Caffeic Acid Enhances the Anti-Leukemic Effect of Imatinib on Chronic Myeloid Leukemia Cells and Triggers Apoptosis in Cells Sensitive and Resistant to Imatinib.

Among the phenolic acids tested on the K562 cell line, a model of chronic myeloid leukemia (CML), caffeic acid (CA) was biologically active on sensitive and imatinib (IM)-resistant cells at micro-molar concentration, either in terms of reduction of cell proliferation or triggering of apoptosis. The CA treatment provoked mitochondrial membrane depolarization, genomic DNA fragmentation and phosphatidylserine exposure, hallmarks of apoptosis. Cell cycle analysis following the treatment with comparable cytotoxic concentrations of IM or CA showed marked differences in the distribution profiles. The reduction of cell proliferation by CA administration was associated with increased expression of two cell cycle repressor genes, CDKN1A and CHES1, while IM at a cytotoxic concentration increased the CHES1 but not the CDKN1A expression. In addition, CA treatment affected the proliferation and triggered the apoptosis in IM-resistant cells. Taken together, these data suggested that CA induced the anti-proliferative effect and triggered apoptosis of CML cells by a different mechanism than IM. Finally, the combined administration of IM and CA at suboptimal concentrations evidenced a synergy of action in determining the anti-proliferative effect and triggering apoptosis. The ability of CA to potentiate the anti-leukemic effect of IM highlighted the nutraceutical potential of CA in CML.

Genome analysis of the new human polyomaviruses.

Polyomaviridae is a growing family of naked, double-stranded DNA viruses that infect birds and mammals. The last few years, several new members infecting birds or primates have been discovered, including seven human polyomaviruses: KI, WU, Merkel cell polyomavirus, HPyV6, HPyV7, trichodysplasia spinulosa-associated polyomavirus, and HPyV9. In addition, DNA and antibodies against the monkey lymphotropic polyomavirus have been detected in humans, indicating that this virus can also infect man. However, little is known about the route of infection, transmission, cell tropism, and, with the exception of Merkel cell polyomavirus and trichodysplasia spinulosa-associated polyomavirus, the pathogenicity of these viruses. This review compares the genomes of these emerging human polyomaviruses with previously known polyomaviruses detected in man, reports mutations in different isolates, and predicts structural and functional properties of their viral proteins.

BK virus-associated infection in cerebrospinal fluid of neurological patients and mutation analysis of the complete VP1 gene in different patient groups.

While BK virus (BKV) is frequently associated with pathological conditions in bone marrow and renal transplant recipients, BKV infection in neurological individuals has been rarely reported. As a result of a BKV, JCV, and SV40 large T antigen-specific multiplex PCR on 2,062 cerebrospinal fluid (CSF) samples from neurological patients suspicious of JCV infection, we identified 20 subjects with at least 1 CSF specimen positive for BKV large T antigen DNA. Because VP1 protein has been suggested to influence the biological/pathological properties of BKV, we tried to sequence the entire VP1 gene in the BKV-positive neurological patients and succeeded in 14 of the 20 neurological patients. To compare the VP1 sequence of the BKV neurological strains with that of non-neurotropic strains in other clinical situations, full-length VP1 DNA was sequenced in 15 renal and 6 bone marrow transplant recipients positive to BKV-viremia, and in 8 pregnant women as non-pathological controls. An increased (respectively, decreased) tendency for mutations in the BC loop (respectively, EF loop) was observed, and no mutations were detected in the CD, GH, and HI loops. Subtype I was predominant (93%) and compared to archetypal BKV (WW), amino acid substitutions were detected in 4/14 neurological patients, 10/15 renal transplant recipients, 3/6 bone marrow transplant patients, and in all the pregnant women. Each patient group had distinctive VP1 mutations, but these unique substitutions were not present in all patients of this group. However, molecular modeling simulations of the VP1 mutants predicted changes in protein surface properties which might affect the VP1-receptor interaction.

The diterpenoid alkaloid noroxoaconitine is a Mapkap kinase 5 (MK5/PRAK) inhibitor.

The mitogen-activated protein kinase-activated protein kinase MK5 is ubiquitously expressed in vertebrates and is implicated in cell proliferation, cytoskeletal remodeling, and anxiety behavior. This makes MK5 an attractive drug target. We tested several diterpenoid alkaloids for their ability to suppress MK5 kinase activity. We identified noroxoaconitine as an ATP competitor that inhibited the catalytic activity of MK5 in vitro (IC50 = 37.5 µM; K(i) = 0.675 µM) and prevented PKA-induced nuclear export of MK5, a process that depends on kinase active MK5. MK5 is closely related to MK2 and MK3, and noroxoaconitine inhibited MK3- and MK5- but not MK2-mediated phosphorylation of the common substrate Hsp27. Molecular docking of noroxoaconitine into the ATP binding sites indicated that noroxoaconitine binds more strongly to MK5 than to MK3. Noroxoaconitine and derivatives may help in elucidating the precise biological functions of MK5 and may prove to have therapeutic values.

Specific interactions and binding free energies between thermolysin and dipeptides: molecular simulations combined with ab initio molecular orbital and classical vibrational analysis.

Thermolysin (TLN) is a metalloprotease widely used as a nonspecific protease for sequencing peptide and synthesizing many useful chemical compounds by the chemical industry. It was experimentally shown that the activity and functions of TLN are inhibited by the binding of many types of amino acid dipeptides. However, the binding mechanisms between TLN and dipeptides have not been clarified at the atomic and electronic levels. In this study, we investigated the binding mechanisms between TLN and four dipeptides. Specific interactions and binding free energies (BFEs) between TLN and the dipeptides were calculated using molecular simulations based on classical molecular dynamics and ab initio fragment molecular orbital (FMO) methods. The molecular systems were embedded in solvating water molecules during calculations. The calculated BFEs were qualitatively consistent with the trend of the experimentally observed inhibition of TLN activity by binding of the dipeptides. In addition, the specific interactions between the dipeptides and each amino acid residue of TLN or solvating water molecules were elucidated by the FMO calculations.

Identification of novel quinazolin-4(3H)-ones as inhibitors of thermolysin, the prototype of the M4 family of proteinases.

A combinatorial series of novel quinazolin-4(3H)-ones were synthesised and their structures were established based on spectroscopic data (IR, NMR, EI-MS, and FAB-MS). The compounds were tested for inhibition of the zinc metalloproteinase thermolysin (TLN) utilizing a chemical array-based approach. Some of the compounds were found to inhibit TLN, with IC(50) values ranging from 0.0115 microM (compound 3) to 122,637 microM (compound 29). Compound 3 [3-phenyl-2-(trifluoromethyl) quinazolin-4(3H)-one] (IC(50)=0.0115 microM) and compound 35 [3-(isopropylideneamino)-2,2-dimethyl-2,3-dihydroquinazolin-4 (1H)-one] (IC(50)=0.2477 microM) were found to be the most potent inhibitors.

Ethnomedicines and ethnomedicinal phytophores against herpesviruses.

Herpesviruses are important human pathogens that can cause mild to severe lifelong infections with high morbidity in susceptible adults. Moreover, Herpes simplex virus (HSV) type 2, for example, has been reported to be responsible for increased transmission and disease progression of human immunodeficiency virus (HIV). Therefore, the discovery of novel anti-HSV drugs deserves great efforts. Herbal medicinal products have been used as source of putative candidate drugs in many diseases. However, in case of viral diseases the development of antivirals from natural source is less explored probably because within the virus there are few specific targets where the small molecules can interact to inhibit or kill the virus. The currently available antiherpes drugs are nucleoside analogs that did not cure the lifelong or recurrent infections and the use of these drugs often lead to the development of viral resistance coupled with the problem of side effects, recurrence and viral latency. However a wide array of herbal products, used by diverse medicinal systems throughout the world, showed high level of antiherpesvirus activities and many of them have complementary and overlapping mechanism of action, either by inhibiting viral replication, or viral genome synthesis. This chapter will summarize some of the promising herbal extracts and purified compounds isolated from the herbal sources by several laboratories. Cases with proven in vitro and documented in vivo activities, along with their structure-activity relationship against herpesviruses are discussed.

Induction of apoptosis of human primary osteoclasts treated with extracts from the medicinal plant Emblica officinalis.

BACKGROUND: Osteoclasts (OCs) are involved in rheumatoid arthritis and in several pathologies associated with bone loss. Recent results support the concept that some medicinal plants and derived natural products are of great interest for developing therapeutic strategies against bone disorders, including rheumatoid arthritis and osteoporosis. In this study we determined whether extracts of Emblica officinalis fruits display activity of possible interest for the treatment of rheumatoid arthritis and osteoporosis by activating programmed cell death of human primary osteoclasts. METHODS: The effects of extracts from Emblica officinalis on differentiation and survival of human primary OCs cultures obtained from peripheral blood were determined by tartrate-acid resistant acid phosphatase (TRAP)-positivity and colorimetric MTT assay. The effects of Emblica officinalis extracts on induction of OCs apoptosis were studied using TUNEL and immunocytochemical analysis of FAS receptor expression. Finally, in vitro effects of Emblica officinalis extracts on NF-kB transcription factor activity were determined by gel shift experiments. RESULTS: Extracts of Emblica officinalis were able to induce programmed cell death of mature OCs, without altering, at the concentrations employed in our study, the process of osteoclastogenesis. Emblica officinalis increased the expression levels of Fas, a critical member of the apoptotic pathway. Gel shift experiments demonstrated that Emblica officinalis extracts act by interfering with NF-kB activity, a transcription factor involved in osteoclast biology. The data obtained demonstrate that Emblica officinalis extracts selectively compete with the binding of transcription factor NF-kB to its specific target DNA sequences. This effect might explain the observed effects of Emblica officinalis on the expression levels of interleukin-6, a NF-kB specific target gene. CONCLUSION: Induction of apoptosis of osteoclasts could be an important strategy both in interfering with rheumatoid arthritis complications of the bone skeleton leading to joint destruction, and preventing and reducing osteoporosis. Accordingly, we suggest the application of Emblica officinalis extracts as an alternative tool for therapy applied to bone diseases.

Ethanolic extract from Hemidesmus indicus (Linn) displays otoprotectant activities on organotypic cultures without interfering on gentamicin uptake.

The ethanolic extract from Hemidesmus indicus (Linn) (Apocynaceae) (Hie) was studied for its otoprotective effects in ex vivo rat organotypic model of gentamicin (GM) toxicity. In organ of Corti organotypic cultures (OC), GM can induce a fast dose-dependent apoptosis of hair cells (HC), both external and internal. We found that, after coadministration of GM and Hie to organotypic cultures, the extract was able to significantly counteract this toxic effect on HC, at the concentration of 25 and 50microg/ml. Interestingly, at these concentrations the extract was present in the cell medium at a concentration 1.6- and 3.3-fold lower than GM, suggesting its otoprotective activity could not merely due to an aspecific inhibition of GM entry. To support this hypothesis, we evaluated the amount of GM present in organotypic cultures after the coadministration of 1.5mg/ml GM and Hie, and found no significant reduction of GM uptake in the presence of 100microg/ml Hie. These data suggest the otoprotective action of Hie derives from specific inhibition of the apoptotic routine induced by GM treatment.

Dragon method for finding novel tyrosinase inhibitors: Biosilico identification and experimental in vitro assays.

QSAR (quantitative structure-activity relationship) studies of tyrosinase inhibitors employing Dragon descriptors and linear discriminant analysis (LDA) are presented here. A data set of 653 compounds, 245 with tyrosinase inhibitory activity and 408 having other clinical uses were used. The active data set was processed by k-means cluster analysis in order to design training and prediction series. Seven LDA-based QSAR models were obtained. The discriminant functions applied showed a globally good classification of 99.79% for the best model Class=-96.067+1.988 x 10(2)X0Av +9 1.907 BIC3 + 6.853 CIC1 in the training set. External validation processes to assess the robustness and predictive power of the obtained model were carried out. This external prediction set had an accuracy of 99.44%. After that, the developed models were used in ligand-based virtual screening of tyrosinase inhibitors from the literature and never considered in either training or predicting series. In this case, all screened chemicals were correctly classified by the LDA-based QSAR models. As a final point, these fitted models were used in the screening of new bipiperidine series as new tyrosinase inhibitors. These methods are an adequate alternative to the process of selection/identification of new bioactive compounds. The biosilico assays and in vitro results of inhibitory activity on mushroom tyrosinase showed good correspondence. It is important to stand out that compound BP4 (IC(50)=1.72 microM) showed higher activity in the inhibition against the enzyme than reference compound kojic acid (IC(50)=16.67 microM) and l-mimosine (IC(50)=3.68 microM). These results support the role of biosilico algorithm for the identification of new tyrosinase inhibitor compounds.

Predictive QSAR modeling for the successful predictions of the ADMET properties of candidate drug molecules.

Chemical breakthrough generates large numbers of prospective drug molecules; the use of ADMET (absorption, distribution, metabolism, excretion and toxicity) properties is flattering progressively more imperative in the drug discovery, assortment, development and promotion processes. Due to the inauspicious ADMET properties a huge amount of molecules in the development stage got failure. In the past years several authors reported that it possible to do some prediction of the ADMET properties using the structural features of the molecules, suing several approaches. One of the most important approaches is QSAR modeling of the data derived from their activity profiles and their different structural features (i.e., quantitative molecular descriptors). This review is critically assessing some of the most important issues for the effective prediction of ADMET properties of drug candidates based on QSAR modeling approaches.

Extracts and molecules from medicinal plants against herpes simplex viruses.

Herpes simplex viruses (HSV-1 and -2) are important pathogens for humans, especially in the case of highly susceptible adults. Moreover, HSV-2 has been reported to be a high risk factor for HIV infection. Therefore, the discovery of novel anti-HSV drugs deserves great efforts. In this paper, we review anti-HSV substances from natural sources, including both extracts and pure compounds from herbal medicines, reported in studies from several laboratories. The role of traditional medicine for the development of anti-HSV compounds is also discussed. Interestingly, it was found that traditional medicines, like Ayurvedic, traditional Chinese (TCM), Chakma medicines, are good and potential sources for promising anti-HSV drugs. A second objective of this review is to discuss several anti-HSV compounds with respect to their structure-activity relationship (SAR). A large number of small molecules, like phenolics, polyphenols, terpenes (e.g., mono-, di-, tri-), flavonoids, sugar-containing compounds, were found to be promising anti-herpetic agents. Our major conclusion is that natural products from medicinal plant extracts are very important source of anti-HSV agents.

Expression of estrogen receptor alpha gene in breast cancer cells treated with transcription factor decoy is modulated by Bangladeshi natural plant extracts.

The aim of the present study was to determine whether the expression of the estrogen receptor alpha (ERalpha) gene may be a possible target for compounds present in plant extracts from Aegle marmelos and Emblica officinalis, used in traditional Asian medicine in the treatment of tissue inflammation and cancer. To this aim, we evaluated the potential of the selected plant extracts to affect proliferation and differentiation of ERalpha-negative MDA-MB-231 breast cancer cells, which become ERalpha positive after treatment with a decoy molecule against a regulatory region of the human ERalpha gene. All the plant extracts inhibited cell proliferation and showed no effect on ERalpha gene expression, but when they were added in combination with the decoy molecule, a modulatory effect was observed, depending on the extract employed. The extracts exhibiting the greatest effects were those obtained from Aegle marmelos. Gas-chromatography/mass-spectrometry (GC/ MS) analysis enabled us to identify lupeol, a known triterpenoid, as the major bioactive component of A. marmelos plant extracts. Similar to the Aegle marmelos extracts, lupeol was found to stimulate the decoy effect of RA4 DNA sequence, increasing at a high level ERa gene expression in MDA-MB-231 ERalpha-negative breast cancer cells, and also inhibited cell proliferation.

Effects of vanadium complexes on cell growth of human leukemia cells and protein-DNA interactions.

Vanadium complexes are known to possess potent insulin-mimetic effects, high affinity for several enzymes and anticancer activity, which deserve increasing attention for application to biomedical sciences. Different vanadium complexes have been found to be more effective than the simple vanadium-(IV) and -(V) salts in experiments performed both in vitro and in vivo. Application of polyoxometalates as potential drugs against Herpes Simplex Virus and AIDS have also increased the interest to study the association between vanadium containing species and proteins. The aim of our research was to investigate the in vitro antiproliferative activity of a variety of vanadium-containing compounds, and study their ability to interfere with the molecular interactions between GATA-1 and NF-kappaB transcription factors and target DNA elements, employing electrophoretic mobility shift assays. All of the used vanadium compounds were found to exhibit antiproliferative activity, despite with differences in efficacy. Inhibition of K562 cell growth was not associated with differentiation, but with activation of apoptosis. Vanadium complexes with a +5 oxidation state and their discrete anionic units appear essential for the respective effects on K562 cells; a +4 oxidation state appears to be important in inhibiting transcription factors/DNA interactions.

Microbial transformation of 17alpha-ethynyl- and 17alpha-ethylsteroids, and tyrosinase inhibitory activity of transformed products.

The microbial transformation of the 17alpha-ethynyl-17beta-hydroxyandrost-4-en-3-one (1) (ethisterone) and 17alpha-ethyl-17beta-hydroxyandrost-4-en-3-one (2) by the fungi Cephalosporium aphidicola and Cunninghamella elegans were investigated. Incubation of compound 1 with C. aphidicola afforded oxidized derivative, 17alpha-ethynyl-17beta-hydroxyandrosta-1,4-dien-3-one (3), while with C. elegans afforded a new hydroxy derivative, 17alpha-ethynyl-11alpha,17beta-dihydroxyandrost-4-en-3-one (4). On the other hand, the incubation of compound 2 with the fungus C. aphidicola afforded 17alpha-ethyl-17beta-hydroxyandrosta-1,4-dien-3-one (5). Two new hydroxylated derivatives, 17alpha-ethyl-11alpha,17beta-dihydroxyandrost-4-en-3-one (6) and 17alpha-ethyl-6alpha,17beta-dihydroxy-5alpha-androstan-3-one (7) were obtained from the incubation of compound 2 with C. elegans. Compounds 1-6 exhibited tyrosinase inhibitory activity, with compound 6 being the most potent member (IC(50)=1.72 microM).

Studies of the anticancer potential of plants used in Bangladeshi folk medicine.

The present study evaluated the anticancer potential of 11 plants used in Bangladeshi folk medicine. The extracts were tested for cytotoxicity using the brine shrimp lethality assay, sea urchin eggs assay, hemolysis assay and MTT assay using tumor cell lines. The extract of Oroxylum indicum showed the highest toxicity on all tumor cell lines tested, with an IC(50) of 19.6 microg/ml for CEM, 14.2 microg/ml for HL-60, 17.2 microg/ml for B-16 and 32.5 microg/ml for HCT-8. On the sea urchin eggs, it inhibited the progression of cell cycle since the frist cleavage (IC(50)=13.5 microg/ml). The extract of Aegle marmelos exhibited toxicity on all used assays, but in a lower potency than Oroxylum indicum. In conclusion, among all tested extracts, only the extracts of Oroxylum indicum, Moringa oleifera and Aegles marmelos could be considered as potential sources of anticancer compounds. Further studies are necessary for chemical characterization of the active principles and more extensive biological evaluations.

Synthesis of methyl ether analogues of sildenafil (Viagra) possessing tyrosinase inhibitory potential.

The microwave-assisted synthesis and characterization of the ten new sildenafil (Viagra; 1) analogues 6-15 are described. A detailed structure-activity-relationship (SAR) study revealed that compounds 10 (= 4-ethoxy-N-hydroxy-3-(7-methoxy-1-methyl-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)benzenesulfonamide) and 12 (= S-(2-hydroxyethyl) 4-ethoxy-3-(7-methoxy-1-methyl-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)benzenesulfonothioate) are extremely potent mushroom tyrosinase inhibitors, with IC50 values (3.59 and 2.15 microM, resp.) below those of the standard inhibitors L-mimosine and kojic acid (IC50 = 3.68 and 16.67 microM, resp.). Compounds 10 and 12 are, thus, the currently most-effective inhibitors of tyrosinase, and bear great potential to be used for the treatment of various skin disorders such as hyperpigmentation, which is associated with high production of melanocytes.

Tyrosinase inhibition studies of diterpenoid alkaloids and their derivatives: structure-activity relationships.

In the present article, tyrosinase inhibition studies on fifteen diterpenoid alkaloids, with lycoctonine skeleton, and their semisynthetic derivatives 1-15 and six napelline-type compounds 16-21 are discussed. Their structure-activity relationship for tyrosinase inhibition is also discussed. These activities were compared with two referenced tyrosinase inhibitors, kojic acid and L-mimosine. The study showed that lappaconitine HBr (1) is the most potent member of the series (IC50 = 13.30 microM).

Effects of extracts from Bangladeshi medicinal plants on in vitro proliferation of human breast cancer cell lines and expression of estrogen receptor alpha gene.

In this study we determined the activity of extracts from Bangladeshi medicinal plants (Emblica officinalis, Aegle marmelos, Vernonia anthelmintica, Oroxylum indicum, Argemone mexicana) on human breast tumor cell lines. Extracts from E. officinalis and O. indicum displayed anti-proliferative activity on MCF7 and MDA-MB-231 breast cancer cell lines, while extracts from A. mexicana were active on MCF7 cells, exhibiting on the contrary low antiproliferative effects on MDA-MB-231 cells. Extracts from A. marmelos and V. anthelmintica were antiproliferative on both cell lines, but at higher concentrations. The accumulation of estrogen receptor alpha (ERalpha) mRNA, a marker of neoplastic status, was analysed by quantitative reverse-transcriptase polymerase chain reaction (RT-PCR). The data obtained demonstrated that only extracts from E. officinalis induce an increase of ERalpha mRNA in MCF7 cells. When MDA-MB-231 cell line was employed, extracts from E. officinalis, V. anthelmintica and A. mexicana were found to be inducers of the increase of ERalpha mRNA accumulation. Since activation of ERalpha gene expression could have clinical impact, our results suggest a possible use of extracts from medicinal plants to identify compounds of possible interest in the treatment of breast cancer.