Natural Products as Anti-HIV Agents and Role in HIV-Associated Neurocognitive Disorders (HAND): A Brief Overview

Profile and in silico analysis of metabolite compounds of the endophytic fungus Alternaria alternata K-10 from Drymoglossum piloselloides as antioxidants and antibacterials

Endophytic fungi are known for producing secondary metabolites with valuable biological activities, including antiviral, anticancer, antibacterial, and antioxidant properties. This study aims to evaluate an endophytic fungus from Dragon Scales leaves (Drymoglossum piloselloides) and analyze its metabolites as antioxidants and antibacterials. In this study, an endophytic fungus was isolated from the leaves of Dragon Scales (D. piloselloides) and identified using molecular analysis of the Internal Transcribed Spacer (ITS) ribosomal RNA locus. The fungus was authenticated as Alternaria alternata strain K-10. Crude extracts were obtained using n-hexane and ethyl acetate and analyzed via GC-MS Shimadzu-QP 2010 Ultra with NIST spectral library. Antibacterial activity was observed against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa using the paper disc method, showing inhibition zones of 8.7-9.3 mm and 8.8-9.4 mm for ethyl acetate and n-hexane extracts, respectively. Ethyl acetate and n-hexane extracts exhibited strong antioxidant potential against 2,2-diphenyl-1-picrylhydrazil (DPPH) radical (IC50 values of 50.99 μg mL-1 and 74.44 μg mL-1, respectively). GC-MS analysis revealed 40 compounds in both extracts, some of which, including 2-ethylhexyl ester benzoic acid, benzo-b-dihydropyran-6-hydroxy-4-4-5-7-8-pentamethyl, diethyl phthalate, and octadecanoic acid, were identified through in silico analysis and found to possess antioxidant properties. These findings hold implications for potential applications of the plant and its biological constituent to be developed as lead compounds in the medical sector.

Optimization of cultural and nutritional conditions to enhance mycelial biomass of Cordyceps militaris using statistical approach

Cordyceps militaris is a fungus with numerous therapeutic properties that has gained worldwide popularity due to its potential health benefits. The fruiting body of this mushroom is highly expensive and takes a longer time to produce, making mycelial a sustainable and cost-effective alternative. The study investigates and optimizes cultural and nutritional conditions to maximize mycelial biomass. The initial optimization was done by the conventional single-factor approach, followed by Plackett-Burman design to screen the most significant variables, with yeast extract, temperature, and glucose being the most significant, contributing 11.58%, 49.74%, and 27.98%, respectively, in mycelial biomass production. These variables were then optimized using response surface methodology (RSM) based on central composite design (CCD). The study observed that temperature and glucose had the highest impact on mycelial biomass, with p-values of 0.0128 and 0.0191, respectively. Under the optimized conditions, temperature 20 °C, glucose 2.5% (w/v), and yeast extract 0.8% (w/v), the maximal yield of mycelial biomass reached 547 ± 2.09 mg/100 mL, which was 1.95-fold higher than the yield in the basal medium. These findings suggest that optimizing the cultural and nutritional conditions can enhance mycelial biomass production of Cordyceps militaris, offering a sustainable and cost-effective source of this valuable fungus.

Curcumin enhances elvitegravir concentration and alleviates oxidative stress and inflammatory response

In this study, we investigated the potential of using curcumin (CUR) as an adjuvant to enhance the delivery of antiretroviral drug elvitegravir (EVG) across the BBB, and alleviate oxidative stress and inflammatory response, which are the major hallmark of HIV neuropathogenesis. In a mouse model, we compared the biodistribution of EVG alone and in combination with CUR using intraperitoneal (IP) and intranasal (IN) routes. IN administration showed a significantly higher accumulation of EVG in the brain, while both IP and IN routes led to increased EVG levels in the lungs and liver. The addition of CUR further enhanced EVG brain delivery, especially when administered via the IN route. The expression of neural marker proteins, synaptophysin, L1CAM, NeuN, and GFAP was not significantly altered by EVG or CUR alone or their combination, indicating preserved neural homeostasis. After establishing improved brain concentration and safety of CUR-adjuvanted EVG in mice in acute treatment, we studied the effect of this treatment in HIV-infected U1 macrophages. In U1 macrophages, we also observed that the addition of CUR enhanced the intracellular concentration of EVG. The total area under the curve (AUCtot) for EVG was significantly higher in the presence of CUR. We also evaluated the effects of CUR on oxidative stress and antioxidant capacity in EVG-treated U1 macrophages. CUR reduced oxidative stress, as evidenced by decreased reactive oxygen species (ROS) levels and elevated antioxidant enzyme expression. Furthermore, the combination of CUR and EVG exhibited a significant reduction in proinflammatory cytokines (TNFα, IL-1β, IL-18) and chemokines (RANTES, MCP-1) in U1 macrophages. Additionally, western blot analysis confirmed the decreased expression of IL-1β and TNF-α in EVG + CUR-treated cells. These findings suggest the potential of CUR to enhance EVG permeability to the brain and subsequent efficacy of EVG, including HIV neuropathogenesis.

Curcumin enhances elvitegravir concentration and alleviates oxidative stress and inflammatory response

In this study, we investigated the potential of using curcumin (CUR) as an adjuvant to enhance the delivery of antiretroviral drug elvitegravir (EVG) across the BBB, and alleviate oxidative stress and inflammatory response, which are the major hallmark of HIV neuropathogenesis. In a mouse model, we compared the biodistribution of EVG alone and in combination with CUR using intraperitoneal (IP) and intranasal (IN) routes. IN administration showed a significantly higher accumulation of EVG in the brain, while both IP and IN routes led to increased EVG levels in the lungs and liver. The addition of CUR further enhanced EVG brain delivery, especially when administered via the IN route. The expression of neural marker proteins, synaptophysin, L1CAM, NeuN, and GFAP was not significantly altered by EVG or CUR alone or their combination, indicating preserved neural homeostasis. After establishing improved brain concentration and safety of CUR-adjuvanted EVG in mice in acute treatment, we studied the effect of this treatment in HIV-infected U1 macrophages. In U1 macrophages, we also observed that the addition of CUR enhanced the intracellular concentration of EVG. The total area under the curve (AUCtot) for EVG was significantly higher in the presence of CUR. We also evaluated the effects of CUR on oxidative stress and antioxidant capacity in EVG-treated U1 macrophages. CUR reduced oxidative stress, as evidenced by decreased reactive oxygen species (ROS) levels and elevated antioxidant enzyme expression. Furthermore, the combination of CUR and EVG exhibited a significant reduction in proinflammatory cytokines (TNFα, IL-1β, IL-18) and chemokines (RANTES, MCP-1) in U1 macrophages. Additionally, western blot analysis confirmed the decreased expression of IL-1β and TNF-α in EVG + CUR-treated cells. These findings suggest the potential of CUR to enhance EVG permeability to the brain and subsequent efficacy of EVG, including HIV neuropathogenesis.

Withania somnifera extracts induced attenuation of HIV-1: a mechanistic approach to restrict viral infection

BACKGROUND

Several anti-retroviral drugs are available against Human immunodeficiency virus type-1, but have multiple adverse side effects. Hence, there is an incessant compulsion for effectual anti-retroviral agents with minimal or no intricacy. Traditionally, natural products have been the most successful source for the development of new medications. Withania somnifera, also known as Ashwagandha, is the utmost treasured medicinal plant used in Ayurveda, which holds the potential to give adaptogenic, immunomodulatory, and antiviral effects. However, its effect on HIV-1 replication at the cellular level has never been explored. Herein, we focused on the anti-HIV-1 activity and the probable mechanism of action of hydroalcoholic and aqueous extracts of Withania somnifera roots and its phytomolecules.

METHODS

The cytotoxicity of the extracts was determined through MTT assay, while the in vitro anti-HIV-1 activity was assessed in TZM-bl cells against the HIV-1 strains of X4 and R5 subtypes. Results were confirmed in peripheral blood mononuclear cells, using the HIV-1 p24 antigen assay. Additionally, the mechanism of action was determined through the Time of Addition assay, which was further validated through the series of enzymatic assays, i.e. HIV-1 Integrase, Reverse transcriptase, and Protease assays. To explore the role of the identified active metabolites of Withania somnifera in antiretroviral activity, molecular docking analyses were performed against these key HIV-1 replication enzymes.

RESULTS

The hydroalcoholic and aqueous extracts of Withania somnifera roots were found to be safer at the sub-cytotoxic concentrations and exhibited their ability to inhibit replication of two primary isolates of HIV-1 through cell-associated and cell-free assays, in dose-dependent kinetics. Several active phytomolecules found in Withania somnifera successfully established hydrogens bonds in the active binding pocket site residues responsible for the catalytic activity of HIV replication and therefore, signifying their role in the attenuation of HIV-1 infection as implied through the in silico molecular docking studies.

CONCLUSIONS

Our research identified both the hydroalcoholic and aqueous extracts of Withania somnifera roots as potent inhibitors of HIV-1 infection. The in silico analyses also indicated the key components of Withania somnifera with the highest binding affinity against the HIV-1 Integrase by 12-Deoxywithastramonolide and 27-Hydroxywithanone, HIV-1 Protease by Ashwagandhanolide and Withacoagin, and HIV-1 Reverse transcriptase by Ashwagandhanolide and Withanolide B, thereby showing possible mechanisms of HIV-1 extenuation. Overall, this study classified the role of Withania somnifera extracts and their active compounds as potential agents against HIV-1 infection.

Epigenetic Induction of Secondary Metabolites Production in Endophytic Fungi Penicillium chrysogenum and GC-MS Analysis of Crude Metabolites with Anti-HIV-1 Activity

The continuous burden of human immunodeficiency virus-1 in Sub-Saharan Africa, coupled with the inability of antiretroviral agents to eradicate HIV-1 from viral reservoirs, the potential risks of drug resistance development, and the development of adverse effects, emphasizes the need to develop a new class of HIV-1 inhibitors. Here, we cultivated four endophytic fungal isolates from a medicinal plant, Albizia adianthifolia with the addition of small epigenetic modifiers, sodium butyrate, and valproic acid, to induce the expression of biosynthetic gene clusters encoding active secondary metabolites with probable anti-HIV activities. We identified a non-toxic crude extract of the endophytic fungus Penicillium chrysogenum treated with sodium butyrate to possess significantly greater anti-HIV activity than the untreated extracts. Penicillium chrysogenum P03MB2 showed anti-HIV activity with an IC₅₀ of 0.6024 µg/mL compared to untreated fungal crude extract (IC₅₀ 5.053 µg/mL) when treated with sodium butyrate. The profile of secondary metabolite compounds from the bioactive, partially purified extracts were identified by gas chromatography-mass spectrometry (GC-MS), and more bioactive compounds were detected in treated P. chrysogenum P03MB2 fractions than in untreated fractions. Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro (13.64%), cyclotrisiloxane, hexamethyl (8.18%), cyclotetrasiloxane, octamethyl (7.23%), cyclopentasiloxane, decamethyl (6.36%), quinoline, 1,2-dihydro-2,24-trimethyl (5.45%), propanenitrile (4.55%), deca-6,9-diene (4.55%), dibutyl phthalate (4.55%), and silane[1,1-dimethyl-2-propenyl)oxy]dimethyl (2.73%) were the most abundant compounds. These results indicate that treatment of endophytic fungi with small epigenetic modifiers enhances the secretion of secondary metabolites with stronger anti-HIV-1 properties, acknowledging the feasibility of epigenetic modification as an innovative approach for the discovery of cryptic fungal metabolites which can be developed into therapeutic compounds.

A comprehensive overview on the role of phytocompounds in human immunodeficiency virus treatment

Acquired immune deficiency syndrome (AIDS) is a worldwide epidemic caused by human immunodeficiency virus (HIV) infection. Newer medicines for eliminating the viral reservoir and eradicating the virus are urgently needed. Attempts to locate relatively safe and non-toxic medications from natural resources are ongoing now. Natural-product-based antiviral candidates have been exploited to a limited extent. However, antiviral research is inadequate to counteract for the resistant patterns. Plant-derived bioactive compounds hold promise as powerful pharmacophore scaffolds, which have shown anti-HIV potential. This review focuses on a consideration of the virus, various possible HIV-controlling methods and the recent progress in alternative natural compounds with anti-HIV activity, with a particular emphasis on recent results from natural sources of anti-HIV agents. Please cite this article as: Mandhata CP, Sahoo CR, Padhy RN. A comprehensive overview on the role of phytocompounds in human immunodeficiency virus treatment. J Integr Med. 2023; Epub ahead of print.

A computational overview of integrase strand transfer inhibitors (INSTIs) against emerging and evolving drug-resistant HIV-1 integrase mutants

AIDS (Acquired immunodeficiency syndrome) is one of the chronic and potentially life-threatening epidemics across the world. Hitherto, the non-existence of definitive drugs that could completely cure the Human immunodeficiency virus (HIV) implies an urgent necessity for the discovery of novel anti-HIV agents. Since integration is the most crucial stage in retroviral replication, hindering it can inhibit overall viral transmission. The 5 FDA-approved integrase inhibitors were computationally investigated, especially owing to the rising multiple mutations against their susceptibility. This comparative study will open new possibilities to guide the rational design of novel lead compounds for antiretroviral therapies (ARTs), more specifically the structure-based design of novel Integrase strand transfer inhibitors (INSTIs) that may possess a better resistance profile than present drugs. Further, we have discussed potent anti-HIV natural compounds and their interactions as an alternative approach, recommending the urgent need to tap into the rich vein of indigenous knowledge for reverse pharmacology. Moreover, herein, we discuss existing evidence that might change in the near future.

Antiviral and ROS scavenging potential of Carica papaya Linn and Psidium guajava leaves extract against HIV-1 infection

Antiretroviral therapy is the only treatment option for HIV-infected patients; however, it has certain drawbacks in terms of developing multiple toxic side effects. Thus, there is a continuous need to explore safe and efficacious anti-retroviral agents. Carica papaya Linn and Psidium guajava are known for their various biological activities. In this study, we characterized the bioactive fractions of methanolic leaves extract from both plants using the High-resolution electrospray ionization mass spectrometry (HR-ESI-MS) technique, followed by the investigation of their potential as anti-HIV-1 and antioxidant agents through in vitro mechanistic assays. The anti-HIV-1 activity was examined in TZM-bl cells through luciferase gene assay against two different clades of HIV-1 strains, whereas the intracellular ROS generation was analyzed by Fluorescence-Activated Cell Sorting. Additionally, the mechanisms of action of these phyto-extracts were determined through the Time-of-addition assay. The characterization of Carica papaya Linn and Psidium guajava leaves extract through HR-ESI-MS fragmentation showed high enrichment of various alkaloids, glycosides, lipids, phenolic compounds, terpenes, and fatty acids like bioactive constituents. Both the phyto-extracts were found to be less toxic and exhibited potent antiviral activity against HIV-1 strains. Furthermore, the phyto-extracts also showed a decreased intracellular ROS in HIV-1 infected cells due to their high antioxidant potential. Overall, our study suggests the anti-HIV-1 potential of Carica papaya Linn and Psidium guajava leaves extract due to the synergistic action of multiple bioactive constituents.

Secondary metabolites produced by endophytic fungi, Alternaria alternata, as potential inhibitors of the human immunodeficiency virus

Antiretroviral treatment has significantly reduced human immunodeficiency virus infection and mortality. However, the current treatment regimen is limited by adverse side effects, the emergence of drug resistance, and the inability to eliminate viral reservoirs. Here, fifteen endophytic fungi were isolated from Sclerocarya birrea and Hypoxis plants. Crude extracts of Alternaria alternata (strain ID PO4PR1, PO4PR2, and PO2PL1) of the fifteen isolate's crude extracts showed anti-HIV-1 activity in TZM-bl cell line at inhibitory concentration (IC₅₀) values ranging from 0.017 to 1.170 μg/ml. The three crude extracts also maintained the virus replication inhibition profile on PBMCs and CD4⁺ T cells at concentrations ranging from 0.3 to 50.2 ng/ml. Partial purification using the solid phase extraction and analysis with Gas Chromatography-Mass spectrophotometry showed a diverse profile. The bioactive compounds were identified based on peak area, retention time, similarity index. The major compounds from GC-MS analysis of A. Alternata revealed the existence of cyclotrisiloxane octamethyl (22.92%); Propaninitrile (16,67%); Pyrrolol[1,2-a]pyrazine-1,4-dione, hexahydro-3-(2-methyl propyl) (10.42%); Silane, diethylethoxy(2-ethoxyethyloxy) (4.17%); Coumarin, 3,4-dihydro-4,5,7-trimethyl- 4,5,7-Trimethyl-2-chromanone (13.7%) and 1,2-Cyclobutanedicarbonitrile (2.08%) with previously reported biological activities such as antimicrobial, anti-inflammatory and antioxidant properties. Therefore, these bioactive compounds from A. alternata fungal endophytes could be repurposed as potential anti-HIV agents. This study showed the potential of endophytic fungi, Alternaria alternata from S. birrea, and Hypoxis species as producers of anti-HIV compounds.

Exploration of Anti-HIV Phytocompounds against SARS-CoV-2 Main Protease: Structure-Based Screening, Molecular Simulation, ADME Analysis and Conceptual DFT Studies

The ever-expanding pandemic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has gained attention as COVID-19 and caused an emergency in public health to an unmatched level to date. However, the treatments used are the only options; currently, no effective and licensed medications are available to combat disease transmission, necessitating further research. In the present study, an in silico-based virtual screening of anti-HIV bioactive compounds from medicinal plants was carried out through molecular docking against the main protease (M^pro) (PDB: 6LU7) of SARS-CoV-2, which is a key enzyme responsible for virus replication. A total of 16 anti-HIV compounds were found to have a binding affinity greater than -8.9 kcal/mol out of 150 compounds screened. Pseudohypericin had a high affinity with the energy of -10.2 kcal/mol, demonstrating amino acid residual interactions with LEU141, GLU166, ARG188, and GLN192, followed by Hypericin (-10.1 kcal/mol). Moreover, the ADME (Absorption, Distribution, Metabolism and Excretion) analysis of Pseudohypericin and Hypericin recorded a low bioavailability (BA) score of 0.17 and violated Lipinski's rule of drug-likeness. The docking and molecular simulations indicated that the quinone compound, Pseudohypericin, could be tested in vitro and in vivo as potent molecules against COVID-19 disease prior to clinical trials.This was also supported by the theoretical and computational studies conducted. The global and local descriptors, which are the underpinnings of Conceptual Density FunctionalTheory (CDFT) have beenpredicted through successful model chemistry, hoping that they could be of help in the comprehension of the chemical reactivity properties of the molecular systems considered in this study.

Theaflavin 3-gallate inhibits the main protease (Mpro) of SARS-CoV-2 and reduces its count in vitro

The main protease (M^pro) of SARS-CoV-2 has been recognized as an attractive drug target because of its central role in viral replication. Our previous preliminary molecular docking studies showed that theaflavin 3-gallate (a natural bioactive molecule derived from theaflavin and found in high abundance in black tea) exhibited better docking scores than repurposed drugs (Atazanavir, Darunavir, Lopinavir). In this study, conventional and steered MD-simulations analyses revealed stronger interactions of theaflavin 3-gallate with the active site residues of M^pro than theaflavin and a standard molecule GC373 (a known inhibitor of M^pro and novel broad-spectrum anti-viral agent). Theaflavin 3-gallate inhibited M^pro protein of SARS-CoV-2 with an IC₅₀ value of 18.48 ± 1.29 μM. Treatment of SARS-CoV-2 (Indian/a3i clade/2020 isolate) with 200 μM of theaflavin 3-gallate in vitro using Vero cells and quantifying viral transcripts demonstrated reduction of viral count by 75% (viral particles reduced from Log10^6.7 to Log10^6.1). Overall, our findings suggest that theaflavin 3-gallate effectively targets the M^pro thus limiting the replication of the SARS-CoV-2 virus in vitro.

Exploring Natural Product Activity and Species Source Candidates for Hunting ABCB1 Transporter Inhibitors: An In Silico Drug Discovery Study

The P-glycoprotein (P-gp/ABCB1) is responsible for a xenobiotic efflux pump that shackles intracellular drug accumulation. Additionally, it is included in the dud of considerable antiviral and anticancer chemotherapies because of the multidrug resistance (MDR) phenomenon. In the search for prospective anticancer drugs that inhibit the ABCB1 transporter, the Natural Product Activity and Species Source (NPASS) database, containing >35,000 molecules, was explored for identifying ABCB1 inhibitors. The performance of AutoDock4.2.6 software to anticipate ABCB1 docking score and pose was first assessed according to available experimental data. The docking scores of the NPASS molecules were predicted against the ABCB1 transporter. Molecular dynamics (MD) simulations were conducted for molecules with docking scores lower than taxol, a reference inhibitor, pursued by molecular mechanics-generalized Born surface area (MM-GBSA) binding energy estimations. On the basis of MM-GBSA calculations, five compounds revealed promising binding affinities as ABCB1 inhibitors with ΔGbinding < −105.0 kcal/mol. The binding affinity and stability of the identified inhibitors were compared to the chemotherapeutic agent. Structural and energetical analyses unveiled great steadiness of the investigated inhibitors within the ABCB1 active site throughout 100 ns MD simulations. Conclusively, these findings point out that NPC104372, NPC475164, NPC2313, NPC197736, and NPC477344 hold guarantees as potential ABCB1 drug candidates and warrant further in vitro/in vivo tests.

Repositioning therapeutics for SARS-CoV-2: Virtual screening of plant-based Anti-HIV compounds as possible inhibitors against COVID-19 viral RdRp

Background:

Coronavirus disease 2019 (COVID-19) has caused a global pandemic with a high mortality rate and infecting people worldwide. The COVID-19 vaccines that are currently in development or already approved are expected to provide at least some protection against the emerging variants of the virus but the mutations may reduce the efficacy of the existing vaccines. Purified phytochemicals from medicinal plants provide a helpful framework for discovering new therapeutic leads as they have long been employed in traditional medicine to treat many disorders.

Objective:

The objectives of the study are to exploit the anti-HIV bioactive compounds against SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) through molecular docking studies and perform the Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) properties of potential compounds.

Methods:

Molecular docking was performed to study the interaction of ligands with the target sites of RdRp protein (PDB: 6M71) using AutoDock Vina. The ADMET properties of potential compounds were predicted using the pkCSM platform.

Results:

A total of 151 phytochemicals derived from the medicinal plants with recognized antiviral activity and 18 anti-HIV drugs were virtually screened against COVID-19 viral RdRp to identify putative inhibitors that facilitate the development of potential anti-COVID-19 drug candidates. The computational studies identified 34 compounds and three drugs inhibiting viral RdRp with binding energies ranging from -10.2 to -8.5 kcal/ mol. Among these, five compounds, namely Michellamine B, Quercetin 3-O-(2'',6''-digalloyl)-beta-D-galactopyranoside, Corilagin, Hypericin, and 1,2,3,4,6-Penta-O-galloyl-beta-D-glucose residues bound efficiently with the binding site of RdRp. Besides, Lopinavir, Maraviroc, and Remdesivir drugs also inhibited SARS-CoV-2 polymerase. In addition, the ADMET properties of top potential compounds were also predicted in comparison to the drugs.

Conclusion:

The present study suggested that these potential drug candidates can be further subjected to in vitro and in vivo studies that may help develop effective anti-COVID-19 drugs.

Voacanga globosa Spirobisindole Alkaloids Exert Antiviral Activity in HIV Latently Infected Cell Lines by Targeting the NF-kB Cascade: In Vitro and In Silico Investigations

Since the efficiency in the transcription of the HIV genome contributes to the success of viral replication and infectivity, we investigated the downregulating effects of the spirobisindole alkaloids globospiramine (1), deoxyvobtusine (2), and vobtusine lactone (3) from the endemic Philippine medicinal plant, Voacanga globosa, during HIV gene transcription. Alkaloids 1-3 were explored for their inhibitory activity on TNF-α-induced viral replication in two latently HIV-infected cell lines, OM10.1 and J-Lat. The induction of HIV replication from OM10.1 and J-Lat cells elicited by TNF-α was blocked by globospiramine (1) within noncytotoxic concentrations. Furthermore, globospiramine (1) was found to target the NF-ĸB activation cascade in a dose-dependent manner when the transcriptional step at which inhibitory activity is exerted was examined in TNF-α-induced 293 human cells using transient reporter (luciferase) gene expression systems (HIV LTR-luc, ĸB-luc, and mutant ĸB-luc). Interrogation through molecular docking against the NF-ĸB p50/p65 heterodimer and target sites of the subunits comprising the IKK complex revealed high binding affinities of globospiramine (1) against the S281 pocket of the p65 subunit (BE = -9.2 kcal/mol) and the IKKα activation loop (BE = -9.1 kcal/mol). These findings suggest globospiramine (1) as a molecular inspiration to discover new alkaloid-based anti-HIV derivatives.

Focus on the high therapeutic potentials of quercetin and its derivatives

BACKGROUND

Polyphenols and particularly flavonoids are of constant interest to the scientific community. Flavonoids are investigated for their biological and pharmacological purposes, notably as antioxidant, anticancer, antiviral and for their anti-inflammatory activities. Certainly, one of the best-known flavonols recognized for its therapeutic and preventive properties, is quercetin. Despite its biological interest, quercetin suffer from some drawbacks, mainly related to its bioavailability. Hence, its synthetic or biosynthetic derivatives have been the subject of intensive research. The health-promoting biological activities of flavonols and derivatives mainly arise from their capacity to disrupt the host-pathogen interactions and/or to regulate host cellular functions including oxidative processes and immunological responses. In the age of coronavirus pandemic, the anti-inflammatory and antiviral potential of flavonols should be put forward to explore these substances for decreasing the viral load and inflammatory storm caused by the infection.

PURPOSE OF STUDY

The present review will decipher and discuss the antioxidant, anti-inflammatory and antiviral capacities of major flavonol with a focus on the molecular basis and structure-activity relationships.

STUDY DESIGN

Current study used a combination of quercetin derivatives, pathway, antioxidant, anti-inflammatory, antiviral activities as keywords to retrieve the literature. This study critically reviewed the current literature and presented the ability of natural analogs of quercetin having superior antioxidant, anti-inflammatory and antiviral effects than the original molecule.

RESULTS

This review allowed the identification of relevant key structure-activity relationship elements and highlight approaches on the mechanisms governing the antioxidant, antiviral and anti-inflammatory activities.

CONCLUSION

Through a critical analysis of the literature, flavonols and more precisely quercetin derivatives reviewed and found to act simultaneously on inflammation, virus and oxidative stress, three key factors that may lead to life threatening diseases.

New robustaflavone from Garcinia latissima Miq. leave and Its antibacterial activity

Isolation and determination of antibacterial compounds from plants are essential to obtain a new antibacterial as a substitute for conventional resistant antibiotics. This study aims to isolate and identify a new robustaflavone as antibacterial activity from Garcinia latissima Miq. leave. In this study, the isolation process was carried out using column chromatography followed by preparative thin layer chromatography (TLC) based on the TLC profile. The fraction D was tested for anti-bacterial Bacillus subtilis using the TLC bioautography method. The isolates obtained were then identified using 1H-NMR, 13C-NMR, distortionless enhancement by polarization transfer, heteronuclear single quantum coherence, and heteronuclear multiple bond coherence. The Activity assay of the isolate was performed using the microdilution method. A pure compound obtained the result of the separation process with eluent n-hexane: Ethyl acetate (3:2) with Rf 0.6. This spot follows the spot in the contact bioautographic result of fraction D, the spot with Rf 0.6 gives an inhibition zone. After identifying and purifying the isolate were known as Robustaflavone, this compound has activity against B. subtilis with a (minimum inhibitory concentration) value of 2500 ppm. Robustaflavone successfully isolated and identified from G. latissima leave and its antibacterial activity.

In Vitro Cytotoxicity and Anti-HIV Activity of Crude Extracts of Croton macrostachyus, Croton megalocarpus and Croton dichogamus

INTRODUCTION

Human immunodeficiency virus (HIV) affects the body's defense mechanisms and leads to a number of opportunistic infections which later cause fatality as a result of an acquired immunodeficiency syndrome (AIDS). More than half a million individuals have lost their life in 2020 due to this disease. Antiretroviral drugs have played a great role in improving the quality of life of HIV infected individuals. The side effects of these drugs coupled with resistance of the virus to the various regimens, necessitates the search for potentially new and effective antiretroviral medication. The objective of this study is to evaluate anti-HIV activity of crude extracts of three Croton plants.

METHODS

As part of our effort in screening anti-HIV medications, we evaluated the cytotoxicity and anti-HIV activity of three Croton species used as herbal medicine in Africa. Crude extracts of Croton macrostachyus, Croton megalocarpus and Croton dichogamus were tested for their replication inhibition activity against laboratory adapted strains HIV-1IIIB in Human T-lymphocytic MT-4 cell line.

RESULTS

Based on our findings, the crude aerial part extract of C. dichogamus displayed the highest anti-HIV activity by inhibiting 73.74% of viral induced cytopathic effect (CPE) at IC50 value of 0.001 + 0.00 μg/mL giving a selectivity index (SI) of 3116.0. In addition, the crude leaf extract of C. megalocarpus showed higher anti-HIV activity by inhibiting 74.65% of CPE at IC50 value of 0.05 + 0.03 μg/mL giving an SI of 571.3.

CONCLUSION

Out of five extracts from three Croton species screened for anti-HIV activity using human T-lymphocytic MT-4 cells, the leaf extract of Croton megalocarpus and aerial part extract of Croton dichogamus could be considered as promising extracts as they display high antiviral activity with low toxicity and high selectivity index values. To investigate the active constituents responsible for the anti-HIV activity, chemical identification of the active constituents is now in progress in our laboratory. Since there is no previously reported anti-HIV activity for these plants, there is a great need to isolate the compounds responsible for the noted activity.

Investigation of HIV-1 Viral Protein R Inhibitory Activities of Twelve Thai Medicinal Plants and Their Commercially Available Major Constituents

Viral protein R (Vpr) is an accessory protein in Human immunodeficiency virus-1 (HIV-1) and has been suggested as an attractive target for HIV disease treatment. Investigations of the ethanolic extracts of twelve Thai herbs revealed that the extracts of the Punica granatum fruits, the Centella asiatica aerials, the Citrus hystrix fruit peels, the Caesalpinia sappan heartwoods, the Piper betel leaves, the Alpinia galangal rhizomes, the Senna tora seeds, the Zingiber cassumunar rhizomes, the Rhinacanthus nasutus leaves, and the Plumbago indica roots exhibited the anti-Vpr activity in HeLa cells harboring the TREx plasmid encoding full-length Vpr (TREx-HeLa-Vpr cells). Moreover, the investigation of the selected main constituents in Punica granatum, Centella asiatica, A. galangal, and Caesalpinia sappan indicated that punicalagin, asiaticoside, ellagic acid, madecassic acid, madecassoside, zingerone, brazilin, and asiatic acid possessed anti-Vpr activities at the 10 μM concentration. Among the tested extracts and compounds, the extracts from Centella asiatica and Citrus hystrix and the compounds, punicalagin and asiaticoside, showed the most potent anti-Vpr activities without any cytotoxicity, respectively.

HIV-1-RT inhibition activity of Satureja spicigera (C.KOCH) BOISS. Aqueous extract and docking studies of phenolic compounds identified by RP-HPLC-DAD

AIDS is a global disease caused by HIV, affecting millions of people and causing death. The current limitations of antiretroviral therapy used in the therapy of HIV/AIDS have led to the need to search for new and effective drugs from natural products, especially plants. Herewith, using the present study, the detection of HIV-1-RT inhibition of aqueous extract of Satureja spicigera (C.KOCH) BOISS. was performed for the first time. Besides, total phenolic content (TPC), analysis of phenolic constituents by RP-HPLC-DAD and antioxidant capacity by DPPH and Ferric reducing antioxidant power (FRAP) methods were determined for the first time. In addition, molecular docking studies were carried out between HIV-1-RT and phenolic substances, the presence of which was determined in the aqueous extract, for the determination of the phenolics that may be responsible for HIV-1-RT activity. HIV-1-RT inhibition was defined as IC₅₀ : 22.83 μg/ml. Benzoic acid, vanillin, rutin, and chlorogenic acid were present as main phenolics in quantities of 621.96, 505.87, 349.33, and 323.23 µg phenolic/g extract, respectively. Further, TPC, DPPH, and FRAP were calculated as in the order of 151.69 mg GAE/g extract, 23.77 µg/ml, and 445.7 µmol TE/g extract. Chlorogenic acid (-8.48 kcal/mol) was found to be the most effective ligand in docking studies, with a value close to positive standard nevirapine (-9.35 kcal/mol). Hereby, although the aqueous extract of S. spicigera can be used as a natural antioxidant, the crude extract or its phenolics have the potential to be used in the treatment of AIDS due to its high HIV-1-RT activity. PRACTICAL APPLICATIONS: In this study, anti-HIV-1-RT and antioxidant activity and total phenolic content of Satureja spicigera aqueous extract were determined. In addition, HPLC analysis of some phytochemicals and the activities of these phytochemicals against HIV-1-RT enzyme was determined by molecular docking studies. The results showed that the aqueous extract of S. spicigera and some of the phytochemicals it contains have the potential to be used as a natural product against HIV infection or in the treatment of AIDS.

Development of Effective Therapeutic Molecule from Natural Sources against Coronavirus Protease

The SARS-CoV-2 main protease (M^pro) is one of the molecular targets for drug design. Effective vaccines have been identified as a long-term solution but the rate at which they are being administered is slow in several countries, and mutations of SARS-CoV-2 could render them less effective. Moreover, remdesivir seems to work only with some types of COVID-19 patients. Hence, the continuous investigation of new treatments for this disease is pivotal. This study investigated the inhibitory role of natural products against SARS-CoV-2 M^pro as repurposable agents in the treatment of coronavirus disease 2019 (COVID-19). Through in silico approach, selected flavonoids were docked into the active site of M^pro. The free energies of the ligands complexed with M^pro were computationally estimated using the molecular mechanics-generalized Born surface area (MM/GBSA) method. In addition, the inhibition process of SARS-CoV-2 Mpro with these ligands was simulated at 100 ns in order to uncover the dynamic behavior and complex stability. The docking results showed that the selected flavonoids exhibited good poses in the binding domain of M^pro. The amino acid residues involved in the binding of the selected ligands correlated well with the residues involved with the mechanism-based inhibitor (N3) and the docking score of Quercetin-3-O-Neohesperidoside (−16.8 Kcal/mol) ranked efficiently with this inhibitor (−16.5 Kcal/mol). In addition, single-structure MM/GBSA rescoring method showed that Quercetin-3-O-Neohesperidoside (−87.60 Kcal/mol) is more energetically favored than N3 (−80.88 Kcal/mol) and other ligands (Myricetin 3-Rutinoside (−87.50 Kcal/mol), Quercetin 3-Rhamnoside (−80.17 Kcal/mol), Rutin (−58.98 Kcal/mol), and Myricitrin (−49.22 Kcal/mol). The molecular dynamics simulation (MDs) pinpointed the stability of these complexes over the course of 100 ns with reduced RMSD and RMSF. Based on the docking results and energy calculation, together with the RMSD of 1.98 ± 0.19 Å and RMSF of 1.00 ± 0.51 Å, Quercetin-3-O-Neohesperidoside is a better inhibitor of M^pro compared to N3 and other selected ligands and can be repurposed as a drug candidate for the treatment of COVID-19. In addition, this study demonstrated that in silico docking, free energy calculations, and MDs, respectively, are applicable to estimating the interaction, energetics, and dynamic behavior of molecular targets by natural products and can be used to direct the development of novel target function modulators.

Small Molecules of Natural Origin as Potential Anti-HIV Agents: A Computational Approach

The human immunodeficiency virus type 1 (HIV-1), one of the leading causes of infectious death globally, generates severe damages to people's immune systems and makes them susceptible to serious diseases. To date, there are no drugs that completely remove HIV from the body. This paper focuses on screening 224,205 natural compounds of ZINC15 NPs subset to identify those with bioactivity similar to non-nucleoside reverse transcriptase inhibitors (NNRTIs) as promising candidates to treat HIV-1. To reach the goal, an in silico approach involving 3D-similarity search, ADMETox, HIV protein-inhibitor prediction, docking, and MM-GBSA free-binding energies was trained. The FDA-approved HIV drugs, efavirenz, etravirine, rilpivirine, and doravirine, were used as queries. The prioritized compounds were subjected to ADMETox, docking, and MM-GBSA studies against HIV-1 reverse transcriptase (RT). Lys101, Tyr181, Tyr188, Trp229, and Tyr318 residues and free-binding energies have proved that ligands can stably bind to HIV-1 RT. Three natural products (ZINC37538901, ZINC38321654, and ZINC67912677) containing oxan and oxolan rings with hydroxyl substituents and one (ZINC2103242) having 3,6,7,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-1,4-dione core exhibited comparable profiles to etravirine and doravirine, with ZINC2103242 being the most promising anti-HIV candidate in terms of drug metabolism and safety profile. These findings may open new avenues to guide the rational design of novel HIV-1 NNRTIs.

Binding Insight of Anti-HIV Phytocompounds with Prime Targets of HIV: A Molecular Dynamics Simulation Analysis

BACKGROUND

Despite intense efforts, AIDS is difficult to tackle by current anti-retroviral therapy (ART) due to its side effects; therefore, there is an urgent need to discover potential, multitarget and low-cost anti-HIV compounds.

OBJECTIVE

We have shown that few phytocompounds can potentially inhibit the prime targets of HIV namely GP120 envelope protein, reverse transcriptase, protease, integrase and ribonulcease. In this study, top ranked prioritized compounds were subjected to Molecular Dynamics (MD) simulation in order to study the conformational dynamics and integrity of crucial interaction in the receptor sites.

METHODS

The system was built for selected protein-ligand complex using TIP3P water model and OPLS_2005 force field. Trajectories were recorded up to 20 ns simulation time in Desmond module of Schrödinger software.

RESULTS

As a result of a comprehensive analysis of molecular properties and dynamics of the complexes, it has been concluded that Chebulic acid, Curcumin and Mulberroside C could be developed as envelope glycoprotein GP120 inhibitor, reverse transcriptase inhibitor and protease inhibitor respectively. However, the fluctuation of Chebulic acid with respect to integrase and ribonuclease protein was higher during the simulation.

CONCLUSION

These findings can aid in the designing of the structural properties for more effective anti-HIV compounds against the given targets.

Plant Secondary Metabolites with an Overview of Populus

Populus trees meet continuous difficulties from the environment through their life cycle. To warrant their durability and generation, Populus trees exhibit various types of defenses, including the production of secondary metabolites. Syntheses derived from the shikimate-phenylpropanoid pathway are a varied and plentiful class of secondary metabolites manufactured in Populus. Amongst other main classes of secondary metabolites in Populus are fatty acid and terpenoid-derivatives. Many of the secondary metabolites made by Populus trees have been functionally described. Any others have been associated with particular ecological or biological processes, such as resistance against pests and microbial pathogens or acclimatization to abiotic stresses. Still, the functions of many Populus secondary metabolites are incompletely understood. Furthermore, many secondary metabolites have therapeutic effects, leading to more studies of secondary metabolites and their biosynthesis. This paper reviews the biosynthetic pathways and therapeutic impacts of secondary metabolites in Populus using a genomics approach. Compared with bacteria, fewer known pathways produce secondary metabolites in Populus despite P. trichocarpa having had its genome sequenced.

Myricetin Inhibits SARS-CoV-2 Viral Replication by Targeting Mpro and Ameliorates Pulmonary Inflammation

The coronavirus disease 2019 (COVID-19) has spread widely around the world and has seriously affected the human health of tens of millions of people. In view of lacking anti-virus drugs target to SARS-CoV-2, there is an urgent need to develop effective new drugs. In this study, we reported our discovery of SARS-CoV-2 M^pro inhibitors. We selected 15 natural compounds, including 7 flavonoids, 3 coumarins, 2 terpenoids, one henolic, one aldehyde and one steroid compound for molecular docking and enzymatic screening. Myricetin were identified to have potent inhibit activity with IC₅₀ 3.684 ± 0.076 μM in the enzyme assay. The binding pose of Myricetin with SARS-CoV-2 M^pro was identified using molecular docking method. In the binding pocket of SARS-CoV-2 M^pro, the chromone ring of Myricetin interacts with His41 through π-π stacking, and the 3'-, 4'- and 7-hydroxyl of Myricetin interact with Phe140, Glu166and Asp187 through hydrogen bonds. Significantly, our results showed that Myricetin has potent effect on bleomycin-induced pulmonary inflammation by inhibiting the infiltration of inflammatory cells and the secretion of inflammatory cytokines IL-6, IL-1α, TNF-α and IFN-γ. Overall, Myricetin may be a potential drug for anti-virus and symptomatic treatment of COVID-19.

Pharmacological Applications of Phlorotannins: A Comprehensive Review

BACKGROUND

Seaweeds, including marine brown algae, are traditional food sources in Asia. Phlorotannins, as the product of the polyketide pathway, are mainly found in brown algae. Different properties have been attributed to this group of marine products ranging from antiallergic to anticancer activity. Mechanism of action is not obvious for all these properties, but there are some explanations for such effects.

OBJECTIVE

The current study aimed to review the phlorotannins and to assess the beneficial uses in medicine.

METHODS

Different databases were explored with the exact terms "Phlorotannin", "Seaweed" and "Brown Algae". Data assembly was finalized by June 2019. The papers showing the effects of phlorotannins in medicine were gathered and evaluated for further assessment.

RESULTS

General physiological aspects of phlorotannins were firstly evaluated. Different arrays of pharmacological properties ranging from anti-diabetic activity to cancer treatment were found. The mechanism of action for some of these beneficiary properties has been confirmed through rigorous examinations, but there are some features with unknown mechanisms.

CONCLUSION

Phlorotannins are characterized as a multifunctional group of natural products. Potential antioxidant characteristics could be attributed to preventive and/or their curative role in various diseases.

Recent advances in natural anti-HIV triterpenoids and analogs

The human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) epidemic is one of the world's most serious health challenges. Although combination antiretroviral therapy provides effective viral suppression, current medicines used against HIV cannot completely eradicate the infectious disease and often have associated toxicities and severe side effects in addition to causing drug resistance. Therefore, the continued development of new antiviral agents with diverse structures and novel mechanisms of action remains a vital need for the management of HIV/AIDS. Natural products are an important source of drug discovery, and certain triterpenes and their analogs have demonstrated potential as pharmaceutical precursors for the treatment of HIV. Over the past decade, natural triterpenoids and analogs have been extensively studied to find new anti-HIV drugs. This review discusses the anti-HIV triterpenoids and analogs reported during the period of 2009-2019. The article includes not only a comprehensive review of the recent anti-HIV agent development from the perspective of medicinal chemistry, but also discusses structure-activity relationship analyses of the described triterpenoids.

Potential pharmacological approaches for the treatment of HIV-1 associated neurocognitive disorders

HIV associated neurocognitive disorders (HAND) are the spectrum of cognitive impairments present in patients infected with human immunodeficiency virus type 1 (HIV-1). The number of patients affected with HAND ranges from 30 to 50% of HIV infected individuals and although the development of combinational antiretroviral therapy (cART) has improved longevity, HAND continues to pose a significant clinical problem as the current standard of care does not alleviate or prevent HAND symptoms. At present, the pathological mechanisms contributing to HAND remain unclear, but evidence suggests that it stems from neuronal injury due to chronic release of neurotoxins, chemokines, viral proteins, and proinflammatory cytokines secreted by HIV-1 activated microglia, macrophages and astrocytes in the central nervous system (CNS). Furthermore, the blood-brain barrier (BBB) not only serves as a route for HIV-1 entry into the brain but also prevents cART therapy from reaching HIV-1 brain reservoirs, and therefore could play an important role in HAND. The goal of this review is to discuss the current data on the epidemiology, pathology and research models of HAND as well as address the potential pharmacological treatment approaches that are being investigated.

Structure-Activity-Relationship and Mechanistic Insights for Anti-HIV Natural Products

Acquired Immunodeficiency Syndrome (AIDS), which chiefly originatesfroma retrovirus named Human Immunodeficiency Virus (HIV), has impacted about 70 million people worldwide. Even though several advances have been made in the field of antiretroviral combination therapy, HIV is still responsible for a considerable number of deaths in Africa. The current antiretroviral therapies have achieved success in providing instant HIV suppression but with countless undesirable adverse effects. Presently, the biodiversity of the plant kingdom is being explored by several researchers for the discovery of potent anti-HIV drugs with different mechanisms of action. The primary challenge is to afford a treatment that is free from any sort of risk of drug resistance and serious side effects. Hence, there is a strong demand to evaluate drugs derived from plants as well as their derivatives. Several plants, such as Andrographis paniculata, Dioscorea bulbifera, Aegle marmelos, Wistaria floribunda, Lindera chunii, Xanthoceras sorbifolia and others have displayed significant anti-HIV activity. Here, weattempt to summarize the main results, which focus on the structures of most potent plant-based natural products having anti-HIV activity along with their mechanisms of action and IC50 values, structure-activity-relationships and important key findings.

Natural Plant Products: A Less Focused Aspect for the COVID-19 Viral Outbreak

The sudden emergence of COVID-19 caused by a novel coronavirus (nCoV) led the entire world to search for relevant solutions to fight the pandemic. Although continuous trials are being conducted to develop precise vaccines and therapeutic antibodies, a potential remedy is yet to be developed. Plants have largely contributed to the treatment of several human diseases and different phytoconstituents have been previously described to impede the replication of numerous viruses. Despite the previous positive reports of plant-based medications, no successful clinical trials of phyto-anti-COVID drugs could be conducted to date. In this article, we discuss varying perspectives on why phyto-anti-viral drug clinical trials were not successful in the case of COVID-19. The issue has been discussed in light of the usage of plant-based therapeutics in previous coronavirus outbreaks. Through this article, we aim to identify the disadvantages in this research area and suggest some measures to ensure that phytoconstituents can efficiently contribute to future random viral outbreaks. It is emphasized that if used strategically phyto-inhibitors with pre-established clinical data for other diseases can save the time required for long clinical trials. The scientific community should competently tap into phytoconstituents and take their research up to the final stage of clinical trials so that potential phyto-anti-COVID drugs can be developed.

Less Cytotoxic Protoflavones as Antiviral Agents: Protoapigenone 1'-O-isopropyl ether Shows Improved Selectivity Against the Epstein-Barr Virus Lytic Cycle

Protoflavones, a rare group of natural flavonoids with a non-aromatic B-ring, are best known for their antitumor properties. The protoflavone B-ring is a versatile moiety that might be explored for various pharmacological purposes, but the common cytotoxicity of these compounds is a limitation to such efforts. Protoapigenone was previously found to be active against the lytic cycle of Epstein-Barr virus (EBV). Further, the 5-hydroxyflavone moiety is a known pharmacophore against HIV-integrase. The aim of this work was to prepare a series of less cytotoxic protoflavone analogs and study their antiviral activity against HIV and EBV. Twenty-seven compounds, including 18 new derivatives, were prepared from apigenin through oxidative de-aromatization and subsequent continuous-flow hydrogenation, deuteration, and/or 4'-oxime formation. One compound was active against HIV at the micromolar range, and three compounds showed significant activity against the EBV lytic cycle at the medium-low nanomolar range. Among these derivatives, protoapigenone 1'-O-isopropyl ether (6) was identified as a promising lead that had a 73-times selectivity of antiviral over cytotoxic activity, which exceeds the selectivity of protoapigenone by 2.4-times. Our results open new opportunities for designing novel potent and safe anti-EBV agents that are based on the natural protoflavone moiety.

Methyl jasmonate promote protostane triterpenes accumulation by up-regulating the expression of squalene epoxidases in Alisma orientale

Protostane triterpenes, which are found in Alisma orientale, are tetracyclic triterpenes with distinctive pharmacological activities. The natural distribution of protostane triterpenes is limited mainly to members of the botanical family Alismataceae. Squalene epoxidase (SE) is the key rate-limiting enzyme in triterpene biosynthesis. In this study, we report the characterization of two SEs from A. orientale. AoSE1 and AoSE2 were expressed as fusion proteins in E. coli, and the purified proteins were used in functional research. In vitro enzyme assays showed that AoSE1 and AoSE2 catalyze the formation of oxidosqualene from squalene. Immunoassays revealed that the tubers contain the highest levels of AoSE1 and AoSE2. After MeJA induction, which is the main elicitor of triterpene biosynthesis, the contents of 2,3-oxidosqualene and alisol B 23-acetate increased by 1.96- and 2.53-fold, respectively. In addition, the expression of both AoSE proteins was significantly increased at four days after MeJA treatment. The contents of 2,3-oxidosqualene and alisol B 23-acetate were also positively correlated with AoSEs expression at different times after MeJA treatment. These results suggest that AoSE1 and AoSE2 are the key regulatory points in protostane triterpenes biosynthesis, and that MeJA regulates the biosynthesis of these compounds by increasing the expression of AoSE1 and AoSE2.

The potential of plant systems to break the HIV-TB link

Tuberculosis (TB) and human immunodeficiency virus (HIV) can place a major burden on healthcare systems and constitute the main challenges of diagnostic and therapeutic programmes. Infection with HIV is the most common cause of Mycobacterium tuberculosis (Mtb), which can accelerate the risk of latent TB reactivation by 20-fold. Similarly, TB is considered the most relevant factor predisposing individuals to HIV infection. Thus, both pathogens can augment one another in a synergetic manner, accelerating the failure of immunological functions and resulting in subsequent death in the absence of treatment. Synergistic approaches involving the treatment of HIV as a tool to combat TB and vice versa are thus required in regions with a high burden of HIV and TB infection. In this context, plant systems are considered a promising approach for combatting HIV and TB in a resource-limited setting because plant-made drugs can be produced efficiently and inexpensively in developing countries and could be shared by the available agricultural infrastructure without the expensive requirement needed for cold chain storage and transportation. Moreover, the use of natural products from medicinal plants can eliminate the concerns associated with antiretroviral therapy (ART) and anti-TB therapy (ATT), including drug interactions, drug-related toxicity and multidrug resistance. In this review, we highlight the potential of plant system as a promising approach for the production of relevant pharmaceuticals for HIV and TB treatment. However, in the cases of HIV and TB, none of the plant-made pharmaceuticals have been approved for clinical use. Limitations in reaching these goals are discussed.

New strategy for identifying potential natural HIV-1 non-nucleoside reverse transcriptase inhibitors against drug-resistance: an in silico study

Non-nucleosides reverse transcriptase inhibitors (NNRTIs), specifically targeting the HIV-1 reverse transcriptase (RT), play a unique role in anti-AIDS agents due to their high antiviral potency, structural diversity, and low toxicity in antiretroviral combination therapies used to treat HIV. However, due to the emergence of new drug-resistant strains, the development of novel NNRTIs with adequate potency, improved resistance profiles and less toxicity is highly required. In this work, a novel virtual screening strategy combined with structure-based drug design was proposed to discover the potential inhibitors against drug-resistant HIV strains. Seven structure-variant RTs, ranging from the wild type to a hypothetical multi-mutant were regarded as target proteins to perform structure-based virtual screening. Totally 23 small molecules with good binding affinity were identified from the Traditional Chinese Medicine database (TCM) as potential NNRTIs candidates. Among these hits, (+)-Hinokinin has confirmed anti-HIV activity, and some hits are structurally identical with anti-HIV compounds. Almost all these hits are consistent with external experimental results. Molecular simulations analysis revealed that top 2 hits (Pallidisetin A and Pallidisetin B) bind stably and in high affinity to HIV-RT, which are ready to be experimental confirmed. These results suggested that the strategy we proposed is feasible, trustworthy and effective. Our finding might be helpful in the identification of novel NNRTIs against drug-resistant, and also provide a new clue for the discovery of HIV drugs in natural products.Communicated by Ramaswamy H. Sarma.

Synthetic routes and structure-activity relationships (SAR) of anti-HIV agents: A key review

The worldwide increase of AIDS, an epidemic infection in constant development has an essential and still requires potent antiretroviral chemotherapeutic agents for reducing the integer of deaths caused by HIV. Thus, there is an urgent need for new anti-HIV drug candidates with increased strength, new targets, superior pharmacokinetic properties, and compact side effects. From this viewpoint, we first review present strategies of anti-HIV drug innovation and the synthesis of heterocyclic or natural compound as anti-HIV agents for facilitating the development of more influential and successful anti-HIV agents.

The Membrane-Active Phytopeptide Cycloviolacin O2 Simultaneously Targets HIV-1-infected Cells and Infectious Viral Particles to Potentiate the Efficacy of Antiretroviral Drugs

Background: Novel strategies to increase the efficacy of antiretroviral (ARV) drugs will be of crucial importance. We hypothesize that membranes of HIV-1-infected cells and enveloped HIV-1 particles may be preferentially targeted by the phytopeptide, cycloviolacin O2 (CyO2) to significantly enhance ARV efficacy. Methods: Physiologically safe concentrations of CyO2 were determined via red blood cell (RBC) hemolysis. SYTOX-green dye-uptake and radiolabeled saquinavir (³H-SQV) uptake assays were used to measure pore-formation and drug uptake, respectively. ELISA, reporter assays and ultracentrifugation were conducted to analyze the antiviral efficacy of HIV-1 protease and fusion inhibitors alone and co-exposed to CyO2. Results: CyO2 concentrations below 0.5 μM did not show substantial hemolytic activity, yet these concentrations enabled rapid pore-formation in HIV-infected T-cells and monocytes and increased drug uptake. ELISA for HIV-1 p24 indicated that CyO2 enhances the antiviral efficacy of both SQV and nelfinavir. CyO2 (< 0.5 μM) alone decreases HIV-1 p24 production, but it did not affect the transcription regulatory function of the HIV-1 long terminal repeat (LTR). Ultracentrifugation studies clearly showed that CyO2 exposure disrupted viral integrity and decreased the p24 content of viral particles. Furthermore, direct HIV-1 inactivation by CyO2 enhanced the efficacy of enfuvirtide. Conclusions: The membrane-active properties of CyO2 may help suppress viral load and augment antiretroviral drug efficacy.

Discovery of a semi-synthesized cyclolignan as a potent HIV-1 non-nucleoside reverse transcriptase inhibitor

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are essential components of highly active antiretroviral therapy (HAART) for human immunodeficiency virus type 1 (HIV-1) infection. In this study, we identified (+)-(7'S,8S,8'S)-3',4,4',5,5'-pentamethoxy-2,7'-cyclolignan (SG-1), a cyclolignan semi-synthesized from Machilus robusta and M. wangchiana extracts, as a potent NNRTI. SG-1 displayed anti-HIV-1 activity with an IC₅₀ of 0.77 μmol/L by inhibiting reverse transcriptase (RT) RNA-dependent DNA polymerase activity through a direct binding. It had synergistic effects when combined with tenofovir/lamivudine or zidovudine/lamivudine. The pharmacodynamics properties of SG-1 render it a valuable lead for the development of novel NNRTIs.

Herbal Gel Formulation Developed for Anti-Human Immunodeficiency Virus (HIV)-1 Activity Also Inhibits In Vitro HSV-2 Infection

Herpes simplex virus-2 (HSV-2) infection is the most common cause of genital ulcers. The impact of ulcers also demonstrates a strong link to the human immunodeficiency virus (HIV) infection. Complications, drug resistance, and side-effects of anti-viral drugs make the treatment of HSV-2 infection challenging. Herbal medicines have shown potential against HSV-2 and HIV infections. In this context, polyherbal gel formulation comprising 50% ethanolic extracts from Acacia catechu, Lagerstroemia speciosa, Terminalia chebula and Phyllanthus emblica has been developed. The gel formulation significantly exhibited virucidal activity against both HIV-1 and HSV-2 infections with IC₅₀, 55.93 ± 5.30 µg/mL and 27.26 ± 4.87 µg/mL, respectively. It also inhibited HSV-2 attachment and penetration to the Vero cells with an IC₅₀ = 46.55 ± 1.25 µg/mL and 54.94 ± 2.52 µg/mL respectively, which were significantly lower than acyclovir. However, acyclovir is more potent in post-infection assay with an IC₅₀ = 0.065 ± 0.01 µg/mL whereas gel formulation showed an IC₅₀ = 469.05 ± 16.65 µg/mL under similar conditions. Gel formulation showed no inhibitory effect on the viability of lactobacilli, human vaginal keratinocyte cells (Vk2/E6E7), and the integrity of the Caco-2 cells monolayer. Gel formulation did not lead to any significant increase in the secretion of pro-inflammatory cytokines and mutagenic index. The proposed gel formulation may be a promising candidate microbicide for the prevention of sexually transmitted HIV-1 and HSV-2.

Medicinal Plants Used in the Treatment of Human Immunodeficiency Virus

Since the beginning of the epidemic, human immunodeficiency virus (HIV) has infected around 70 million people worldwide, most of whom reside is sub-Saharan Africa. There have been very promising developments in the treatment of HIV with anti-retroviral drug cocktails. However, drug resistance to anti-HIV drugs is emerging, and many people infected with HIV have adverse reactions or do not have ready access to currently available HIV chemotherapies. Thus, there is a need to discover new anti-HIV agents to supplement our current arsenal of anti-HIV drugs and to provide therapeutic options for populations with limited resources or access to currently efficacious chemotherapies. Plant-derived natural products continue to serve as a reservoir for the discovery of new medicines, including anti-HIV agents. This review presents a survey of plants that have shown anti-HIV activity, both in vitro and in vivo.

Effect of Zhen Qi Fu Zheng granules on the bone marrow depression model induced by Zidorf

Zidorf is a commonly used drug for the treatment of AIDS, the most common side effects of AZT was bone marrow depression. Therefore, we investigated the effects of Zhen Qi Fu Zheng (AQFZ) granules on the model of bone marrow depression induced by AZT. We showed that the high, medium and low doses of AQFZ granules could increase the number of WBC in the mice model induced by AZT, and the difference was significant (P < 0.01) compared with the model group. Each dose of AQFZ granules can increase the thymus cortex thickness, the number of thymus lymphocytes, spleen nodule size, the number of lymphocytes in the spleen (P < 0.01). The medium dose of AQFZ granules can also significantly improve the number of BMC in the bone marrow depression model (P < 0.01). As well as, the low dose of AQFZ granules can clearly increase the number of nucleated cells in a bone marrow (P < 0.05) and IL-2blood serum. So, AQFZ granules can improve and regulate the hemogram, bone marrow and immune level of bone marrow depression model induced by AZT.

Inhibition of NF-κB-dependent HIV-1 replication by the marine natural product bengamide A

HIV-1 inhibitors that act by mechanisms distinct from existing antiretrovirals can provide novel insights into viral replication and potentially inform development of new therapeutics. Using a multi-cycle HIV-1 replication assay, we screened 252 pure compounds derived from marine invertebrates and microorganisms and identified 6 (actinomycin Z₂, bastadin 6, bengamide A, haliclonacyclamine A + B, keramamine C, neopetrosiamide B) that inhibited HIV-1 with 50% effective concentrations (EC₅₀s) of 3.8 μM or less. The most potent inhibitor, bengamide A, blocked HIV-1 in a T cell line with an EC₅₀ of 0.015 μM and in peripheral blood mononuclear cells with an EC₅₀ of 0.032 μM. Bengamide A was previously described to inhibit NF-κB signaling. Consistent with this mechanism, bengamide A suppressed reporter expression from an NF-κB-driven minimal promoter and an HIV-1 long terminal repeat (LTR) with conserved NF-κB response elements, but lacked activity against an LTR construct with mutation of these elements. In single-cycle HIV-1 infection assays, bengamide A also suppressed viral protein expression when viruses encoded an intact LTR but exhibited minimal activity against those with mutated NF-κB elements. Finally, bengamide A did not inhibit viral DNA accumulation, indicating that it likely acts downstream of this step in HIV-1 replication. Our study identifies multiple new antiviral compounds including an unusually potent inhibitor of HIV-1 gene expression.

Targeting the Brain Reservoirs: Toward an HIV Cure

One of the top research priorities of the international AIDS society by the action “Towards an HIV Cure” is the purge or the decrease of the pool of all latently infected cells. This strategy is based on reactivation of latently reservoirs (the shock) followed by an intensifying combination antiretroviral therapy (cART) to kill them (the kill). The central nervous system (CNS) has potential latently infected cells, i.e., perivascular macrophages, microglial cells, and astrocytes that will need to be eliminated. However, the CNS has several characteristics that may preclude the achievement of a cure. In this review, we discuss several limitations to the eradication of brain reservoirs and how we could circumvent these limitations by making it efforts in four directions: (i) designing efficient latency-reversal agents for CNS-cell types, (ii) improving cART by targeting HIV transcription, (iii) improving delivery of HIV drugs in the CNS and in the CNS-cell types, and (iv) developing therapeutic immunization. As a prerequisite to these efforts, we also believe that a better comprehension of molecular mechanisms involved in establishment and persistence of HIV latency in brain reservoirs are essential to design new molecules for strategies aiming to achieve a cure for instance the “shock and kill” strategy.