Methotrexate, an anti-inflammatory drug, inhibits Hepatitis E viral replication

Hepatitis E Virus (HEV) is a positively oriented RNA virus having a 7.2 kb genome. HEV consists of three open reading frames (ORF1-3). Of these, ORF1 codes for the enzymes Methyltransferase (Mtase), Papain-like cysteine protease (PCP), RNA helicase, and RNA-dependent RNA polymerase (RdRp). Unavailability of a vaccine or effective drug against HEV and considering the side effects associated with the off-label use of ribavirin (RBV) and pegylated interferons, an alternative approach is required by the modulation of specific enzymes to prevent the infection. HEV helicase is involved in unwinding the double-stranded RNA, RNA processing, transcriptional regulation, and pre-mRNA processing. Therefore, we screened FDA-approved compounds from the ZINC15 database against the modelled 3D structure of HEV helicase and found that methotrexate and compound A (Pubchem ID BTB07890) inhibit the NTPase and dsRNA unwinding activity leading to inhibition of HEV RNA replication. This may be further authenticated by in vivo study.

Inhibition of HEV Replication by FDA-Approved RdRp Inhibitors

Hepatitis E virus (HEV) is primarily a hepatotropic virus that is responsible for acute hepatitis E in the general population and for chronic hepatitis in immunocompromised individuals. In the absence of a globally accessible vaccine, pegylated interferon-α and ribavirin are the only antiviral agents available for the treatment of chronic patients. As viral RNA-dependent RNA polymerases (RdRps) are indispensable for RNA replication, they are considered potential drug targets. In this study, we screened some well-known RdRp inhibitor molecules, notably, favipiravir, sofosbuvir, remdesivir, filibuvir, and tegobuvir. Of these, monotherapy with favipiravir and sofosbuvir inhibited the RdRp activity with an IC50 value of 10.2 ± 4.9 and 5.2 ± 2.9 μM, respectively, compared to the reference drug ribavirin (3.5 ± 1.6 μM). Further investigation of the combination therapy showed a reduction in viral RNA copy numbers by approximately 90%. Therefore, favipiravir has an additive effect when used with sofosbuvir. Therefore, we propose that favipiravir is a promising anti-HEV drug that can be used in combination with sofosbuvir.

Deep-sea fungal metabolites as potential inhibitors of glucose-regulatory enzymes: In silico structure-activity analysis

Chronic diabetes mellites related hyperglycemia is a major cause of mortality and morbidity due to further complications like retinopathy, hypertension and cardiovascular diseases. Though several synthetic anti-diabetes drugs specifically targeting glucose-metabolism enzymes are available, they have their own limitations, including adverse side-effects. Unlike other natural or marine-derived pharmacologically important molecules, deep-sea fungi metabolites still remain under-explored for their anti-diabetes potential. We performed structure-based virtual screening of deep-sea fungal compounds selected by their physiochemical properties, targeting crucial enzymes viz., α -amylase, α -glucosidase, pancreatic-lipoprotein lipase, hexokinase-II and protein tyrosine phosphatase-1B involved in glucose-metabolism pathway. Following molecular docking scores and MD simulation analyses, the selected top ten compounds for each enzyme, were subjected to pharmacokinetics prediction based on their AdmetSAR- and pharmacophore-based features. Of these, cladosporol C, tenellone F, ozazino-cyclo-(2,3-dihydroxyl-trp-tyr), penicillactam and circumdatin G were identified as potential inhibitors of α -amylase, α -glucosidase, pancreatic-lipoprotein lipase, hexokinase-II and protein tyrosine phosphatase-1B, respectively. Our in silico data therefore, warrants further experimental and pharmacological studies to validate their anti-diabetes therapeutic potential.

In silico identification of deep-sea fungal alkaloids as potential inhibitors of SARS-CoV-2, Delta and Omicron spikes

Aim: Virtual screening of deep-sea fungal metabolites against SARS-CoV-2 Delta and Omicron spikes as potential antivirals. Materials & methods: Deep-sea fungal alkaloids (n ≥ 150) were evaluated against SARS-CoV-2, Delta and Omicron spikes, using various in silico approaches, including Admet scores, physiochemical properties, molecular docking (MD) and MD simulation (150 ns). Results: The test alkaloids complied with Admet scores and physiochemical properties within acceptable ranges, and followed Lipinski's rule of five. Of these, Cladosporium sphaerospermum-derived cladosin K (tetramate alkaloid) for SARS-CoV-2, Cystobasidium laryngis-derived saphenol (phenazine alkaloid) for Delta and Chaetomium globosum-derived chaetoglobosin E (quinoline alkaloid) for Omicron were identified as potential spike-inhibitors. Conclusion: Our data therefore, strongly warrants further experimental validations of cladosin K, saphenol and chaetoglobosin E, especially against the Omicron and Delta spikes.

Novel anti‑hepatitis B virus flavonoids sakuranetin and velutin from Rhus retinorrhoea

Drug‑resistance in hepatitis B virus (HBV), especially due to prolonged treatment with nucleoside analogs, such as lamivudine (LAM), remains a clinical challenge. Alternatively, several plant products and isolated phytochemicals have been used as promising anti‑HBV therapeutics with no sign of resistance. Among all known Rhus species, R. coriaria, R. succedanea and R. tripartite have been widely studied for their anti‑HBV efficacy, however, the effects of R. retinorrhoea have not been previously investigated. The current study reported the isolation of two flavonoids, namely sakuranetin (SEK) and velutin (VEL), from the dichloromethane fraction of R. retinorrhoea aerial parts using chromatography and spectral analyses. The two flavonoids (6.25‑50 µg/ml) were pre‑tested for non‑hepatocytotoxicity using an MTT assay and their dose‑ and time‑dependent inhibitory activities against HBV [hepatitis B surface antigen (HBsAg) and hepatitis B 'e' antigen (HBeAg)] in cultured HepG2.2.15 cells were assessed by ELISA. SEK and VEL at the selected doses (12.5 µg/ml) significantly inhibited HBsAg by ~58.8 and ~56.4%, respectively, and HBeAg by ~55.5 and ~52.4%, respectively, on day 5. The reference drugs LAM and quercetin (anti‑HBV flavonoids), suppressed the production of HBsAg/HBeAg by ~86.4/~64 and ~84.5/~62%, respectively. Furthermore, molecular docking of the flavonoids with HBV polymerase and capsid proteins revealed the formation of stable complexes with good docking energies, thus supporting their structure‑based antiviral mechanism. In conclusion, the present study was the first to demonstrate the anti‑HBV therapeutic activities of SEK and VEL isolated from R. retinorrhoea.

Inhibition of hepatitis B virus activities by Rhazya stricta‑derived acacetin and acetyl‑β‑carboline

Hepatitis B virus (HBV) causes acute and chronic liver diseases, leading to cirrhosis and hepatocellular carcinoma. Although direct-acting nucleoside analogs, such as lamivudine (LAM), adefovir and famciclovir, are available, emergence of drug-resistance due to mutations in HBV polymerase (POL) restricts their further use. Alternatively, numerous plant products and compounds isolated from plants have been reported to confer anti-HBV efficacies without any sign of resistance in vitro or in vivo. As, flavonoids and alkaloids are the most widely reported antivirals, the anti-HBV activities of the flavonoid acacetin (ACT) and the alkaloid acetyl-β-carboline (ABC) from the aerial parts of Rhazya stricta were assessed in the present study. Both compounds were isolated from the ethyl acetate fraction of the total methanol extract using column and thin-layer chromatography, and their structures were determined by nuclear magnetic resonance spectroscopy (NMR). Both compounds (at 6.25-50 µg/ml) showed a lack of hepatocytotoxicity in cultured HepG2.2.15 cells. Anti-HBV ELISA [hepatitis B surface antigen (HBsAg) and hepatitis B pre-core-antigen (HBeAg)] on HepG.2.2.15 cells following treatment with selected concentrations (12.5, 25 and 50 µg/ml) of both compounds showed dose- and time-dependent anti-HBV activities. Compared with those in the untreated control at day 5, ACT and ABC (25 µg/ml, each) maximally inhibited HBsAg synthesis by 43.4 and 48.7%, respectively, whilst also maximally inhibiting HBeAg synthesis by 41.2 and 44.2%, respectively, in HepG2.2.15 cells. Comparatively, quercetin and LAM (standards; POL inhibitors) suppressed HBsAg (63.9 and 60.2%, respectively) and HBeAg synthesis (87.1 and 84.3%, respectively) by larger magnitudes. Molecular docking of ACT and ABC structures performed in AutoDock revealed their hydrogen bonding with the drug-sensitive [wild-type (wt)-POL] 'Tyr-Met-Asp-Asp' motif, in addition to the drug-resistant [mutant (mut)-POL] 'Tyr-Ile-Asp-Asp' motif residues of the polymerase binding-pocket, along with other electrostatic interactions. In the wt-POL complex, both compounds showed good interactions with Asp205. In the mut-POL complex, ACT and ABC interacted with Tyr203-Asp205 and Tyr203-Ile204, respectively. In conclusion, to the best of our knowledge, the present study demonstrates anti-HBV efficacies of ACT and ABC in vitro for the first time, endorsed by in silico data. However, further molecular and pharmacological studies are required to validate their pre-clinical therapeutic potential.

Structure-based virtual identification of natural inhibitors of SARS-CoV-2 and its Delta and Omicron variant proteins

Aim

Structure-based identification of natural compounds against SARS-CoV-2, Delta and Omicron target proteins.

Materials & methods

Several known antiviral natural compounds were subjected to molecular docking and MD simulation against SARS-CoV-2 Mpro, Helicase and Spike, including Delta and Omicron Spikes.

Results

Of the docked ligands, 20 selected for each complex exhibited overall good binding affinities (-7.79 to -5.06 kcal/mol) with acceptable physiochemistry following Lipinski's rule. Finally, two best ligands from each complex upon simulation showed structural stability and compactness.

Conclusion

Quercetin-3-acetyl-glucoside, Rutin, Kaempferol, Catechin, Orientin, Obetrioside and Neridienone A were identified as potential inhibitors of SARS-CoV-2 Mpro, Helicase and Spike, while Orientin and Obetrioside also showed good binding affinities with Omicron Spike. Catechin and Neridienone A formed stable complexes with Delta Spike.

Intrinsic disorder in the open reading frame 2 of hepatitis E virus: a protein with multiple functions beyond viral capsid

BACKGROUND

Hepatitis E virus (HEV) is the cause of a liver disease hepatitis E. The translation product of HEV ORF2 has recently been demonstrated as a protein involved in multiple functions besides performing its major role of a viral capsid. As intrinsically disordered regions (IDRs) are linked to various essential roles in the virus's life cycle, we analyzed the disorder pattern distribution of the retrieved ORF2 protein sequences by employing different online predictors. Our findings might provide some clues on the disorder-based functions of ORF2 protein that possibly help us in understanding its behavior other than as a HEV capsid protein.

RESULTS

The modeled three dimensional (3D) structures of ORF2 showed the predominance of random coils or unstructured regions in addition to major secondary structure components (alpha helix and beta strand). After initial scrutinization, the predictors VLXT and VSL2 predicted ORF2 as a highly disordered protein while the predictors VL3 and DISOPRED3 predicted ORF2 as a moderately disordered protein, thus categorizing HEV-ORF2 into IDP (intrinsically disordered protein) or IDPR (intrinsically disordered protein region) respectively. Thus, our initial predicted disorderness in ORF2 protein 3D structures was in excellent agreement with their predicted disorder distribution patterns (evaluated through different predictors). The abundance of MoRFs (disorder-based protein binding sites) in ORF2 was observed that signified their interaction with binding partners which might further assist in viral infection. As IDPs/IDPRs are targets of regulation, we carried out the phosphorylation analysis to reveal the presence of post-translationally modified sites. Prevalence of several disordered-based phosphorylation sites further signified the involvement of ORF2 in diverse and significant biological processes. Furthermore, ORF2 structure-associated functions revealed its involvement in several crucial functions and biological processes like binding and catalytic activities.

CONCLUSIONS

The results predicted ORF2 as a protein with multiple functions besides its role as a capsid protein. Moreover, the occurrence of IDPR/IDP in ORF2 protein suggests that its disordered region might serve as novel drug targets via functioning as potential interacting domains. Our data collectively might provide significant implication in HEV vaccine search as disorderness in viral proteins is related to mechanisms involved in immune evasion.

Inhibition of Hepatitis E Virus Replication by Novel Inhibitor Targeting Methyltransferase

Hepatitis E Virus (HEV) is a quasi-enveloped virus having a single-stranded, positive-sense RNA genome (~7.2 kb), flanked with a 5′ methylated cap and a 3′ polyadenylated tail. The HEV open reading frame 1 (ORF1) encodes a 186-kDa polyprotein speculated to get processed and produce Methyltransferase (MTase), one of the four essential replication enzymes. In this study, we report the identification of the MTase inhibitor, which may potentially deplete its enzymatic activity, thus causing the cessation of viral replication. Using in silico screening through docking, we identified ten putative compounds, which were tested for their anti-MTase activity. This resulted in the identification of 3-(4-Hydroxyphenyl)propionic acid (HPPA), with an IC₅₀ value of 0.932 ± 0.15 μM, which could be perceived as an effective HEV inhibitor. Furthermore, the compound was tested for inhibition of HEV replication in the HEV culture system. The viral RNA copies were markedly decreased from ~3.2 × 10⁶ in untreated cells to ~4.3 × 10^2.8 copies in 800 μM HPPA treated cells. Therefore, we propose HPPA as a potential drug-like inhibitor against HEV-MTase, which would need further validation through in vivo analysis using animal models and the administration of Pharmacokinetic and Pharmacodynamic (PK/PD) studies.

Novel anti-hepatitis B virus-active catechin and epicatechin from Rhus tripartita

Bioactive natural or phytoproducts have emerged as a potential source of antiviral agents. Of the Rhus spp., R. coriaria and R. succedanea have been reported for their antiviral activities against hepatitis B virus (HBV), while the anti-HBV efficacy of R. tripartita has remained elusive. In the present study, the anti-HBV activities of R. tripartita-derived novel catechin [3,5,13,14-flavantetrol-catechin or rhuspartin (RPT)] and epicatechin-3-O-rhamnoside (ECR), were assessed using the HBV-reporter cell line HepG2.2.15. RPT and ECR proved to efficiently inhibit HBV surface antigen (HBsAg) synthesis by 68.8 and 71.3%, respectively, and HBV pre-core antigen (HBeAg) production by 62.3 and 71.2%, respectively, after 5 days of treatment. Of note, RPT had a lower anti-HBV activity than ECR. In comparison, the reference drug lamivudine (LAM) inhibited HBsAg and HBeAg expression by 83.6 and 85.4%, respectively. Further molecular docking analysis revealed formations of strong complexes of RPT, ECR and LAM with HBV polymerase through interactions with binding pocket residues. Taken together, the present results demonstrated promising therapeutic potential of the novel R. tripartita-derived catechin and epicatechin for HBV, warranting their further molecular and pharmacological evaluation.

Sequence to structure analysis of the ORF4 protein from Hepatitis E virus

Hepatitis E virus (HEV) is the main cause of acute hepatitis worldwide. HEV accounts for up to 30% mortality rate in pregnant women, with highest incidences reported for genotype 1 (G1) HEV. The contributing factors in adverse cases during pregnancy in women due to HEV infection is still debated. The mechanism underlying the pathogenesis of viral infection is attributed to different genomic component of HEV, i.e., open reading frames (ORFs): ORF1, ORF2, ORF3 and ORF4. Recently, ORF4 has been discovered in enhancing the replication of GI isolates of HEV through regulation of an IRES-like RNA element. However, its characterization through computational methodologies remains unexplored. In this novel study, we provide comprehensive overview of ORF4 protein's genetic and molecular characteristics through analyzing its sequence and different structural levels. A total of three different datasets (Human, Rat and Ferret) of ORF4 genomes were built and comparatively analyzed. Several non-synonymous mutations in conjunction with higher entropy values were observed in rat and ferret datasets, however, limited variation was observed in human ORF4 genomes. Higher transition to tranversion ratio was observed in the ORF4 genomes. Studies have reported the association of intrinsic disordered proteins (IDP) with drug discovery due to its role in several signaling and regulatory processes through protein-protein interactions (PPIs). As PPIs are potent drug target sources, thus the ORF4 protein was explored by analyzing its polypeptide structure in order to shed light on its intrinsic disorder. Pressures that lead towards preponderance of disordered-promoting amino acid residues shaped the evolution of ORF4. The intrinsic disorder propensity analysis revealed ORF4 protein (Human) as a highly disordered protein (IDP). Predominance of coils and lack of secondary structure further substantiated our findings suggesting its involvement in binding to ligand molecules. Thus, ORF4 contributes to cellular signaling processes through protein-protein interactions, as IDPs are targets for regulation to accelerate the process of drug designing strategies against HEV infections.

Analysis of codon usage patterns in open reading frame 4 of hepatitis E viruses

Background

Hepatitis E virus (HEV) is a member of the family Hepeviridae and causes acute HEV infections resulting in thousands of deaths worldwide. The zoonotic nature of HEV in addition to its tendency from human to human transmission has led scientists across the globe to work on its different aspects. HEV also accounts for about 30% mortality rates in case of pregnant women. The genome of HEV is organized into three open reading frames (ORFs): ORF1 ORF2 and ORF3. A reading frame encoded protein ORF4 has recently been discovered which is exclusive to GT 1 isolates of HEV. The ORF4 is suggested to play crucial role in pregnancy-associated pathology and enhanced replication. Though studies have documented the ORF4’s importance, the genetic features of ORF4 protein genes in terms of compositional patterns have not been elucidated. As codon usage performs critical role in establishment of the host–pathogen relationship, therefore, the present study reports the codon usage analysis (based on nucleotide sequences of HEV ORF4 available in the public database) in three hosts along with the factors influencing the codon usage patterns of the protein genes of ORF4 of HEV.

Results

The nucleotide composition analysis indicated that ORF4 protein genes showed overrepresentation of C nucleotide and while A nucleotide was the least-represented, with random distribution of G and T(U) nucleotides. The relative synonymous codon usage (RSCU) analysis revealed biasness toward C/G-ended codons (over U/A) in all three natural HEV-hosts (human, rat and ferret). It was observed that all the ORF4 genes were richly endowed with GC content. Further, our results showed the occurrence of both coincidence and antagonistic codon usage patterns among HEV-hosts. The findings further emphasized that both mutational and selection forces influenced the codon usage patterns of ORF4 protein genes.

Conclusions

To the best of our knowledge, this is first bioinformatics study evaluating codon usage patterns in HEV ORF4 protein genes. The findings from this study are expected to increase our understanding toward significant factors involved in evolutionary changes of ORF4.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43088-022-00244-w.

Glutathione S-transferase gene polymorphism and asthma: a case-control study in a pediatric population

Aim: To carry out a case-control study of the association of GST gene polymorphisms in pediatric asthma-related oxidative stress. Materials & methods: Asthma patients (n = 250) and age-matched healthy subjects (n = 250) DNA were genotyped for GSTM1/GSTT1 (+/+, +/-, -/+ and -/-) frequencies using multiplex-PCR and plasma oxidative stress markers (examined spectrophotometrically). Results: Asthma patients had significantly more common null-genotype GSTM1^-/GSTT1^- (10.4%; p = 0.002) and elevated levels of malondialdehyde, protein carbonyl and 8-hydroxy-2-deoxyguanosine as compared with controls. In addition, the level of plasma glutathione, GST activity and ferric-reducing ability were significantly decreased as compared with controls. Conclusion: Our data revealed significant associations between GSTM1^-/GSTT1^- genotype and oxidative stress markers in asthmatic children, which may very likely contribute to increased incidence of bronchial asthma.

Machine learning-based predictive models for identifying high active compounds against HIV-1 integrase

HIV-integrase is an important drug target because it catalyzes chromosomal integration of proviral DNA towards establishing latent infection. Computer-aided drug design has immensely contributed to identifying and developing novel antiviral drugs. We have developed various machine learning-based predictive models for identifying high activity compounds against HIV-integrase. Multiclass models were built using support vector machine with reasonable accuracy on the test and evaluation sets. The developed models were evaluated by rigorous validation approaches and the best features were selected by Boruta method. As compared to the model developed from all descriptors set, a slight improvement was observed among the selected descriptors. Validated models were further used for virtual screening of potential compounds from ChemBridge library. Of the six high active compounds predicted from selected models, compounds 9103124, 6642917 and 9082952 showed the most reasonable binding-affinity and stable-interaction with HIV-integrase active-site residues Asp64, Glu152 and Asn155. This was in agreement with previous reports on the essentiality of these residues against a wide range of inhibitors. We therefore highlight the rigorosity of validated classification models for accurate prediction and ranking of high active lead drugs against HIV-integrase.

Decoding the codon usage patterns in Y-domain region of hepatitis E viruses

Background

Hepatitis E virus (HEV) is a positive-sense RNA virus belonging to the family Hepeviridae. The genome of HEV is organized into three open-reading frames (ORFs): ORF1, ORF2, and ORF3. The ORF1 non-structural Y-domain region (YDR) has been demonstrated to play an important role in the HEV pathogenesis. The nucleotide composition, synonymous codon usage bias in conjunction with other factors influencing the viral YDR genes of HEV have not been studied. Codon usage represents a significant mechanism in establishing the host-pathogen relationship. The present study for the first time elucidates the detailed codon usage patterns of YDR among HEV and HEV-hosts (Human, Rabbit, Mongoose, Pig, Wild boar, Camel, Monkey).

Results

The overall nucleotide composition revealed the abundance of C and U nucleotides in YDR genomes. The relative synonymous codon usage (RSCU) analysis indicated biasness towards C and U over A and G ended codons in HEV across all hosts. Codon frequency comparative analyses among HEV-hosts showed both similarities and discrepancies in usage of preferred codons encoding amino acids, which revealed that HEV codon preference neither completely differed nor completely showed similarity with its hosts. Thus, our results clearly indicated that the synonymous codon usage of HEV is a mixture of the two types of codon usage: coincidence and antagonism. Mutation pressure from virus and natural selection from host seems to be accountable for shaping the codon usage patterns in YDR. The study emphasised that the influence of compositional constraints, codon usage biasness, mutational alongside the selective forces were reflected in the occurrence of YDR codon usage patterns.

Conclusions

Our study is the first in its kind to have reported the analysis of codon usage patterns on a total of seven different natural HEV hosts. Therefore, knowledge of preferred codons obtained from our study will not only augment our understanding towards molecular evolution but is also envisaged to provide insight into the efficient viral expression, viral adaptation, and host effects on the HEV YDR codon usage.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43141-022-00319-2.

Euphocactoside, a New Megastigmane Glycoside from Euphorbia cactus Growing in Saudi Arabia

A phytochemical investigation of the aerial parts of Euphorbia cactus Ehrenb. ex Boiss. revealed a new megastigmane, euphocactoside (5), along with eleven known metabolites. Euphocactoside (5) is the 3-O-glucoside derivative of a polyhydroxylated megastigmane showing unprecedented structural features. The structure of euphocactoside, including stereochemical details, was elucidated by extensive spectroscopic analysis based on 1D and 2D nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HR-ESIMS). The isolated compounds were evaluated for their cytotoxic activity against three different human cancer cell lines, namely, A549 (lung), LoVo (colon), and MCF-7 (breast), using MTT assay, and moderate to marginal activities were observed for compounds 1–3, 8 and 9 against all three cell lines.

Intrinsically disordered regions in the rodent hepevirus proteome

Hepatitis E virus (HEV) is the causative agent of Hepatitis E infections across the world. Intrinsically disordered protein regions (IDPRs) or intrinsically disordered proteins (IDPs) are regions or proteins that are characterized by lack of definite structure. These IDPRs or IDPs play significant roles in a wide range of biological processes, such as cell cycle regulation, control of signaling pathways, etc. IDPR/IDP in proteins is associated with the virus's pathogenicity and infectivity. The prevalence of IDPR/IDP in rat HEV proteome remains undetermined. Hence, we examined the unstructured/disordered regions of the open reading frame (ORF) encoded proteins of rat HEV by analyzing the prevalence of intrinsic disorder. The intrinsic disorder propensity analysis showed that the different ORF proteins consisted of varying fraction of intrinsic disorder. The protein ORF3 was identified with maximum propensity for intrinsic disorder while the ORF6 protein had the least fraction of intrinsic disorder. The analysis revealed ORF6 as a structured protein (ORDP); ORF1 and ORF4 as moderately disordered proteins (IDPRs); and ORF3 and ORF5 as highly disordered proteins (IDPs). The protein ORF2 was found to be moderately as well as highly disordered using different predictors, thus, was categorized into both IDPR and IDP. Such disordered regions have important roles in pathogenesis and replication of viruses.

The anti-hepatitis B virus and anti-hepatotoxic efficacies of solanopubamine, a rare alkaloid from Solanum schimperianum

Chronic liver disease caused by hepatitis B virus (HBV) remains an important health issue. Though there are effective HBV-polymerase inhibitors (e.g., lamivudine), their prolonged use leads to emergence of drug-resistant (polymerase mutant) strains. Several herbal formulations and phytochemicals have been therefore, reported as potential anti-HBV agents with no sign of resistance in experimental and clinical settings. In this study, we assessed the anti-HBV as well as hepatoprotective salutations of solanopubamine, a rare alkaloid isolated from S. schimperianum. In cultured HepG2.2.15 cells, solanopubamine showed marked anti-HBV activity in a time and dose-dependent manner. Solanopubamine (30 μM) efficiently inhibited HBsAg and HBeAg expressions by 66.5%, 70.5%, respectively as compared to 82.5% and 86.5% respective inhibition by lamivudine (2 μM) at day 5. Molecular docking analyses of solanopubamine revealed formations of stable complexes with lamivudine-sensitive as well as lamivudine-resistant polymerase through interactions of catalytic ‘YMDD/YIDD’ motif residues. Moreover, solanopubamine attenuated DCFH-induced oxidative and apoptotic damage and restored HepG2 cell viability by 28.5%, and downregulated caspase-3/7 activations by 33%. Further docking analyses of solanopubamine showed formation of stable complexes with caspase-3/7. Taken together, our data demonstrates promising anti-HBV and anti-hepatotoxic therapeutic potential of solanopubamine, and warrants further molecular and pharmacological studies.

Sequence to structural analysis of ORF5 protein in Norway rat Hepatitis E Virus

Hepatitis E virus (HEV) is a major causative agent of acute hepatitis in developing countries. The Norway rat HEV genome consists of six open reading frames (ORFs), i.e., ORF1, ORF2, ORF3, ORF4, ORF5 and ORF6. The additional reading frame encoded protein ORF5 is attributed to life cycle of rat HEV. The ORFF5 protein's function remains undetermined. Therefore, it is of interest to analyze the ORF5 protein for its physiochemical properties, primary structure, secondary structure, tertiary structure and functional characteristics using bioinformatics tools. Analysis of the ORF5 protein revealed it as highly unstable, hydrophilic with basic pI. The ORF5 protein consisted mostly of Arg, Pro, Ser, Leu and Gly. The 3D structural homology model of the ORF5 protein generated showed mixed α/β structural fold with predominance of coils. Structural analysis revealed the presence of clefts, pores and a tunnel. This data will help in the sequence, structure and functional annotation of ORF5.

Isolation and Characterization of Two Chalcone Derivatives with Anti-Hepatitis B Virus Activity from the Endemic Socotraen Dracaena cinnabari (Dragon’s Blood Tree)

Hepatitis B virus (HBV) infection is prevalent and continues to be a global health concern. In this study, we determined the anti-hepatitis B virus (HBV) potential of the Socotra-endemic medicinal plant Dracaena cinnabari and isolated and characterized the responsible constituents. A bioassay-guided fractionation using different chromatographic techniques of the methanolic extract of D. cinnabari led to the isolation of two chalcone derivatives. Using a variety of spectroscopic techniques, including ¹H-, ¹³C-, and 2D-NMR, these derivatives were identified as 2,4’-dihydroxy-4-methoxydihydrochalcone (compound 1) and 2,4’-dihydroxy-4-methoxyhydrochalcone (compound 2). Both compounds were isolated for the first time from the red resin (dragon’s blood) of D. cinnabari. The compounds were first evaluated for cytotoxicity on HepG2.2.15 cells and 50% cytotoxicity concentration (CC50) values were determined. They were then evaluated for anti-HBV activity against HepG2.2.15 cells by assessing the suppression of HBsAg and HBeAg production in the culture supernatants and their half maximum inhibitory concentration (IC₅₀) and therapeutic index (TI) values were determined. Compounds 1 and 2 indicated inhibition of HBsAg production in a dose- and time-dependent manner with IC₅₀ values of 20.56 and 6.36 μg/mL, respectively.

Corrigendum to "New terpenic and phenolic compounds from Suaeda monoica reverse oxidative and apoptotic damages in human endothelial cells". [Saudi Pharm. J. 29(10) (2021) 1102-1111]

[This corrects the article DOI: 10.1016/j.jsps.2021.08.007.].

The anti-oxidative, anti-cell proliferative and anti-microbial efficacies of cold-adapted Crepis flexuosa: HPTLC and GC/MS analyses

The genus Crepis constitutes cold-adapted plant spp., of these some are traditionally used in folk medicine against inflammation or fungal infections without scientific validations. Here, we report the biological activities of Crepis flexuosa total ethanol-extract (CF-EtOH) and its hexane (CF-Hex), ethyl acetate (CF-EtOA), butanol (CF-ButOH), and aqueous (CF-Aqua) fractions. Our in vitro DPPH and ABTS radical-scavenging assays showed CF-EtOH, CF-ButOH and CF-Aqua with maximal, CF-EtOA with moderate, and CF-Hex with mild anti-oxidant activities. When tested on human cancer cell lines, high cytotoxicity was demonstrated by CF-EtOH (IC₅₀: 42.45 μg/ml) and CF-Aqua (IC₅₀: 46.37 μg/ml) on HepG2, followed by CF-Hex (IC₅₀: 63.24 μg/ml) and CF-ButOH (IC₅₀: 65.32 μg/ml) on MCF7 cells. The human primary cell line (HUVEC) had comparatively lower cytotoxicity for the tested samples. Moreover, when assessed for anti-microbial efficacy, CF-ButOH and CF-Aqua exhibited the strongest activity (MIC: 156.25 μg/ml) against S. aureus, E. faecalis and C. albicans. Further, while the developed RP-HPTLC identified the bioactive flavonoid luteolin-7-O-glucoside (17.58 mg/g), GS/MS analysis revealed sixteen compounds in C. flexuosa extract. In conclusion, we for the first time show the promising anti-oxidative, anti-cell proliferative and anti-microbial efficacies of C. flexuosa. This warrants further phytochemical and bio-efficacy studies towards isolations and identifications of active principles.

Molecular insights into the Y-domain of hepatitis E virus using computational analyses

Background

Hepatitis E virus (HEV) of the family Hepeviridae is a major causative agent of acute hepatitis in developing countries. The Y-domain is derived from multi-domain non-structural polyprotein encoded by open reading frame 1 (ORF1). Previous studies have demonstrated the essentiality of Y-domain sequences in HEV life cycle; however, its function remains completely unexplored. The following study was thus conceptualized to examine the detailed computational investigation for the putative Y-domain to estimate its phylogenetic assessment, physiochemical properties, structural and functional characteristics using in silico analyses.

Results

The phylogenetic assessment of Y-domain with a vast range of hosts indicated that the protein was very well conserved throughout the course of evolution. The Y-domain was found to be unstable, hydrophilic and basic in nature with high thermostability value. Structural analysis of Y-domain revealed mixed α/β structural fold of the protein having higher percentage of alpha-helices. The three-dimensional (3D) protein model generated through homology modelling revealed the presence of clefts, tunnels and pore. Gene ontology analysis predicted Y-domain protein’s involvement in several binding and catalytic activities as well as significant biological processes. Mutations in the conserved amino acids of the Y-domain suggested that it may stabilize or de-stabilize the protein structure that might affect its structure–function relationship.

Conclusions

This theoretical study will facilitate towards deciphering the role of unexplored Y-domain, thereby providing better understanding towards the pathogenesis of HEV infection.

Novel Anti-Hepatitis B Virus Activity of Euphorbia schimperi and Its Quercetin and Kaempferol Derivatives

Natural or plant products, because of their structural diversity, are a potential source for identifying new anti-hepatitis B virus (HBV) agents. Here, we report the anti-HBV activity of Euphorbia schimperi and its quercetin (QRC) and kaempferol derivatives. The anti-HBV-active methanol fraction of E. schimperi was subjected to chromatographic techniques, leading to isolation of three flavonols, following their structure determination by ¹H and ¹³C NMR spectroscopies. Their cytotoxicity and anti-HBV potential were assessed using HBV reporter HepG2.2.15 cells, and their modes of action were delineated by molecular docking. The isolated compounds identified as quercetin-3-O-glucuronide (Q3G), quercetin-3-O-rhamnoside (Q3R), and kaempferol-3-O-glucuronide (K3G) were non-cytotoxic to HepG2.2.15 cells. The viral HBsAg/HBeAg production on day 5 was significantly inhibited by K3G (∼70.2/∼73.4%), Q3G (∼67.8/∼72.1%), and Q3R (∼63.2%/∼68.2%) as compared to QRC (∼70.3/∼74.8%) and lamivudine (∼76.5/∼84.5%) used as standards. The observed in vitro anti-HBV potential was strongly supported by in silico analysis, which suggested their structure-based activity via interfering with viral Pol/RT and core proteins. In conclusion, this is the first report on the anti-HBV activity of E. schimperi-derived quercitrin-3-O-glucuronide, quercitrin-3-O-rhamnoside, and kaempferol-3-O-glucuronide, most likely through interfering with HBV proteins.

Role of "dual-personality" fragments in HEV adaptation-analysis of Y-domain region

BACKGROUND

Hepatitis E is a liver disease caused by the pathogen hepatitis E virus (HEV). The largest polyprotein open reading frame 1 (ORF1) contains a nonstructural Y-domain region (YDR) whose activity in HEV adaptation remains uncharted. The specific role of disordered regions in several nonstructural proteins has been demonstrated to participate in the multiplication and multiple regulatory functions of the viruses. Thus, intrinsic disorder of YDR including its structural and functional annotation was comprehensively studied by exploiting computational methodologies to delineate its role in viral adaptation.

RESULTS

Based on our findings, it was evident that YDR contains significantly higher levels of ordered regions with less prevalence of disordered residues. Sequence-based analysis of YDR revealed it as a "dual personality" (DP) protein due to the presence of both structured and unstructured (intrinsically disordered) regions. The evolution of YDR was shaped by pressures that lead towards predominance of both disordered and regularly folded amino acids (Ala, Arg, Gly, Ile, Leu, Phe, Pro, Ser, Tyr, Val). Additionally, the predominance of characteristic DP residues (Thr, Arg, Gly, and Pro) further showed the order as well as disorder characteristic possessed by YDR. The intrinsic disorder propensity analysis of YDR revealed it as a moderately disordered protein. All the YDR sequences consisted of molecular recognition features (MoRFs), i.e., intrinsic disorder-based protein-protein interaction (PPI) sites, in addition to several nucleotide-binding sites. Thus, the presence of molecular recognition (PPI, RNA binding, and DNA binding) signifies the YDR's interaction with specific partners, host membranes leading to further viral infection. The presence of various disordered-based phosphorylation sites further signifies the role of YDR in various biological processes. Furthermore, functional annotation of YDR revealed it as a multifunctional-associated protein, due to its susceptibility in binding to a wide range of ligands and involvement in various catalytic activities.

CONCLUSIONS

As DP are targets for regulation, thus, YDR contributes to cellular signaling processes through PPIs. As YDR is incompletely understood, therefore, our data on disorder-based function could help in better understanding its associated functions. Collectively, our novel data from this comprehensive investigation is the first attempt to delineate YDR role in the regulation and pathogenesis of HEV.

New terpenic and phenolic compounds from Suaeda monoica reverse oxidative and apoptotic damages in human endothelial cells

Elevation in hyperglycemia-associated methylglyoxal level can trigger vascular endothelial cells oxidative stress and apoptosis. The present work assesses the cell proliferative, anti-oxidative and anti-apoptotic potential of Suaeda monoica derived four new terpenes: a norsesquaterpenol (normonisesquaterpenol), a monocyclic triterpenoid (suaedanortriterpene dione), an aromatic monoterpenic ester and a labdane-type norditerpenic xyloside as well as two new phenols: an alkylated β-naphthol and a β-methoxy naphthalene in cultured human umbilical vein endothelial cells (HUVEC). Of these, suaedanortriterpenedione (53.7%), normonisesquaterpenol (51.4%) and norditerpenic xyloside (48%) showed the most promising cell proliferative activities compared to others. Moreover, normonisesquaterpenol, norditerpenic xyloside and suaedanortriterpenedione efficiently reversed the oxidative and apoptotic cell damage via downregulation of capase-3/7 by 44.3%, 42.2% and 39.4%, respectively against dichlorofluorescin, whereas by 46.2%, 43.5% and 42.5%, respectively against methylglyoxal. Aminoguanidine, the reference drug inhibited caspase-3/7 activity by 56.2% and 54.7% through attenuation of dichlorofluorescin and methylglyoxal, respectively. Further in silico molecular docking analysis revealed formation of stable complexes between the tested compounds and caspase-3/7. Conclusively, we for the first time demonstrate the growth stimulatory, anti-oxidative and anti-apoptotic salutations of S. monoica derived novel compounds in human endothelial cells. This warrants their further assessment as vascular cell protective and rejuvenating therapeutics, especially in hyperglycemic conditions.

Structural exploration of Y-domain reveals its essentiality in HEV pathogenesis

Hepatitis E virus (HEV) is a major causative agent of hepatitis E infections across the globe. Although the essentiality of HEV nonstructural polyprotein (pORF1) putative Y-domain (Yd) has been established in viral pathogenesis, its structural-functional role remains elusive. The current research discusses the novel exploration on Yd protein expression, purification, biophysical characterization and structure-based docking analysis. The codon optimized synthetic gene and optimized expression parameters i.e., 5 h induction with 0.25 mM IPTG at 37 °C, resulted in efficient production of Yd protein (∼40 kDa) in E. coli BL21(DE3) cells. Majority of the recombinant Yd (rYd) protein expressed as inclusion bodies was solubilized in 0.5% N-lauroylsarcosine and purified using Ni-NTA chromatography. Circular dichroism (CD) and UV visible absorption spectroscopic studies on Yd revealed both secondary and tertiary structure stability in alkaline range (pH 8.0-10.0), suggesting correlation with its physiological activity. Thus, loss in structure at low pH perhaps play crucial role in cytoplasmic-membrane interaction. The biophysical data were in good agreement with in-silico structural analyses, which suggested mixed α/β fold, non-random and basic nature of Yd protein. Furthermore, due to Yd protein essentiality in HEV replication and pathogenesis, it was considered as a template for docking and drug-likeness analyses. The 3D modeling of Yd protein and structure-based screening and drug-likeness of inhibitory compounds, including established antiviral drugs led to the identification of top nine promising candidates. Nonetheless, in vitro studies on the predicted interaction of Yd with intracellular-membrane towards establishing replication-complexes as well as validations of the proposed therapeutic agents are warranted.

The Genomic and Structural Organization of SARS-CoV-2: A Mutational Perspective

The ongoing pandemic due to the novel SARS-CoV-2 disease (COVID-19) has exerted a great toll on human health. The SARS-CoV-2 is the third most pathogenic human CoV after SARS-CoV-1 and MERS-CoV, which is classified within the genus Betacoronavirus. Though the actual source of its origin and transmission is still unclear, genetic analysis has shown its very close similarity (~96%) with bat SARS-like CoV. SARS-CoV-2 is a spherically-icosahedral virus with a plus-sense single-strand RNA (~30 kb) genome defined into thirteen open reading frames, which encode 2 non-structural polyproteins, 4 structural proteins and 6 accessory proteins. Of its structural proteins the ‘S1’ subunit of spike (S) contains the cellular ACE-2 receptor binding domain (RBD) whereas the ‘S2’ subunit is required for cell membrane fusion. The membrane (M) protein participates in cell-fusion whereas envelope (E) is necessary for virion assembly and morphogenesis. The non-structural polyproteins (pp1a and pp1b) undergo proteolytic processing to produce a total of 16 small proteins, which are involved in mRNA synthesis and replication. Of the accessory proteins (3a, 6, 7a, 7b, 8 and 9b), few are known to modulate host-innate immunity. Interestingly, ‘3b’ is absent in SARS-CoV-2 that significantly differentiates it from other human CoV. Detection of several novel mutations in ‘3a’, ‘3b’ and ‘ORF8’ proteins, notably in the ‘S’ RBD strongly suggest SARS-CoV-2 enhanced cell attachment and facilitated entry, its high infectivity and disease severity in humans. The recent emergence of highly contagious SARS-CoV-2 RBD variants in the United Kingdom (B.1.1.7 strain), South Africa (B.1.351 strain) and Brazil (P.1 strain), and their subsequent spread to other counties have raised serious concerns. Doi: 10.28991/SciMedJ-2021-0301-8 Full Text: PDF

Comparative sequence analysis of SARS-CoV-2 suggests its high transmissibility and pathogenicity

Aim: Because the highly pathogenic SARS-CoV-2 is newly introduced to humans, we aimed to understand the unique features of its genome and proteins, crucial for high transmissibility and disease severity. Materials & methods: The available genome and protein sequences of SARS-CoV-2 with known human and nonhuman CoV were analyzed using multiple sequence alignment programs. Results: Our analysis revealed some unique mutations in SARS-CoV-2 spike, ORF1a/b, ORF3a/3b and ORF8. The most interesting ones were in the spike angiotensin-converting enzyme 2 receptor binding-motif and generation of a furin-like cleavage site as well as deletions of ORF3a ‘diacidic motif’ and the entire ORF3b. Conclusion: Our data suggest that SARS-CoV-2 has diverged from SARS-CoV-1 but is most close to bat-SL-CoV. Unique mutations in spike and ORF3a/b proteins strongly endorse its adaptive evolution, enhanced infectivity and severe pathogenesis in humans.

Structure and ligand-based drug discovery of IL-4 inhibitors via interaction-energy-based learning approaches

Interleukin-4 (IL-4), an anti-inflammatory cytokine plays significant in the development of various diseases especially asthmatic allergies. Previous structural and functional studies of IL-4 with its receptor bring forth different types of inhibitors to block their interaction but each of them failed in clinical trials. Since, no synthetic molecules have been identified against IL-4, so far. Therefore, 21 in-house tested IL-4 inhibitors were blindly docked over the entire surface of IL-4 to predict a suitable and druggable binding site as the crystal structure of IL-4 protein in complex with ligand has not been reported yet. After binding site prediction, both ligand-based and structure-based pharmacophore were generated to screen three ZINC libraries (24.5 M) i.e. purchasable, natural product and natural derivative. A total 5,800 top-scored compounds were further subjected towards score-based screening to find the potential leads. Following protein-ligand interaction fingerprints (PLIF) and molecular visualization of selected hits, six top-scored compounds (five from purchasable and one from natural product library) were further moved towards their stability dynamics, followed by their absolute binding free energy and residue-based energy decomposition calculation by MM-GBSA method. These efforts help us to reveal the key factors responsible for ligand binding that might help to improve the binding and stability of these newly discovered hits by structural modifications.Communicated by Freddie R. Salsbury.

Bioassay-guided isolation of anti-hepatitis B virus flavonoid myricetin-3-O-rhamnoside along with quercetin from Guiera senegalensis leaves

Recently, we have shown in vitro anti-hepatitis B virus (HBV) activity of G. senegalensis J.F. Gmel leaves, and Identified quercetin and other flavonoids by HPTLC. Here we report bioassay-directed fractionation of G. senegalensis leaves using column chromatography and isolation of two flavonoinds from the n-butanol fraction, their structure determination (1H NMR, 13C NMR and 2D-NMR) and assessment of antiviral activities (HBsAg and HBeAg assay) in HBV-reporter HepG2.2.2.15 cells. Further molecular docking was performed against HBV polymerase (Pol/RT) and capsid (Core) proteins as well as host-receptor sodium taurocholate co-transporting polypeptide (NTCP). The two isolated bioactive compounds were identified as quercetin and myricetin-3-O-rhamnoside. Quercetin significantly inhibited synthesis of HBsAg and HBeAg by about 60% and 62%, respectively as compared to myricetin-3-O-rhamnoside by 44% and 35%, respectively. Molecular docking of the two anti-HBV flavonoids revealed their higher binding affinities towards Pol/RT than Core and NTCP. In conclusion, this is the first report on anti-HBV active myricetin-3-O-rhamnoside along with quercetin isolated from G. senegalensis leaves. Their possible mode of anti-HBV activities are suggested through binding with viral Pol/RT and Core as well as host NTCP proteins.

Oncoglabrinol C, a new flavan from Oncocalyx glabratus protects endothelial cells against oxidative stress and apoptosis, and modulates hepatic CYP3A4 activity

Active herbal or natural compounds have high chemical diversity and specificity than synthetic drugs. Recently, we have validated the hypoglycemic salutation of Oncocalyx glabratus in rodent model, and demonstrated the activation of PPARα/γ by its newly ioslated flavan derivative Oncoglabrinol C (5,3′-Dihydroxyflavan 7-4′-O-digallate) in liver cells (HepG2). Here we evaluated the potential of Oncoglabrinol C against Dichlorofluorescin (DCFH) and Methylglyoxal (MGO) induced endothelial cells (HUVEC) oxidative and apoptotic damage, including activation of PXR-mediated hepatic CYP3A4. Our MTT assay showed protection of ~57% and ~63.5% HUVEC cells by 10 and 20 μg/ml doses of Oncoglabrinol C, respectively through attenuating DCFH triggered free-radicals. Also, the two doses effectively protected ~53% and ~65.5% cells, respectively by reversing MGO toxicity. In DCFH and MGO treated cells, Oncoglabrinol C (20 μg/ml) effectively downregulated caspase 3/7 activity by ~33% and ~43.5%, respectively. Moreover, in reporter gene (dual-luciferase) assay, Oncoglabrinol C (20 μg/ml) moderately activated hepatic CYP3A4. Molecular docking of Oncoglabrinol C indicated its strong interactions with cellular caspase 3/7, PPARα/γ and PXR proteins, which supported its anti-apoptotic (antagonistic) as well as pro-hypoglycemic and PXR/CYP activating (agonistic) activities. Taken together, our findings demonstrated the potential of Oncoglabrinol C in reversing the endothelial oxidative and apoptotic damage as well as in the activation of hepatic CYP3A4. This warrants further evaluations of Oncoglabrinol C and related compounds towards developing effective and safe drugs against diabetes associated cardiovascular disorders.

The first bioactivity studies of Acantholimon lycopodioides from high altitude Karakoram-Himalayan desert

Couple of ethnopharmacological surveys in the Indian Ladakh and Pakistani Shigar valleys has reported the medicinal use of Acantholimon lycopodioides against cardiac and gastric disorders that however, remains without scientific rationale or experimental validations. Here, we assess the in vitro bio/therapeutic activities of A. lycopodioides extracts as well as chloroform, ethyl acetate, n-butanol and aqueous fractions. The in vitro β-carotene-linoleic acid bleaching and DPPH radical scavenging methods demonstrated a very high anti-oxidative property of chloroform and ethyl acetate fractions compared to others. Cell viability assay (MTT) on human cervical (HeLa), breast (MDA-MB321) and liver (HepG2) cancer cells revealed their differential cytotoxicity, except the chloroform fraction. Of these, the precipitate exerted highest cytotoxicity on HepG2 cells followed by aqueous fraction on MDA-MB321 cells. Notably, the non-cytotoxicity of chloroform fraction coincided with its highest anti-oxidative activity. Further, the chloroform fraction showed marked hepatoprotection (up to 84%) against 3'7'dichlorofluorescin triggered free radicals induced oxidative damage. Also, the hepatoprotective chloroform fraction mildly activated CYP3A4 in HepG2 cells (dual-luciferase assay). Moreover, the A. lycopodioides extracts and fractions showed differential anti-bacterial and anti-fungal activities. Of these, while S. aureus was more sensitive to the water-insoluble extract, ethyl acetate fraction showed moderate activity against E. coli and C. albicans. On the other hand, the chloroform fraction showed promising activity against S. Aureus, C. albicans, P. vulgaris and E. faecalis. In conclusion, our data for the first time, demonstrated promising anti-oxidative, hepatoprotective, anti-cancer, anti-microbial and CYP3A4 activating salutations of A. lycopodioides. This warrants further studies towards isolation and identification of its therapeutically active principles.

Novel polycyclic pyrroloquinazoline alkaloids from Anisotes trisulcus and their biological activity

Two new polycyclic pyrroloquinazoline alkaloids with unprecedented skeleton, anisulcusines A (1) and B (2), along with four known compounds (3-6), were identified from the aerial parts of Anisotes trisulcus (Forssk.) Nees. To our knowledge, anisulcusines A and B are the first polycyclic pyrroloquinazoline alkaloids that possess a unique N-methyl-1,2-dihydro-1'H-spiro[benzo[d][1,3]oxazine moiety. The chemical structures of the new compounds were elucidated through extensive spectroscopic analyses and high-resolution mass spectroscopy. Anisulcusine B (2) exerted moderate cytotoxic effect on cultured human hepatoma (HuH7) cells, whereas compounds 1 and 3-5 exhibited mild cell proliferative or growth stimulatory activity. HIGHLIGHTS Two new polycyclic pyrroloquinazoline alkaloids from Anisotes trisulcus. Structures were elucidated on the basis of 1D- and 2D-NMR and HR-ESI-MS spectra. Compound (2) exerted moderate cytotoxic effect against human hepatoma (HuH7) cells. Compounds (1, 3-5) exhibited mild cell proliferative or growth stimulatory activity.

Cell proliferation activity delineated by molecular docking of four new compounds isolated from the aerial parts of Suaeda monoica Forssk. ex. J.F. Gmel

Using different chromatographic methods, four new compounds were isolated from the aerial parts of Suaeda monoica (Chenopodiaceae) along with 2-hydroxy-1-naphthoic acid (SCM-3). The structures of the new compounds were established as 6'-hydroxy-10'-geranilanyl naphtha-1-oate (SMC-1), 4,4,8β,10β-Tetramethyl-9β-isobutanyl decalin-13-ol-13-O-β-D-xylopyranoside (SCM-2), 6'-(2-hydroxynaphthalen-3-yl) hexanoic acid (SCM-4) and 1'-(2-Methoxy-3-naphthyl)-4'-(2''-methylbenzoyl)-n-butane (SMC-5) by IR, EIMS and NMR (1 & 2D) analyses. All compounds (50 μg/mL) were tested for cell proliferative potential on cultured human liver cell HepG2 cells by MTT assay. The results revealed a marked cell proliferative potential of all compounds (1.42-1.48 fold) as compared to untreated control. The results of molecular docking and binding with specific proteins such as PTEN (Phosphatase and Tensin homolog) and p53 also justify the cell proliferative potential of the isolated compounds. Glide program with Schrodinger suit 2018 was used to evaluate the binding between SMC compounds and proteins (PTEN and p53). The binding affinity of all compounds was in order of 10⁴-10⁵ M^-1 towards both PTEN and p53. All the SMC compounds have been found to bind at the active site of PTEN, thereby may prevent the binding of phosphatidylinositiol 3,4,5-triphosphate (PI3P). In the locked position, PTEN would not be able to hydrolyze PI3P and hence the PI3P regulated signaling pathway remains active. Similarly, SMC molecules were found to interact with the amino acid residues (Ser99, Thr170, Gly199, and Asp224) which are critically involved in the formation of tetrameric p53. The blockage of p53 to attain its active conformation thus may prevent the recruitment of p53 on DNA and hence may promote cell proliferation.

Herb-Drug Interactions and Hepatotoxicity

BACKGROUND

In recent times, herbals or phytomedicines have become very popular due to their global acceptance as a complementary and alternative remedy. While modern drugs are commercially available only after laboratory validations, clinical trials, as well as approval from drug regulatory authorities, majority of the marketed herbal products lack such scientific evidence of efficacy and safety. This results in herb or herb-drug interaction induced unfavorable clinical outcomes without crucial documentation on their temporal relations and concomitant use.

METHODS

An online literature search for peer-reviewed articles was conducted on the PubMed, Europe PMC, Medline and Google Scholar portals, using the phrases: complementary & alternative medicine, traditional Chinese medicine, herb-drug interaction, mechanisms of herb-drug interaction, herb-induced toxicity, herbal hepatotoxicity and causality, traditional medicine, viral hepatitis, etc.

Results

The retrieved data showed that globally, patients are attracted to herbal remedies with the misconception that these are completely safe and therefore, use them simultaneously with prescription drugs. Notably, there exists a potential risk of herb-drug interactions leading to some adverse side effects, including hepatotoxicity. The toxicological effect of a drug or herb is due to the inhibition of drug metabolizing enzymes (e.g., cytochrome P450), including interactions with certain prescription drugs through various mechanisms. Several cases of hepatotoxicity due to use of herbals in viral hepatitis-related liver diseases have been recently reported. However, limited experimental data and clinical evidence on herbal pharmacokinetics hamper the evaluation and reporting of adverse reactions and the underlying mechanisms.

CONCLUSION

Herb-drug interaction related morbidity is thus an emerging serious public health issue with broad implications for clinicians, pharmaceutical industries and health authorities. Nonetheless, despite increasing recognition of herb-drug interaction, a standard system for interaction prediction and evaluation is still nonexistent. This review article discusses the herb-drug interactions related hepatotoxicity and underlying mechanisms, including drug metabolizing enzymes and their regulation.

The anti-hepatitis B virus therapeutic potential of anthraquinones derived from Aloe vera

Although the approved hepatitis B virus (HBV)-polymerase inhibitors (e.g., lamivudine) often lead to drug-resistance, several natural products have shown promising efficacies. Though Aloe vera (AV) gel and its constituents are shown inhibitors of many viruses, their anti-HBV activity still remains elusive. We therefore, tested the anti-HBV potential of AV extract and its anthraquinones in hepatoma cells, including molecular docking, high-performance thin layer chromatography (HPTLC), and cytochrome P450 (CYP3A4) activation analyses. Our anti-HBV assays (HBsAg/HBeAg Elisa) showed maximal inhibition of viral antigens production by aloe-emodin (~83%) > chrysophanol (~62%) > aloin B (~61%) > AV extract (~37%) in HepG2.2.15 cells. Interestingly, the effect of aloe-emodin was comparable with lamivudine (~86%). Moreover, sequential treatment with lamivudine (pulse) followed by aloe-emodin (chase) enhanced the efficacy of monotherapy by ~12%. Docking (AutoDock Vina) of the anthraquinones indicated strong interactions with HBV-polymerase residues that formed stable complexes with high Gibbs's free energy. Further, identification of aloe-emodin and aloin B by validated HPTLC in AV extract strongly endorsed its anti-HBV potential. In addition, our luciferase-reporter gene assay of transfected HepG2 cells showed moderate induction of CYP3A4 by aloe-emodin. In conclusion, this is the first report on anti-HBV potential of AV-derived anthraquinones, possibly via HBV-polymerase inhibition. Of these, although aloin B exhibits novel antiviral effect, aloe-emodin appears as the most promising anti-HBV natural drug with CYP3A4 activating property towards its enhanced therapeutic efficacy.

Hepatoprotective effect of Solanum surattense leaf extract against chemical- induced oxidative and apoptotic injury in rats

Background

Of over 35 Saudi plants traditionally used to treat liver disorders, majority still lack scientific validations. We therefore, evaluated the anti-oxidative, anti-apoptotic and hepatoprotective potential of Solanum surattense leaves total ethanol-extract (SSEE).

Methods

The cytoprotective (4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide/ MTT assay) and anti-apoptotic (caspase-3/7) potential of SSEE (25–200 μg/mL) were assessed in cultured HepG2 cells against dichlorofluorescein (DCFH)-induced toxicity. The hepatoprotective salutation of SSEE (100 and 200 mg/kg.bw/day) in carbon tetrachloride (CCl₄)-intoxicated rats was evaluated by serum biochemistry and histopathology. The anti-oxidative activity of SSEE (31.25–500 μg/mL) was tested by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging and linoleic acid bleaching assays. Also, SSEE was subjected to qualitative phytochemical analysis, and standardized by validated high-performance liquid chromatography (HPTLC).

Results

SSEE at doses 50, 100 and 200 μg/mL showed HepG2 cell proliferative and protective potential by about 61.0, 67.2 and 95%, respectively through inhibition of caspase-3/7 against DCFH-toxicity. In CCl₄-injured rats, SSEE (200 mg/kg) significantly (P < 0.001) normalized serum transaminases, alkaline phosphatase, bilirubin, cholesterol, triglycerides, and total protein, including tissue malondialdehyde and nonprotein sulfhydryls levels, supported by the liver histopathology. SSEE further showed strong in vitro anti-oxidative and anti-lipid peroxidative activities, evidenced by the presence of alkaloids, flavonoids, tannins, sterols and saponins. Identification of β-sitosterol (3.46 μg/mg) strongly supported the anti-oxidative and hepatoprotective salutation of SSEE.

Conclusion

Our findings suggest the therapeutic potential of S. surattense against chemical-induced oxidative stress and liver damage. However, isolation of the active principles and elucidation of mechanism of action remain to be addressed.

Proanthocyanidins from the stem bark of Rhus tripartita ameliorate methylgloxal-induced endothelial cell apoptosis

In traditional Arabian medicine, the Rhus tripartita plant (family Anacardiaceae) has been used to treat inflammatory conditions. Although Rhus extracts have been reported for their cardioprotective effects, information regarding their active principle compounds remains insufficient. The present investigation was aimed at determining the antioxidant chemical constituents of the methanolic extract of R. tripartita stem bark and evaluating their ability to ameliorate methylglyoxal-induced endothelial cell apoptosis. Ten flavonoid compounds (1–10) were isolated and identified using DPPH radical scavenging bioassay-guided chromatographic separation. A new proanthocyanidin (rhuspartin) (1) was isolated and identified as 3,5,13,14-flavantetrol-(4β→8)-catechin, using extensive spectroscopic data and high resolution-mass spectrometry. Among the compounds (1, 5, 7–10) tested for toxicity toward cultured endothelial cells (HUVECs), the non-cytotoxic compounds 1 and 7 evinced cytoprotective potential that reversed the methylglyoxal-induced apoptosis (by 62% and 64%, respectively) through downregulation of caspase 3/7.

Plant-derived antiviral drugs as novel hepatitis B virus inhibitors: Cell culture and molecular docking study

Despite high anti-HBV efficacies, while the nucleoside analogs (e.g., lamivudine) lead to the emergence of drug-resistance, interferons (e.g., IFN-α causes adverse side-effects. Comparatively, various natural or plant products have shown similar or even better efficacy. Hence, new antiviral strategies must focus not only on synthetic molecules but also on potential natural compounds. In this report, we have combined the in vitro cell culture and in silico molecular docking methods to assess the novel anti-HBV activity and delineate the inhibitory mechanism of selected plant-derived pure compounds of different classes. Of the tested (2.5-50 μg/ml) twelve non-cytotoxic compounds, ten (10 μg/ml) were found to maximally inhibit HBsAg production at day 5. Compared to quercetin (73%), baccatin III (71%), psoralen (67%), embelin (65%), menisdaurin (64%) and azadirachtin (62%) that showed high inhibition of HBeAg synthesis, lupeol (52%), rutin (47%), β-sitosterol (43%) and hesperidin (41%) had moderate efficacies against HBV replication. Further assessment of quercetin in combination with the highly active compounds, enhanced its anti-HBV activity up to 10%. Being the most important drug target, a 3-D structure of HBV polymerase (Pol/RT) was modeled and docked with the active compounds, including lamivudine as standard. Docking of lamivudine indicated strong interaction with the modeled HBV Pol active-site residues that formed stable complex (∆G = -5.2 kcal/mol). Similarly, all the docked antiviral compounds formed very stable complexes with HBV Pol (∆G = -6.1 to -9.3 kcal/mol). Taken together, our data suggest the anti-HBV potential of the tested natural compounds as novel viral Pol/RT inhibitors.

The in vitro and in vivo anti-hepatotoxic, anti-hepatitis B virus and hepatic CYP450 modulating potential of Cyperus rotundus

In the present study we investigated the hepatotoprotective, hepatitis B virus (HBV) inhibitory and hepatic CYP450 enzyme (CYP3A4) modulatory potential of Cyperus rotundus rhizome fractions. The crude ethanol-extract, including different organic and aqueous fractions were tested for in vitro cytoprotection on HepG2 cells (MTT assay), followed by in vivo evaluation in Wistar rats (serum biochemistry and lipid profile). The in vitro anti-HBV activity was tested on HepG2.2.15 cells (HBsAg and HBeAg Elisa). Of these, the n-butanol and aqueous fractions showed the most promising, dose-dependent hepatoprotection in DCFH-injured HepG2 cells. Further, in CCl₄-injured rats, oral administration of C. rotundus (100 and 200 mg/kg·bw/day) significantly normalized serum markers of healthy liver function (SGOT, SGPT, GGT, ALP and bilirubin) and lipid profile (cholesterol, HDL, LDL, VLDL, TG and MDA), including tissue NP-SH and TP levels. Compared to other fractions, the ethyl acetate, n-butanol and aqueous fractions exhibited the best inhibitory effects on viral HBsAg and HBeAg secretions in dose- and time-dependent manner. In addition, reporter gene assay (Dual-luciferase) of transfected HepG2 cells showed mild activation of nuclear PXR-mediated CYP3A4 gene by the three active fractions. Taken together, C. rotundus showed very promising hepatoprotective and anti-HBV potential in experimental settings. In addition, this is the first report on modulation of CYP3A4 by C. rotundus that suggests its safe consumption in relation to drug metabolism and efficacy. Our data could therefore, provide the basis for the ethnobotanical medicinal use of C. rotundus in metabolic liver disorder and hepatitis B patients.

Novel plant inducers of PXR-dependent cytochrome P450 3A4 expression in HepG2 cells

The cytochrome P450 3A4 (CYP3A4) is the most abundant CYP450 enzyme involved in the metabolism of endogenous products and xenobiotics, including prescription drugs and herbals. Modulation of hepatic CYP3A4 gene expression via nuclear receptors, like pregnane X receptor (PXR), is a major cause of adverse effects like drug-unresponsiveness and toxicity. In the present study, ethanol extracts of 58 medicinal plants, belonging to 27 families, were evaluated for potential activities in CYP3A4 induction in HepG2 cells by reporter gene assay. For PXR-mediated CYP3A4 induction, a 50 μg/ml concentration was used for all non-cytotoxic plants extracts. Rifampicin (10 μM) and DMSO (0.1%) were used as standard inducer and untreated (negative) control, respectively. The comparative fold-induction of CYP34A by the plant extracts in relation to the untreated control was determined. As a result, Dodonaea angustifolia (2.62 fold; P < 0.0001) was found to be the most promising inducer of CYP3A4, followed by Euphorbia tirucalli (1.95 fold; P = 0.0004), Alternanthera pungens (1.74 fold, P = 0.0035), and Ficus palmata (1.65 fold; P = 0.0097). Further phytochemical characterizations of the active plants are therefore, warranted.

Protective effect of Atriplex suberecta extract against oxidative and apoptotic hepatotoxicity

Atriplex suberecta I. Verd is a known phytomedicinal species of Atriplex; however, studies into its bioactivity remain inconclusive. The in vitro and in vivo antioxidative and hepatoprotective potential of A. suberecta ethanol-extract (ASEE) was assessed in the present study. 1,1-diphenyl-2-picrylhydrazyl radical scavenging and β-carotene bleaching assays revealed that ASEE possesses free radical scavenging and anti-lipid peroxidative activities. These results were supported by the in vitro protection of HepG2 hepatoblastoma cells via abating 2,7-dichlorofluorescein-activated oxidative and apoptotic molecules (caspase-3/-7). In carbon tetrachloride-treated rats, the oral administration of ASEE significantly normalized serum biomarkers of liver function (serum glutamate oxaloacetate, serum pyruvate transaminase, alkaline phosphatase, γ-glutamyl transferase and bilirubin) and the lipid profile (total cholesterol, high-density lipoprotein, low-density lipoprotein, triglycerides and malondialdehyde), including tissue non-protein sulfhydryl and total protein levels. These results were also supported by liver histopathology, which demonstrated that the therapeutic effect of ASEE was comparable to silymarin. Furthermore, phytochemical analysis of ASEE revealed the presence of flavonoids, alkaloids, tannins and saponins. Rutin, an antioxidant flavonoid, was identified using the validated high-performance thin-layer chromatography method. In conclusion, this is the first report on the therapeutic potential of A. suberecta against chemical-induced oxidative stress and liver damage.

Analysis of antioxidative and antiviral biomarkers β-amyrin, β-sitosterol, lupeol, ursolic acid in Guiera senegalensis leaves extract by validated HPTLC methods

Guiera senegalensis J.F. Gmel is a broad-spectrum African folk- medicinal plant, having activities against fowlpox and herpes viruses. Very recently, we have shown the anti-hepatitis B vius (HBV) potential of G. senegalensis leaves extract (GSLE). Here, we report the antioxidative and hepatoprotective efficacy of GSLE, including HPTLC quantification of four biomarkers of known antioxidative and antiviral activities. In cultured liver cells (HuH7) GSLE attenuated DCFH-induced oxidative stress and cytotoxicity. This was supported by in vitro DPPH radical-scavenging and β-carotene-linoleic acid bleaching assays that showed strong antioxidant activity of GSLE. Further, two simple and sensitive HPTLC methods (I and II) were developed and validated to quantify β-amyrin, β- sitosterol, lupeol, ursolic acid in GSLE. While HPTLC-I (hexane: ethylacetate; 75:25; v/v) enabled quantification of β-amyrin (Rf = 0.39; 20.64 μg/mg) and β-sitosterol (Rf = 0.25; 18.56 μg/mg), HPTLC-II (chloroform: methanol; 97:3; v/v) allowed estimation of lupeol (Rf = 0.47; 6.72 μg/mg) and ursolic acid (Rf = 0.23; 5.81 μg/mg) in GSLE. Taken together, the identified biomarkers strongly supported the antioxidant and anti-HBV potential of GSLE, suggesting its activity via abating the oxidative stress. To our knowledge, this is the first report on HPTLC analysis of these biomarkers in G. senegalensis that could be adopted for standardization and quality-control of herbal-formulations.

Quantitative analysis of rutin, quercetin, naringenin, and gallic acid by validated RP- and NP-HPTLC methods for quality control of anti-HBV active extract of Guiera senegalensis

CONTEXT

Guiera senegalensis J.F. Gmel (Combretaceae) is a folk medicinal plant used in various metabolic and infectious diseases. In addition to its antiviral activities against herpes and fowlpox, the anti-HBV efficacy is very recently reported.

OBJECTIVE

To develop and validate simple, sensitive RP-/NP-HPTLC methods for quantitative determination of biomarkers rutin, quercetin, naringenin, and gallic acid in the anti-HBV active G. senegalensis leaves ethanol-extract.

MATERIALS AND METHODS

RP-HPTLC (rutin & quercetin; phase- acetonitrile:water, 4:6) and NP-HPTLC (naringenin & gallic acid; phase- toluene:ethyl acetate:formic acid, 6:4:0.8) were performed on glass-backed silica gel plates 60F254-RP18 and 60F254, respectively. The methods were validated according to the ICH guidelines.

RESULTS

Well-separated and compact spots (Rf) of rutin (0.52 ± 0.006), quercetin (0.23 ± 0.005), naringenin (0.56 ± 0.009) and gallic acid (0.28 ± 0.006) were detected. The regression equations (Y) were 12.434x + 443.49, 10.08x + 216.85, 11.253x + 973.52 and 11.082x + 446.41 whereas the coefficient correlations (r2) were 0.997 ± 0.0004, 0.9982 ± 0.0001, 0.9974 ± 0.0004 and 0.9981 ± 0.0001, respectively. The linearity ranges (ng/spot) were 200-1400 (RP-HPTLC) and 100-1200 (NP-HPTLC). The LOD/LOQ (ng/band) were 33.03/100.1 (rutin), 9.67/29.31 (quercetin), 35.574/107.8 (naringenin), and 12.32/37.35 (gallic acid). Gallic acid (7.01 μg/mg) was the most abundant biomarker compared to rutin (2.42 μg/mg), quercetin (1.53 μg/mg) and naringenin (0.14 μg/mg) in the extract.

CONCLUSION

The validated NP-/RP-HPTLC methods were simple, accurate, and sensitive for separating and quantifying antiviral biomarkers in G. senegalensis, and endorsed its anti-HBV activity. The developed methods could be further employed in the standardization and quality-control of herbal formulations.

Isolation and validated HPTLC analysis of four cytotoxic compounds, including a new sesquiterpene from aerial parts of Plectranthus cylindraceus

We report isolation of a new sesquiterpene (compound 2: plectranol A) along with three known compounds (1: maaliol, 3: penduletin and 4: chrysosplenol D) from the aerial parts of Plectranthus cylindraceus Hoechst. Ex. Benth ethyl acetate extract (PCEAE). Their structures were established by UV, IR, NMR (¹H & ¹³C), HRESIMS and HSQC methods. The MTT cell proliferation assay of the compounds and the extract performed on human breast, skin and cervical cancer cell lines showed high toxicity, and their IC₅₀ (μg/mL) values were determined. The validated HPTLC analyses of maaliol and PCEAE (method I) and, penduletin, chrysosplenol D and PCEAE (method II) furnished sharp and compact peaks. The estimated high contents (μg/mg) of maaliol (17.06), penduletin (39.36) and chrysosplenol D (31.66) in PCEAE approved the plant's cytotoxic property. Since, P. cylindraceus contains a variety of cytotoxic terpenoids and flavonoids; our data warrant its further phytochemical and biological characterisation towards developing promising anti-cancer drugs.