Inhibition of HIV-1 entry by extracts derived from traditional Chinese medicinal herbal plants

Andrographolide as a potent and promising antiviral agent

Andrographolide is a labdane diterpenoid extracted and purified from the aerial parts of plants belonging to genus Andrographis (Acanthaceae). The research has shown the plant based compound is low cytotoxic, having antimicrobial, anti-cancer, antiviral and anti-parasitic effects. Andrographolide both prevent spread as well as transmission of virus to neighboring cells by interfering with different cell signaling pathways. In addition to its medicinal value, plant has been found having nutritional value. Therefore being cost effective, easy availability and having nutritional value as a natural supplement, can be used to improve the quality of life in countries having low standard of living. Due to the limited number of effective vaccines, the plant-based antiviral drugs have provided considerable hope for fighting against the viral infections. The plant-derived compound when produced in large quantities is cost effective with low cytotoxic effects. However, much deep insight research at the molecular level is needed to develop the molecules against the viral infection. This paper aims to highlight the antiviral role of Andrographolide that can made significant contributions toward the improvement of human health and will also summarize the current status and future strategies concerning the therapeutic applications of Andrographolide to combat different viral disease in humans.

Computational Prospecting for the Pharmacological Mechanism of Activity: HIV-1 Inhibition by Ixoratannin A-2

BACKGROUND

Ixora coccinea is a tropical ornamental shrub employed in ethnomedicine for the treatment of a number of diseases none of which include the Human Immunodeficiency Virus (HIV) infection. Ixoratannin A-2, one of the constituents, was previously identified via virtual-screening and experimentally confirmed to possess significant anti-HIV-1 activity in an in vitro CD4+ replication assay. This activity was observed to be significantly reduced in degree in viruses lacking the protein Vpu. This suggests the involvement of Vpu as well as other extra-Vpu macromolecules in its antiviral activity.

METHODS

In the present computational search for the identity of the other macromolecules that could possibly explain the observed activity, a panel of fourteen established HIV-1 macromolecular targets was assembled against which ixoratannin A-2 and other major phytoconstituents of I. coccinea were virtually screened.

RESULTS

Structural analyses of the computed ligand-bound complexes, as well as the careful investigation of the thermodynamic attributes of the predicted binding, revealed subtle selectivity patterns at the atomistic level that suggest the likely involvement of multiple macromolecular processes. Some of the binding interactions were found to be thermodynamically favourable, including the multidrug-resistant HIV protease enzyme, CXCR4 and the human elongin C protein all of which formed reasonably strong interactions with ixoratannin A-2 and other constituents of I. coccinea.

CONCLUSION

Ixoratannin A-2's ability to favourably interact with multiple HIV-1 and human targets could explain its observed extra-Vpu antiviral activity. This, however, does not imply uncontrolled binding with all available targets; on the other hand, molecular size of ixoratannin A-2 and combination of functional groups confer on it a decent level of selectivity against many of the investigated HIV/AIDS targets.

Pharmacological Therapeutics Targeting RNA-Dependent RNA Polymerase, Proteinase and Spike Protein: From Mechanistic Studies to Clinical Trials for COVID-19

An outbreak of novel coronavirus-related pneumonia COVID-19, that was identified in December 2019, has expanded rapidly, with cases now confirmed in more than 211 countries or areas. This constant transmission of a novel coronavirus and its ability to spread from human to human have prompted scientists to develop new approaches for treatment of COVID-19. A recent study has shown that remdesivir and chloroquine effectively inhibit the replication and infection of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2, 2019-nCov) in vitro. In the United States, one case of COVID-19 was successfully treated with compassionate use of remdesivir in January of 2020. In addition, a clinically proven protease inhibitor, camostat mesylate, has been demonstrated to inhibit Calu-3 infection with SARS-CoV-2 and prevent SARS-2-spike protein (S protein)-mediated entry into primary human lung cells. Here, we systemically discuss the pharmacological therapeutics targeting RNA-dependent RNA polymerase (RdRp), proteinase and S protein for treatment of SARS-CoV-2 infection. This review should shed light on the fundamental rationale behind inhibition of SARS-CoV-2 enzymes RdRp as new therapeutic approaches for management of patients with COVID-19. In addition, we will discuss the viability and challenges in targeting RdRp and proteinase, and application of natural product quinoline and its analog chloroquine for treatment of coronavirus infection. Finally, determining the structural-functional relationships of the S protein of SARS-CoV-2 will provide new insights into inhibition of interactions between S protein and angiotensin-converting enzyme 2 (ACE2) and enable us to develop novel therapeutic approaches for novel coronavirus SARS-CoV-2.

Daphnane Diterpenoids from Trigonostemon lii and Inhibition Activities Against HIV-1

Natural products are the important source for the discovery of more potent anti-HIV agents. In this study, six daphnane diterpenoids including three unreported structures were isolated from Trigonostemon lii, which showed significant activities against HIV-1 strains replication in the nanomolar/picomolar range. Meanwhile, these diterpenoids significantly inhibited the fusion of H9/HIV-1 IIIB cells with uninfected C8166 cells, with the EC_50s from 1.06 to 8.73 ng/mL, and did not show any inhibition activities against HIV-1 reverse transcriptase. Moreover, all of the diterpenoids shows significant inhibitions against T20-resistan HIV-1 strains, PNL4-3gp41(36G)V38E, N42S and pNL4-3gp41(36G)V38A, N42T. The results revealed that the six diterpenoids could be a new type of potential lead candidate as an HIV entry inhibitor, particularly for those infected by T20-resistant variants.

The Potential Use of the CRISPR-Cas System for HIV-1 Gene Therapy

The HIV-1 virus (human immunodeficiency virus) affects 36.9 million people worldwide, with approximately 900000 deaths in 2017. The virus carrier can develop severe immunodeficiency since CD4⁺ T lymphocytes are the main target, leading to acquired immunodeficiency syndrome (AIDS). Despite advances in pharmacological treatment, it is still difficult to eliminate latent reservoirs, becoming one of the main obstacles for viral eradication. The CRISPR- (clustered regularly interspaced short palindromic repeat-) Cas system is a genome-editing method which uses a guide RNA, a complementary sequence to the interested site, recruiting a nuclease that can break the viral or the host cell genetic material. From this double-stranded break, cellular repair mechanisms are activated being able to generate deletions, insertions, or substitutions, in order to inactivate specific gene loci, leading to loss of function. The objective of this minireview is to synthesize the current knowledge on the application of CRISPR-Cas-based gene therapy for HIV-1. The strategies encompass all steps of the viral infection cycle, from inhibition of cell invasion, through viral replication and integration inhibition, to excision of the latent provirus. Off-target effects and ethical implications were also discussed to evaluate the safety of the approach and viability of its application in humans, respectively. Although preclinical and clinical tests are still needed, the recent results establish an exciting possibility of applying this technology for prophylaxis and treatment of HIV-1.

Role of medicinal plants in HIV/AIDS therapy

Human immunodeficiency virus (HIV) causes the potentially life-threatening and chronic disease called acquired immune deficiency syndrome (AIDS). The main target of this viral disease is to suppress the immune system and make the body unresponsive to external stimuli. According to global health observatory data since epidemic, more than 78 million people were affected by HIV and 39 million people died globally. Until 2017, 36.5 million people were living with HIV. An estimated 0.8% (0.6%-0.9%) of adults aged 15-49 years worldwide is living with HIV. The World Health Organization (WHO) reported that the African region remains most severely affected, with nearly one in every 25 adults (4.1%) living with HIV and accounting for nearly two-thirds of the people living with HIV worldwide. WHO reported that globally only 21.7 million (19.1 million-22.6 million) people have had access to antiretroviral therapy up to 2017. Currently, antiretroviral therapy (ART) is available for the control of HIV but has serious associated side effects such as lipodystrophy. Because of the limitations, associated with ART, researchers throughout the world are trying to explore and develop more reliable and safe drugs from natural resources to manage HIV infection. A wide range of medicinal plants have been studied and have reported significant potential against HIV. Plants like Rheum palmatum L., Rheum officinale, Trigonostem axyphophylloides, Vatica astrotricha, Vernonia amygdalina, Hypoxias pelargonium, Sidoides hemerocallidea and Sutherlandia frutescens etc. have high efficacy to cure HIV. The exact mechanism of action is still not known but various phytoconstituents isolated from medicinal plants such as alkaloids, flavonoids, polyphenols, terpenoids, tannins, proteins and coumarins have the potential to interrupt the life cycle of HIV as well as act as immunomodulators to enhance the immune system of infected patients with no well reported side effects. It could be concluded that medicinal plants have potential for the management of HIV/AIDS but more studies are needed to reveal rigorous efficacy and safety concerns by conducting clinical trials at vast level to explore therapeutic impact of medicinal plants.

Cellular RelB interacts with the transactivator Tat and enhance HIV-1 expression

BACKGROUND

Human immunodeficiency virus type 1 (HIV-1) Tat protein plays an essential role in HIV-1 gene transcription. Tat transactivates HIV-1 long terminal repeat (LTR)-directed gene expression through direct interactions with the transactivation-responsive region (TAR) element and other cis elements in the LTR. The TAR-independent Tat-mediated LTR transactivation is modulated by several host factors, but the mechanism is not fully understood.

RESULTS

Here, we report that Tat interacts with the Rel homology domain of RelB through its core region. Furthermore, RelB significantly increases Tat-mediated transcription of the HIV-1 LTR and viral gene expression, which is independent of the TAR. Both Tat and RelB are recruited to the HIV-1 promoter, of which RelB facilitates the recruitment of Tat to the viral LTR. The NF-κB elements are key to the accumulation of Tat and RelB on the LTR. Knockout of RelB reduces the accumulation of RNA polymerase II on the LTR, and decreases HIV-1 gene transcription. Together, our data suggest that RelB contributes to HIV-1 transactivation.

CONCLUSIONS

Our results demonstrate that RelB interacts with Tat and enhances TAR-independent activation of HIV-1 LTR promoter, which adds new insights into the multi-layered mechanisms of Tat in regulating the gene expression of HIV-1.

Broad-spectrum antiviral properties of andrographolide

Andrographolide, a diterpenoid, is known for its anti-inflammatory effects. It can be isolated from various plants of the genus Andrographis, commonly known as 'creat'. This purified compound has been tested for its anti-inflammatory effects in various stressful conditions, such as ischemia, pyrogenesis, arthritis, hepatic or neural toxicity, carcinoma, and oxidative stress, Apart from its anti-inflammatory effects, andrographolide also exhibits immunomodulatory effects by effectively enhancing cytotoxic T cells, natural killer (NK) cells, phagocytosis, and antibody-dependent cell-mediated cytotoxicity (ADCC). All these properties of andrographolide form the foundation for the use of this miraculous compound to restrain virus replication and virus-induced pathogenesis. The present article covers antiviral properties of andrographolide in variety of viral infections, with the hope of developing of a new highly potent antiviral drug with multiple effects.

An 84-month observational study of the changes in CD4 T-lymphocyte cell count of 110 HIV/AIDS patients treated with traditional Chinese medicine

This study aimed to evaluate the therapeutic effect of traditional Chinese medicine (TCM) by observing the changes in CD4 T-lymphocyte cell count of 110 cases with human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) treated continuously with TCM for 84 months. Information of 110 HIV/AIDS patients from 19 provinces and cities treated with TCM from 2004 to 2013 was collected. Changes in the indexes of CD4 counts ( ≤ 200, 201-350, 351-500 and > 500 cells/mm(3)) at five time points (0, 12, 36, 60 and 84 months) and different treatments [TCM and TCM plus antiretroviral therapy (ART)] were compared. Repeated measures test indicated no interaction between group and time (P > 0.05). Degrees of increasing and decreasing CD4 count of the two groups at four different frames were statistically significant compared with the baseline. The CD4 count between the two groups was not statistically significant. For CD4 count of ≤ 200 cells/mm(3), the mean CD4 count changes were 21 and 28 cells/mm(3) per year for the TCM group and TCM plus ART group, respectively. For CD4 count of 201-350 cells/mm(3), the mean CD4 count changes were 6 and 25 cells/mm(3) per year for the TCM group and TCM plus ART group, respectively. For CD4 count of 351-500 cells/mm(3), the mean CD4 count changes were -13 and -7 cells/mm(3) per year for the TCM group and TCM plus ART group, respectively. For CD4 count of > 500 cells/mm(3), the mean CD4 count changes were -34 and -17 cells/mm(3) per year for the TCM group and TCM plus ART group, respectively. Long-term use of TCM could maintain or slow the pace of declining CD4 counts in patients with HIV/AIDS, and may achieve lasting effectiveness.

HIV-1 Nef is transferred from expressing T cells to hepatocytic cells through conduits and enhances HCV replication

HIV-1 infection enhances HCV replication and as a consequence accelerates HCV-mediated hepatocellular carcinoma (HCC). However, the precise molecular mechanism by which this takes place is currently unknown. Our data showed that infectious HIV-1 failed to replicate in human hepatocytic cell lines. No discernible virus replication was observed, even when the cell lines transfected with HIV-1 proviral DNA were co-cultured with Jurkat T cells, indicating that the problem of liver deterioration in the co-infected patient is not due to the replication of HIV-1 in the hepatocytes of the HCV infected host. Instead, HIV-1 Nef protein was transferred from nef-expressing T cells to hepatocytic cells through conduits, wherein up to 16% (average 10%) of the cells harbored the transferred Nef, when the hepatocytic cells were co-cultured with nef-expressing Jurkat cells for 24 h. Further, Nef altered the size and numbers of lipid droplets (LD), and consistently up-regulated HCV replication by 1.5∼2.5 fold in the target subgenomic replicon cells, which is remarkable in relation to the initially indolent viral replication. Nef also dramatically augmented reactive oxygen species (ROS) production and enhanced ethanol-mediated up-regulation of HCV replication so as to accelerate HCC. Taken together, these data indicate that HIV-1 Nef is a critical element in accelerating progression of liver pathogenesis via enhancing HCV replication and coordinating modulation of key intra- and extra-cellular molecules for liver decay.

HIV-1 Vpr stimulates NF-κB and AP-1 signaling by activating TAK1

BACKGROUND

The Vpr protein of human immunodeficiency virus type 1 (HIV-1) plays an important role in viral replication. It has been reported that Vpr stimulates the nuclear factor-κB (NF-κB) and activator protein 1 (AP-1) signaling pathways, and thereby regulates viral and host cell gene expression. However, the molecular mechanism behind this function of Vpr is not fully understood.

RESULTS

Here, we have identified transforming growth factor-β-activated kinase 1 (TAK1) as the important upstream signaling molecule that Vpr associates with in order to activate NF-κB and AP-1 signaling. HIV-1 virion-associated Vpr is able to stimulate phosphorylation of TAK1. This activity of Vpr depends on its association with TAK1, since the S79A Vpr mutant lost interaction with TAK1 and was unable to activate TAK1. This association allows Vpr to promote the interaction of TAB3 with TAK1 and increase the polyubiquitination of TAK1, which renders TAK1 phosphorylation. In further support of the key role of TAK1 in this function of Vpr, knockdown of endogenous TAK1 significantly attenuated the ability of Vpr to activate NF-κB and AP-1 as well as the ability to stimulate HIV-1 LTR promoter.

CONCLUSIONS

HIV-1 Vpr enhances the phosphorylation and polyubiquitination of TAK1, and as a result, activates NF-κB and AP-1 signaling pathways and stimulates HIV-1 LTR promoter.

Extracts of medicinal herb Sanguisorba officinalis inhibit the entry of human immunodeficiency virus type one

Highly active antiretroviral therapy (HAART) has been successful in reducing human immunodeficiency virus (HIV)-1-associated morbidity and mortality since its introduction in 1996. However, it fails to eradicate HIV-1 infection. The high cost of life-long highly active antiretroviral therapy and the emergence of drug resistance among HIV-1-infected individuals have brought renewed pressure for the discovery of novel antivirals and alternative medicines. Traditional Chinese medicine (TCM) is a complementary and alternative medicine, and serves as a rich resource for new drug development. Despite the almost 100 plant-derived compounds that are in clinical trials, few target HIV-1 infection. In this study, we discovered that Sanguisorba officinalis extract (SOE) has anti-HIV-1 properties. Using a cell-based assay and single-cycle luciferase reporter viruses pseudotyped with envelopes from HIV-1 or control viruses, we found that SOE exhibited significant inhibitory ability against both CCR5 and CXCR4 tropic HIV-1 (ADA and HXB2), with respective IC₅₀ values of 1.91 ± 0.16 μg/mL and 3.70 ± 0.53 μg/mL. SOE also inhibited simian immunodeficiency virus infection but failed to block vesicular stomatitis virus, severe acute respiratory syndrome coronavirus, and influenza H5N1 pseudoviruses. Furthermore, we showed that SOE had no effect on postentry events of HIV-1 replication. Because SOE pretreatment with the virus but not with cell lines expressing viral receptors showed the maximal inhibitory activity, we can state that SOE probably blocks entry by acting on the viral envelope directly. In addition, SOE was able to inhibit reverse transcriptase inhibitor resistant viruses (K103N, Y188L, and K103N/Y188L/G190A) and a protease inhibitor resistant strain (PI-2840). Our findings demonstrate SOE as a novel and specific entry inhibitor, which sheds light on the discovery of anti-HIV-1 drugs from traditional herbal medicines.

Melaleuca alternifolia concentrate inhibits in vitro entry of influenza virus into host cells

Influenza virus causes high morbidity among the infected population annually and occasionally the spread of pandemics. Melaleuca alternifolia Concentrate (MAC) is an essential oil derived from a native Australian tea tree. Our aim was to investigate whether MAC has any in vitro inhibitory effect on influenza virus infection and what mechanism does the MAC use to fight the virus infection. In this study, the antiviral activity of MAC was examined by its inhibition of cytopathic effects. In silico prediction was performed to evaluate the interaction between MAC and the viral haemagglutinin. We found that when the influenza virus was incubated with 0.010% MAC for one hour, no cytopathic effect on MDCK cells was found after the virus infection and no immunofluorescence signal was detected in the host cells. Electron microscopy showed that the virus treated with MAC retained its structural integrity. By computational simulations, we found that terpinen-4-ol, which is the major bioactive component of MAC, could combine with the membrane fusion site of haemagglutinin. Thus, we proved that MAC could prevent influenza virus from entering the host cells by disturbing the normal viral membrane fusion procedure.

A potential in vitro and in vivo anti-HIV drug screening system for Chinese herbal medicines

Chinese herbal medicines are often applied as an alternative therapy for viral diseases. However, the development of anti-HIV herbal drugs has proceeded slowly, partly because of the lack of a high-throughput system for screening these drugs. The present study evaluated 16 herbal medicines for anti-HIV activities in vitro and in vivo. Herbal medicines were first screened for the ability to regulate C-X-C receptor 4 (CXCR4) and C-C receptor 5 (CCR5) promoter activities. A single-round pseudotyped HIV-luciferase reporter virus system (HIV-Luc) was used to identify potential anti-HIV mechanisms. CD4+ T cells from healthy volunteers were examined for changes in CXCR4 and CCR5 levels. HIV-1 replication was evaluated by ELISA. Spica Prunellae and Herba Andrographitis were found to down-regulate the activities of both the CXCR4 and CCR5 promoters. Also, Spica Prunellae and Herba Andrographitis (>1000 μM) inhibited HIV-1 in a dose-dependent manner. CXCR4 and CCR5 levels were reduced in CD4+ T cells from healthy volunteers (p<0.05). Spica Prunellae and Herba Andrographitis (EC₅₀: 3.18 and 5.49 μg/mL, respectively) could suppress cell fusion and decrease p24 antigen. In conclusion, the data demonstrated that Spica Prunellae and Herba Andrographitis possessed anti-HIV-1 capabilities, perhaps through the inhibition of the CXCR4 and CCR5 promoters and HIV-1 replication.

Inhibitory effect of aqueous Dandelion extract on HIV-1 replication and reverse transcriptase activity

BACKGROUND

Acquired immunodeficiency syndrome (AIDS), which is caused by the human immunodeficiency virus (HIV), is an immunosuppressive disease that results in life-threatening opportunistic infections. The general problems in current therapy include the constant emergence of drug-resistant HIV strains, adverse side effects and the unavailability of treatments in developing countries. Natural products from herbs with the abilities to inhibit HIV-1 life cycle at different stages, have served as excellent sources of new anti-HIV-1 drugs. In this study, we aimed to investigate the anti-HIV-1 activity of aqueous dandelion extract.

METHODS

The pseudotyped HIV-1 virus has been utilized to explore the anti-HIV-1 activity of dandelion, the level of HIV-1 replication was assessed by the percentage of GFP-positive cells. The inhibitory effect of the dandelion extract on reverse transcriptase activity was assessed by the reverse transcriptase assay kit.

RESULTS

Compared to control values obtained from cells infected without treatment, the level of HIV-1 replication and reverse transcriptase activity were decreased in a dose-dependent manner. The data suggest that dandelion extract has a potent inhibitory activity against HIV-1 replication and reverse transcriptase activity. The identification of HIV-1 antiviral compounds from Taraxacum officinale should be pursued.

CONCLUSIONS

The dandelion extract showed strong activity against HIV-1 RT and inhibited both the HIV-1 vector and the hybrid-MoMuLV/MoMuSV retrovirus replication. These findings provide additional support for the potential therapeutic efficacy of Taraxacum officinale. Extracts from this plant may be regarded as another starting point for the development of an antiretroviral therapy with fewer side effects.

Traditional herbal medicine in far-west Nepal: a pharmacological appraisal

BACKGROUND

Plant species have long been used as principal ingredients of traditional medicine in far-west Nepal. The medicinal plants with ethnomedicinal values are currently being screened for their therapeutic potential but their data and information are inadequately compared and analyzed with the Ayurveda and the phytochemical findings.

METHODS

The present study evaluated ethnomedicinal plants and their uses following literature review, comparison, field observations, and analysis. Comparison was made against earlier standard literature of medicinal plants and ethnomedicine of the same area, the common uses of the Ayurveda and the latest common phytochemical findings. The field study for primary data collection was carried out from 2006-2008.

RESULTS

The herbal medicine in far-west Nepal is the basis of treatment of most illness through traditional knowledge. The medicine is made available via ancient, natural health care practices such as tribal lore, home herbal remedy, and the Baidhya, Ayurveda and Amchi systems. The traditional herbal medicine has not only survived but also thrived in the trans-cultural environment with its intermixture of ethnic traditions and beliefs. The present assessment showed that traditional herbal medicine has flourished in rural areas where modern medicine is parsimoniously accessed because of the high cost and long travel time to health center. Of the 48 Nepalese medicinal plants assessed in the present communication, about half of the species showed affinity with the common uses of the Ayurveda, earlier studies and the latest phytochemical findings. The folk uses of Acacia catechu for cold and cough, Aconitum spicatum as an analgesic, Aesculus indica for joint pain, Andrographis paniculata for fever, Anisomeles indica for urinary affections, Azadirachta indica for fever, Euphorbia hirta for asthma, Taxus wallichiana for tumor control, and Tinospora sinensis for diabetes are consistent with the latest pharmacological findings, common Ayurvedic and earlier uses.

CONCLUSIONS

Although traditional herbal medicine is only a primary means of health care in far-west Nepal, the medicine has been pursued indigenously with complementing pharmacology and the Ayurveda. Therefore, further pharmacological evaluation of traditional herbal medicine deserves more attention.