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Khan M, Rauf W, Habib FE, Rahman M, Iqbal S, Shehzad A, Iqbal M. Hesperidin identified from Citrus extracts potently inhibits HCV genotype 3a NS3 protease. BMC Complement Med Ther 2022; 22:98. [PMID: 35366855 PMCID: PMC8976278 DOI: 10.1186/s12906-022-03578-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 03/25/2022] [Indexed: 11/29/2022] Open
Abstract
Background Hepatitis C virus infection is the main cause of liver ailments across the globe. Several HCV genotypes have been identified in different parts of the world. Effective drugs for combating HCV infections are available but not affordable, particularly to infected individuals from resource-limited countries. Hence, cost-effective drugs need to be developed against important HCV drug targets. As Citrus fruits naturally contain bioactive compounds with antiviral activities, the current study was designed to identify antiviral inhibitors from Citrus fruit extracts against an important drug target, NS3 protease, of HCV genotype 3a which is found predominantly in South Asian countries. Methods The full-length NS3 protease alone and the NS3 protease domain in fusion with the cognate NS4A cofactor were expressed in Escherichia coli, and purified by chromatographic techniques. Using the purified protein as a drug target, Citrus extracts were evaluated in a FRET assay, and active ingredients, identified using ESI–MS/MS, were docked to observe the interaction with active site residues of NS3. The best interacting compound was further confirmed through the FRET assay as the inhibitor of NS3 protease. Results Fusion of the NS3 protease domain to the NS4A cofactor significantly improved the purification yield, and NS3-NS4A was functionally more active than the full-length NS3 alone. The purified protein (NS3-NS4A) was successfully employed in a validated FRET assay to evaluate 14 Citrus fruit extracts, revealing that the mesocarp extract of Citrus paradisi, and whole fruit extracts of C. sinesis, C. aurantinum, and C. reticulata significantly inhibited the protease activity of HCV NS3 protease (IC50 values of 5.79 ± 1.44 µg/mL, 37.19 ± 5.92 µg/mL, 42.62 ± 6.89 µg/mL, and 57.65 ± 3.81 µg/mL, respectively). Subsequent ESI-MSn analysis identified a flavonoid, hesperidin, abundantly present in all the afore-mentioned Citrus extracts. Importantly, docking studies suggested that hesperidin interacts with active site residues, and acts as a potent inhibitor of NS3 protease, exhibiting an IC50 value of 11.34 ± 3.83 µg/mL. Conclusions A FRET assay was developed using NS3-NS4A protease, which was successfully utilized for the evaluation of Citrus fruit extracts. Hesperidin, a compound present in the Citrus extracts, was identified as the main flavonoid, which can serve as a cost-effective potent inhibitor of NS3 protease, and could be developed as a drug for antiviral therapy against HCV genotype 3a. Supplementary Information The online version contains supplementary material available at 10.1186/s12906-022-03578-1.
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Hasanshahi Z, Hashempour A, Ghasabi F, Moayedi J, Musavi Z, Dehghani B, Sharafi H, Joulaei H. First report on molecular docking analysis and drug resistance substitutions to approved HCV NS5A and NS5B inhibitors amongst Iranian patients. BMC Gastroenterol 2021; 21:443. [PMID: 34819046 PMCID: PMC8612383 DOI: 10.1186/s12876-021-01988-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 10/22/2021] [Indexed: 12/13/2022] Open
Abstract
Background NS5A and NS5B proteins of hepatitis C virus (HCV) are the main targets of compounds that directly inhibit HCV infections. However, the emergence of resistance-associated substitutions (RASs) may cause substantial reductions in susceptibility to inhibitors. Methods Viral load and genotyping were determined in eighty-seven naïve HCV-infected patients, and the amplified NS5A and NS5B regions were sequenced by Sanger sequencing. In addition, physicochemical properties, structural features, immune epitopes, and inhibitors-protein interactions of sequences were analyzed using several bioinformatics tools. Results Several amino acid residue changes were found in NS5A and NS5B proteins; however, we did not find any mutations related to resistance to the treatment in NS5B. Different phosphorylation and few glycosylation sites were assessed. Disulfide bonds were identified in both proteins that had a significant effect on the function and structure of HCV proteins. Applying reliable software to predict B-cell epitopes, 3 and 5 regions were found for NS5A and NS5B, respectively, representing a considerable potential to induce the humoral immune system. Docking analysis determined amino acids involved in the interaction of inhibitors and mentioned proteins may not decrease the drug efficiency. Conclusions Strong interactions between inhibitors, NS5A and NS5B proteins and the lack of efficient drug resistance mutations in the analyzed sequences may confirm the remarkable ability of NS5A and NS5B inhibitors to control HCV infection amongst Iranian patients. The results of bioinformatics analysis could unveil all features of both proteins, which can be beneficial for further investigations on HCV drug resistance and designing novel vaccines. Supplementary Information The online version contains supplementary material available at 10.1186/s12876-021-01988-y.
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Affiliation(s)
- Zahra Hasanshahi
- Shiraz HIV/AIDS Research Center, Institute of Health, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Ava Hashempour
- Shiraz HIV/AIDS Research Center, Institute of Health, Shiraz University of Medical Sciences, Shiraz, Iran.
| | - Farzane Ghasabi
- Shiraz HIV/AIDS Research Center, Institute of Health, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Javad Moayedi
- Shiraz HIV/AIDS Research Center, Institute of Health, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Zahra Musavi
- Shiraz HIV/AIDS Research Center, Institute of Health, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Behzad Dehghani
- Shiraz HIV/AIDS Research Center, Institute of Health, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Heidar Sharafi
- Baqiyatallah Research Center for Gastroenterology and Liver Diseases, Baqiyatallah University of Medical Sciences, Tehran, Iran.,Middle East Liver Diseases (MELD) Center, Tehran, Iran
| | - Hassan Joulaei
- Shiraz HIV/AIDS Research Center, Institute of Health, Shiraz University of Medical Sciences, Shiraz, Iran
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Shaheen A, Ismat F, Iqbal M, Haque A, Ul-Haq Z, Mirza O, De Zorzi R, Walz T, Rahman M. Characterization of the multidrug efflux transporter styMdtM from Salmonella enterica serovar Typhi. Proteins 2021; 89:1193-1204. [PMID: 33983672 DOI: 10.1002/prot.26141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 02/14/2021] [Accepted: 05/07/2021] [Indexed: 11/09/2022]
Abstract
Salmonellae are foodborne pathogens and the major cause of gastroenteritis in humans. Salmonellae express multidrug efflux transporters that play a key role in their drug resistance, which is becoming an increasing problem for therapeutic intervention. Despite their biomedical importance, the mechanisms underlying substrate transport by multidrug efflux transporters remain poorly understood. Here, we describe the first characterization of a multidrug transporter belonging to the major facilitator superfamily from the genus Salmonella. We show that several clinical Salmonella Typhi (S. Typhi) isolates constitutively express the styMdtM (STY4874) gene, which encodes a known multidrug-resistance (MDR) transporter. Guided by the structure of the Escherichia coli (E. coli) homolog, we studied two residues critical for substrate transport, Asp25 and Arg111. Mutation of Asp25 to glutamate did not affect the transport function of styMdtM, whereas mutation to alanine reduced its transport activity, suggesting that a negative charge at this position is critical for substrate translocation across the membrane. Substrate-affinity measurements by intrinsic fluorescence spectroscopy showed that the Asp25Ala mutant retained its capacity to bind substrate, albeit at a lower level. Mutation of Arg111 to alanine resulted in a decrease in secondary structure content of the transporter, and mutation to lysine completely destabilized the structure of the transporter. A homology model of styMdtM suggests that Arg111 is important for stabilizing the transmembrane domain by mediating necessary interactions between neighboring helices. Together, our studies provide new structural and mechanistic insights into the Salmonella MDR transporter styMdtM.
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Affiliation(s)
- Aqsa Shaheen
- Drug Discovery and Structural Biology Group, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Punjab, Pakistan.,Department of Biochemistry and Biotechnology, University of Gujrat, Gujrat, Punjab, Pakistan.,Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA
| | - Fouzia Ismat
- Drug Discovery and Structural Biology Group, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Punjab, Pakistan
| | - Mazhar Iqbal
- Drug Discovery and Structural Biology Group, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Punjab, Pakistan
| | - Abdul Haque
- Drug Discovery and Structural Biology Group, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Punjab, Pakistan.,Akhuwat First University, Faisalabad, Punjab, Pakistan
| | - Zaheer Ul-Haq
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Sindh, Pakistan
| | - Osman Mirza
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rita De Zorzi
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.,Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste, Italy
| | - Thomas Walz
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.,Laboratory of Molecular Electron Microscopy, Rockefeller University, New York, New York, USA
| | - Moazur Rahman
- Drug Discovery and Structural Biology Group, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Punjab, Pakistan.,Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.,School of Biological Sciences, University of the Punjab, Lahore, Punjab, Pakistan
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Khan M, Rauf W, Habib FE, Rahman M, Iqbal M. Screening and identification of bioactive compounds from citrus against non-structural protein 3 protease of hepatitis C virus genotype 3a by fluorescence resonance energy transfer assay and mass spectrometry. World J Hepatol 2020; 12:976-992. [PMID: 33312423 PMCID: PMC7701965 DOI: 10.4254/wjh.v12.i11.976] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/03/2020] [Accepted: 09/16/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Hepatitis C virus genotype 3a (HCV G3a) is highly prevalent in Pakistan. Due to the elevated cost of available Food and Drug Administration-approved drugs against HCV, medicinal natural products of potent antiviral activity should be screened for the cost-effective treatment of the disease. Furthermore, from natural products, active compounds against vital HCV proteins like non-structural protein 3 (NS3) protease could be identified to prevent viral proliferation in the host. AIM To develop cost-effective HCV genotype 3a NS3 protease inhibitors from citrus fruit extracts. METHODS Full-length NS3 without co-factor non-structural protein 4A (NS4A) and codon optimized NS3 protease in fusion with NS4A were expressed in Escherichia coli. The expressed protein was purified by metal ion affinity chromatography and gel filtration. Citrus fruit extracts were screened using fluorescence resonance energy transfer (FRET) assay against the protease and polyphenols were identified as potential inhibitors using electrospray ionization-mass spectrometry (MS)/MS technique. Among different polyphenols, highly potent compounds were screened using molecular modeling approaches and consequently the most active compound was further evaluated against HCV NS4A-NS3 protease domain using FRET assay. RESULTS NS4A fused with NS3 protease domain gene was overexpressed and the purified protein yield was high in comparison to the lower yield of the full-length NS3 protein. Furthermore, in enzyme kinetic studies, NS4A fused with NS3 protease proved to be functionally active compared to full-length NS3. So it was concluded that co-factor NS4A fusion is essential for the purification of functionally active protease. FRET assay was developed and validated by the half maximal inhibitory concentration (IC50) values of commercially available inhibitors. Screening of citrus fruit extracts against the native purified fused NS4A-NS3 protease domain showed that the grapefruit mesocarp extract exhibits the highest percentage inhibition 91% of protease activity. Among the compounds identified by LCMS analysis, hesperidin showed strong binding affinity with the protease catalytic triad having S-score value of -10.98. CONCLUSION Fused NS4A-NS3 protease is functionally more active, which is effectively inhibited by hesperidin from the grapefruit mesocarp extract with an IC50 value of 23.32 µmol/L.
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Affiliation(s)
- Mahim Khan
- Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering College, Pakistan Institute of Engineering and Applied Sciences (NIBGE-C, PIEAS), Faisalabad 38000, Punjab, Pakistan
| | - Waqar Rauf
- Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering College, Pakistan Institute of Engineering and Applied Sciences (NIBGE-C, PIEAS), Faisalabad 38000, Punjab, Pakistan
| | - Fazal-E- Habib
- Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering College, Pakistan Institute of Engineering and Applied Sciences (NIBGE-C, PIEAS), Faisalabad 38000, Punjab, Pakistan
| | - Moazur Rahman
- Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering College, Pakistan Institute of Engineering and Applied Sciences (NIBGE-C, PIEAS), Faisalabad 38000, Punjab, Pakistan
| | - Mazhar Iqbal
- Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering College, Pakistan Institute of Engineering and Applied Sciences (NIBGE-C, PIEAS), Faisalabad 38000, Punjab, Pakistan.
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