Andrographolide and Its 14-Aryloxy Analogues Inhibit Zika and Dengue Virus Infection

Plant-Derived Epi-Nutraceuticals as Potential Broad-Spectrum Anti-Viral Agents

Although the COVID-19 pandemic appears to be diminishing, the emergence of SARS-CoV-2 variants represents a threat to humans due to their inherent transmissibility, immunological evasion, virulence, and invulnerability to existing therapies. The COVID-19 pandemic affected more than 500 million people and caused over 6 million deaths. Vaccines are essential, but in circumstances in which vaccination is not accessible or in individuals with compromised immune systems, drugs can provide additional protection. Targeting host signaling pathways is recommended due to their genomic stability and resistance barriers. Moreover, targeting host factors allows us to develop compounds that are effective against different viral variants as well as against newly emerging virus strains. In recent years, the globe has experienced climate change, which may contribute to the emergence and spread of infectious diseases through a variety of factors. Warmer temperatures and changing precipitation patterns can increase the geographic range of disease-carrying vectors, increasing the risk of diseases spreading to new areas. Climate change may also affect vector behavior, leading to a longer breeding season and more breeding sites for disease vectors. Climate change may also disrupt ecosystems, bringing humans closer to wildlife that transmits zoonotic diseases. All the above factors may accelerate the emergence of new viral epidemics. Plant-derived products, which have been used in traditional medicine for treating pathological conditions, offer structurally novel therapeutic compounds, including those with anti-viral activity. In addition, plant-derived bioactive substances might serve as the ideal basis for developing sustainable/efficient/cost-effective anti-viral alternatives. Interest in herbal antiviral products has increased. More than 50% of approved drugs originate from herbal sources. Plant-derived compounds offer diverse structures and bioactive molecules that are candidates for new drug development. Combining these therapies with conventional drugs could improve patient outcomes. Epigenetics modifications in the genome can affect gene expression without altering DNA sequences. Host cells can use epigenetic gene regulation as a mechanism to silence incoming viral DNA molecules, while viruses recruit cellular epitranscriptomic (covalent modifications of RNAs) modifiers to increase the translational efficiency and transcript stability of viral transcripts to enhance viral gene expression and replication. Moreover, viruses manipulate host cells' epigenetic machinery to ensure productive viral infections. Environmental factors, such as natural products, may influence epigenetic modifications. In this review, we explore the potential of plant-derived substances as epigenetic modifiers for broad-spectrum anti-viral activity, reviewing their modulation processes and anti-viral effects on DNA and RNA viruses, as well as addressing future research objectives in this rapidly emerging field.

Andrographolide inhibits infectious bronchitis virus-induced apoptosis, pyroptosis, and inflammation

BACKGROUND

Avian infectious bronchitis virus (IBV), a coronavirus, causes a huge economic loss to the poultry industry. Andrographolide (APL) is a compound with a variety of pharmacological properties, including antiviral and anti-inflammatory effects. In this study, APL was evaluated for antiviral activity by its anti-apoptotic, anti-pyroptosis, and anti-inflammatory effects.

METHODS

The cytotoxicity of APL was determined by the MTT method. We investigated the therapeutic impact of APL on IBV through a plate assay. We explored that APL inhibited IBV-induced apoptosis, pyroptosis, and inflammation in HD11 cells by RT-qPCR and immunofluorescence. Also, it was verified in the clinical chicken embryo trial.

RESULTS

We found that APL down-regulated apoptosis-related genes Caspase-3, Caspase-8, Caspase-9, Bax, Bid, and Bak, down-regulated pyroptosis gene DFNA5, and down-regulated inflammation-related genes (NF-κB, NLRP3, iNOS, TNF-α, and IL-1β). In addition, APL reduced the reactive oxygen species (ROS) production in cells. Finally, clinical trials showed that APL inhibited IBV-induced apoptosis, pyroptosis, and inflammation, as well as reduced the mortality and malformation of chicken embryos.

CONCLUSIONS

In this study, we delved into the antiviral properties of APL in the context of chicken macrophage (HD11) infection with IBV. Our findings confirm that andrographolide effectively inhibits apoptosis, pyroptosis, and inflammation by IBV infection. Furthermore, this inhibition was verified on chicken embryos in vivo. This inhibition suggests a substantial potential for APL as a therapeutic agent to mitigate the harmful effects of IBV on host cells.

Whole transcriptome analysis identifies full-length genes for neoandrographolide biosynthesis from Andrographis alata, an alternate source for antiviral compounds

Andrographolide and related compounds are effective against several viral diseases, including dengue, COVID-19, influenza, and chikungunya. Andrographis paniculata is the primary source for these compounds, but its availability is limited. A. alata is a potential alternative source, and neoandrographolide (NAG) is the major antiviral compound in this species. Since molecular studies in A. alata are scarce, we sequenced its leaf transcriptome to identify the full-length genes involved in neoandrographolide biosynthesis. We assembled 13.6 Gb RNA-Seq data and generated 81,361 transcripts with 1007 bp average length and 1,810 bp N50. The transcripts were categorized under biological processes (2,707), cellular components (678), and molecular functions (2,036). KEGG analysis mapped 975 transcripts to the secondary metabolite pathways. Among the 420 transcripts mapped to terpenoids and polyketides pathways, 142 transcripts were related to the biosynthesis of andrographolide and its derivatives. After a detailed analysis of these transcripts, we identified 32 full-length genes coding for all the 22 enzymes needed for andrographolide biosynthesis. Among them, 15 full-length genes were identified for the first time from Andrographis species. These full-length genes and the transcripts shall serve as an invaluable resource for the metabolic engineering of andrographolides and neoandrographolide in Andrographis and other species.

Targeting the DENV NS2B-NS3 protease with active antiviral phytocompounds: structure-based virtual screening, molecular docking and molecular dynamics simulation studies

Dengue fever has been a global health concern. Mitigation is a challenging problem due to non-availability of workable treatments. The most difficult objective is to design a perfect anti-dengue agent capable of inhibiting infections caused by all four serotypes. Various tactics have been employed in the past to discover dengue antivirals, including screening of chemical compounds against dengue virus enzymes. The objective of the current study is to investigate phytocompounds as anti-dengue remedies that target the non-structural 2B and non-structural 3 protease (NS2B-NS3^pro), a possible therapeutic target for dengue fever. Initially, 300 + antiviral phytocompounds were collected from Duke’s phytochemical and ethnobotanical database and 30 phytocompounds with anti-dengue properties were identified from previously reported studies, which were virtually screened against NS2B-NS3^pro using molecular docking and toxicity evaluation. The top five most screened ligands were naringin, hesperidin, gossypol, maslinic acid and rhodiolin with binding affinities of − 8.7 kcal/mol, − 8.5 kcal/mol, − 8.5 kcal/mol, − 8.5 kcal/mol and − 8.1 kcal/mol, respectively. The finest docked compounds complexed with NS2B-NS3^pro were subjected for molecular dynamics (MD) simulations and binding free energy estimations through molecular mechanics generalized born surface area–based calculations. The results of the study are intriguing in the context of computer-aided screening and the binding affinities of the phytocompounds, proposing maslinic acid (MAS) as a potent bioactive antiviral for the development of phytocompound-based anti-dengue agent.

Molecular Docking and In-Silico Analysis of Natural Biomolecules against Dengue, Ebola, Zika, SARS-CoV-2 Variants of Concern and Monkeypox Virus

The emergence and rapid evolution of human pathogenic viruses, combined with the difficulties in developing effective vaccines, underline the need to develop innovative broad-spectrum antiviral therapeutic agents. The present study aims to determine the in silico antiviral potential of six bacterial antimicrobial peptides (AMPs), two phytochemicals (silvestrol, andrographolide), and two bacterial secondary metabolites (lyngbyabellin A, hapalindole H) against dengue virus, Zika virus, Ebola virus, the major variants of SARS-CoV-2 and monkeypox virus. The comparison of docking scores obtained with natural biomolecules was performed with specific neutralizing antibodies (positive controls for ClusPro) and antiviral drugs (negative controls for Autodock Vina). Glycocin F was the only natural biomolecule tested to show high binding energies to all viral surface proteins and the corresponding viral cell receptors. Lactococcin G and plantaricin ASM1 also achieved high docking scores with all viral surface proteins and most corresponding cell surface receptors. Silvestrol, andrographolide, hapalindole H, and lyngbyabellin A showed variable docking scores depending on the viral surface proteins and cell receptors tested. Three glycocin F mutants with amino acid modifications showed an increase in their docking energy to the spike proteins of SARS-CoV-2 B.1.617.2 Indian variant, and of the SARS-CoV-2 P.1 Japan/Brazil variant, and the dengue DENV envelope protein. All mutant AMPs indicated a frequent occurrence of valine and proline amino acid rotamers. AMPs and glycocin F in particular are the most promising biomolecules for the development of broad-spectrum antiviral treatments targeting the attachment and entry of viruses into their target cell.

Synthesis and Characterization of Andrographolide Derivatives as Regulators of βAPP Processing in Human Cells

Alzheimer's disease (AD) is a devastating neurodegenerative disorder, one of the main characteristics of which is the abnormal accumulation of amyloid peptide (Aβ) in the brain. Whereas β-secretase supports Aβ formation along the amyloidogenic processing of the β-amyloid precursor protein (βAPP), α-secretase counterbalances this pathway by both preventing Aβ production and triggering the release of the neuroprotective sAPPα metabolite. Therefore, stimulating α-secretase and/or inhibiting β-secretase can be considered a promising anti-AD therapeutic track. In this context, we tested andrographolide, a labdane diterpene derived from the plant Andrographis paniculata, as well as 24 synthesized derivatives, for their ability to induce sAPPα production in cultured SH-SY5Y human neuroblastoma cells. Following several rounds of screening, we identified three hits that were subjected to full characterization. Interestingly, andrographolide (8,17-olefinic) and its close derivative 14α-(5',7'-dichloro-8'-quinolyloxy)-3,19-acetonylidene (compound 9) behave as moderate α-secretase activators, while 14α-(2'-methyl-5',7'-dichloro-8'-quinolyloxy)-8,9-olefinic compounds 31 (3,19-acetonylidene) and 37 (3,19-diol), whose two structures are quite similar although distant from that of andrographolide and 9, stand as β-secretase inhibitors. Importantly, these results were confirmed in human HEK293 cells and these compounds do not trigger toxicity in either cell line. Altogether, these findings may represent an encouraging starting point for the future development of andrographolide-based compounds aimed at both activating α-secretase and inhibiting β-secretase that could prove useful in our quest for the therapeutic treatment of AD.

Andrographolide: A review of its pharmacology, pharmacokinetics, toxicity and clinical trials and pharmaceutical researches

Andrographis paniculata (Burm. f.) Wall. ex Nees, a renowned herb medicine in China, is broadly utilized in traditional Chinese medicine (TCM) for the treatment of cold and fever, sore throat, sore tongue, snake bite with its excellent functions of clearing heat and toxin, cooling blood and detumescence from times immemorial. Modern pharmacological research corroborates that andrographolide, the major ingredient in this traditional herb, is the fundamental material basis for its efficacy. As the main component of Andrographis paniculata (Burm. f.) Wall. ex Nees, andrographolide reveals numerous therapeutic actions, such as antiinflammatory, antioxidant, anticancer, antimicrobial, antihyperglycemic and so on. However, there are scarcely systematic summaries on the specific mechanism of disease treatment and pharmacokinetics. Moreover, it is also found that it possesses easily ignored security issues in clinical application, such as nephrotoxicity and reproductive toxicity. Thereby it should be kept a lookout over in clinical. Besides, the relationship between the efficacy and security issues of andrographolide should be investigated and evaluated scientifically. In this review, special emphasis is given to andrographolide, a multifunctional natural terpenoids, including its pharmacology, pharmacokinetics, toxicity and pharmaceutical researches. A brief overview of its clinical trials is also presented. This review intends to systematically and comprehensively summarize the current researches of andrographolide, which is of great significance for the development of andrographolide clinical products. Noteworthy, those un-cracked issues such as specific pharmacological mechanisms, security issues, as well as the bottleneck in clinical transformation, which detailed exploration and excavation are still not to be ignored before achieving integration into clinical practice. In addition, given that current extensive clinical data do not have sufficient rigor and documented details, more high-quality investigations in this field are needed to validate the efficacy and/or safety of many herbal products.

Andrographolide: A Herbal-Chemosynthetic Approach for Enhancing Immunity, Combating Viral Infections, and Its Implication on Human Health

Plants consistently synthesize and accumulate medically valuable secondary metabolites which can be isolated and clinically tested under in vitro conditions. An advancement with such important phytochemical production has been recognized and utilized as herbal drugs. Bioactive andrographolide (AGL; C20H30O5) isolated from Andrographis paniculate (AP) (Kalmegh) is a diterpenoid lactones having multifunctional medicinal properties including anti-manic, anti-inflammatory, liver, and lung protective. AGL is known for its immunostimulant activity against a variety of microbial infections thereby, regulating classical and alternative macrophage activation, Ag-specific antibody production during immune disorder therapy. In vitro studies with AGL found it to be effective against multiple tumors, neuronal disorders, diabetes, pneumonia, fibrosis, and other diverse therapeutic misadventures. Generally, virus-based diseases like ZIKA, influenza A virus subtype (H1NI), Ebola (EBOV), Dengue (DENV), and coronavirus (COVID-19) epidemics have greatly increased scientific interest and demands to develop more effective and economical immunomodulating drugs with minimal side effects. Trials and in vitro pharmacological studies with AGL and medicinally beneficial herbs might contribute to benefit the human population without using chemical-based synthetic drugs. In this review, we have discussed the possible role of AGL as a promising herbal-chemo remedy during human diseases, viral infections and as an immunity booster.

Discovery of 14S-(2'-chloro-4'-nitrophenoxy)-8R/S,17-epoxy andrographolide as EV-A71 infection inhibitor

Human enterovirus A71 (EV-A71) is a major etiological agent of hand-foot-and-mouth disease (HFMD) and there is presently no internationally approved antiviral against EV-A71. In this study, it is disclosed that 14S-(2'-chloro-4'-nitrophenoxy)-8R/S,17-epoxy andrographolide (2) was discovered to be an effective inhibitor against EV-A71 infection showing significant reduction of viral titre. In addition to EV-A71, compound 2 exerts broad-spectrum antiviral effects against other enteroviruses. It is revealed that compound 2 inhibits the post-entry stages of EV-A71 viral replication cycle and significantly reduces viral protein expression of structural proteins such as VP0 and VP2 via inhibiting EV-A71 RNA replication. Moreover, the inhibitory property of compound 2 is specific to viral RNA replication. Furthermore, compound 2 is more likely to target a host factor in EV-A71 RNA replication. As a result, introduction of epoxide at positions 8 and 17 of andrographolide is effective for anti-EV-A71 infection and is a potential anti-EV-A71 strategy. Further work to discover more potent andrographolide derivatives and elucidate comprehensive SAR is under way.

Inhibition of NLRP3 inflammasome activation in myeloid-derived suppressor cells by andrographolide sulfonate contributes to 5-FU sensitization in mice

5-Fluorouracil (5-FU)-based chemotherapy is the first-line recommended regimen in colorectal cancer (CRC), but resistance limits its clinical application. Andrographolide sulfonate, a traditional Chinese medicine, is mainly used to treat infectious diseases. In the present study, we reported that andrographolide sulfonate could significantly inhibit the growth of transplanted CT26 colon cancer in mice and improve survival when combined with 5-FU. Furthermore, TUNEL assay and immunohistochemistry analysis of proliferating cell nuclear antigen, Ki-67 and p-STAT3 confirmed that co-treatment could inhibit tumor proliferation and promote apoptosis. In tumor tissues of groups that received 5-FU and andrographolide sulfonate, CD4⁺ and CD8⁺ T cell infiltration was increased, and the expression of IFN-γ and Granzyme B detected by immunohistochemistry and qPCR was upregulated, reflecting improved antitumor immunity. Finally, we verified that 5-FU significantly activated the NLR Family Pyrin Domain Containing 3 (NLRP3) inflammasome in myeloid-derived suppressor cells (MDSCs) and that andrographolide sulfonate reversed this process to sensitize cells to 5-FU. In summary, andrographolide sulfonate synergistically enhanced antitumor effects and improved antitumor immunity by inhibiting 5-FU-induced NLRP3 activation in MDSCs. These findings provide a novel strategy to address 5-FU resistance in the treatment of CRC.

Andrographis paniculata (Burm. F.) Wall. Ex Nees, Andrographolide, and Andrographolide Analogues as SARS-CoV-2 Antivirals? A Rapid Review

Drug repurposing is commonly employed in the search for potential therapeutic agents. Andrographis paniculata, a medicinal plant commonly used for symptomatic relief of the common cold, and its phytoconstituent andrographolide, have been repeatedly identified as potential antivirals against SARS-CoV-2. In light of new evidence emerging since the onset of the COVID-19 pandemic, this rapid review was conducted to identify and evaluate the current SARS-CoV-2 antiviral evidence for A. paniculata, andrographolide, and andrographolide analogs. A systematic search and screen strategy of electronic databases and gray literature was undertaken to identify relevant primary articles. One target-based in vitro study reported the 3CLpro inhibitory activity of andrographolide as being no better than disulfiram. Another Vero cell-based study reported potential SARS-CoV-2 inhibitory activity for both andrographolide and A. paniculata extract. Eleven in silico studies predicted the binding of andrographolide and its analogs to several key antiviral targets of SARS-CoV-2 including the spike protein-ACE-2 receptor complex, spike protein, ACE-2 receptor, RdRp, 3CLpro, PLpro, and N-protein RNA-binding domain. In conclusion, in silico and in vitro studies collectively suggest multi-pathway targeting SARS-CoV-2 antiviral properties of andrographolide and its analogs, but in vivo data are needed to support these predictions.

Andrographis paniculata (Burm. F) Wall ex Nees: Antiviral properties

Andrographis paniculata is home to a rich variety of molecules especially andrographolide and its derivatives. Clinical properties of the andrographolide are multifarious and include: analgesic, antipyretic, antiretroviral, antiproliferative, antimalarial, antithrombotic, antihyperglycemic, antiurolethial, antilesihmaniasis, hepatoprotective, immune-modulatory, protective against alcohol induced toxicity and cardioproetcive activity and anticancer activity. Andrographolide, neoandrographolide, dehydroandrographolide and several natural and synthetic derivatives of it: 14-deoxy-11,12-didehydroandrographolide and 14-deoxyandrographolide, dehydroandrographolide succinic acid monoester (DAMS), 14-ά-lipoyl andrographolide (AL-1), 14-acetyl-3,9-isopropyl-ideneandrographolide, 14-acetylandrographolide, 3,14,19-triacetylandrographolide, and 3,9-isopropyl-idene andrographolide, are shown to possess significant antiviral activity against HIV, influenza A, HBV, HCV, HPP and HSV. Studies on SARS CoV 2 is restricted to in silico molecular docking studies on viral targets and selected host target proteins. The main targets of andrographolide and its derivatives are fusion and adsorption of virus to the host cell, binding to viral receptor and co-receptor, enzymes involved in DNA/RNA/Genome replication by the virus, translation, post-translation and reverse transcription. Andrographolide as a drug is yet to reach its full therapeutic potential since this molecule shows low bioavailability. Andrographolide therapy is in need of an appropriate delivery system that may increase its bioavailability. Further high-quality studies are needed to firmly establish the clinical efficacy of the plant.

Arthropod-Borne Disease Control at a Glance: What's New on Drug Development?

Discovering and validating effective drugs to manage arthropod-borne diseases (ABD) is a timely and important research challenge with major impacts on real-world control programs at the time of quick resistance development in the targeted pathogens. This editorial highlights major research advances in the development of drugs for the control of vector-borne diseases, with a significant focus on malaria, Chagas disease, dengue, human African trypanosomiasis, leishmaniasis, and Zika. Broad reviews providing new insights on ABD recently published in Molecules have also been covered in “The Editors’ pick” section.