pharmacokinetic marker, correlation analysis was performed between total icaritin and its glucuronide conjugates, and a strong correlation (r > 0.5) was found, indicating that total icaritin content accurately reflected changes in the exposure levels of the glucuronide conjugates over time. Therefore, icaritin is a sufficient pharmacokinetic marker for evaluating dynamic prenylflavonoid exposure levels. Next, a mathematical model was developed based on the prenylflavonoid content of EWH and the exposure levels in rats, using icaritin as the pharmacokinetic marker. This model accurately predicted exposure levels in vivo, with similar predicted vs. experimental area under the curve (AUC)(0-96 h) values for total icaritin (24.1 vs. 32.0 mg/L h).

CONCLUSION

Icaritin in hydrolyzed plasma can be used as a pharmacokinetic marker to reflect prenylflavonoid exposure levels, as well as the changes over time of its glucuronide conjugates.

Resonance energy transfer, pH-induced folded states and the molecular interaction of human serum albumin and icariin

Icariin is a flavonol glycoside with a wide range of pharmacological and biological activities. The pharmacological and biological functions of flavonoid compounds mainly originate from their binding to proteins. The mode of interaction of icariin with human serum albumin (HSA) has been characterized by fluorescence spectroscopy and far- and near-UV circular dichroism (CD) spectroscopy under different pH conditions. Fluorescence quenching studies showed that the binding affinity of icariin with HSA in the buffer solution at different pH values is: Ka (pH 4.5) > Ka (pH 3.5) > Ka (pH 9.0) > Ka (pH 7.0). Red-edge excitation shift (REES) studies revealed that pH had an obvious effect on the mobility of the tryptophan microenvironment and the addition of icariin made the REES effect more distinct. The static quenching mechanism and number of binding sites (n ≈ 1) were obtained from fluorescence data at three temperatures (298, 304 and 310 K). Both ∆H(0) < 0 and ∆Ѕ(0) < 0 suggested that hydrogen bonding and van der Waal's interaction were major driving forces in the binding mechanism, and this was also confirmed by the molecular simulation results. The distance r between the donor (HSA) and the acceptor (icariin) was calculated based on Förster non-radiation energy transfer theory. We found that pH had little impact on the energy transfer between HSA and icariin. Far- and near-UV CD spectroscopy studies further indicated the influence of pH on the complexation process and the alteration in the protein conformation upon binding.

Icariin enhances radiosensitivity of colorectal cancer cells by suppressing NF-κB activity

Radiation therapy is an integral part of the current therapeutic protocols in colorectal cancer. However, only a small proportion of the patients achieved complete pathological response because of the treatment-induced resistance to radiation. Previous studies have shown that radioresistance is associated with NF-κB activation and that suppression of NF-κB could potentiate the response of colorectal cancer cells to radiotherapy. Icariin, a natural flavonoid, has been shown to suppress NF-κB activity. The present study was carried out to investigate whether icariin could act as a radiosensitizer in colorectal cancer cells and murine model of the colorectal cancer. We also sought to understand the mechanisms underlying the icariin-mediated radiosensitization. Our results showed that icariin enhanced the radiation-mediated anti-proliferative effect both in vitro and in vivo. Further, icariin exerted the anti-proliferative and/or pro-apoptotic effect possibly, by: (1) inducing the cell arrest in G2/M phases of the cell cycle, or by (2) downregulating NF-κB and the anti-apoptotic gene products monitored by this transcription factor. Icariin could also potentiate the efficacy of radiotherapy in the murine model of colorectal cancer. Taken together, these results suggest that the use of icariin may provide with a new approach for sensitizing the radiotherapy in colorectal cancer.

Anticancer agent icaritin induces apoptosis through caspase-dependent pathways in human hepatocellular carcinoma cells

Icaritin is an active ingredient derived from the plant Herba epimedium, which exhibits various pharmacological and biological activities. However, the function, and the underlying mechanisms of icaritin on the growth of SMMC‑7721 human hepatoma cells have yet to be elucidated. The present study aimed to investigate the function and underlying mechanisms of icaritin in the growth of SMMC‑7721 cells. The cells were treated with varying concentrations of icaritin for 12, 24 and 48 h, respectively, prior to cytotoxic analysis. Apoptosis of SMMC‑7721 cells following treatment with icaritin was measured using flow cytometry. The gene expression of mitochondria‑ and Fas‑mediated caspase‑dependent pathways was detected by reverse transcription‑quantitative polymerase chain reaction and western blotting. Statistical analysis was performed by Student's t‑test and one‑way analysis or variance. The present study demonstrated that treatment with icaritin significantly inhibited growth, and induced apoptosis of SMMC‑7721 cells, in a time‑ and dose‑dependent manner. In addition, icaritin triggered the mitochondrial/caspase apoptotic pathway, by decreasing the Bcl‑2/Bax protein ratio and increasing activation of caspase‑3. Icaritin also activated the Fas‑mediated apoptosis pathway, as was evident by the increased expression levels of Fas and activation of caspase‑8. These data suggest that icaritin may be a potent growth inhibitor and induce apoptosis of SMMC‑7721 cells through the mitochondria‑ and Fas‑mediated caspase‑dependent pathways. The present study may provide experimental evidence for preclinical and clinical evaluations of icaritin for HCC therapy.

Biodistribution evaluation of icaritin in rats by ultra-performance liquid chromatography-tandem mass spectrometry

ETHNOPHARMACOLOGICAL RELEVANCE

Icaritin (ICT) is a major bioactive prenylflavonoid derivative contained in the Epimedium which is a widely used herbal medicine for the treatment of infertility, impotence, cardiovascular and skeletal diseases listed in the Chinese Pharmacopoeia. The aim of this study is to investigate the tissue distribution of ICT in rats by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) MATERIALS AND METHODS: ICT was intraperitoneally administrated to rats for 7 consecutive days at dose levels of 20, 40 and 60 mg/kg/day, respectively. Various tissue homogenates were pretreated by protein precipitation with acetonitrile. ICT and internal standard coumestrol were separated on a BEH C18 column with a gradient mobile phase and detected using precursor-product ion transitions of m/z 367.1→297.1 for ICT and 267.0→211.1 for coumestrol at the negative ionization mode, respectively.

RESULTS

ICT was widely distributed in rat's various tissues and its concentrations in tissues increased with elevated doses. A sensitive and reliable UPLC-MS/MS method was firstly established to quantify ICT in rat tissues. The lower limit of quantification was 0.5 ng/mL based on 100 μL of tissue homogenates. The intra- and inter-day accuracy at all levels fell in the ranges of 90.8-103.4% and 91.6-100.3%, and the intra- and inter-day precision (RSD) were in the ranges of 2.9-10.5% and 2.6-9.1%, respectively.

CONCLUSIONS

The UPLC-MS/MS showed good accuracy, precision and recovery and was suitable for the quantification of ICT in rat tissues. Wide distribution of ICT could helpfully elucidate systemic effects and various functions of ICT.

Anticancer effect of icaritin on human lung cancer cells through inducing S phase cell cycle arrest and apoptosis

Icaritin, a prenylflavonoid derivative from Epimedium Genus, has been shown to exhibit many pharmacological and biological activities. However, the function and the underlying mechanisms of icaritin in human non-small cell lung cancer have not been fully elucidated. The purpose of this study was to investigate the anticancer effects of icaritin on A549 cells and explore the underlying molecular mechanism. The cell viability after icaritin treatment was tested by MTT assay. The cell cycle distribution, apoptosis and reactive oxygen species (ROS) levels were analyzed by flow cytometry. The mRNA and protein expression levels of the genes involved in proliferation and apoptosis were respectively detected by RT-PCR and Western blotting. The results demonstrated that icaritin induced cell cycle arrest at S phase, and down-regulated the expression levels of S regulatory proteins such as Cyclin A and CDK2. Icaritin also induced cell apoptosis characterized by positive Hoechst 33258 staining, accumulation of the Annexin V-positive cells, increased ROS level and alteration in Bcl-2 family proteins expression. Moreover, icaritin induced sustained phosphorylation of ERK and p38 MAPK. These findings suggested that icaritin might be a new potent inhibitor by inducing S phase arrest and apoptosis in human lung carcinoma A549 cells.

Cytotoxic effect of icaritin and its mechanisms in inducing apoptosis in human burkitt lymphoma cell line

Icaritin (ICT), a hydrolytic product of icariin from Epimedium genus, exhibits antitumor activities in several human solid-tumor and myeloid leukemia cells with extensive influence on various cell signal molecules, such as MAPKs being involved in cell proliferation and Bcl-2 participating in cell apoptosis. However, the effect of icaritin on Burkitt Lymphoma has not been elucidated. In the present study, we first screened the potential effect of icaritin on Burkitt lymphoma Raji and P3HR-1 cell lines and found that icaritin showed cytotoxicity in both cell lines. We further found that icaritin could significantly inhibit Raji cells proliferation with S-phase arrest of cell cycle and induced cell apoptosis accompanied by activation of caspase-8 and caspase-9 and cleavage of PARP. We also observed that icaritin was able to decrease Bcl-2 levels, thus shifting the Bcl-2/Bax ratio, and it could obviously reduce c-Myc, a specific molecular target in Burkitt lymphoma. Our findings demonstrated that icaritin showed cytotoxicity, inhibited cell growth, caused S arrest, and induced apoptosis in Burkitt lymphoma cells and provided a rationale for the further evaluation of icaritin for Burkitt lymphoma therapy.

Icariin and icaritin stimulate the proliferation of SKBr3 cells through the GPER1-mediated modulation of the EGFR-MAPK signaling pathway

Icariin (ICA) and icaritin (ICT), with a similar structure to genistein, are the important bioactive components of the genus Epimedium, and regulate many cellular processes. In the present study, using the estrogen receptor (ER)-negative breast cancer cell line, SKBr3, as a model, we examined the hypothesis that ICA and ICT at low concentrations stimulate SKBr3 cell proliferation in vitro through the functional membrane, G protein‑coupled estrogen receptor 1 (GPER1), mediated by the epithelial growth factor receptor (EGFR)‑mitogen-activated protein kinase (MAPK) signaling pathway. MTT assay revealed that ICA and ICT at doses of 1 nM to 1 µM markedly stimulated SKBr3 cell proliferation in a dose-dependent manner. The ICA- and ICT-stimulated cell growth was completely suppressed by the GPER1 antagonist, G-15, indicating that the ICA‑ and ICT-stimulated cell proliferation was mediated by GPER1 activation. Semi-quantitative RT-PCR analysis revealed that treatment with ICA and ICT enhanced the transcription of c-fos, a proliferation-related early gene. The ICA- and ICT-stimulated mRNA expression was markedly attenuated by G-15, AG-1478 (an EGFR antagonist) or PD98059 (a MAPK inhibitor). Our data also demonstrated that ICA and ICT increased the phosphorylation of ERK1/2. The ICA- and ICT-stimulated ERK1/2 phosphorylation was blocked by pre-treatment of the cells with G-15 and AG-1478 or PD 98059. Flow cytometric analysis confirmed that the ICA- and ICT-stimulated SKBr3 cell proliferation involved the GPER1-mediated modulation of the EGFR‑MAPK signaling pathway. To the best of our knowledge, our current findings demonstrate for the first time that ICA and ICT promote the progression of ER-negative breast cancer through the activation of membrane GPER1.

Icaritin suppresses the proliferation of human osteosarcoma cells in vitro by increasing apoptosis and decreasing MMP expression

AIM

To explore whether icaritin, a prenylflavonoid derivative of the Chinese tonic herb Epimedium, could suppress the proliferation of human osteosarcoma cells in vitro, and to elucidate the mechanisms of the action.

METHODS

Human osteosarcoma SaOS2 cell line was used in the present study. The proliferation of the cells was examined using MTT assay and immunofluorescence DAPI staining. Cell motility was studied with the scratch assay. Cell apoptosis was determined by Annexin V-FITC and PI double staining using flow cytometry. Western blotting and RT-PCR were used to measure the expression of mRNAs and proteins in the cells.

RESULTS

Icaritin (5-15 μmol/L) suppressed the proliferation of SaOS2 cells in vitro in a dose-dependent manner. Furthermore, the cell motility was significantly decreased after exposure to icaritin. Moreover, icaritin (5 μmol/L) time-dependently induced the apoptosis of SaOS2 cells, markedly suppressed MMP-2 and MMP-9 expression, upregulated caspase-3 and caspase-9 expression, and increased the level of cleaved caspase-3 in the cells. Co-exposure to the caspase-3 inhibitor zVAD-fmk (10 μmol/L) compromised the icaritin-induced caspase-3 expression and apoptosis in SaOS2 cells.

CONCLUSION

Icaritin suppresses the proliferation of SaOS2 human osteosarcoma cells by increasing apoptosis and downregulating MMP expression.

β-cyclodextrin assistant flavonoid glycosides enzymatic hydrolysis

BACKGROUND

The content of icaritin and genistein in herba is very low, preparation with relatively large quantities is an important issue for extensive pharmacological studies.

OBJECTIVE

This study focuses on preparing and enzymic hydrolysis of flavonoid glycosides /β-cyclodextrin inclusion complex to increase the hydrolysis rate.

MATERIALS AND METHODS

The physical property of newly prepared inclusion complex was tested by differential scanning calorimetry (DSC). The conditions of enzymatic hydrolysis were optimized for the bioconversion of flavonoid glycosides /β-cyclodextrin inclusion complex by mono-factor experimental design. The experiments are using the icariin and genistein as the model drugs.

RESULTS

The solubility of icariin and genistein were increased almost 17 times from 29.2 μg/ml to 513.5 μg/ml at 60°C and 28 times from 7.78 μg/ml to 221.46 μg/ml at 50°C, respectively, demonstrating that the inclusion complex could significantly increase the solubility of flavonoid glycosides. Under the optimal conditions, the reaction time of icariin and genistin decreased by 68% and 145%, when compared with that without β-CD inclusion. By using this enzymatic condition, 473 mg icaritin (with the purity of 99.34%) and 567 mg genistein(with the purity of 99.46%), which was finally determined by melt point, ESI-MS, UV, IR, (1)H NMR and (13)C NMR, was obtained eventually by transforming the inclusion complex(contains 1.0 g substrates).

CONCLUSION

This study can clearly indicate a new attempt to improve the speed of enzyme-hydrolysis of poorly water-soluble flavonoid glycosides and find a more superior condition which is used to prepare icaritin and genistein.

Icaritin reverses multidrug resistance of HepG2/ADR human hepatoma cells via downregulation of MDR1 and P‑glycoprotein expression

Multidrug resistance (MDR) of tumor cells is a serious obstacle encountered in cancer treatment. In the current study a multiple drug‑resistant HepG2/adriamycin (HepG2/ADR) cell line was established and its MDR was characterized. Icaritin, an active ingredient isolated from the medical plant Herba Epimedium, was observed to reverse MDR in the present model. Icaritin significantly increased the intracellular accumulation of ADR and decreased the expression of the MDR1 gene in HepG2/ADR cells compared with drug‑sensitive HepG2 cells. In addition, the present results showed that icaritin may significantly downregulate the expression of P‑glycoprotein. These results indicate that icaritin is a novel and potent MDR reversal agent and may be a promising drug for tumor chemotherapy.

Prenylation enhances quercetin uptake and reduces efflux in Caco-2 cells and enhances tissue accumulation in mice fed long-term

Prenyl flavonoids are widely distributed in plant foods and have attracted appreciable attention in relation to their potential benefits for human health. Prenylation may enhance the biological functions of flavonoids by introducing hydrophobic properties in their basic structures. Previously, we found that 8-prenyl naringenin exerted a greater preventive effect on muscle atrophy than nonprenylated naringenin in a mouse model. Here, we aimed to estimate the effect of prenylation on the bioavailability of dietary quercetin (Q). The cellular uptake of 8-prenyl quercetin (PQ) and Q in Caco-2 cells and C2C12 myotube cells was examined. Prenylation significantly enhanced the cellular uptake by increasing the lipophilicity in both cell types. In Caco-2 cells, efflux of PQ to the basolateral side was <15% of that of Q, suggesting that prenylation attenuates transport from the intestine to the circulation. After intragastric administration of PQ or Q to mice or rats, the area under the concentration-time curve for PQ in plasma and lymph was 52.5% and 37.5% lower than that of Q, respectively. PQ and its O-methylated form (MePQ) accumulated at much higher amounts than Q and O-methylated Q in the liver (Q: 3400%; MePQ: 7570%) and kidney (Q: 385%; MePQ: 736%) of mice after 18 d of feeding. These data suggest that prenylation enhances the accumulation of Q in tissues during long-term feeding, even though prenylation per se lowers its intestinal absorption from the diet.

Icaritin synergistically enhances the radiosensitivity of 4T1 breast cancer cells

Icaritin (ICT) is a hydrolytic form of icariin isolated from plants of the genus Epimedium. This study was to investigate the radiosensitization effect of icaritin and its possible underlying mechanism using murine 4T1 breast cancer cells. The combination of Icaritin at 3 µM or 6 µM with 6 or 8 Gy of ionizing radiation (IR) in the clonogenic assay yielded an ER (enhancement ratio) of 1.18 or 1.28, CI (combination index) of 0.38 or 0.19 and DRI (dose reducing index) of 2.51 or 5.07, respectively. These strongly suggest that Icaritin exerted a synergistic killing (?) effect with radiation on the tumor cells. This effect might relate with bioactivities of ICT: 1) exert an anti-proliferative effect in a dose- and time-dependent manner, which is different from IR killing effect but likely work together with the IR effect; 2) suppress the IR-induced activation of two survival paths, ERK1/2 and AKT; 3) induce the G2/M blockage, enhancing IR killing effect; and 4) synergize with IR to enhance cell apoptosis. In addition, ICT suppressed angiogenesis in chick embryo chorioallantoic membrane (CAM) assay. Taken together, ICT is a new radiosensitizer and can enhance anti-cancer effect of IR or other therapies.

Icariside II induces apoptosis of melanoma cells through the downregulation of survival pathways

This study evaluated the antitumor effects of icariside II (IS), isolated from Herba Epimedii, on in vitro and in vivo models of melanoma and determined its mechanism of apoptosis. Mouse (B16) and human (A375, SK-MEL-5) melanoma cell lines were treated with IS at different concentrations (0-100 μM). Cell viability and proliferation was detected by WST-1 assay and with the xCELLigence system, respectively. Apoptosis was measured by the annexin-V/PI flow cytometric assay. Western blot was used to measure cleaved caspase 3, survivin, P-STAT3, P-ERK and P-AKT. B16 and A375 cells were injected subcutaneously into C57BL/6J and BALB/c-nu mice, respectively. After 1 wk, IS solution at (50 mg/kg, 100 mg/kg) was administered by intraperitoneal injection 3 times for a week. Tumor size was measured with an electronic digital caliper. IS inhibited the proliferation of melanoma cells in a dose- and time-dependent manner. Treatment of A375 cells with IS resulted in an increased number of apoptotic cells ranging from 5.6% to 26.3% mirrored by increases in cleaved caspase-3 and a decrease in survivin expression. IS significantly inhibited the activation of the JAK-STAT3 and MAPK pathways but promoted an unsustained activation peak of the PI3K-AKT pathway. IS administration (50 mg/kg) resulted in a 47.5% decreased tumor volume in A375 bearing mice. Furthermore, IS administration (50 mg/kg, 100 mg/kg) resulted in 41% and 49% decreased tumor volume in B16 bearing mice, respectively. IS dramatically inhibited the proliferation of melanoma cells in vivo and in vitro through the regulation of apoptosis. These effects demonstrate the ability of IS to effectively overcome the survival signals of tumor cells, which support further preclinical evaluation of IS in cancer as a new potential chemotherapeutic agent.

Icariin potentiates the antitumor activity of gemcitabine in gallbladder cancer by suppressing NF-κB

AIM

Gemcitabine has been increasingly prescribed for the treatment of gallbladder cancer. However, the response rate is low. The aim of this study is to determine whether icariin, a flavonoid isolated from Epimedi herba, could potentiate the antitumor activity of gemcitabine in gallbladder cancer.

METHODS

Human gallbladder carcinoma cell lines GBC-SD and SGC-996 were tested. Cell proliferation and apoptosis were analyzed using MTT assay and flow cytometry, respectively. The expression of apoptosis- and proliferation-related molecules was detected with Western blotting. Caspase-3 activity was analyzed using colorimetric assay, and NF-κB activity was measured with ELISA. A gallbladder cancer xenograft model was established in female BALB/c (nu/nu) mice. The mice were intraperitoneally administered gemcitabine (125 mg/kg) in combination with icariin (40 mg/kg) for 2 weeks.

RESULTS

Icariin (40-160 μg/mL) dose-dependently suppressed cell proliferation and induced apoptosis in both GBC-SD and SGC-996 cells, with SGC-996 cells being less sensitive to the drug. Icariin (40 μg/mL) significantly enhanced the antitumor activity of gemcitabine (0.5 μmol/L) in both GBC-SD and SGC-996 cells. The mice bearing gallbladder cancer xenograft treated with gemcitabine in combination with icariin exhibited significantly smaller tumor size than the mice treated with either drug alone. In GBC-SD cells, icariin significantly inhibited both the constitutive and gemcitabine-induced NF-κB activity, enhanced caspase-3 activity, induced G(0)-G(1) phase arrest, and suppressed the expression of Bcl-2, Bcl-xL and surviving proteins.

CONCLUSION

Icariin, by suppressing NF-κB activity, exerts antitumor activity, and potentiates the antitumor activity of gemcitabine in gallbladder cancer. Combined administration of gemcitabine and icariin may offer a better therapeutic option for the patients with gallbladder cancer.

Enhancement of epimedium fried with suet oil based on in vivo formation of self-assembled flavonoid compound nanomicelles

The purpose of this work was to research the enhancement of Epimedium fried with suet oil based on the in vivo formation self-assembled flavonoid nanomicelles. Taking icariin as the representative, under the action of suet oil, self-assembled nanomicelles were prepared under simulated gastrointestinal tract conditions and were characterized by dynamic light scattering and transmission electron microscopy (TEM). The experiments with icariin self-assembled nanomicelles without suet oil were done according to the above. The influence of suet oil on the transportation of icariin across Caco-2 cell monolayers and the absorption in rat intestine of self-assembled nanomicelles were evaluated. The particle size of icariin self-assembled nanomicelles with suet oil was smaller than without suet oil. The nanomicelles seemed to be monodisperse spherical particle with smooth surfaces. The icariin entrapment efficiency of self-assembled nanomicelles with suet oil was increased from 43.1% to 89.7%. In Caco-2 cell monolayers, the absorptive permeability, secretory permeability and efflux ratio of icariin self-assembled nanomicelles with suet oil was 1.26 × 10−6 cm/s, 5.91 × 10−6 cm/s and 4.69, respectively, while that of icariin self-assembled nanomicelles without suet oil was 0.62 × 10−6 cm/s, 3.00 × 10−6 cm/s, and 4.84, respectively. In rat intestinal perfusion experiments, the permeability coefficient of icariin self-assembled nanomicelles with suet oil in duodenum was higher than the value of icariin self-assembled nanomicelles without suet oil (p < 0.05). With the action of suet oil, icariin self-assembled nanomicelles were more stable and the entrapment efficiency was higher than that without suet oil, which could increase the solubility of icariin and improve its intestinal absorption. Therefore, suet oil plays a role in its enhancement.

Prevention of disuse muscle atrophy by dietary ingestion of 8-prenylnaringenin in denervated mice

Flavonoids have attracted considerable attention in relation to their effects upon health. 8-Prenylnaringenin (8-PN) is found in the common hop (Humulus lupulus) and assumed to be responsible for the health impact of beer consumption. We wanted to clarify the effects of prenylation on the physiological functions of dietary flavonoids by comparing the effects of 8-PN with that of intact naringenin in the prevention of disuse muscle atrophy using a model of denervation in mice. Consumption of 8-PN (but not naringenin) prevented loss of weight in the gastrocnemius muscle further supported by the lack of induction of the protein content of a key ubiquitin ligase involved in muscle atrophy, atrogin-1, and by the activation of Akt phosphorylation. 8-PN content in the gastrocnemius muscle was tenfold higher than that of naringenin. These results suggested that, compared with naringenin, 8-PN was effectively concentrated into skeletal muscle to exert its preventive effects upon disuse muscle atrophy. It is likely that prenylation generates novel functions for 8-PN by enhancing its accumulation into muscle tissue through dietary intake.

Oral absorption and excretion of icaritin, an aglycone and also active metabolite of prenylflavonoids from the Chinese medicine Herba Epimedii in rats

Icaritin (ICT) is a main aglycone and also active intestinal metabolite of prenylflavonoids from the Chinese medicine Herba Epimedii. In the present study, the oral absorption and excretion of this compound was investigated using rats for exploring its fate in the body, so as to better understanding its in vivo pharmacological activities. The free (parent) and total (parent plus conjugated metabolites) ICT concentrations in rat plasma, urine and bile, after intravenous (i.v.) and oral administration both at 5mg/kg, were determined before and after enzymatic hydrolysis with β-glucuronidase/sulphatase, respectively, by a HPLC-UV method. The results showed that free ICT plasma concentration after i.v. dose was rapidly decreased with average t(1/2, λ) of 0.43 h, while the total ICT concentration was decreased slowly with t(1/2, λ) of 6.86 h. The area under the curve of ICT conjugated metabolites was about 11-fold higher than that of free ICT. The majority of ICT in the body was excreted from the bile with 68.05% of dose over 8 h after i.v. dosing, in which only 0.15% was in parent form. While very little amount of ICT was excreted from the urine with 3.01% of dose over 24 h, in which the parent form was 0.62%. After oral administration, very little amount of parent ICT was detected only in 0.5, 1 or 2 h plasma samples with the concentration less than LOQ, however, its total plasma concentration after enzymatic hydrolysis treatment was at relative high level with average maximum concentration of 0.49 μg/ml achieved at 1h post dose. The oral bioavailability of ICT was 35% of dose, estimated by its total plasma drug concentrations. It is concluded that ICT can be easily absorbed into the body, and then rapidly conversed to its conjugated metabolites, and finally removed from the body mainly by biliary excretion.

Changes in the intestinal absorption mechanism of icariin in the nanocavities of cyclodextrins

Icariin is a bioactive herbal ingredient isolated from Herba epimedii, which has been widely used for the treatment of osteoporosis and male sexual dysfunction in traditional Chinese medicine. The major objective of this work is to investigate the different enhancing effects of β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) on the intestinal absorption of icariin, and to identify the molecular mechanisms of this action. Host-guest-type interactions of icariin with cyclodextrins nanocavities were unambiguously demonstrated by the phase-solubility diagram, ultraviolet spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray powder diffractometry, and two dimensional proton nuclear magnetic resonance rotating-frame Overhauser effect spectroscopy. These results were further supported using molecular modeling studies. The rat single-pass intestinal perfusion model showed that the absorption of icariin was affected by P-glycoprotein (Pgp). The icariin/HP-β-CD inclusion complex provided greater enhancement in the intestinal absorption than the icariin/β-CD inclusion complex. Therefore, the enhancing effect was involved in a solubilizing effect and/or Pgp inhibitory effect. Finally, fluorescence anisotropy measurements and Pgp adenosine triphosphatase (ATPase) assay demonstrated that β-CD exhibited no effect on Pgp, while HP-β-CD showed inhibition by restraining the Pgp ATPase activity rather than changing the fluidity of cell membrane.

Reactive oxygen species-mediated mitochondrial pathway is involved in Baohuoside I-induced apoptosis in human non-small cell lung cancer

Baohuoside I (also known as Icariside II) is a flavonoid isolated from Epimedium koreanum Nakai. Although Baohuoside I exhibits anti-inflammatory and anti-cancer activities, its molecular targets/pathways in human lung cancer cells are poorly understood. Therefore, in the present study, we investigated the usefulness of Baohuoside I as a potential apoptosis-inducing cytotoxic agent using human adenocarcinoma alveolar basal epithelial A549 cells as in vitro model. The apoptosis induced by Baohuoside I in A549 cells was confirmed by annexin V/propidium iodide double staining, cell cycle analysis and dUTP nick end labeling. Further research revealed that Baohuoside I accelerated apoptosis through the mitochondrial apoptotic pathway, involving the increment of BAX/Bcl-2 ratio, dissipation of mitochondrial membrane potential, transposition of cytochrome c, caspase 3 and caspase 9 activation, degradation of poly (ADP-ribose) polymerase and the over-production of reactive oxygen species (ROS). A pan-caspase inhibitor, Z-VAD-FMK, only partially prevented apoptosis induced by Baohuoside I, while NAC, a scavenger of ROS, diminished its effect more potently. In addition, the apoptotic effect of Baohuoside I was dependent on the activation of ROS downstream effectors, JNK and p38(MAPK), which could be almost abrogated by using inhibitors SB203580 (an inhibitor of p38(MAPK)) and SP600125 (an inhibitor of JNK). These findings suggested that Baohuoside I might exert its cytotoxic effect via the ROS/MAPK pathway.