Design, synthesis and biological evaluation of heteroaryl diketohexenoic and diketobutanoic acids as HIV-1 integrase inhibitors endowed with antiretroviral activity

Quinolinonyl Non-Diketo Acid Derivatives as Inhibitors of HIV-1 Ribonuclease H and Polymerase Functions of Reverse Transcriptase

Novel anti-HIV agents are still needed to overcome resistance issues, in particular inhibitors acting against novel viral targets. The ribonuclease H (RNase H) function of the reverse transcriptase (RT) represents a validated and promising target, and no inhibitor has reached the clinical pipeline yet. Here, we present rationally designed non-diketo acid selective RNase H inhibitors (RHIs) based on the quinolinone scaffold starting from former dual integrase (IN)/RNase H quinolinonyl diketo acids. Several derivatives were synthesized and tested against RNase H and viral replication and found active at micromolar concentrations. Docking studies within the RNase H catalytic site, coupled with site-directed mutagenesis, and Mg²⁺ titration experiments demonstrated that our compounds coordinate the Mg²⁺ cofactor and interact with amino acids of the RNase H domain that are highly conserved among naïve and treatment-experienced patients. In general, the new inhibitors influenced also the polymerase activity of RT but were selective against RNase H vs the IN enzyme.

Magnetic sulfonated polysaccharides as efficient catalysts for synthesis of isoxazole-5-one derivatives possessing a substituted pyrrole ring, as anti-cancer agents

Four polysaccharides (chitosan, cellulose, starch, and pectin) were magnetized with magnetic iron oxide (Fe₃O₄) and then sulfonated (except pectin) with chlorosulfonic acid. The obtained solid acids were used as a catalyst in three-component reactions between N-substituted-2-formylpyrrole, hydroxylamine-hydrochloride, and β-keto esters for the synthesis of 4-(2-pyrrolyl) methylene-isoxazole-5-ones. The optimal catalyst system was selected and studied by IR, SEM, TEM and XRD methods. The diverse isoxazoline derivatives (obtained via a mild and simple approach) were also fully characterized by spectroscopic methods and screened for anti-cancer activities against HT-29 and MCF-7 colon and breast cancer and HEK 293 normal cells. The results revealed interesting anti-cancer activities.

Four magnetic polysaccharides containing acidic groups were used as catalysts for the synthesis of 4-(2-pyrrolyl) methylene-isoxazole-5-ones. The products showed anti-cancer activities.

The anti-inflammatory activity of curcumin protects the genital mucosal epithelial barrier from disruption and blocks replication of HIV-1 and HSV-2

Inflammation is a known mechanism that facilitates HIV acquisition and the spread of infection. In this study, we evaluated whether curcumin, a potent and safe anti-inflammatory compound, could be used to abrogate inflammatory processes that facilitate HIV-1 acquisition in the female genital tract (FGT) and contribute to HIV amplification. Primary, human genital epithelial cells (GECs) were pretreated with curcumin and exposed to HIV-1 or HIV glycoprotein 120 (gp120), both of which have been shown to disrupt epithelial tight junction proteins, including ZO-1 and occludin. Pre-treatment with curcumin prevented disruption of the mucosal barrier by maintaining ZO-1 and occludin expression and maintained trans-epithelial electric resistance across the genital epithelium. Curcumin pre-treatment also abrogated the gp120-mediated upregulation of the proinflammatory cytokines tumor necrosis factor-α and interleukin (IL)-6, which mediate barrier disruption, as well as the chemokines IL-8, RANTES and interferon gamma-induced protein-10 (IP-10), which are capable of recruiting HIV target cells to the FGT. GECs treated with curcumin and exposed to the sexually transmitted co-infecting microbes HSV-1, HSV-2 and Neisseria gonorrhoeae were unable to elicit innate inflammatory responses that indirectly induced activation of the HIV promoter and curcumin blocked Toll-like receptor (TLR)-mediated induction of HIV replication in chronically infected T-cells. Finally, curcumin treatment resulted in significantly decreased HIV-1 and HSV-2 replication in chronically infected T-cells and primary GECs, respectively. All together, our results suggest that the use of anti-inflammatory compounds such as curcumin may offer a viable alternative for the prevention and/or control of HIV replication in the FGT.

Structure-activity relationship of pyrrolyl diketo acid derivatives as dual inhibitors of HIV-1 integrase and reverse transcriptase ribonuclease H domain

The development of HIV-1 dual inhibitors is a highly innovative approach aimed at reducing drug toxic side effects as well as therapeutic costs. HIV-1 integrase (IN) and reverse transcriptase-associated ribonuclease H (RNase H) are both selective targets for HIV-1 chemotherapy, and the identification of dual IN/RNase H inhibitors is an attractive strategy for new drug development. We newly synthesized pyrrolyl derivatives that exhibited good potency against IN and a moderate inhibition of the RNase H function of RT, confirming the possibility of developing dual HIV-1 IN/RNase H inhibitors and obtaining new information for the further development of more effective dual HIV-1 inhibitors.

Biodegradable m-PEG/PCL Core-Shell Micelles: Preparation and Characterization as a Sustained Release Formulation for Curcumin

PURPOSE

Among the potent anticancer agents, curcumin is known as a very efficacious against many different types of cancer cells, but its clinical applications has been limited because of hydrophobicity, low gastrointestinal absorption, poor bioavailability and rapid metabolism. In this way, a novel micellar delivery system with mPEG-PCL was synthesized and the release profile of the curcumin from the drug-loaded micelles was evaluated.

METHODS

In this study, curcumin was encapsulated within monomethoxypoly(ethylene glycol)-poly(ε-caprolactone) (mPEG-PCL) micelles through a single-step nano-precipitation method, leading to creation of curcumin-loaded mPEG-PCL (Cur/mPEG-PCL) micelles. Di-block mPEG-PCL copolymers were synthesized and used to prepare micelles. mPEG-PCL copolymer was characterized in vitro by HNMR, FTIR, DSC and GPC techniques. Then, mPEG-PCL copolymers with curcumin were self-assembled into micelles in aqueous solution. The resulting micelles were characterized further by various techniques such as dynamic light scattering (DLS) and atomic force microscopy (AFM).

RESULTS

The findings showed the successful formation of smooth and spherical curcumin-loaded micelles. The encapsulation efficiency of curcumin was 88 ± 3.32%. The results of AFM revealed that the micelles have spherical shapes with size of 73.8 nm. The release behavior of curcumin from micelles was compared in different media. In vitro release of curcumin from curcumin-entrapped micelles was followed remarkably sustained profile. The sustained release of drug was hypothetically due to the entrapment of curcumin in core of micelles.

CONCLUSION

The results indicate the successful formulation of curcumin loaded m-PEG/PCL micelles. From the results, iIt can be concluded that curcumin m-PEG-PCL micelles may be considered as an effective treatment strategy for cancer in the future.

Curcumin ameliorates hippocampal neuron damage induced by human immunodeficiency virus-1

Our previous studies have shown that infection with the gp120 V3 loop can cause human immunodeficiency virus-1 associated neurocognitive disorders. Curcumin has been shown to improve these effects to some degree, but the precise mechanisms remain unknown. The present study analyzed the neuroprotective effect and mechanism of curcumin in relation to hippocampal neurons. Results showed that 1 nmol/L gp120 V3 loop suppressed the growth of synapses. After administration of 1 μmol/L curcumin, synaptic growth improved. Curcumin is neuroprotective against gp120 V3 loop-induced neuronal damage by inhibiting the activation of L-type calcium currents, relieving intracellular Ca(2+) overload, promoting Bcl-2 expression, and inhibiting Bax activation. The effect of curcumin was identical to nimodipine, suggesting that curcumin has the same neuroprotective effects against gp120 V3 loop-induced neuronal damage.

Inhibiting the HIV integration process: past, present, and the future

HIV integrase (IN) catalyzes the insertion into the genome of the infected human cell of viral DNA produced by the retrotranscription process. The discovery of raltegravir validated the existence of the IN, which is a new target in the field of anti-HIV drug research. The mechanism of catalysis of IN is depicted, and the characteristics of the inhibitors of the catalytic site of this viral enzyme are reported. The role played by the resistance is elucidated, as well as the possibility of bypassing this problem. New approaches to block the integration process are depicted as future perspectives, such as development of allosteric IN inhibitors, dual inhibitors targeting both IN and other enzymes, inhibitors of enzymes that activate IN, activators of IN activity, as well as a gene therapy approach.

6-(1-Benzyl-1H-pyrrol-2-yl)-2,4-dioxo-5-hexenoic acids as dual inhibitors of recombinant HIV-1 integrase and ribonuclease H, synthesized by a parallel synthesis approach

The increasing efficiency of HAART has helped to transform HIV/AIDS into a chronic disease. Still, resistance and drug-drug interactions warrant the development of new anti-HIV agents. We previously discovered hit 6, active against HIV-1 replication and targeting RNase H in vitro. Because of its diketo-acid moiety, we speculated that this chemotype could serve to develop dual inhibitors of both RNase H and integrase. Here, we describe a new series of 1-benzyl-pyrrolyl diketohexenoic derivatives, 7a-y and 8a-y, synthesized following a parallel solution-phase approach. Those 50 analogues have been tested on recombinant enzymes (RNase H and integrase) and in cell-based assays. Approximately half (22) exibited inhibition of HIV replication. Compounds 7b, 7u, and 8g were the most active against the RNase H activity of reverse-transcriptase, with IC50 values of 3, 3, and 2.5 μM, respectively. Compound 8g was also the most potent integrase inhibitor with an IC50 value of 26 nM.

Codelivery of curcumin and doxorubicin by MPEG-PCL results in improved efficacy of systemically administered chemotherapy in mice with lung cancer

Systemic administration of chemotherapy for cancer often has toxic side effects, limiting the doses that can be used in its treatment. In this study, we developed methoxy poly(ethylene glycol)-poly(caprolactone) (MPEG-PCL) micelles loaded with curcumin and doxorubicin (Cur-Dox/MPEG-PCL) that were tolerated by recipient mice and had enhanced antitumor effects and fewer side effects. It was shown that these Cur-Dox/MPEG-PCL micelles could release curcumin and doxorubicin slowly in vitro. The long circulation time of MPEG-PCL micelles and the slow rate of release of curcumin and doxorubicin in vivo may help to maintain plasma concentrations of active drug. We also demonstrated that Cur-Dox/MPEG-PCL had improved antitumor effects both in vivo and in vitro. The mechanism by which Cur-Dox/MPEG-PCL micelles inhibit lung cancer might involve increased apoptosis of tumor cells and inhibition of tumor angiogenesis. We found advantages using Cur-Dox/MPEG-PCL micelles in the treatment of cancer, with Cur-Dox/MPEG-PCL achieving better inhibition of LL/2 lung cancer growth in vivo and in vitro. Our study indicates that Cur-Dox/MPEG-PCL micelles may be an effective treatment strategy for cancer in the future.

Curcumin inhibits glutamate release from rat prefrontal nerve endings by affecting vesicle mobilization

Curcumin, one of the major constituents of Curcuma longa, has been shown to inhibit depolarization-evoked glutamate release from rat prefrontocortical nerve terminals by reducing voltage-dependent Ca²⁺ entry. This study showed that curcumin inhibited ionomycin-induced glutamate release and KCl-evoked FM1-43 release, suggesting that some steps after Ca²⁺ entry are regulated by curcumin. Furthermore, disrupting the cytoskeleton organization using cytochalasin D abolished the inhibitory action of curcumin on ionomycin-induced glutamate release. Mitogen-activated protein kinase kinase (MEK) inhibition also prevented the inhibitory effect of curcumin on ionomycin-induced glutamate release. Western blot analyses showed that curcumin decreased the ionomycin-induced phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and synaptic vesicle-associated protein synapsin I, the main presynaptic target of ERK. These results show that curcumin-mediated inhibition of glutamate release involves modulating downstream events by controlling synaptic vesicle recruitment and exocytosis, possibly through a decrease of MAPK/ERK activation and synapsin I phosphorylation, thereby decreasing synaptic vesicle availability for exocytosis.

Curcumin mediates presenilin-1 activity to reduce β-amyloid production in a model of Alzheimer's Disease

Curcumin has been reported to inhibit the generation of Aβ, but the underlying mechanisms by which this occurs remain unknown. Aβ is thought to play an important role in the pathogenesis of Alzheimer's disease (AD). The amyloid hypothesis argues that aggregates of Aβ trigger a complex pathological cascade that leads to neurodegeneration. Aβ is generated by the processing of APP (amyloid precursor protein) by β- and γ-secretases. Presenilin 1 (PS1) is central to γ-secretase activity and is a substrate for GSK-3β, both of which are implicated in the pathogenesis of AD. The present study aimed to investigate the effects of curcumin on the generation of Aβ in cultured neuroblastoma cells and on the in vitro expression of PS1 and GSK-3β. To stimulate Aβ production, a plasmid expressing APP was transfected into human SH-SY5Y neuroblastoma cells. The transfected cells were then treated with curcumin at 0-20 μM for 24 h or with 5 μM curcumin for 0-48 h, and the extracellular levels of Aβ(40/42) were determined by ELISA. The levels of PS1 and GSK-3β mRNA were measured by RT-PCR, and the expression of the PS1 and GSK-3β proteins (including the phosphorylated form of GSK-3β, p-GSK-3β-Ser9) were evaluated by western blotting. Curcumin treatment was found to markedly reduce the production of Aβ(40/42). Treatment with curcumin also decreased both PS1 and GSK-3β mRNA and protein levels in a dose- and time-dependent manner. Furthermore, curcumin increased the inhibitory phosphorylation of GSK-3β protein at Ser9. Therefore, we propose that curcumin decreases Aβ production by inhibiting GSK-3β-mediated PS1 activation.

Computer tools in the discovery of HIV-1 integrase inhibitors

Computer-aided drug design (CADD) methodologies have made great advances and contributed significantly to the discovery and/or optimization of many clinically used drugs in recent years. CADD tools have likewise been applied to the discovery of inhibitors of HIV-1 integrase, a difficult and worthwhile target for the development of efficient anti-HIV drugs. This article reviews the application of CADD tools, including pharmacophore search, quantitative structure-activity relationships, model building of integrase complexed with viral DNA and quantum-chemical studies in the discovery of HIV-1 integrase inhibitors. Different structurally diverse integrase inhibitors have been identified by, or with significant help from, various CADD tools.

Involvement of PPAR-gamma in curcumin-mediated beneficial effects in experimental dementia

The present study was undertaken to investigate the possible mechanism of curcumin-mediated beneficial effects in memory deficits associated with experimental dementia. Dementia was induced in Swiss albino mice by administering streptozotocin (3 mg kg(-1)) intracerebroventricularly on first and third day. Morris water maze test was employed to assess learning and memory of the animals. Biochemical analysis of brain homogenate was performed to assess brain acetyl cholinesterase (AChE) activity and total oxidative stress. Streptozotocin (STZ) produced a significant decrease in water maze performance of mice indicative of impairment in spatial reference memory. Curcumin (20 mg/kg p.o. daily for 14 days) successfully attenuated STZ-induced memory deficits. Higher levels of brain AChE activity and oxidative stress were observed in STZ-treated animals, which were significantly attenuated by curcumin. Furthermore, the noted beneficial effect of curcumin on STZ-induced dementia was significantly abolished by pretreatment with PPAR-gamma receptor antagonist bisphenol-A-diglycidyl ether, i.e., BADGE (30 mg/kg intraperitoneally (i.p.)). It may be concluded that the beneficial effects of curcumin are mediated through the activation of PPAR-gamma receptors.

Integration of human immunodeficiency virus as a target for antiretroviral therapy

PURPOSE OF REVIEW

Most of the studies investigating inhibition of human immunodeficiency virus integration have focused on blocking the enzymatic functions of HIV integrase, with the predominant judgment that integration inhibitors need to block at least one of the integrase-catalyzed reactions. Recent studies, however, have highlighted the importance of other proteins and their contacts with integrase in the preintegration complex, and their involvement in chromosomal integration of the viral DNA.

RECENT FINDINGS

Promising results of clinical trials for two new integrase inhibitors were announced recently, providing the proof of the concept for using HIV-1 integrase inhibitors as antiretroviral therapy. Two strategies are currently employed for the development of novel inhibitors of HIV integrase: synthesis of hybrid molecules comprising core structures of two or more known inhibitors, and three-dimensional pharmacophore searches based on previously discovered compounds. By highlighting the role of the cellular cofactor LEDGF/p75 in HIV integration, novel approaches are indicated that aim to develop compounds altering contact between HIV integrase and integration cofactors.

SUMMARY

By the discovery of novel inhibitors and targets for HIV integration, coupled with recent studies in characterizing preintegration complex formation, new insight is provided for the rational design of anti-HIV integration inhibitors.

CURCUMIN: THE INDIAN SOLID GOLD

Turmeric, derived from the plant Curcuma longa, is a gold-colored spice commonly used in the Indian subcontinent, not only for health care but also for the preservation of food and as a yellow dye for textiles. Curcumin, which gives the yellow color to turmeric, was first isolated almost two centuries ago, and its structure as diferuloylmethane was determined in 1910. Since the time of Ayurveda (1900 Bc) numerous therapeutic activities have been assigned to turmeric for a wide variety of diseases and conditions, including those of the skin, pulmonary, and gastrointestinal systems, aches, pains, wounds, sprains, and liver disorders. Extensive research within the last half century has proven that most of these activities, once associated with turmeric, are due to curcumin. Curcumin has been shown to exhibit antioxidant, anti-inflammatory, antiviral, antibacterial, antifungal, and anticancer activities and thus has a potential against various malignant diseases, diabetes, allergies, arthritis, Alzheimer's disease, and other chronic illnesses. These effects are mediated through the regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other enzymes. Curcumin exhibits activities similar to recently discovered tumor necrosis factor blockers (e.g., HUMIRA, REMICADE, and ENBREL), a vascular endothelial cell growth factor blocker (e.g., AVASTIN), human epidermal growth factor receptor blockers (e.g., ERBITUX, ERLOTINIB, and GEFTINIB), and a HER2 blocker (e.g., HERCEPTIN). Considering the recent scientific bandwagon that multitargeted therapy is better than monotargeted therapy for most diseases, curcumin can be considered an ideal "Spice for Life".

A historical sketch of the discovery and development of HIV-1 integrase inhibitors

The long process of HIV-1 integrase inhibitor discovery and development can be attributed to both the complexity of HIV-1 integration and poor 'integration' of these researches into mainstream investigations on antiretroviral therapy in the mid-1990s. Of note, some fungal extracts investigated during this period contain the beta-hydroxyketo group, later recognised to be a key structural requirement for keto-enol acids (also referred to as diketo acids) and other integrase inhibitors. This review reconstructs (in the general context of the history of AIDS research) the principal steps that led to the integrase inhibitors currently in clinical trials, and discusses possible future directions.

Design, synthesis, and biological evaluation of novel tricyclic HIV-1 integrase inhibitors by modification of its pyridine ring

This communication details both the syntheses and biological evaluation of a novel class of HIV-1 integrase inhibitors. When the quinoline moiety is replaced with the quinoxoline moiety, the antiviral activity is significantly compromised. Similarly, introduction of imidazole to replace the pyridine ring is deleterious to the potency of the compound against the enzyme. Substitution at the 3-position of the pyridine has been investigated. The presence of the pyridine ring in the tricyclic core is preferred for antiviral activity against HIV integrase.

Novel bifunctional quinolonyl diketo acid derivatives as HIV-1 integrase inhibitors: design, synthesis, biological activities, and mechanism of action

The virally encoded integrase protein is an essential enzyme in the life cycle of the HIV-1 virus and represents an attractive and validated target in the development of therapeutics against HIV infection. Drugs that selectively inhibit this enzyme, when used in combination with inhibitors of reverse transcriptase and protease, are believed to be highly effective in suppressing the viral replication. Among the HIV-1 integrase inhibitors, the beta-diketo acids (DKAs) represent a major lead for anti-HIV-1 drug development. In this study, novel bifunctional quinolonyl diketo acid derivatives were designed, synthesized, and tested for their inhibitory ability against HIV-1 integrase. The compounds are potent inhibitors of integrase activity. Particularly, derivative 8 is a potent IN inhibitor for both steps of the reaction (3'-processing and strand transfer) and exhibits both high antiviral activity against HIV-1 infected cells and low cytotoxicity. Molecular modeling studies provide a plausible mechanism of action, which is consistent with ligand SARs and enzyme photo-cross-linking experiments.