Introduction: Human papillomavirus (HPV) is a small, non-enveloped double-stranded circular DNA virus. The high risk types of HPV are claimed to be responsible for over 99% of cervical cancers while the most common oncogenic genotypes 16 and 18, implicated in approximately 70% of all cervical cancers. HPV has six early genes (E1, E2, E4, E5, E6 and E7) that code for regulatory proteins involved in viral DNA replication, transcription control and cellular transformation. The E7 protein is responsible for the escape from cell cycle arrest in HPV infected cells by binding to the retinoblastoma protein (pRB) through its LXCXE binding motif. This inhibits the tumour suppressor protein from regulating the cell cycle progression from G1 to S phase. In this study, the pocket domain of pRB which is targeted by LXCXE is used as a target to design peptide inhibitors using in silico methods. Methods: Biovia Discovery Studio Visualizer and UCSF Chimera softwares were used in designing the peptides. Results: Two crystal structures: 1GUX and 4YOZ were superimposed and studied. The similar amino acid sequences which bind to LXCXE were cut to form the potential peptide inhibitors. Based on this, peptide 1 was selected for further in vitro analysis. The cytotoxicity of the peptide 1 was analysed on three cell lines: CaSki (HPV16+ cervical cancer cell), C33a (cervical cancer cell), and HaCaT (normal keratinocyte). As a result, the IC50 of one of the designed peptide inhibitor – peptide 1, on CaSki cell line was 180 μM. The inhibitory effect of the peptide 1 was also analysed validated using Western Blot using antibodies from the B-Myb and pRB family. The changes in cell cycle before and after treatment of the peptide inhibitor will be further monitored using a cell analyser. Conclusion: Peptide 1 had shown potential as an inhibitor of the HPV E7 protein based on the in silico analysis, but further functional studies are needed to validate its potential.
Structure-based virtual screening (SBVS) has served as a popular strategy for rational drug discovery. In this study, we aimed to discover novel benzopyran-based inhibitors that targeted the NS3 enzymes (NS3/4A protease and NS3 helicase) of HCV G3 using a combination of in silico and in vitro approaches. With the aid of SBVS, six novel compounds were discovered to inhibit HCV G3 NS3/4A protease and two phytochemicals (ellagic acid and myricetin) were identified as dual-target inhibitors that inhibited both NS3/4A protease and NS3 helicase in vitro (IC50 = 40.37 ± 5.47 nm and 6.58 ± 0.99 µm, respectively). Inhibitory activities against the replication of HCV G3 replicons were further assessed in a cell-based system with four compounds showed dose-dependent inhibition. Compound P8 was determined to be the most potent compound from the cell-based assay with an EC50 of 19.05 µm. The dual-target inhibitor, ellagic acid, was determined as the second most potent (EC50 = 32.37 µm) and the most selective in its inhibitory activity against the replication of HCV replicons, without severely affecting the viability of the host cells (selectivity index > 6.18).
Dengvaxia® (CTD-TDV), the only licensed tetravalent dengue vaccine by Sanofi Pasteur, was made available since 2015. However, administration of CTD-TDV, in general, has not received the prequalification recommendation from the World Health Organization. Having a universal antidengue agent for treatment will therefore beneficial. Accordingly, the development of nucleoside inhibitors specific to dengue viral polymerase that perturb dengue infection has been studied by many. Alternatively, we have used a marketed anti-HCV prodrug sofosbuvir to study its in silico and in vitro effects against dengue. As a result, the active metabolite of sofosbuvir (GS-461203) was predicted to bind to the catalytic motif (Gly-Asp-Asp) of dengue viral polymerase with binding affinity of -6.9 kcal/mol. Furthermore, sofosbuvir demonstrated excellent in vitro viral inhibition with an EC90 of 0.4 μm. In addition, this study demonstrated the requirement of specific liver enzymes to activate the prodrug into GS-461203 to exert its antidengue potential. All in all, sofosbuvir should be subjected to in-depth studies to provide information of its efficacy toward dengue and its lead potential as DENV polymerase inhibitor in human subjects. In conclusion, we have expended the potential of the clinically available drug sofosbuvir as treatment for dengue.
To date, there is still no approved anti-dengue agent to treat dengue infection in the market. Although the only licensed dengue vaccine, Dengvaxia is available, its protective efficacy against serotypes 1 and 2 of dengue virus was reported to be lower than serotypes 3 and 4. Moreover, according to WHO, the risk of being hospitalized and having severe dengue increased in seronegative individuals after they received Dengvaxia vaccination. Nevertheless, various studies had been carried out in search of dengue virus inhibitors. These studies focused on the structural (C, prM, E) and non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B and NS5) of dengue virus as well as host factors as drug targets. Hence, this article provides an overall up-to-date review of the discovery of dengue virus inhibitors that are only targeting the structural and non-structural viral proteins as drug targets.
Staphylococcus aureus is a highly adaptable opportunistic pathogen that can form biofilms and generate persister cells, leading to life-threatening infections that are difficult to treat with antibiotics alone. Therefore, there is a need for an effective S. aureus biofilm inhibitor to combat this public health threat. In this study, a small library of indolenine-substituted pyrazoles and pyrimido[1,2-b]indazole derivatives were synthesised, of which the hit compound exhibited promising antibiofilm activities against methicillin-susceptible S. aureus (MSSA ATCC 29213) and methicillin-resistant S. aureus (MRSA ATCC 33591) at concentrations significantly lower than the planktonic growth inhibition. The hit compound could prevent biofilm formation and eradicate mature biofilms of MSSA and MRSA, with a minimum biofilm inhibitory concentration (MBIC50) value as low as 1.56 µg/mL and a minimum biofilm eradication concentration (MBEC50) value as low as 6.25 µg/mL. The minimum inhibitory concentration (MIC) values of the hit compound against MSSA and MRSA were 50 µg/mL and 25 µg/mL, respectively, while the minimum bactericidal concentration (MBC) values against MSSA and MRSA were > 100 µg/mL. Preliminary structure-activity relationship analysis reveals that the fused benzene ring and COOH group of the hit compound are crucial for the antibiofilm activity. Additionally, the compound was not cytotoxic to human alveolar A549 cells, thus highlighting its potential as a suitable candidate for further development as a S. aureus biofilm inhibitor.