Aspartic peptidase of Phialophora verrucosa as target of HIV peptidase inhibitors: blockage of its enzymatic activity and interference with fungal growth and macrophage interaction.

Phialophora verrucosa causes several fungal human diseases, mainly chromoblastomycosis, which is extremely difficult to treat. Several studies have shown that human immunodeficiency virus peptidase inhibitors (HIV-PIs) are attractive candidates for antifungal therapies. This work focused on studying the action of HIV-PIs on peptidase activity secreted by P. verrucosa and their effects on fungal proliferation and macrophage interaction. We detected a peptidase activity from P. verrucosa able to cleave albumin, sensitive to pepstatin A and HIV-PIs, especially lopinavir, ritonavir and amprenavir, showing for the first time that this fungus secretes aspartic-type peptidase. Furthermore, lopinavir, ritonavir and nelfinavir reduced the fungal growth, causing remarkable ultrastructural alterations. Lopinavir and ritonavir also affected the conidia-macrophage adhesion and macrophage killing. Interestingly, P. verrucosa had its growth inhibited by ritonavir combined with either itraconazole or ketoconazole. Collectively, our results support the antifungal action of HIV-PIs and their relevance as a possible alternative therapy for fungal infections.

Synthetic Attempts Towards Eminent Anti-viral Candidates of SARS-CoV.

Severe Acute Respiratory Syndrome (SARS) aka SARS-CoV spread over southern China for the first time in 2002-2003 and history repeated again since last year and took away lives of more than two million people so far. On March 11, 2020 COVID-19 outbreak was officially declared as pandemic by World Health Organization (WHO). The entire world united to fight back against this ultimate destruction. Around 90 vaccines are featured against SARS-CoV-2 and more than 300 active clinical trials are underway by several groups and individuals. So far, no drugs have been currently approved that can completely eliminate the deadly coronavirus. The promising SARS-CoV-2 antiviral drugs are favipiravir, remdesivir, lopinavir, ribavirin and avifavir. In this review, we have discussed the synthetic approaches elaborately made so far by different groups and chemical companies all around the world towards top three convincing anti-viral drugs against SARS-CoV-2, which are favipiravir, remdesivir and lopinavir.

Site mapping and small molecule blind docking reveal a possible target site on the SARS-CoV-2 main protease dimer interface.

The SARS-CoV-2 virus is causing COVID-19 resulting in an ongoing pandemic with serious health, social, and economic implications. Much research is focused in repurposing or identifying new small molecules which may interact with viral or host-cell molecular targets. An important SARS-CoV-2 target is the main protease (Mpro), and the peptidomimetic α-ketoamides represent prototypical experimental inhibitors. The protease is characterised by the dimerization of two monomers each which contains the catalytic dyad defined by Cys145 and His41 residues (active site). Dimerization yields the functional homodimer. Here, our aim was to investigate small molecules, including lopinavir and ritonavir, α-ketoamide 13b, and ebselen, for their ability to interact with the Mpro. The sirtuin 1 agonist SRT1720 was also used in our analyses. Blind docking to each monomer individually indicated preferential binding of the ligands in the active site. Site-mapping of the dimeric protease indicated a highly reactive pocket in the dimerization region at the domain III apex. Blind docking consistently indicated a strong preference of ligand binding in domain III, away from the active site. Molecular dynamics simulations indicated that ligands docked both to the active site and in the dimerization region at the apex, formed relatively stable interactions. Overall, our findings do not obviate the superior potency with respect to inhibition of protease activity of covalently-linked inhibitors such as α-ketoamide 13b in the Mpro active site. Nevertheless, along with those from others, our findings highlight the importance of further characterisation of the Mpro active site and any potential allosteric sites.

Tuning HIV drug release from a nanogel-based in situ forming implant by changing nanogel size.

HIV is a global public health threat and requires life-long, daily oral dosing to effectively treat. This pill burden often results in poor adherence to the medications. An injectable in situ forming implant with tuneable drug release kinetics would allow patients to replace some of their daily pills with a single infrequent injection. In this work, we investigate how the size of poly(N-isopropylacrylamide) (polyNIPAm) nanogels influences the long-acting release behaviour of the HIV drug lopinavir from an in situ forming implant. Four sizes of polyNIPAm nanogels were prepared with mean diameters of 65, 160, 310 and 450 nm as characterised by dynamic light scattering. These nanogels all displayed synergistic dual stimuli responsive behaviour by aggregating only upon heating above 31 °C at physiological ionic strength. Mixing the nanogels with solid drug nanoparticles (SDNs) of lopinavir and exposing this concentrated dispersion to physiological temperature and ionic strength resulted in the in situ formation of nanocomposite implants. Three different loadings of the SDNs (33, 50 and 66% w/w) with each of the nanogels were prepared. The drug release behaviour and stability of these nanocomposite implants were then assessed in vitro over 360 hours. All samples displayed a single phase of drug release and application of the Ritger-Peppas equation indicated Fickian diffusion. Nanocomposites with the lowest loading of SDNs (33%) showed a linear relationship between nanogel diameter and the dissolution constant. These results show an attractive method for tuning the release of lopinavir from in situ loading implants with high drug loadings.