New HIV-NNRTIs Lead Diarylanilines: Optimization And Evaluation Of Drug-like Properties

The human immunodeficiency virus (HIV) caused AIDS (Acquired Immune Deficiency Syndrome), which is an incurable disease. Although current anti-HIV drugs can inhibit HIV replication efficiently and prolong patients'life, the rapid appearance of drug resistance, high cost, and huge quantity greatly limited their clinical use. Therefore, it is necessary and urgent to find new drug with new structure scaffolds and new mechanism of action to overcome the problems of current anti-HIV drugs.NNRTIs (Non-nucleoside Reverse Transcriptase Inhibitors) non-competitively binding to an allosteric hydrophobic pocket adjacent to the substrate binding site of RT enzyme and result conformation alternation of RT, thus inhibiting the enzymatic function of RT. NNRTIs are indispensable component of highly active anti-retroviral therapy (HAART). So far, five NNRTI drugs (nevirapine, delavirdine, efavirine, etravirine, rilpivirine) have been approved for treating HIV-1 infection. Although the structures of the five drugs are diversity, they all bind to the same binging pocket of HIV-1 RT. As next-generation NNRTIs, new drugs Etravirine (TMC125, 2008) and rilpivirine (TMC278, 2011) showed very highly potency against wild-type and many drug resistant viral strains, such as K103N, Y181C and K103N/Y181C. Both TMC125 and TMC278 belong to diaryprimidine (DAPY) family compounds, and TMC278 is more potent than TMC125 against both wild and resistant HIV viral strains.In our previous studies, we have discovered a novel class of diarylanilines (DAANs) as new next-generation NNRTIs based on known biological information and NNRTI drug structures. As new leads, DAANs with a new structural scaffold that consist of three substituted phenyl moieties exhibited high potency against both wild-type and drug-resistant HIV viral strains. Previous SAR studies indicated that the presence of an ortho-amino group on the middle phenyl ring (B-ring) is very important for enhancing anti-HIV activity of DAANs. Molecular modeling results demonstrated that the amino group can serve as H-bond donor and acceptor to provide two hydrogen bonds with the main chain carbonyl group of key amino acid K101 and the side chain amino of K101 respectively. Additionally, the p-cyanophenyl (A-ring) and the linker NH between A-ring and B-ring are also necessary and essential structural moieties for anti-HIV activity.As a continue study, we currently structural optimization of new leads focused on the further improvement of molecular potency against HIV wild-type and drug-resistant viral strains and drug-like properties. We introduced different polar groups on the middle phenyl-ring (B-ring) and changed the para-substitutes on the tri-substituted phenyl-ring (C-ring). The former aimed at to improve molecular water-soluble and probably provide additional interaction points and the latter for introducing a suitable hydroohobic linear groups to interact with the high conserved amino acid residues W229 in the deep and narrow hydrophobic tunnel to enhance anti-HIV potency. Herein, we reported the design, synthesis and bioorganical evaluation of 20 new DAANs compounds. Their all structures were identified by 1HNMR and MS and all purities reached above 95% by HPLC, thus ensuring biodata reliable. Twenty new DAAN compounds were first tested against wild-type HIV viral strain (NL4-3) in the TZM-bl cell line and all exhibited obvious or significant high potency with an EC50 value range of <1-100 nM. Among them, new compounds 41, 43 and 49 exhibited extremely hign potencies with very low EC50 values of 0.53 nM,0.87 nM and 0.39 nM, respectively, which are more potent than TMC125 (1.5 nM) and comparable with TMC278 (0.52 nM), a very promising candidat in clinical trial III, in the same assays. Additionally, other 11 new compounds were also very potent with a low EC50 value range of 1-10 nM and rest 6 compounds showed EC50 values of less than 0.1μM. Next, some active compounds were evaluated against K101E and E138K mutated virus strains. The most potent compounds 43 and 49 still showed high potency with EC50 values of 4-9 nM comparable to TMC278 (~5 nM) in the same assay. These very promising results confirmed our previous SAR and supported current structural optimization strategy.Furthermore, water solubility of all new target compounds in pH 7.0 and 7.4 respectively, were evaluated, indicating that 43 and 49 are more soluble than TMC278 in above two conditions. Following, human liver microsome assay were performed to evaluate the metabolic stability of 10 new active compounds. However, quite different half-life values (32 -365 min) were observed, thus indicating that minor structural change might greatly affect molecular metabolic stability. The half-life time of high potent compounds 41, 43 and 49 are less than TMC278 (90 min) in the same assay.In summary, 20 of new active DAAN compounds were designed and synthesized successfully. New compounds 43 and 49 exhibited extremely high potency against both wild-type and mutanted HIV viral strains and improved water-solubility, which are comparable to or better than TMC278 in the same assays. Current promising results will greatly encourage us to further improve drug-like properties of active DAANs aimed at to determine new NNRTI drug candidate(s). More assays are underway.