Reverse Transcriptase Inhibitory Activity Research Articles

Antiretroviral activity from elderberry (<i>Sambucus nigra</i> L.) flowers against HIV-2 infection via reverse transcriptase inhibition: a viroinformatics study

HIV-2 infection is a unique concern with fewer cases than HIV-1, but it poses a high mortality rate due to its resistance to all HIV-1 antiretroviral treatments. This study focuses on one type of antiretroviral, reverse transcriptase (RT) inhibitors, as they play an important role in HIV-2 replication. The screening of potential HIV-2 antiretroviral candidates was carried out using compounds from elderberry (Sambucus nigra L.) flower extract. There is a lack of research on the antiviral potential of elderberry flower extracts, particularly in HIV-2; therefore, this study is important to explain the molecular mechanism underlying the potential of elderberry (Sambucus nigra L.) flower extracts to inhibit RT activity in HIV-2 through bioinformatics simulations. This study uses the in silico method, involving sample preparation in the database, drug-like molecular prediction through the server, molecular docking simulation, chemical bond interaction analysis, and three-dimensional structure visualization. Isorhamnetin has the most negative binding affinity of -9.9 kcal/mol compared to other compounds. It interacts with the HIV-2 RT domain at residues Trp4(B), Pro25(B), Asn137(B), Pro133(B), Gln23(B), Pro140(B), Leu21(B), Ile90(A), Thr131(B), Asn57(B), Arg22(B), and Glu89(A) with hydrophobic bond interactions. Hydrogen bond interactions are formed at the positions of Ser134(B), Gly141(B), and Thr88(A). Isorhamnetin from elderberry (Sambucus nigra L.) flower extract could be a potential HIV-2 antiretroviral candidate because it has the most negative binding affinity and the formation of hydrophobic hydrogen bond interactions on the RT domain.

Pleurotus citrinopileatus Extracts in HepG2 Cancer Cell Study

Introduction: Pleurotus citrinopileatus is a mushroom with n-number of biomolecules expressing both nutraceutical and pharmaceutical qualities. In recent years, there are many medicinal properties of the mushroom brought to light, be it the biomolecules that inhibits fat-induced weight gain; cancer treatments for hepatoma, colon or HIV-1 reverse transcriptase inhibitory activity by novel lectins present in it. Objective: The present study is to find the degree of cell damage in HepG2 cancer cell lines caused by the extracts of Pleurotus citrinopileatus. Method: Herein, we are going to compare the level of cell damage caused by acetone, ethanol and aqueous extracts of Pleurotus citrinopileatus using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Result: Acetone extracts of the mushroom showed higher cell damage in HepG2 cell line, indicated by MTT assay with the half-maximal inhibitory concentration (IC50) value of 37.03µg/ml, compared to the ethanolic and aqueous extracts of Pleurotus citrinopileatus. Conclusion: The acetone extract appears to possess biologically active compounds that might help reduce the viable cancer cells. If used as an adjuvant drug with cisplatin can reduce the effects caused by it and activate P53 action. Novelty: Further study on the biomolecules present in oyster mushrooms can give us an insight into the apoptotic behavior of cancer cells.

Pyridine/Pyrimidine Substituted Imidazol-5-one Analogs as HIV-1 RT Inhibitors: Design, Synthesis, Docking and Molecular Dynamic Simulation Studies.

This paper reports the synthesis, Non-nucleoside reverse transcriptase inhibitory (NNRTIs) activity and computational studies of 2-((4-chloro-2-subtitutedphenoxy) methyl)-4-(furan-2-ylmethylene)-1-substituted Pyridine/-pyrimidine-1H-imidazol-5(4H)-ones. The imidazol-5-one analogs were synthesized by conventional method and characterized by FT-IR, NMR and mass spectral data. All compounds were evaluated for in-vitro NNRTI activity by using reverse transcriptase (RT) assay kit (Roche). The in-silico docking studies were conducted on RT enzyme to investigate binding site interactions of synthesized compounds. The MMGBSA method was also used to calculate the binding free energy between the inhibitors and RT enzyme. The MD simulation was further performed for the apo form of the RT enzyme and docked complex of compound A6-RT enzyme to better understand the stability of the protein-ligand complex. The bioactivity analysis revealed that most of the synthesized compounds showed significant inhibitory activity against RT enzyme and the IC50 value was found to be in the range of 1.76-3.88 μM. The computational studies suggest that the docked compounds form the H-bonding with amino acid residue Lys101 and hydrophobic interactions with amino acid residues Tyr188, Tyr181, Trp229, and Tyr318, which act as the primary driving forces for protein-ligand interaction. The reported imidazol-5-one analogs can act as lead for further development of prospective RT inhibitors.

HIV-1 Protease and Reverse Transcriptase Inhibitory Activities of Curcuma aeruginosa Roxb. Rhizome Extracts and the Phytochemical Profile Analysis: In Vitro and In Silico Screening.

Human immunodeficiency virus type-1 (HIV-1) infection causes acquired immunodeficiency syndrome (AIDS). Currently, several anti-retroviral drugs are available, but adverse effects of these drugs have been reported. Herein, we focused on the anti-HIV-1 activity of Curcuma aeruginosa Roxb. (CA) extracted by hexane (CA-H), ethyl acetate (CA-EA), and methanol (CA-M). The in vitro HIV-1 protease (PR) and HIV-1 reverse transcriptase (RT) inhibitory activities of CA extracts were screened. CA-M potentially inhibited HIV-1 PR (82.44%) comparable to Pepstatin A (81.48%), followed by CA-EA (67.05%) and CA-H (47.6%), respectively. All extracts exhibited moderate inhibition of HIV-1 RT (64.97 to 76.93%). Besides, phytochemical constituents of CA extracts were identified by GC-MS and UPLC-HRMS. Fatty acids, amino acids, and terpenoids were the major compounds found in the extracts. Furthermore, drug-likeness parameters and the ability of CA-identified compounds on blocking of the HIV-1 PR and RT active sites were in silico investigated. Dihydroergocornine, 3β,6α,7α-trihydroxy-5β-cholan-24-oic acid, and 6β,11β,16α,17α,21-Pentahydroxypregna-1,4-diene-3,20-dione-16,17-acetonide showed strong binding affinities at the active residues of both HIV-1 PR and RT. Moreover, antioxidant activity of CA extracts was determined. CA-EA exhibited the highest antioxidant activity, which positively related to the amount of total phenolic content. This study provided beneficial data for anti-HIV-1 drug discovery from CA extracts.

Reverse transcriptase inhibition potentiates target therapy in BRAF-mutant melanomas: effects on cell proliferation, apoptosis, DNA-damage, ROS induction and mitochondrial membrane depolarization

Target therapies based on BRAF and MEK inhibitors (MAPKi) have changed the therapeutic landscape for metastatic melanoma patients bearing mutations in the BRAF kinase. However, the emergence of drug resistance imposes the necessity to conceive novel therapeutic strategies capable to achieve a more durable disease control. In the last years, retrotransposons laying in human genome have been shown to undergo activation during tumorigenesis, where they contribute to genomic instability. Their activation can be efficiently controlled with reverse transcriptase inhibitors (RTIs) frequently used in the treatment of AIDS. These drugs have demonstrated anti-proliferative effects in several cancer models, including also metastatic melanoma. However, to our knowledge no previous study investigated the capability of RTIs to mitigate drug resistance to target therapy in BRAF-mutant melanomas. In this short report we show that the non-nucleoside RTI, SPV122 in combination with MAPKi strongly inhibits BRAF-mutant melanoma cell growth, induces apoptosis, and delays the emergence of resistance to target therapy in vitro. Mechanistically, this combination strongly induces DNA double-strand breaks, mitochondrial membrane depolarization and increased ROS levels. Our results shed further light on the molecular activity of RTI in melanoma and pave the way to their use as a novel therapeutic option to improve the efficacy of target therapy.7fN6r4qRQJy_8CfHGxK4XPVideo Graphical abstract

Novel peptides with HIV-1 reverse transcriptase inhibitory activity derived from the fruits of Quercus infectoria.

The HIV-1 reverse transcriptase (HIV-1 RT), which is responsible for transcription of viral RNA genomes into DNA genomes, has become an important target for the treatment of patients with HIV infection. Hydrolyzed peptides from plants are considered a new source of potential drugs. In order to develop new effective inhibitors, peptides extracted from 111 Asian medicinal plants were screened against the HIV-1 RT. The crude hydrolyzed peptides from the fruit peel of Quercus infectoria were selected for purification and peptide sequence determination by HPLC and LC-MS. Two peptides of interest were synthesized, and an IC50 test was performed to determine their ability to inhibit the HIV-1 RT. The IC50 values of the peptides AIHIILI and LIAVSTNIIFIVV were determined to be 274±5.10nm and 236.4±7.07nm, respectively. This indicated that these peptides could be further developed as potential HIV-1 RT inhibitors.

Inhibition of HIV-1 RT activity by a new series of 3-(1,3,4-thiadiazol-2-yl)thiazolidin-4-one derivatives

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) represent potent anti-HIV agents targeting HIV-1 reverse transcriptase (RT), a crucial enzyme for the viral life cycle. We have previously identified a series of NNRTIs bearing a 2,3-diaryl-1,3-thiazolidin-4-one core and some compounds proved to be effective in inhibiting HIV-1 replication at micromolar concentration. As a continuation in this research work we report the design, the synthesis and the structure–activity relationship studies of a further series of 3-(1,3,4-thiadiazol-2-yl)thiazolidin-4-one derivatives containing an arylthioacetamide group as pharmacophoric structural requirement for binding to the RT catalytic area. The new compounds proved to be effective to inhibit RT activity at micromolar concentrations. Finally, docking studies were carried out in order to rationalize the biological results of the new synthesized inhibitors.

Human Immunodeficiency Virus (HIV-1) reverse transcriptase inhibitory activity of Phyllanthus emblica plant extract

Human Immunodeficiency Virus type-1 (HIV-1) is the cause of Acquired Immune Deficiency Syndrome (AIDS), a major human viral disease with about 33.2 million people infected worldwide. The high cost of the HAART regimen has impeded its delivery to over 90% of the HIV/AIDS population in the world. The aim of the present study was to evaluate the in vitro anti-HIV activity of Phyllanthus emblica plant extracts. Extracts were prepared from dried fruit in n-hexane, ethyl acetate, and n-butanol. Peripheral Blood Mononuclear Cells (PBMCs) isolated from healthy donors by ficoll-hypaque density gradient centrifugation method. A toxicity study was performed on all crude extracts by MTT assay using PBMCs isolated from whole blood. HIV-1 RT inhibition activity of the all solvent extracts of P. emblica was determined. AQF and HXF fractions show highest inhibition of recombinant HIV-RT (91% and 89% respectively) at 1 mg/ml concentration. CFF fraction shows highest inhibition of HIV-RT at 0.5 mg/ml and CTF fraction at 0.12 mg/ml concentration. Experimental results thus suggested that the P. emblica plant extracts which have been tested in the present study exert their anti-HIV activity via inhibition of HIV reverse transcriptase activity. Thus the present study seems to justify the traditional use of plant for the treatment of infectious disease of viral origin. However, in order to assess the usefulness of this herb, it is necessary to isolate the active principle(s) from the crude and fractions, identify them and study their mechanism of action.

Insights into the key structural features of triazolothienopyrimidines as anti-HIV agents using QSAR, molecular docking, and pharmacophore modeling

The development of severe drug resistance caused by the extensive use of anti-HIV agents has resulted in resistance mutation that compromise efficacy of anti-retroviral. We have selected triazolothienopyrimidine derivatives for our study since these derivatives have potentially inhibited HIV-1 replication. The objectives of our study were to identify the important pharmacophoric features and correlate 3D chemical structure of of triazolothienopyrimidines and predict their anti-HIV activity using 2D-, 3D-QSAR, pharmacophore modeling, and docking studies to explore their binding to HIV-1 reverse transcriptase. Partial least square and k-nearest neighbor methodology were used to develop 2D-QSAR and 3D-QSAR models. The statistical significance of developed QSAR models was checked by internal and external validation. The developed 2D-QSAR model indicated that a significance of presence of electron withdrawing groups, number of hydrogen bond acceptor, Z component dipole moment, and the moment of inertia at X axis of the compounds on their anti-HIV potential. 3D-QSAR results indicated the influence of electrostatic and steric field descriptors in the anti-HIV potential of triazolothienopyrimidines. The pharmacophore mapping represented the importance of aromatic and hydrogen bond acceptor features of compounds to interact with the target. Docking studies revealed that the binding of the triazolothienopyrimidines to HIV-1 reverse transcriptase involved extensive hydrophobic and polar interactions. Collectively, the results of QSAR, pharmacophore mapping, and the docking studies provide an insight into the understanding of the relationship between triazolothienopyrimidines and anti-HIV activity, which may assist in designing new triazolothienopyrimidines with enhanced HIV-1 reverse transcriptase inhibitory and anti-HIV activity.

A Novel Peroxidase from Fresh Fruiting Bodies of the Mushroom Pleurotus pulmonarius

A novel peroxidase has been isolated from fresh fruiting bodies of the mushroom Pleurotus pulmonarius, with a purification protocol of ion exchange chromatography on DEAE-cellulose, affinity chromatography on ConA-Sepharose, ion exchange chromatography on CM-cellulose, and gel filtration by FPLC on Superdex 75. The peroxidase was unadsorbed on either DEAE-cellulose or ConA-Sepharose, but was adsorbed on CM-cellulose. It exhibited a molecular mass of 55 kDa in gel filtration and also in sodium dodecyl sulfate–polyacrylamide gel electrophoresis, indicating that it is a monomeric protein. It possessed a distinctive N-terminal amino acid sequences from other isolated mushroom peroxidases. The optimal pH and temperature for the enzyme were 4.0 and 70 °C, respectively. All enzyme activity was destroyed after exposured in 100 °C for 10 min. The peroxidase did not exhibit HIV-1 reverse transcriptase inhibitory activity and antifungal activity. The stability against high temperature and extreme pH supported that the enzyme could be a potential peroxidase source for special industrial applications.

Aqueous two phase partitioning of Pisum sativum lectin in PEG/citrate salt system

Pisum sativum lectin (Psl) is a metalloprotein which is in the center of research interest because of its HIV-1 reverse transcriptase inhibitory activity and mitogenic activity. The application of this lectin in various fields demands the economically feasible and scalable purification strategy other than affinity chromatography. The suitability of aqueous two phase system (ATPS) composed of poly ethylene glycol (PEG) with different salts (sodium citrate, potassium citrate, and ammonium citrate) was evaluated for better partitioning of Psl. The significant factors such as molar mass and concentration of PEG, type and concentration of salts, the effect of tie line length (TLL), ionic strength, and pH were studied to select a suitable system for better partitioning of Psl. ATPS comprising of 18% PEG 6000, 16% sodium citrate, 1% NaCl at the operating condition of pH 8, 40.23% of TLL, and the volume ratio of 1.32 was found to be the best system which gave a maximum partition coefficient and yield of 14.5% and 98.66%, respectively.

First discovery of a potential carbonate prodrug of NNRTI drug candidate RDEA427 with submicromolar inhibitory activity against HIV-1 K103N/Y181C double mutant strain

In the present work, we described the synthesis, antiviral profiles and metabolic stability in human plasma of compound 6, a potential carbonate prodrug of HIV-1 NNRTI drug candidate RDEA427. Compound 6 was found to inhibit the wild-type (WT) and K103N/Y181C double mutant HIV-1 strains at nano- and submicromolar concentrations, respectively. Moreover, it displayed potent HIV-1 reverse transcriptase inhibitory activity (IC50 = 0.264 μM). Further stability test in human plasma showed that 6 could release its active form RDEA427 in a linearly time-independent manner, possibly acting as a potential prodrug.

Synthesis of tetracyclic azasugars fused benzo[e][1,3]thiazin-4-one by the tandem Staudinger/aza-Wittig/cyclization and their HIV-RT inhibitory activity

Azasugar aldehydes 6a and 6b containing azido groups were prepared from D-mannose. Three novel tetracyclic azasugars fused benzo[e][1,3]thiazin-4-one 9a-1, 9a-2 and 9a-3 were conveniently synthesized from 6a by the tandem intramolecular Staudinger/aza-Wittig/cyclization reaction under microwave radiation. Two unexpected elimination compounds 8b-1 and 8b-2 were achieved as the main products from 6b in the same processes. The newly synthesized azasugars were examined for their HIV reverse transcriptase (RT) inhibitory activities. The results showed that all the tested compounds could effectively inhibit RT activity. Among them, compound 8b-1 with the protective group (isopropylidene group) was the best one with the IC50 value of 0.76 μM. The structure activity relationship analysis suggested that improvement of the molecular hydrophilicity might be beneficial for their anti-HIV RT activities.

Synthesis of pentacyclic iminosugars with constrained butterfly-like conformation and their HIV-RT inhibitory activity

Novel pentacyclic iminosugars 1 and 2 with the constrained butterfly-like conformation were first synthesized by the key intramolecular click reaction from the tricyclic iminosugars fused benzo[e][1,3]thiazin-4-one 3 and 4. The pentacyclic iminosugar was constructed by fusing both benzo[e][1,3]thiazin-4-one and triazolo[5,1-c][1,4]oxazepine scaffolds. Their structures were determined by their 1H, 13C NMR, and HRMS (ESI) spectra and X-ray. The pentacyclic iminosugars 1(a–c), 2(a–b) and their corresponding protected precursors 13(a–c) and 14(a–b) were examined for their HIV reverse transcriptase (RT) inhibitory activities. The result showed that all compounds could effectively inhibit RT activity. Among them, compound 13c was the best one with the IC50 value of RT inhibitory activity of 0.69 μM. Structure-activity relationship analysis suggested that the improvement of the hydrophilicity of the pentacycles was of benefit to their anti-HIV RT activity.

Dihydropyrimidinone-isatin hybrids as novel non-nucleoside HIV-1 reverse transcriptase inhibitors

A novel series of substituted N-(2-(2,3-dioxoindolin-1-yl)acetyl)-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxamide was designed, synthesized and evaluated for in vitro Reverse Transcriptase (RT) inhibitory activity. This series is a combination of peculiar structural features from leading scaffolds of [(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) and oxyindole. In vitro screening led to identification of two hybrids (9c and 9d) possessing higher RT inhibitory activity than the standard rilpivirine. Docking study was performed to study the binding orientations of synthesized hybrids towards RT enzyme.

Synthesis of novel benzofluorenone derivatives and their HIV reverse transcriptase inhibitory activity

Novel benzofluorenone derivatives have been prepared in remarkably outstanding yield through intramolecular cyclization of β-arylidene-β-benzoylpropionic acid. The reaction was promoted proficiently by extremely small amounts of montmorillonite K10 acting as a heterogeneous catalyst using ethanolic medium at 100 °C. It is for the first time that, these newly synthesized benzofluorenone derivatives exhibited anti-HIV (antiretroviral) activity. This important activity was estimated by using regular assay kits. Further, among the synthesized basic benzofluorenone derivatives, the compound named ‘2C’ was found to be most potent with the lowest IC50 (21.86 µg/mL) followed by the compound ‘2G’ with IC50 (27.40 µg/mL).

Mangrove-Mediated Green Synthesis of Silver Nanoparticles with High HIV-1 Reverse Transcriptase Inhibitory Potential

Nowadays, the interactions of metal nanoparticles with microorganisms and parasites of public health importance receive increasing attention due to their functional versatility and multipurpose effectiveness. In this research, green biosynthesis of antiviral silver nanomaterials was achieved allowing the reduction of Ag+ ions by the aqueous leaf extract of mangrove Rhizophora lamarckii. The reduction of metal ions to metallic nanosilver occurred readily in the aqueous solution and resulted in high density of extremely stable and crystalline silver nanoparticles, with mean size ranging from 12 to 28 nm. Green-fabricated silver nanoparticles exhibit high HIV type 1 reverse transcriptase inhibitory activity, even when tested at low doses. In vitro, the mangrove-fabricated silver nanoparticles showed an IC50 of 0.4 μg/ml on the HIV-1 RTase. Overall, our results highlighted the promising potential of mangrove-synthesized metal nanoparticles in the fight against HIV and other viruses of public health importance.

Design and anti-HIV activity of arylsulphonamides as non-nucleoside reverse transcriptase inhibitors

Design and anti-HIV activity of a series of arylsulphonamide derivatives as possible non-nucleoside reverse transcriptase inhibitors have been discussed. Compounds designed on the basis of Lipinski’s rule of five and having H-bond donor and acceptor sites were synthesized and screened in vitro to assess their human immunodeficiency virus type 1 reverse transcriptase inhibitory activity using TZM-bl cells. In silico studies using Discovery Studio 3.0 software showed that these molecules formed H-bonds and exhibited π–π, π–+ interactions, with amino acids in the non-nucleoside inhibitor binding pocket, and formed more stable complexes (total interaction energy in the range of (−) 47.85–(−) 77.01 kcal/mol) with human immunodeficiency virus type 1 reverse transcriptase in comparison to nevirapine and etravirine, (−) 45.79 and (−) 61.43 kcal/mol, respectively, and thus, lower EC50 values were predicted. The molecule, 4-(4-chloro-benzenesulphonyl amino)-N-(1H-indazole-5-yl)-benzamide showed significant inhibition of human immunodeficiency virus type 1 growth under in vitro conditions with EC50 value in the range of 4.89 × 10−5 μm. However, its selectivity index value was 2.45 only, which was much lower than nevirapine and etravirine. The reverse transcriptase analysis, based on luciferase reporter assay, of this compound proved its nature as non-nucleoside reverse transcriptase inhibitors. Though the molecules showed low inhibitory action against human immunodeficiency virus type 1 under in vitro conditions, the idea to develop non-nucleoside reverse transcriptase inhibitors was vindicated.

Purification and Characterization of a White Laccase with Pronounced Dye Decolorizing Ability and HIV-1 Reverse Transcriptase Inhibitory Activity from Lepista nuda.

A strain LN07 with high laccase yield was identified as basidiomycete fungus Lepista nuda from which a white laccase without type I copper was purified and characterized. The laccase was a monomeric protein with a molecular mass of 56 kDa. Its N-terminal amino acid sequence was AIGPAADLHIVNKDISPDGF. Besides, eight inner peptide sequences were determined and lac4, lac5 and lac6 sequences were in the Cu2+ combination and conservation zones of laccases. HIV-1 reverse transcriptase was inhibited by the laccase with a half-inhibitory concentration of 0.65 μM. Cu2+ ions (1.5 mM) enhanced the laccase production and the optimal pH and temperature of the laccase were pH 3.0 and 50 °C, respectively. The Km and Vmax of the laccase using ABTS as substrate were respectively 0.19 mM and 195 μM. Several dyes including laboratory dyes and textile dyes used in this study, such as Methyl red, Coomassie brilliant blue, Reactive brilliant blue and so on, were decolorized in different degrees by the purified laccase. By LC-MS analysis, Methyl red was structurally degraded by the laccase. Moreover, the laccase affected the absorbance at the maximum wavelength of many pesticides. Thus, the white laccase had potential commercial value for textile finishing and wastewater treatment.

Arylazolyl(azinyl)thioacetanilides: Part 19: Discovery of Novel Substituted Imidazo[4,5-b]pyridin-2-ylthioacetanilides as Potent HIV NNRTIs Via a Structure-based Bioisosterism Approach.

With the continuation of our unremitting efforts toward the discovery of potent HIV-1 NNRTIs, a series of novel imidazo[4,5-b]pyridin-2-ylthioacetanilides were designed, synthesized, and evaluated for their antiviral activities through combining bioisosteric replacement and structure-based drug design. Almost all of the title compounds displayed moderate to good activities against wild-type (wt) HIV-1 strain with EC50 values ranging from 0.059 to 1.41 μm in a cell-based antiviral assay. Thereinto, compounds 12 and 13 were the most active two analogues possessing an EC50 value of 0.059 and 0.073 μm against wt HIV-1, respectively, which was much more effective than the control drug nevirapine (EC50 = 0.26 μm) and comparable to delavirdine (EC50 = 0.038 μm). In addition, one selected compound showed a remarkable reverse transcriptase inhibitory activity compared to nevirapine and etravirine. In the end of this manuscript, preliminary structure-activity relationships (SARs) and molecular modeling studies were detailedly discussed, which may provide valuable insights for further optimization.