DNA polymerase and topoisomerase II inhibitors from Psoralea corylifolia

Isobavachalcone attenuates lipopolysaccharide-induced ICAM-1 expression in brain endothelial cells through blockade of toll-like receptor 4 signaling pathways

Inflammation has been implicated in the pathogenesis of various cerebral diseases. Thus, control of brain inflammation is regarded as one of the important therapeutic strategies for the treatment of neurodegenerative diseases such as Alzheimer׳s disease and stroke. Isobavachalcone, a flavonoid from Psoralea corylifolia, is known to possess a wide spectrum of biological activities and is expected to be useful in preventing or treating neurodegenerative diseases. However, very little is known regarding its effects on cerebral inflammation. In this study, we examined the effect of isobavachalcone on leukocyte adhesion and intercellular adhesion molecule-1 (ICAM-1) expression in brain endothelial cells activated with lipopolysaccharide (LPS) and explored the possible mechanisms involved. Isobavachalcone significantly down-regulated LPS-induced ICAM-1 expression and leukocyte-endothelial cell adhesion and suppressed NF-κB activity which is implicated in the expression of ICAM-1. It attenuated ICAM-1 expression as well as NF-κB transcriptional activity induced by macrophage-activating lipopeptide 2-kDa (MALP-2) or polyriboinosinic polyribocytidylic acid (poly[I:C]). Isobavachalcone also down-regulated LPS or poly[I:C]-induced expression of IFN-β, which can indirectly activate NF-κB. These data imply that isobavachalcone can modulate both MyD88-dependent and TRIF-dependent signaling of toll-like receptor 4 (TLR4). Taken together, our data suggest that isobavachalcone inhibits LPS-induced ICAM-1 expression and leukocyte adhesion to brain endothelial cell by blocking TLR4 signaling and thus, has the potential to ameliorate neuronal injury in brain diseases associated with inflammation.

Development of an HPLC Method for Absolute Quantification and QAMS of Flavonoids Components in Psoralea corylifolia L

The seeds of Psoralea corylifolia L. (Fabaceae) are a commonly used medicinal herb in eastern Asia with many beneficial effects in clinical therapies. In this study, a simple, sensitive, precise, and specific reverse phase high-performance liquid chromatography (HPLC) method was established for quantification of 9 flavonoids in P. corylifolia, including isobavachin, neobavaisoflavone, bavachin, corylin, bavachalcone, bavachinin, isobavachalcone, corylifol A, and 4'-O-methylbavachalcone. Based on this method, a quantitative analysis of multicomponents by single marker (QAMS) was carried out, and the relative correction factors (RCFs) were calculated for determining the contents of other flavonoids. The accuracy of QAMS method was verified by comparing with the results of external standard method, as well as the feasibility and adaptability of the method applied on quality control of P. corylifolia. The 9 compounds were baseline separated in 60 min with a good linearity of regression coefficient (R (2)) over 0.9991. The accuracies of QAMS were between 92.89% and 109.5%. The RSD values of f in different injection volume were between 2.3% and 3.6%. The results obtained from QAMS suggested that it was a convenient and accurate method to determine multicomponents especially when some authentic standard substances were unavailable. It can be used to control the quality of P. corylifolia.

In vitro evidence for bakuchiol's influence towards drug metabolism through inhibition of UDP-glucuronosyltransferase (UGT) 2B7

BACKGROUND

Inhibition of drug-metabolizing enzymes (DMEs) has been regarded as one of the most important reason for clinical drug-drug interaction.

AIM

The aim of the present study is to evaluate the inhibition of bakuchiol towards UDP-glucuronosyltransferase (UGT) 2B isoforms.

METHODS

In vitro recombinant UGT2B-catalyzed 4-methylumbelliferone glucuronidation was used as the probe reaction. Dixon plot and Lineweaver-Burk plot were employed to determine the inhibition kinetic type, and nonlinear regression of data was utilized to calculate the inhibition kinetic parameter (Ki). In vitro-in vivo extrapolation (IVIVE) was carried out to predict in vivo inhibition magnitude.

RESULTS

Among the tested UGT2B isoforms, UGT2B7 was inhibited by the strongest intensity. The noncompetitive inhibition was demonstrated by the results obtained from Dixon plot and Lineweaver-Burk plot. The Ki value was calculated to be 10.7 µM. In combination with the reported concentration after an intravenous administration of bakuchiol (15 mg/kg) in rats, the high risk of in vivo inhibition of bakuchiol towards UGT2B7-catalyzed metabolism of drugs was indicated.

CONCLUSION

All these results provide an important information for the risk evaluation of the clinical utilization of bakuchiol.

Grape phytochemicals and associated health benefits

The phytochemicals present in fruits and vegetables may play an important role in deceasing chronic disease risk. Grapes, one of the most popular and widely cultivated and consumed fruits in the world, are rich in phytochemicals. Epidemiological evidence has linked the consumption of grapes with reduced risk of chronic diseases, including certain types of cancer and cardiovascular disease. In vitro and in vivo studies have shown that grapes have strong antioxidant activity, inhibiting cancer cell proliferation and suppressing platelet aggregation, while also lowering cholesterol. Grapes contain a variety of phytochemicals, like phenolic acids, stilbenes, anthocyanins, and proanthocyanidins, all of which are strong antioxidants. The phytochemical composition of grapes, however, varies greatly among different varieties. While extensive research exists, a literature review of the health benefits of grapes and their phytochemicals has not been compiled to summarize this work. The aim of this paper is to critically review the most recent literature regarding the concentrations, biological activities, and mechanisms of grape phytochemicals.

Synthesis of ∆3-2-hydroxybakuchiol analogues and their growth inhibitory activity against rat UMR106 cells

A series of ∆³-2-hydroxybakuchiol analogues have been synthesized and tested for their growth inhibitory activity against rat UMR106 cells by using the MTT method. Some of them exhibit enhanced activities compared with the natural product, and the preliminary SAR profile shows that the chain tail on the natural product could be subtly modified to enhance the activity and the aromatic moiety or the terminal olefin on the main chain can also be modified without any evident loss of activity. The stereo-configuration of the quaternary chiral center has an important influence on the activity.

Isopsoralen Induces Differentiation of Prechondrogenic ATDC5 Cells via Activation of MAP Kinases and BMP-2 Signaling Pathways

Endochondral bone formation is the process by which mesenchymal cells condense to become chondrocytes, which ultimately form new bone. The process of chondrogenic differentiation and hypertrophy is critical for bone formation and as such is regulated by many factors. In this study, we aimed to indentify novel factors that regulate chondrogenesis. We investigated the possible role of isopsoralen in induction of chondrogenic differentiation in clonal mouse chondrogenic ATDC5 cells. Isopsoralen treatment stimulated the accumulation of cartilage nodules in a dose-dependent manner. Further, ATDC5 cells treated with isopsoralen were stained more intensely with Alcian blue than control cells, suggesting that isopsoralen increases the synthesis of matrix proteoglycans. Similarly, isopsoralen markedly induced the activation of alkaline phosphatase activity compared with control cells. Isopsoralen enhanced the expressions of chondrogenic marker genes such as collagen II, collagen X, OCN, Smad4 and Sox9 in a time-dependent manner. Furthermore, isopsoralen induced the activation of extracellular signal-regulated kinase (ERK) and p38 MAP kinase, but not that of c-jun N-terminal kinase (JNK). Isopsoralen significantly enhanced the protein expression of BMP-2 in a time-dependent manner. PD98059 and SB 203580, inhibitors of ERK and p38 MAPK, respectively, decreased the number of stained cells treated with isopsoralen. Taken together, these results suggest that isopsoralen mediates a chondromodulating effect by BMP-2 or MAPK signaling pathways, and is therefore a possible therapeutic agent for bone growth disorders.

Psoralen inhibits bone metastasis of breast cancer in mice

Breast cancer is the most common female malignancy and it frequently metastasizes to bone. Metastatic breast cancer continues to be the primary cause of death for women in East and Southeast Asia. Psoralen is a furocoumarin that can be isolated from the seeds of Psoralea corylifolia L. Psoralen exhibits a wide range of biological properties and has been demonstrated as an antioxidant, antidepressant, anticancer, antibacterial, and antiviral agent. Additionally, it is involved in the formation and regulation of bone. This study investigated whether psoralen can inhibit metastasis of breast cancer to bone in vivo. Histological, molecular biological, and imaging analyses revealed that psoralen inhibits bone metastases in mice. Psoralen may function to inhibit breast cancer cell growth in the bone microenvironment and regulate the function of osteoblasts and osteoclasts in tumor-bearing mice. The results of this study suggest that psoralen is a bone-modifying agent and a potential therapeutic to treat patients with bone metastases.

Psoralea corylifolia L. (Buguchi) - folklore to modern evidence: review

Psoralea corylifolia is an important medicinal plant which is used in several traditional medicines to cure various diseases. The plant extracts have been reported to possess antibacterial, antitumor, antioxidant, anti-inflammatory, antifungal and immunomodulatory activity. A wide range of chemical compounds including psoralen, isopsoralen, bakuchiol, psoralidin, bakuchalcone, bavachinin, flavones, volatile oils, lipids etc. are found in different parts of the plant. The present review is therefore, an effort to give a detailed survey of the literature on its botany, phytochemistry and ethnopharmacology along with special emphasis given on pharmacological activities of plant P. corylifolia.

Studies on lymphangiogenesis inhibitors from Korean and Japanese crude drugs

Metastasis occurs when cancer cells detach from a tumor, travel to distant sites in the body and develop into tumors in these new locations. Most cancer patients die from metastases. Among the various forms of cancer metastasis, lymphatic metastasis is an important determinant in cancer treatment and staging. In this study, we investigated lymphangiogenesis inhibitors from crude drugs used in Japan and Korea. The three crude drugs Saussureae Radix, Psoraleae Semen and Aurantti Fructus Immaturus significantly inhibited the proliferation of temperature-sensitive rat lymphatic endothelial (TR-LE) cells in vitro. By a chromatographic method using bioassay-guided fractionation methods, costunolide (1) and dehydrocostus lactone (2) from S. Radix, p-hydroxybenzaldehyde (3), psoralen (4), angelicin (5), psoracorylifol D (6), isobavachalone (7), bavachinin (8) Δ(3),2-hydroxybakuchiol (9) and bakuchiol (10) from P. Semen and cis-octadecyl ferulate (11), (2R)-3β,7,4'-trihydroxy-5-methoxy-8-(γ,γ-dimethylallyl)-flavanone (12), (2S)-7,4'-dihydroxy-5-methoxy-8-(γ,γ-dimethylallyl)-flavanone (13) and umbelliferone (14) from A. F. Immaturus were obtained. Three compounds (compounds 11-13) from A. F. Immaturus were isolated for the first time from this medicinal plant. Among isolated compounds, ten compounds (compounds 1, 2, 6-12, 13) showed an inhibitory effect on the proliferation and the capillary-like tube formation of TR-LE cells. In addition, all compounds except compound 12 showed selective inhibition of the proliferation of TR-LE cells compared to Hela and Lewis lung carcinoma (LLC) cells. These compounds might offer clinical benefits as lymphangiogenesis inhibitors and may be good candidates for novel anti-cancer and anti-metastatic agents.

Resveratrol inhibits proliferation, angiogenesis and induces apoptosis in colon cancer cells: calorie restriction is the force to the cytotoxicity

The aim of this study was to examine the antitumour activity of resveratrol in human colorectal cancer cell lines (HCT116 and Caco2) and to explore its mechanism of action assuming that it is by calorie-restriction effect. Resveratrol inhibited the proliferation of colon cancer cells with half maximal inhibitory concentration (IC(50)) equal to 50 and 130 μM for HCT116 and Caco2, respectively. Caco2 cells appeared with significant time-dependent increase in the glycolytic pathway, a behaviour that was absent in HCT116 cells. Resveratrol (100 μM) significantly decreased the glycolytic enzymes (pyruvate kinase and lactate dehydrogenase) in Caco2 cells, while an increase in citrate synthase activity and a decrease in glucose consumption were observed in both cell lines. Moreover, resveratrol downregulated the expressions of leptin and c-Myc, and decreased the content of vascular endothelial growth factor. The apoptotic markers, caspases 3 and 8, were activated and the Bax/BCl2 ratio was increased. The study suggested a promising anticancer activity of resveratrol, calorie-restriction pathway may be one of the driving forces for this activity.

Phenolic phytochemical displaying SARS-CoV papain-like protease inhibition from the seeds of Psoralea corylifolia

Severe acute respiratory syndrome coronavirus (SARS-CoV) papain-like protease (PLpro) is a key enzyme that plays an important role in SARS virus replication. The ethanol extract of the seeds of Psoralea corylifolia showed high activity against the SARS-CoV PLpro with an IC50 of value of 15 µg/ml. Due to its potency, subsequent bioactivity-guided fractionation of the ethanol extract led to six aromatic compounds (1-6), which were identified as bavachinin (1), neobavaisoflavone (2), isobavachalcone (3), 4'-O-methylbavachalcone (4), psoralidin (5) and corylifol A (6). All isolated flavonoids (1-6) inhibited PLpro in a dose-dependent manner with IC50 ranging between 4.2 and 38.4 µM. Lineweaver-Burk and Dixon plots and their secondary replots indicated that inhibitors (1-6) were mixed inhibitors of PLpro. The analysis of KI and KIS values proved that the two most promising compounds (3 and 5) had reversible mixed type I mechanisms.

An analogue of resveratrol HS-1793 exhibits anticancer activity against MCF-7 cells via inhibition of mitochondrial biogenesis gene expression

Resveratrol is a phytoalexin and polyphenol derived from grapes, berries, and peanuts. It has been shown to mediate death of a wide variety of cancer cells. Although resveratrol is considered an important potential chemotherapeutic agent, it is required at high doses to achieve a biologically or physiologically significant effect, which may be impractical for treating cancer. Thus, a more stable and potent derivative of resveratrol, with more effective tumoricidal activity, must be developed. A novel resveratrol analog, HS-1793, has recently been synthesized and was determined to exhibit a greater decrease in cancer cell viability than resveratrol. However, the underlying mechanism of HS-1793-induced cancer cell death remains unknown. We thus investigated the mechanism by which HS-1793 induces cell death and assessed whether this occurs through a mitochondrial-mediated mechanism. Using the MCF-7 breast cancer cell line, we determined that HS-1793 treatment significantly increased cell death at a relatively low dose compared with resveratrol. HS-1793 treatment more significantly decreased mitochondrial membrane potential, cellular ATP concentration, and cellular oxygen consumption rate than resveratrol treatment. At the molecular level, HS-1793 treatment down-regulated the expression of major mitochondrial biogenesis-regulating proteins, including mitochondrial transcriptional factor A (TFAM), Tu translation elongation factor (TUFM), and single-stranded DNA-binding protein. We conclude that HS- 1793 acts by regulating the expression of TFAM and TUFM, leading to a block in normal mitochondrial function, which sensitizes cancer cells to cell death. We therefore propose that HS-1793 can be a useful chemosensitization agent, which together with other such agents can efficiently target cancer cells.

Effects of resveratrol on growth and function of rat ovarian granulosa cells

OBJECTIVE

To evaluate the effects of resveratrol on growth and function of granulosa cells. Previously, we demonstrated that resveratrol exerts profound proapoptotic effects on theca-interstitial cells.

DESIGN

In vitro study.

SETTING

Research laboratory.

ANIMAL(S)

Immature Sprague-Dawley female rats.

INTERVENTION(S)

Granulosa cells were cultured in the absence or presence of resveratrol.

MAIN OUTCOME MEASURE(S)

DNA synthesis was determined by thymidine incorporation assay, apoptosis by activity of caspases 3/7, cell morphology by immunocytochemistry, steroidogenesis by mass spectrometry, antimüllerian hormone (AMH), and vascular endothelial growth factor (VEGF) expression by polymerase chain reaction and Western blot.

RESULT(S)

Resveratrol induced a biphasic effect on DNA synthesis, whereby a lower concentration stimulated thymidine incorporation and higher concentrations inhibited it. Additionally, resveratrol slightly increased the cell number and modestly decreased the activity of caspases 3/7 with no effect on cell morphology or progesterone production. However, resveratrol decreased aromatization and VEGF expression, whereas AMH expression remained unaltered.

CONCLUSION(S)

Resveratrol, by exerting cytostatic but not cytotoxic effects, together with antiangiogenic actions mediated by decreased VEGF in granulosa cells, may alter the ratio of theca-to-granulosa cells and decrease vascular permeability, and therefore may be of potential therapeutic use in conditions associated with highly vascularized theca-interstitial hyperplasia and abnormal angiogenesis, such as those seen in women with polycystic ovary syndrome.

Resveratrol, MicroRNAs, Inflammation, and Cancer

MicroRNAs are short noncoding RNAs that regulate the expression of many target genes posttranscriptionally and are thus implicated in a wide array of cellular and developmental processes. The expression of miR-155 or miR-21 is upregulated during the course of the inflammatory response, but these microRNAs are also considered oncogenes due to their upregulation of expression in several types of tumors. Furthermore, it is now well established that inflammation is associated with the induction or the aggravation of nearly 25% of cancers. Therefore, the above microRNAs are thought to link inflammation and cancer. Recently, resveratrol (trans-3,4′,5-trihydroxystilbene), a natural polyphenol with antioxidant, anti-inflammatory, and anticancer properties, currently at the stage of preclinical studies for human cancer prevention, has been shown to induce the expression of miR-663, a tumor-suppressor and anti-inflammatory microRNA, while downregulating miR-155 and miR-21. In this paper we will discuss how the use of resveratrol in therapeutics may benefit from the preanalyses on the status of expression of miR-155 or miR-21 as well as of TGFβ1. In addition, we will discuss how resveratrol activity might possibly be enhanced by simultaneously manipulating the levels of its key target microRNAs, such as miR-663.

Bakuchicin induces vascular relaxation via endothelium-dependent NO-cGMP signaling

Bakuchicin is a furanocoumarin derived from the seeds of Psoralea corylifolia. The aim of the present study was to investigate the effect of bakuchicin on vascular tone in rat aortic tissue. Bakuchicin induced a dose-dependent relaxation of phenylephrine-precontracted rat aorta which was abolished by removal of the endothelium. Pretreatment of the endothelium-intact aortic tissues with NG-nitro-L-arginine methylester (L-NAME) or 1H-[1,2,4]-oxadiazole-[4,3-α]-quinoxalin-1-one (ODQ) significantly inhibited the vascular relaxation induced by bakuchicin. Incubation with bakuchicin increased the production of cGMP in a concentration-dependent manner, and this effect was blocked by pretreatment with both L-NAME and ODQ. Vascular relaxation induced by bakuchicin was significantly inhibited by pretreatment with verapamil and diltiazem, but not by several other inhibitors including tetraethylammonium (TEA), glibenclamide, indomethacin, atropine or propranolol. These results suggested that bakuchicin-induced vasodilatation is closely associated with the endothelium-dependent nitric oxide (NO)/cGMP signaling pathway, with the possible involvement of L-type Ca(2+) channels.

Resveratrol commonly displays hormesis: occurrence and biomedical significance

Resveratrol induces hormetic dose responses in a wide range of biological models, affecting numerous endpoints of biomedical and therapeutic significance. These responses were reported for numerous human tumor cell lines affecting breast, prostate, colon, lung, uterine and leukemia. In such cases, low concentrations of resveratrol enhanced tumor cell proliferation whereas higher concentrations were inhibitory. Similar resveratrol-induced biphasic dose responses were seen with several parasitic diseases, including Leishmaniasis and trichinella. Hormetic effects were also reported in animal models for cardiovascular induced injury, gastric lesions, ischemic stroke, Alzheimer's disease and osteoporosis. In these cases, there was often a protective effect at low doses but an adverse effect at higher doses, exacerbating the disease process/incidence. This analysis indicates that many effects induced by resveratrol are dependent on dose and that opposite effects occur at low and high doses, being indicative of a hormetic dose response. Despite consistent occurrence of hormetic dose responses of resveratrol in a wide range of biomedical models, epidemiologic and clinical trials are needed to assess the nature of its dose-response in humans.

Quantum-chemical study of interactions of trans-resveratrol with guanine-thymine dinucleotide and DNA-nucleobases

Trans-resveratrol, a natural phytoalexin present in red wine and grapes, has gained considerable attention because of its antiproliferative, chemopreventive and proapoptotic activity against human cancer cells. The accurate quantum-chemical computations based on the density functional theory (DFT) and ab initio second-order Møller-Plesset perturbation method (MP2) have been performed for the first time to study interactions of trans-resveratrol with guanine-thymine dinucleotide and DNA-derived nitrogenous bases: adenine, guanine, cytosine and thymine in vacuum and water medium. This compound is found to show high affinity to nitrogenous bases and guanine-thymine dinucleotide. The electrostatic interactions from intermolecular hydrogen bonding increase the stability of complexes studied. In particular, significantly strong hydrogen bonds between 4'-H atom of trans-resveratrol and imidazole nitrogen as well as carbonyl oxygen atoms of nucleobases studied stabilize these systems. The stabilization energies computed reveal that the negatively charged trans-resveratrol-dinucleotide complex is more energetically stable in water medium than in vacuum. MP2 method gives more reliable and significantly high values of stabilization energy of trans-resveratrol-dinucleotide, trans-resveratrol-guanine and trans-resveratrol-thymine complexes than B3LYP exchange-correlation functional because it takes into account London dispersion energy. According to the results, in the presence of trans-resveratrol the 3'-5' phosphodiester bond in dinucleotide can be cleaved and the proton from 4'-OH group of trans-resveratrol migrates to the 3'-O atom of dinucleotide. It is concluded that trans-resveratrol is able to break the DNA strand. Hence, the findings obtained help understand antiproliferative and anticancer properties of this polyphenol.

Isolation of antioxidants from Psoralea corylifolia fruits using high-speed counter-current chromatography guided by thin layer chromatography-antioxidant autographic assay

A combinative method using high-speed counter-current chromatography (HSCCC) and thin layer chromatography (TLC) as an antioxidant autographic assay was developed to separate antioxidant components from the fruits of Psoralea corylifolia. Under the guidance of TLC bioautography, eight compounds including five flavonoids and three coumarins were successfully separated from the fruits of P. corylifolia by HSCCC with an optimized two-phase solvent system, n-hexane-ethyl acetate-methanol-water (1:1.1:1.3:1, v/v/v/v). The separation produced 5.91mg psoralen, 6.26mg isopsoralen, 3.19mg psoralidin, 0.92mg corylifol A, and 2.43mg bavachinin with corresponding purities of 99.5, 99.8, 99.4, 96.4, and 99.0%, as well as three sub-fractions, in a single run from 250mg ethyl acetate fraction of P. corylifolia extract. Following an additional clean-up step by preparative TLC, 0.4mg 8-prenyldaidzein (purity 91.7%), 4.18mg neobavaisoflavone (purity 97.4%) and 4.36mg isobavachalcone (purity 96.8%) were separated from the three individual sub-fractions. The structures of the isolated compounds were identified by (1)H NMR and (13)C NMR. The results of antioxidant activity estimation by electron spin resonance (ESR) method showed that psoralidin was the most active antioxidant with an IC50 value of 44.7microM. This is the first report on simultaneous separation of eight compounds from P. corylifolia by HSCCC.

In vivo pharmacokinetics of bakuchiol after oral administration of bakuchiol extraction in rat plasma

ETHNOPHARMACOLOGICAL RELEVANCE

Psoralea corylifolia L. (Fabaceae) was a traditional Chinese medicine for the treatment of various skin diseases such as psoriasis, vitiligo and chronic graft-versus-host, and has been proved to show anticancer, cytotoxic, anti-bacterial, cardiac, diaphoretic, diuretic, stimulant, aphrodisiac and tonic effects. Bakuchiol was one of the main active ingredients of this traditional Chinese medicine.

AIM OF THE STUDY

In this paper, pharmacokinetic study was conducted to obtain pharmacokinetic parameters of bakuchiol.

MATERIALS AND METHODS

Bakuchiol was enriched using resin inform the ethanol extract of Psoralea corylifolia L., HPLC-UV was used to determine the concentration of bakuchiol in rat plasma at different time points after administration. The main pharmacokinetic parameters of bakuchiol in rat were obtained based on the analysis of the plasma sample.

RESULTS

The pharmacokinetics of bakuchiol was fitted with a two-compartment model and it was eliminated relative slowly in rats.

CONCLUSIONS

The HPLC-UV method was successfully applied to study the pharmacokinetics of bakuchiol in rats.

Novel bisstyryl derivatives of bakuchiol: targeting oral cavity pathogens

Novel bisstyryl derivatives of bakuchiol using Heck coupling reaction as the key step were synthesized and screened against a panel of six oral cavity pathogens for their antimicrobial activity. Four compounds (9-12) showed two to fourfold and four to eightfold better activity (MIC 0.25-16 microg/ml) than bakuchiol and triclosan respectively. These compounds effectively inhibit the biofilm formation of single and multiple species at 2 - 8 x MICs. 4- and 4'-Hydroxy/methoxy styryl moieties of the bakuchiol derivatives play a pivotal role towards the activity as established in the SAR studies. Mechanism of action studies revealed microbial membrane structure disruption as the probable mode of action of these compounds.

Phytoestrogens from Psoralea corylifolia reveal estrogen receptor-subtype selectivity

The seed of Psoralea corylifolia L. (PCL), a well-known traditional Chinese medicine, has been applied as a tonic or an aphrodisiac agent and commonly used as a remedy for bone fracture, osteomalacia and osteoporosis in China. In our study, the estrogen receptor subtype-selective activities of the extracts and compounds derived from PCL were analyzed using the HeLa cell assay. The different fractions including petroleum ether, CH(2)Cl(2) and EtOAc fractions of the EtOH extract of PCL showed significant activity in activating either ERalpha or ERbeta whereas the n-BuOH fraction showed no estrogenic activity. Further chromatographic purification of the active fractions yielded seven compounds including the two coumarins isopsoralen and psoralen, the four flavonoids isobavachalcone, bavachin, corylifol A and neobavaisoflavone, and the meroterpene phenol, bakuchiol. In reporter gene assay, the two coumarins (10(-8)-10(-5)M) acted as ERalpha-selective agonists while the other compounds (10(-9)-10(-6)M) activated both ERalpha and ERbeta. The estrogenic activities of all compounds could be completely suppressed by the pure estrogen antagonist, ICI 182,780, suggesting that the compounds exert their activities through ER. Only psoralen and isopsoralen as ERalpha agonists promoted MCF-7 cell proliferation significantly. Although all the compounds have estrogenic activity, they may exert different biological effects. In conclusion, both ER subtype-selective and nonselective activities in compounds derived from PCL suggested that PCL could be a new source for selective estrogen-receptor modulators.

Secondary metabolites as DNA topoisomerase inhibitors: A new era towards designing of anticancer drugs

A large number of secondary metabolites like alkaloids, terpenoids, polyphenols and quinones are produced by the plants. These metabolites can be utilized as natural medicines for the reason that they inhibit the activity of DNA topoisomerase which are the clinical targets for anticancer drugs. DNA topoisomerases are the cellular enzymes that change the topological state of DNA through the breaking and rejoining of DNA strands. Synthetic drugs as inhibitors of topoisomerases have been developed and used in the clinical trials but severe side effects are a serious problem for them therefore, there is a need for the development of novel plant-derived natural drugs and their analogs which may serve as appropriate inhibitors with respect to drug designing. The theme for this review is how secondary metabolites or natural products inactivate the action of DNA topoisomerases and open new avenues towards isolation and characterization of compounds for the development of novel drugs with anticancer potential.

The resveratrol analogue 4,4'-dihydroxy-trans-stilbene inhibits cell proliferation with higher efficiency but different mechanism from resveratrol

Resveratrol (3,4',5-trihydroxy-trans-stilbene) is a natural phytoalexin found in grapes and wine, which shows antiproliferative activity. We previously found that 4-hydroxy group in the trans conformation was absolutely required for the inhibition of cell proliferation. In the present work we have synthesized the resveratrol analogue 4,4'-dihydroxy-trans-stilbene, which contains two OH in 4' and 4 positions, with the aim of developing a compound with an antiproliferative potential higher than that of resveratrol, on the basis of the correlation between structure and activity previously observed. In comparison with resveratrol, 4,4'-dihydroxy-trans-stilbene inhibited cell clonogenic efficiency of fibroblasts nine times more although with a different mechanism. First, 4,4'-dihydroxy-trans-stilbene induced predominantly an accumulation of cells in G1 phase, whereas resveratrol perturbed the G1/S phase transition. Second, although both compounds were able to inhibit DNA polymerase (pol) delta in an in vitro assay, 4, 4'-dihydroxy-trans-stilbene did not affect pol alpha activity. Finally, 4,4'-dihydroxy-trans-stilbene increased p21(CDKN1A) and p53 protein levels, whereas resveratrol led to phosphorylation of the S-phase checkpoint protein Chk1. Taken together, our results demonstrated for the first time that the two hydroxyl groups on 4- and 4'- positions of the stilbenic backbone enhance the antiproliferative effect and introduce additional targets in the mechanism of action of resveratrol. In conclusion, 4,4'-dihydroxy-trans-stilbene has potent antiproliferative activities that differ from the effect of resveratrol shown in this system, suggesting that it warrants further development as a potential chemopreventive or therapeutic agent.

Multiple molecular targets of resveratrol: Anti-carcinogenic mechanisms

Plant-derived polyphenolic compounds, such as the stilbene resveratrol (trans-3,4',5-trihydroxystilbene), have been identified as potent anti-cancer agents. Extensive in vitro studies revealed multiple intracellular targets of resveratrol, which affect cell growth, inflammation, apoptosis, angiogenesis, and invasion and metastasis. These include tumor suppressors p53 and Rb; cell cycle regulators, cyclins, CDKs, p21WAF1, p27KIP and INK and the checkpoint kinases ATM/ATR; transcription factors NF-kappaB, AP-1, c-Jun, and c-Fos; angiogenic and metastatic factors, VEGF and matrix metalloprotease 2/9; cyclooxygenases for inflammation; and apoptotic and survival regulators, Bax, Bak, PUMA, Noxa, TRAIL, APAF, survivin, Akt, Bcl2 and Bcl-X(L). In addition to its well-documented anti-oxidant properties, there is increasing evidence that resveratrol exhibits pro-oxidant activity under certain experimental conditions, causing oxidative DNA damage that may lead to cell cycle arrest or apoptosis. This review summarizes in vitro mechanistic data available for resveratrol and discusses new potential anti-cancer targets and the antiproliferative mechanisms of resveratrol.

Antitumor effects of KITC, a new resveratrol derivative, in AsPC-1 and BxPC-3 human pancreatic carcinoma cells

Pancreatic cancer is a very aggressive malignant disease due to lack of early diagnosis and chemotherapeutic resistance of the tumor cells. There is distinct evidence that food derived polyphenols possess chemopreventive effects in the development of several cancers including pancreatic carcinoma. Resveratrol is one of those phenolic compounds found in grape skins and other fruits with known anticancer activity. Various polymethoxylated resveratrol derivatives showed stronger antiproliferative effects than resveratrol in tumor cell lines. The aim of our study was to evaluate the cytotoxic and biochemical effects of a newly synthesized polymethoxylated resveratrol analogue, N-hydroxy-N'-(3,4,5-trimethoxphenyl)-3,4,5-trimethoxy-benzamidine (KITC) in two human pancreatic cancer cell lines. The human pancreatic cancer cell lines, AsPC-1 and BxPC-3 were used to test the potential inhibitory effect of the resveratrol derivative on cell proliferation and the underlying mechanisms of this effect. After 7 days of incubation, KITC inhibited the growth of AsPC-1 and BxPC-3 cells with IC(50) values of 9.6 and 8.7 microM, respectively. KITC (40 microM) arrested cells in the G0/G1 phase and depleted cells in the S phase of the cell cycle (-105% and -35% of control, respectively). KITC induced dose-dependent apoptosis in both pancreatic cancer cell lines and was found to significantly reduce the in situ activity of ribonucleotide reductase, the key enzyme of DNA synthesis. Employing growth inhibition assays, KITC acted synergistically with gemcitabine in both cell lines. In summary, we found that KITC exerted considerable antitumor activity against human pancreatic cancer cells and could be a promising candidate for further investigations to establish a new chemotherapeutic regimen.

Immunomodulatory activity of synthetic triterpenoids: inhibition of lymphocyte proliferation, cell-mediated cytotoxicity, and cytokine gene expression through suppression of NF-kappaB

Synthetic oleanane triterpenoids (CDDO, CDDO-Im and CDDO-Me) are potent anti-inflammatory agents, but have not been investigated for effects on T cell-mediated immune responses. Here we demonstrate that CDDOs have profound immunosuppressive effects on T cell proliferation, development of IL-2 activated LAK cells and cytotoxic T lymphocytes (CTLs), and expression of cytokines at concentrations of 1.25 microM to 0.078 microM. Treatment with CDDO-Me also inhibited the generation of allo-reactive T cell responses in vivo. The suppression of these cell-mediated immune responses by CDDO-Me was associated with the inhibition of NF-kappaB transcription factor.

Resveratrol disrupts peroxynitrite-triggered mitochondrial apoptotic pathway: a role for Bcl-2

Resveratrol (3,4',5-trihydroxystilbene) is a phytochemical believed to be partly responsible for the cardioprotective effects of red wine due to its numerous biological activities. Here, we studied biochemical pathways underlying peroxynitrite-mediated apoptosis in endothelial cells and potential mechanisms responsible for resveratrol cytoprotective action. Peroxynitrite triggered endothelial cell apoptosis through caspases-8, -9 and -3 activation implying both mitochondrial and death receptor apoptotic pathways. Resveratrol was able to prevent peroxynitrite-induced caspases-3 and -9 activation, but not caspase-8 activation. Additionally, peroxynitrite increased intracellular levels of Bax without affecting those of Bcl-2, increasing consequently the Bax/Bcl-2 ratio. This ratio decreased when cells where pre-incubated with 10 and 50 muM resveratrol, mainly due to resveratrol ability per se to increase Bcl-2 intracellular levels without affecting Bax intracellular levels. These results propose an additional mechanism whereby resveratrol may exert its cardioprotective effects and suggest a key role for Bcl-2 in the resveratrol anti-apoptotic action, especially in disrupting peroxynitrite-triggered mitochondrial pathway.

Resveratrol inhibits nitric oxide and prostaglandin E2 production by lipopolysaccharide-activated C6 microglia

Resveratrol, a natural polyphenolic antioxidant found in red wine and grapes, has been reported to exert a variety of important pharmacological effects, including anti-inflammatory, cardioprotective, and cancer chemopreventive properties. In the present study, we investigated the effect of resveratrol on the production of nitric oxide (NO) and prostaglandin (PG) E2 by lipopolysaccharide (LPS)-activated C6 microglia. Exposure of cultured rat C6 astroglioma cells to LPS increased their release of NO and PGE2 and their inducible expression of NO synthase and cyclooxygenase-2, all of which were significantly inhibited by resveratrol pretreatment. Further studies revealed that resveratrol suppressed LPS-induced nuclear translocation and activation of nuclear factor kappaB (NF-kappaB). These results demonstrate a potent suppressive effect of resveratrol on pro-inflammatory responses of microglia by modulation of NF-kappaB activity, suggesting a therapeutic potential for this compound in neurodegenerative diseases accompanied by microglial activation.

Chronic treatment with resveratrol induces redox stress- and ataxia telangiectasia-mutated (ATM)-dependent senescence in p53-positive cancer cells

The induction of senescence, an irreversible growth arrest, in cancer cells is regarded as a mean to halt tumor progression. The phytoalexin resveratrol (RV) is known to possess a variety of cancer-preventive, -therapeutic, and -chemosensitizing properties. We report here that chronic treatment with RV in a subapoptotic concentration induces senescence-like growth arrest in tumor cells. In contrast to the widely accepted antioxidant property of RV, we demonstrate that one causative stimulus for senescence induction by chronic RV is an increased level of reactive oxygen species (ROS). The ROS formed upon RV exposure include hydrogen peroxide and superoxide and originate largely from mitochondria. Consistently, co-incubation with the antioxidant N-acetyl cysteine interfered with RV-mediated reactivation of the senescence program. Molecular mediators on the way from increased ROS levels to the observed growth arrest include p38 MAPK, p53, and p21. Moreover, we provide evidence that RV-initiated replication stress, apparent by activation of the ataxia telangiectasia-mutated kinase pathway, is associated with increased ROS levels and senescence induction. This is the first report linking cell cycle effects with a pro-oxidant and pro-senescent effect of RV in cancer cells.

Chemical fingerprint and quantitative analysis of fructus psoraleae by high-performance liquid chromatography

Fructus Psoraleae, a widely used traditional Chinese medicine, is well known as a health supplement ingredient. In our study, an improved and comprehensive HPLC fingerprint of Fructus Psoraleae was established. Two important new benzofuran glycosides, psoralenoside and isopsoralenoside, were identified as characteristic constituents for the first time. HPLC separation was performed on an RP-C8 column. The mobile phase was acetonitrile and 0.1% acetic acid solution with linear gradient change of acetonitrile from 10 to 82% in 40 min. The flow rate was 1.0 mL/min, and the detection wavelength was set at 310 nm. The HPLC chromatograms of twenty-six samples from different regions of China showed a similar pattern. Twelve peaks were selected as characteristic peaks and further identified as psoralenoside, isopsoralenoside, psoralen, isopsoralen, bavachromene, corylifolin, corylin, psoralidin, isobavachalcone, bavachinin, corylifol A, and bakuchiol, respectively. Nine of them were simultaneously quantitatively analyzed for the first time. A more comprehensive analytical method was established for the fingerprint of Fructus Psoraleae. It is very useful for authentication and quality assessment of the crude drug.