The Anti-HIV Actions of 7-and 10-Substituted Camptothecins

Camptothecin (CPT), a traditional anti-tumor drug, has been shown to possess anti-HIV-1 activity. To increase the antiviral potency, the anti-HIV activities of two CPT derivatives, 10-hydroxy-CPT and 7-hydroxymethyl-CPT, were evaluated in vitro. The therapy index (TI) of CPT, 10-hydroxy-CPT and 7-hydroxymethyl-CPT against HIV-1(IIIB) in C8166 were 24.2, 4.2 and 198.1, and against clinical isolated strain HIV-1(KM018) in PBMC were 10.3, 3.5 and 66.0, respectively. While the TI of CPT, 10-hydroxy-CPT and 7-hydroxymethyl-CPT against HIV-2(CBL-20) were 34.5, 10.7 and 317.0, respectively, and the TI of the three compounds against HIV-2(ROD) showed the similar values. However, when the antiviral mechanisms were considered, we found there was no inhibition of 7-hydroxymethyl-CPT on viral cell-to-cell transmission, and was no inhibition on reverse transcriptase, protease or integrase in cell-free systems. 7-Hydroxymethyl-CPT showed no selective killing of chronically infected cells after 3 days of incubation. In conclusion, 7-hydroxymethyl-CPT showed more potent anti-HIV activity, while 10-hydroxy-CPT had less efficient activity, compared with the parent CPT. Though the antiviral mechanisms remain to be further elucidated; the modification of -OH residues at C-7 of CPT could enhance the antiviral activity, while of -OH residues at C-10 of CPT had decreased the antiviral activity, which provides the preliminary modification strategy for anti-viral activities enhancement of this compound.

Anti-CTLA-4 treatment induces IL-10-producing ICOS+ regulatory T cells displaying IDO-dependent anti-inflammatory properties in a mouse model of colitis.

BACKGROUND AND AIMS: Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) has been shown to act as a negative regulator of T cell function and has been implicated in the regulation of T helper 1 (Th1)/Th2 development and the function of regulatory T cells. Tests were carried out to determine whether anti-CTLA-4 treatment would alter the polarisation of naive T cells in vivo. METHODS: Mice were treated with anti-CTLA-4 monoclonal antibody (mAb) (UC10-4F10) at the time of immunisation or colonic instillation of trinitrobenzene sulfonic acid (TNBS). The cytokines produced by lymph node cells after in vitro antigenic stimulation and the role of indoleamine 2,3 dioxygenase (IDO) and of interleukin-10 (IL-10) were tested, and the survival of mice was monitored. RESULTS: Injection of anti-CTLA-4 mAb in mice during priming induced the development of adaptive CD4(+) regulatory T cells which expressed high levels of ICOS (inducible co-stimulator), secreted IL-4 and IL-10. This treatment inhibited Th1 memory responses in vivo and repressed experimental intestinal inflammation. The anti-CTLA-4-induced amelioration of disease correlated with IDO expression and infiltration of ICOS(high) Foxp3(+) T cells in the intestine, suggesting that anti-CTLA-4 acted indirectly through the development of regulatory T cells producing IL-10 and inducing IDO. CONCLUSIONS: These observations emphasise the synergy between IL-10 and IDO as anti-inflammatory agents and highlight anti-CTLA-4 treatment as a potential novel immunotherapeutic approach for inducing adaptive regulatory T cells.

Prevention of retinal capillary basement membrane thickening in diabetic dogs by a non-steroidal anti-inflammatory drug

AIMS/HYPOTHESIS: To investigate the effect of treatment with the non-steroidal anti-inflammatory drug Sulindac on the early vascular pathology of diabetic retinopathy in the dog, and it's effect on recognised biochemical indices of hyperglycaemia-related pathophysiology. METHODS: Experimental diabetes (streptozotocin/alloxan) was induced in 22 male beagle dogs and 12 of the animals were assigned at random to receive oral Sulindac (10 mg/kg daily). Age- and sex-matched control animals were maintained as non-diabetic controls. After 4 years, several morphological parameters were quantified in the retinal microvasculature of each animal group using an established stereological method. Also, the following diabetes-associated biochemical parameters were analysed: accumulation of advanced glycation end products (AGEs), red blood cell polyol levels and antioxidant status. RESULTS: Diabetes increased red blood cell sorbitol levels when compared to non-diabetic controls (p<or =0.05), however, there was no difference in sorbitol levels between the untreated and the treated diabetic animals. No significant differences were found in red blood cell myoinositol levels between the three groups of animals. Pentosidine and other AGEs were increased two- to three-fold in the diabetic animals (p<or =0.001) although treatment with Sulindac did not affect their accumulation in diabetic skin collagen or alter diabetes-induced rises in plasma malondialdehyde. Retinal capillary basement membrane volume was significantly increased in the untreated diabetic dogs compared to non-diabetic controls or Sulindac-treated diabetic animals (p<or =0.0001). CONCLUSION/INTERPRETATION: This study has confirmed the beneficial effect of a non-steroidal anti-inflammatory drug on the early vascular pathology of diabetic retinopathy. However the treatment benefit was not dependent on inhibition of polyol pathway activity, advanced glycation, or oxidative stress.

Comparison of the anti-diabetic effects of GIP- and GLP-1-receptor activation in obese diabetic (ob/ob) mice: studies with DPP IV resistant N-AcGIP and exendin(1-39)amide

Background The two major incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are being actively explored as anti-diabetic agents because they lower blood glucose through multiple mechanisms. The rapid inactivation of GIP and GLP-1 by the ubiquitous enzyme, dipeptidyl peptidase IV (DPP IV) makes their biological actions short-lived, but stable agonists such as N-acetylated GIP (N-AcGIP) and exendin(1-39)amide have been advocated as stable and specific GIP and GLP-1 analogues.

Non-thiazolidinedione antihyperglycaemic agents. Part 3: The effects of stereochemistry on the potency of alpha-methoxy-beta-phenylpropanoic acids.

Rhizopus delemar lipase catalyzed ester hydrolysis of the alpha-methoxy-beta-phenylpropanoate (I) affords the (R)-(+) and (S)-(-) isomers in > 84% enantiomeric excess. Abs. stereochem. was detd. by a single crystal X-ray anal. of a related synthetic analog. The activity of these two enantiomers on glucose transport in vitro and as anti-diabetic agents in vivo is reported and their unexpected equivalence attributed to an enzyme-mediated stereospecific isomerization of the (R)-(+) isomer. Binding studies using recombinant human PPAR-gamma (peroxisomal proliferator activated receptor gamma), now established as a mol. target for this compd. class, indicate a 20-fold higher binding affinity for the (S) antipode relative to the (R) antipode.

Dual targeting of tumour cells and host endothelial cells by novel microtubule-targeting agents, pyrrolo-1,5-benzoxazepines

PURPOSE: Some members of a novel series of pyrrolo-1,5-benzoxazepines (PBOXs) are microtubule-targeting agents capable of inducing apoptosis in a variety of human cancerous cells, hence, they are currently being developed as potential anti-cancer agents. The purpose of this study was to first characterise the activities of a novel PBOX analogue, PBOX-16 and then investigate the anti-angiogenic potential of both PBOX-16 and its prototype PBOX-6.

METHODS: The effects of PBOX-6 and -16 on cancerous cells (chronic myeloid leukaemia K562 cells and ovarian carcinoma A2780 cells) and primary cultured human umbilical vein endothelial cells (HUVECs) were examined by assessing cell proliferation, microtubular organisation, DNA analysis of cell cycle progression and caspase-3/7 activity. Their anti-angiogenic properties were then investigated by examining their ability to interfere with HUVEC differentiation into capillary-like structures and vascular endothelial growth factor (VEGF)-stimulated HUVEC migration.

RESULTS: PBOX-6 and -16 inhibited proliferation of K562, A2780 and HUVEC cells in a concentration-dependent manner. PBOX-16, confirmed as a novel depolymerising agent, was approximately tenfold more potent than PBOX-6. Inhibition of cell proliferation was mediated by G(2)/M arrest followed by varying degrees of apoptosis depending on the cell type; endothelial cells underwent less apoptosis than either of the cancer cell lines. In addition to the antitumourigenic properties, we also describe a novel antiangiogenic function for PBOXs: treatment with PBOXs inhibited the spontaneous differentiation of HUVECs into capillary-like structures when grown on a basement membrane matrix preparation (Matrigel™) and also significantly reduced VEGF-stimulated HUVEC migration.

CONCLUSION: Dual targeting of both the tumour cells and the host endothelial cells by PBOX compounds might enhance the anti-cancer efficacy of these drugs.

Y1 receptor knockout increases nociception and prevents the anti-allodynic actions of NPY.

OBJECTIVE: Recent pharmacologic studies in our laboratory have suggested that the spinal neuropeptide Y (NPY) Y1 receptor contributes to pain inhibition and to the analgesic effects of NPY. To rule out off-target effects, the present study used Y1-receptor-deficient (-/-) mice to further explore the contribution of Y1 receptors to pain modulation. METHODS AND RESULTS: Y1(-/-) mice exhibited reduced latency in the hotplate test of acute pain and a longer-lasting heat allodynia in the complete Freund's adjuvant (CFA) model of inflammatory pain. Y1 deletion did not change CFA-induced inflammation. Upon targeting the spinal NPY systems with intrathecal drug delivery, NPY reduced tactile and heat allodynia in the CFA model and the partial sciatic nerve ligation model of neuropathic pain. Importantly, we show for the first time that NPY does not exert these anti-allodynic effects in Y1(-/-) mice. Furthermore, in nerve-injured CD1 mice, concomitant injection of the potent Y1 antagonist BIBO3304 prevented the anti-allodynic actions of NPY. Neither NPY nor BIBO3304 altered performance on the Rotorod test, arguing against an indirect effect of motor function. CONCLUSION: The Y1 receptor contributes to pain inhibition and to the analgesic effects of NPY.

Inhibition of tumor angiogenesis by non-steroidal anti-inflammatory drugs: emerging mechanisms and therapeutic perspectives.

Chronic intake of non steroidal anti-inflammatory drugs (NSAIDs) is associated with a reduced risk of developing gastrointestinal tumors, in particular colon cancer. Increasing evidence indicates that NSAID exert tumor-suppressive activity on pre-malignant lesions (polyps) in humans and on established experimental tumors in mice. Some of the tumor-suppressive effects of NSAIDs depend on the inhibition of cyclooxygenase-2 (COX-2), a key enzyme in the synthesis of prostaglandins and thromboxane, which is highly expressed in inflammation and cancer. Recent findings indicate that NSAIDs exert their anti-tumor effects by suppressing tumor angiogenesis. The availability of COX-2-specific NSAIDs opens the possibility of using this drug class as anti-angiogenic agents in combination with chemotheapy or radiotherapy for the treatment of human cancer. Here we will briefly review recent advances in the understanding of the mechanism by which NSAIDs suppress tumor angiogenesis and discuss their potential clinical application as anti-cancer agents.

Future innovations in anti-platelet therapies

Platelets have long been recognized to be of central importance in haemostasis, but their participation in pathological conditions such as thrombosis, atherosclerosis and inflammation is now also well established. The platelet has therefore become a key target in therapies to combat cardiovascular disease. Anti-platelet therapies are used widely, but current approaches lack efficacy in a proportion of patients, and are associated with side effects including problem bleeding. In the last decade, substantial progress has been made in understanding the regulation of platelet function, including the characterization of new ligands, platelet-specific receptors and cell signalling pathways. It is anticipated this progress will impact positively on the future innovations towards more effective and safer anti-platelet agents. In this review, the mechanisms of platelet regulation and current anti-platelet therapies are introduced, and strong, and some more speculative, potential candidate target molecules for future anti-platelet drug development are discussed.

The neurokinin 1 receptor: a potential new target for anti-platelet therapy?

The important role of platelets in the development of arterial thrombosis and cardiovascular disease is well established. Current treatments for arterial thrombosis include anti-platelet agents such as aspirin, thienopyridines and glycoprotein IIb-IIIa inhibitors. Despite these drugs being effective there remains a substantial unmet clinical demand for more effective therapeutic approaches, which may reflect the existence of alternative underlying regulatory mechanisms to those already targeted. Recent publications have demonstrated a key role for tachykinins in the positive feedback regulation of platelet aggregation and thrombus formation. The pro-thrombotic effects of tachykinins on platelets are mediated through the neurokinin 1 receptor, which may therefore offer a novel therapeutic drug target in the prevention and the treatment of arterial thrombosis.

Novel synthesised flavone derivatives provide significant insight into the structural features required for enhanced anti-proliferative activity

With many cancers showing resistance to current chemotherapies, the search for novel anti-cancer agents is attracting considerable attention. Natural flavonoids have been identified as useful leads in such programmes. However, since an in-depth understanding of the structural requirements for optimum activity is generally lacking, further research is required before the full potential of flavonoids as anti-proliferative agents can be realised. Herein a broad library of 76 methoxy and hydroxy flavones, and their 4-thio analogues, was constructed and their structure-activity relationships for anti-proliferative activity against the breast cancer cell lines MCF-7 (ER+ve), MCF-7/DX (ER+ve, anthracycline resistant) and MDA-MB-231 (ER-ve) were probed. Within this library, 42 compounds were novel, and all compounds were afforded in good yields and > 95% purity. The most promising lead compounds, specifically the novel hydroxy 4-thioflavones 15f and 16f, were further evaluated for their anti-proliferative activities against a broader range of cancer cell lines by the National Cancer Institute (NCI), USA and displayed significant growth inhibition profiles (e.g Compound-15f: MCF-7 (GI50 = 0.18 μM), T-47D (GI50 = 0.03 μM) and MDA-MB-468 (GI50 = 0.47 μM) and compound-16f: MCF-7 (GI50 = 1.46 μM), T-47D (GI50 = 1.27 μM) and MDA-MB-231 (GI50 = 1.81 μM). Overall, 15f and 16f exhibited 7-46 fold greater anti-proliferative potency than the natural flavone chrysin (2d). A systematic structure-activity relationship study against the breast cancer cell lines highlighted that free hydroxyl groups and the B-ring phenyl groups were essential for enhanced anti-proliferative activities. Substitution of the 4-C=O functionality with a 4-C=S functionality, and incorporation of electron withdrawing groups at C4’ of the B-ring phenyl, also enhanced activity. Molecular docking and mechanistic studies suggest that the anti-proliferative effects of flavones 15f and 16f are mediated via ER-independent cleavage of PARP and downregulation of GSK-3β for MCF-7 and MCF-7/DX cell lines. For the MDA-MB-231 cell line, restoration of the wild-type p53 DNA binding activity of mutant p53 tumour suppressor gene was indicated.

Three-dimensional quantitative structure-activity relationships for a large series of potent antitubercular agents

Comparative molecular field analysis (CoMFA) studies were conducted on a series of 100 isoniazid derivatives as anti-tuberculosis agents using two receptor-independent structural data set alignment strategies: (1) rigid-body fit, and (2) pharmacophore-based. Significant cross-validated correlation coefficients were obtained (CoMFA(1), q(2) = 0,75 and CoMFA(2), q(2) = 0.74), indicating the potential of the models for untested compounds. The models were then used to predict the inhibitory potency of 20 test set compounds that were not included in the training set, and the predicted values were in good agreement with the experimental results.

Insights into the Molecular Requirements for the Anti-obesity Activity of a Series of CB1 Ligands

Two-dimensional and 3D quantitative structure-activity relationships studies were performed on a series of diarylpyridines that acts as cannabinoid receptor ligands by means of hologram quantitative structure-activity relationships and comparative molecular field analysis methods. The quantitative structure-activity relationships models were built using a data set of 52 CB1 ligands that can be used as anti-obesity agents. Significant correlation coefficients (hologram quantitative structure-activity relationships: r 2 = 0.91, q 2 = 0.78; comparative molecular field analysis: r 2 = 0.98, q 2 = 0.77) were obtained, indicating the potential of these 2D and 3D models for untested compounds. The models were then used to predict the potency of an external test set, and the predicted (calculated) values are in good agreement with the experimental results. The final quantitative structure-activity relationships models, along with the information obtained from 2D contribution maps and 3D contour maps, obtained in this study are useful tools for the design of novel CB1 ligands with improved anti-obesity potency.

Avaliação do potencial anti-inflamatório de composto tipo heparina (cCTH) extraído do caranguejo Goniopsis cruentata em modelo experimental de peritonite

Heparin, a sulfated polysaccharide, was the first compound used as an anticoagulant and antithrombotic agent. Due to their structural characteristics, also has great potential anti-inflammatory, though such use is limited in inflammation because of their marked effects on coagulation. The occurrence of heparin-like compounds that exhibit anticoagulant activity decreased in aquatic invertebrates, such as crab Goniopsis cruentata, sparked interest for the study of such compounds as anti-inflammatory drugs. Therefore, the objective of this study was to evaluate the potential modulator of heparin-like compound extracted from Goniopsis cruentata in inflammatory events, coagulation, and to evaluate some aspects of its structure. The heparin-type compound had a high degree of N-sulphation in its structure, being able to reduce leukocyte migration into the peritoneal cavity at lower doses compared to heparin and diclofenac sodium (anti-inflammatory commercial). Furthermore, it was also able to inhibit the production of nitric oxide and tumor necrosis factor alpha by activated macrophages, inhibited the activation of the enzyme neutrophil elastase in low concentrations and showed a lower anticoagulant effect in high doses as compared to porcine mucosal heparin. Because of these observations, the compound extracted from crab Goniopsis cruentata can be used as a structural model for future anti-inflammatory agents