Anti-HIV-1 activities of 1,3-dioxolane guanine and 2,6-diaminopurine dioxolane.

DXG and its prodrug DAPD have been demonstrated to be effective inhibitors of HIV-1 in various cells. The EC50s for DXG were 0.032 microM in CBMCs and 0.05 microM in MT-4 cells, which were generally equipotent as 3TC. 3TC-resistant, but not AZT-resistant, HIV-1 had minimum diminished sensitivity to the compounds. Both DXG and DAPD were non-toxic to cells up to 500 microM.     

High-performance liquid chromatographic determination of (−)-β-d-2,6-diaminopurine dioxolane and its metabolite,dioxolane guanosine,using ultraviolet and on-line radiochemical detection

(−)-β-d-2,6-Diaminopurine dioxolane (DAPD) and its metabolite dioxolane guanosine (DXG) have potent activity against hepatitis B virus and HIV, in vitro. A reversed-phase HPLC analytical method using UV and on-line radiochemical detection for the determination of DAPD and DXG in monkey serum and urine is described in this report. Retention times for DXG, DAPD and internal standard (2′,3′-didehydro-2′ deoxythymidine, D4T) were 5.0, 6.0 and 13.0 min, respectively. The extraction recovery was greater than 97% for DAPD and 94% for DXG. The limit of quantitation for UV detection was 100 ng/ml and 125 ng/ml for DXG and DAPD in monkey serum. The standard curves were linear from 0.1 μg/ml to 5 μg/ml for DXG and 0.125 μg/ml to 5 μg/ml for DAPD. For radiochemical detection, calibration curves of standard solutions of DAPD and DXG were linear in the range of 3500 Bq to 32 000 Bq and 7500 Bq to 60 000 Bq. The intra- and inter-day relative standard deviations were less than 7.2% using UV and less than 8.6% using on-line radiochemical detection. The HPLC method was applied to serum and urine samples collected from a male rhesus monkey that was administered 33.3 mg/kg DAPD with 200 μgCi of [³H]DAPD intravenously.     

New AZT Analogues Having 5′-Alkylsulfonyl Groups: Synthesis and Anti-HIV Activity

New derivatives of azidothymidine (AZT) substituted by alkyl and alkylsulphonyl groups at N-3 and C-5′, respectively, have been synthesized. The new synthesized derivatives showed remarkable anti-HIV-1 and HIV-2 activity in MT-4 cells. Compounds 8 and 10 have IC₅₀ values of 0.83 and 0.31 μg/mL against HIV-1 with therapeutic index of 83 and 403, respectively, and IC₅₀ values of 0.93 and 0.29 μg/mL against HIV-2 with therapeutic index of 74 and 431, respectively. This means that compounds 8 and 10 were cytotoxic to MT-4 cells at CC₅₀ of 69.2 μg/mL and 125 μg/mL, respectively.     

Inhibition of Human Immunodeficiency Virus Type-1 (HIV-1) Replication by Immunor (Im28), a New Analog of Dehydroepiandrosterone

Abstract

The inhibition of' HIV-I replication in vitro by Immunor 28 (IM²⁸), an analog of dehydroepiandrosterone (DHEA), was monitored using the HIV- 1 laboratory wild-type strain IIIB. Evaluation of the 50% inhibitory dose (IC₅₀) revealed a decrease in HIV-1 replication giving an IC, value around 22 μM. The toxicity of the drug has been determined also, in MT2 cells and PBMCs. 60 μM of IM²⁸ provoked a 50% decrease in cell viability while DHEA caused the same decrease at 75 μM in MT2 cells. These values are 125 μM for IM²⁸ in PBMCs and 135 μM for DIIBA. Thus, DHEA is less toxic than IM²⁸, but IM²⁸ has a higher antiviral activity.     

Synthesis of Zidovudine Derivatives with Anti-HIV-1 and Antibacterial Activities

Twelve novel zidovudine derivatives were prepared by modifying 5 ′-hydroxyl group of sugar moiety (1–8) and 5-methyl group of thymidine nucleus (9–12) and characterized spectrally. The compounds were evaluated for anti-HIV-1, antitubercular and antibacterial activities. Compound (3-azido-tetrahydro-5- (3,4-dihydro-5-methyl-2,4-dioxopyrimidin- 1 (2H)-yl) furan-2-yl)methyl 7- (4- (2-phenylacetoyloxy) -3,5- dimethylpiperazin-1-yl) -5- (2-phenylacetoyloxyamino) -1-cyclopropyl-6,8-difluoro-1,4-dihydro-4-oxoquinoline-3-carboxylate (5) was found to be the most potent anti-HIV-1 agent with EC₅₀ of 0.0012 μM against HIV-1_IIIB and CC₅₀ of 34.05 μM against MT-4 with selectivity index of 28,375. Compound 5 inhibited Mycobacterium tuberculosis with MIC of 1.72 μM and inhibited four pathogenic bacteria with MIC of less than 1 μM.     

Structure–activity relationship studies of 3-dodecanoylindole-2-carboxylic acid inhibitors of cytosolic phospholipase A2α-mediated arachidonic acid release in intact platelets: variation of the keto moiety

Recently we found that 1-methyldodecanoylindole-2-carboxylic acid (1) and 1-[2-(4-carboxyphenoxy)ethyl]-3-dodecanoylindole-2-carboxylic acid (4) were inhibitors of the cytosolic phospholipase A₂α (cPLA₂α)-mediated arachidonic acid release in calcium ionophore A23187-stimulated human platelets with IC₅₀-values of 4.8 μM (1) and 0.86 μM (4). We have now replaced the 3-acyl residue of these compounds by alkylated sulfinyl-, sulfony-, sulfinamoyl-, sulfamoyl-, carbonylamino-, or carbonylaminomethyl-substituents. Structure–activity relationship studies revealed that the pronounced cellular activity of 4 strongly depends on the presence of the 3-acyl moiety. Surprisingly, when testing 4 and its derivatives in an assay with the isolated cPLA₂, none of these compounds showed an inhibitory potency at 10 μM indicating that they do not inhibit cPLA₂α in the cells by a direct interaction with the active site of the enzyme.     

Novel Series of [ddN]-[TSAO-T] Heterodimers as Potential Bi-Functional Inhibitors of HIV-1 RT. Studies in the Linker and ddN Region

Abstract

Novel series of [ddN]-(CH₂)_n-[TSAO-T] heterodimers have been prepared and tested for their anti-HIV-1 and HIV-2 activity. The most active compound of this series was the [d4T]-(CH₂)₃-[TSAO-T] heterodimer (EC₅₀ = 0.018 ± 0.03 μM).     

Anti-cancer activity of 5-O-alkyl 1,4-imino-1,4-dideoxyribitols

New derivatives of 1,4-dideoxy-1,4-imino-d-ribitol have been prepared and evaluated for their cytotoxicity on solid and haematological malignancies. 1,4-Dideoxy-5-O-[(9Z)-octadec-9-en-1-yl]-1,4-imino-d-ribitol (13, IC₅₀ ∼2 μM) and its C₁₈-analogues (IC₅₀ <10 μM) are cytotoxic toward SKBR3 (breast cancer) cells. 13 also inhibits (IC₅₀ ∼8 μM) growth of JURKAT cells.     

Nitrogen-containing polyhydroxylated aromatics as HIV-1 integrase inhibitors: synthesis,structure-activity relationship analysis,and biological activity

Four series of forty-five nitrogen-containing polyhydroxylated aromatics based on caffeic acid phenethyl ester were designed and synthesized as HIV-1 integrase (IN) inhibitors. Most of these compounds inhibited IN catalytic activities in low micromolar range. Among these new analogues, compounds 9e and 9f were the most potent IN inhibitors with IC₅₀ value of 0.7 μM against strand transfer reaction. Their key structure-activity relationships were also discussed.     

Synthesis of C-2 and C-3 substituted quinolines and their evaluation as anti-HIV-1 agents

A plenty of natural products and synthetic derivatives containing quinoline moiety have been reported to possess various pharmacological activities. Quinolines such as 2-styrylquinolines and 8-hydroxyquinolines are extensively studied for their anti-HIV-1 activity and found to act mainly through HIV-1 integrase enzyme inhibition. In continuation of our efforts to search for newer anti-HIV-1 molecules, thirty-one quinoline derivatives with different linkers to ancillary phenyl ring were synthesized and evaluated for in vitro anti-HIV-1 activity using TZM-bl assays. Compound 31 showed higher activity in TZM-bl cell line against HIV-1_VB59 and HIV-1_UG070 cell associated virus (IC₅₀ 3.35 ± 0.87 and 2.57 ± 0.71 μM) as compared to other derivatives. Compound 31 was further tested against cell free virus HIV-1_VB59 and HIV-1_UG070 (IC₅₀ 1.27 ± 0.31 and 2.88 ± 1.79 μM, TI 42.20 and 18.61, respectively). This lead molecule also showed good activity in viral entry inhibition assay and cell fusion assay defining its mode of action. The activity of compound 31 was confirmed by testing against HIV-1_VB51 in activated peripheral blood mononuclear cells (PBMCs). Binding interactions of 31 were compared with known entry inhibitors.     

A Novel Assay System for Anti-Human Immunodeficiency Virus Type 1 (HIV-1) Activity Using a Subclone of a Monocytic Cell Line,U937

A subclonal cl.1–14 cell was established from a monocytic cell line U937 by a limiting dilution method. The anti-HIV-1 activity of some antiviral compounds was evaluated in HIV-1-infected cl.1–14 cells. The results demonstrated that although AZT was a potent inhibitor of HIV-1 replication in cl.1–14 cells, its 50% effective concentration (EC₅₀) values was 80 times higher than that in HIV-1 infected MT-4 cells; the EC₅₀ of AZT was 0.16 μM and 0.002 μM in cl.1–14 and MT-4 cells, respectively. In contrast, the anti-HIV-1 activity of ddA, ddI and ddC in cl.1–14 cells was comparable to that in MT-4 cells. The antiviral activity of nevirapine, dextran sulfate, curdlan sulfate and T22 did not differ significantly between the cl. 1–14 and MT-4 cells. The antiviral activity of several compounds in the HIV-1-infected cl.1–14 cells was similar to that in the HIV-1jr -fl -infected human peripheral macrophages. Our results suggest that cl.1–14 cell cultures are very useful for estimating antiviral activity and more advantageous than the use of peripheral blood macrophages.     

Synthesis of 3′-O-Propargylthymidine as a Candidate Antiretroviral Agent

Abstract

3′-O-Propargylthymidinc, which may be viewed as a stnictural analogue of the potent antiretroviral agent 3′-azido-3′-deoxythymidine (AZT), was synthesized from 5′-O-(4,4′-dimethoxytritylthymidine by reaction with propargyl bromide followed by gentle acidolysis. The 3′-O-propargyl derivative was tested for antiretroviral activity in SC-1 mouse fibroblasts infected with Rauscher murine leukemia virus (MuLV). No inhibition of MuLV proliferation was observed at concentrations of 3′-O-propargylthymidine from 0.001 to 100 μM. whereas the IC₅₀ against the host cells was 30 μM. By comparison, AZT had an IC₅₀ for MuLV growth of 0.01 μM and an IC₅₀ for cell growth of >100 μM. Thus, replacement of the 3′-N-N≡N group in AZT by a 3′-OCH₂C≡CH group increased cytotoxicity but decreased antiretroviral activity relative to AZT.     

The melatonin receptor antagonist luzindole induces Ca2+ mobilization,reactive oxygen species generation and impairs trypsin secretion in mouse pancreatic acinar cells

BackgroundIn this work we studied the effects of the melatonin receptor-antagonist luzindole (1 μM–50 μM) on isolated mouse pancreatic acinar cells.MethodsChanges in intracellular free-Ca²⁺ concentration, reactive oxygen species production and trypsin secretion were analyzed.ResultsLuzindole induced increases in [Ca²⁺]_i that diminished CCK-8 induced Ca²⁺ mobilization, compared with that observed when CCK-8 was applied alone. Treatment of cells with thapsigargin (1 μM), in the absence of Ca²⁺ in the extracellular medium, evoked a transient increase in [Ca²⁺]_i. The additional incubation of cells with luzindole (10 μM) failed to induce further mobilization of Ca²⁺. In the presence of luzindole a concentration-dependent increase in ROS generation was observed that decreased in the absence of Ca²⁺ or by pretreatment of cells with melatonin (100 μM). Incubation of pancreatic acinar cells with luzindole (10 μM) impaired CCK-8-induced trypsin secretion. Melatonin was unable to revert the effect of luzindole on CCK-8-induced trypsin secretion.ConclusionThe melatonin receptor-inhibitor luzindole induces Ca²⁺-mediated pro-oxidative conditions and impairment of enzyme secretion, which creates a situation in pancreatic acinar cells that might compromise their function.General significanceThe effects of luzindole that we have observed, might be unspecific and could mislead the observations when it is used to study the actions of melatonin on the gland. Another possibility is that melatonin receptors exhibit a basal or agonist-independent activity in pancreatic acinar cells, which might be modulated by melatonin or luzindole.     

Inhibitory Effects of 1-Deazaadenosine Analogues on HIV Replication and Adenosine Deaminase

Abstract

A series of 2′,3′-dideoxy-N⁶-(cyclo)alkyl-1-deazaadenosine derivatives were synthesized starting from 2,6-dichloro-1-deazapurine (9). The new nucleosides proved to be good inhibitors of HIV-1 replication, the most active being the 2′,3′-dideoxy-2-chloro-N⁶-cycloctyl-1-deazaadenosine (14h, ED₅₀ = 0.4 μ).     

Mild and efficient synthesis of new tetraketones as lipoxygenase inhibitors and antioxidants

A mild and efficient route to tetraketones (2–22) has been developed by way of tetraethyl ammonium bromide (Et₄N⁺Br^? ) mediated condensation of dimedone (5,5-dimethylcyclohexane-1,3-dione, 1) with a variety of aldehydes. All these compounds showed significant lipoxygenase inhibitory activity and moderate to strong antioxidant potential. Compounds 19 (IC₅₀ = 7.8 μM), 22 (IC₅₀ = 12.5 μM), 3 (IC₅₀ = 16.3 μM), 11 (IC₅₀ = 17.5 μM) and 8 (IC₅₀ = 21.3 μM) showed significant inhibitory potential against lipoxygenase (baicalein, IC₅₀ = 22.4 μM). On the other hand compound 19 (IC₅₀ = 33.6 μM) also showed strong antioxidant activity compared to the standard (IC₅₀ = 44.7 μM). This study is likely to lead to the discovery of therapeutically efficient agents against very important disorders including inflammation, asthma, cancer and autoimmune diseases.     

Urease inhibitors from Hypericum oblongifolium WALL.

The bioassay-guided fractionation of H. oblongifolium has led to the isolation of potent urease inhibitors 1–3. The structures were elucidated by NMR and mass spectroscopic techniques. Compound 2 showed a potent enzyme inhibition activity (IC₅₀ 20.96?±?0.93), which is comparatively higher than that for the standard thiourea (IC₅₀ 21.01?±?0.51 μM). Compounds 1 and 3 also showed a significant activity, with IC₅₀ 37.95?±?1.93 and 138.43?±?1.23 μM, respectively. The sub crude fractions (F1, F2, F3, and F4) were tested in vitro for their urease inhibition activity. Fractions F2 and F4 showed significant activity with IC₅₀ 140.37?±?1.93 and 167.43?±?3.03 μM, respectively.     

Synthesis and Biological Evaluation of a New N4-(N-Formyl Peptide)- 2′,3′-Dideoxy-3′-Thiacytidine as Anti-Hiv Prodrug

Abstract

The synthesis of a new analogue of 2′,3′-dideoxy-3′-thiacytidine 9 covalently linked to an N-formyl methionyl leucyl phenylalanine peptide is described. This new prodrug analogue has been tested on the one hand as activator of human polymorphonuclear leukocytes (an EC₅₀ value of 1.8 10^?5 M was determined from dose-response curve for superoxide production) and on the other hand as inhibitor of the syncitium formation caused by HIV-1 in MT4-cells (IC₅₀ = 8.0± 0.8 μM). In so far as this new prodrug possesses these two biological properties, it represents a useful “chemical-head” capable of targeting specific receptors located on leukocytes membranes.     

Compounds with neuroprotective activity from the medicinal plant Machilus thunbergii

The dichloromethane fraction of the bark of Machilus thunbergii Sieb. et Zucc. (Lauraceae) significantly protected primary cultures of rat cortical cells exposed to the excitotoxic amino acid, L-glutamate. Through the activity-guided isolation from the CH₂Cl₂ fraction, (+)-9′-hydroxygalbelgin (1), isogalcatin B (2), (7S,8S,8′R)-3′,4′-dimethoxy-3,4,-methylenedioxylignan-7-ol (3), 1-hydroxy-7-hydroxymethyl-6-methoxyxanthone (4), 5,7-dimethoxy-3′,4′-methylenedioxyflavan-3-ol (5), (+)-(3S,4S,6R)-3,6-dihydroxypiperitone (6), protocatechuic acid methyl ester (7) and tyrosol (8) were obtained. All of them had significant neuroprotective activities against glutamate-induced neurotoxicity in primary cultures of rat cortical cells at concentrations ranging from 0.1 μM to 10.0 μM and were comparable to MK-801, a well-known inhibitor of glutamate receptor.