Virologica Sinica www.virosin.org https://doi.org/10.1007/s12250-020-00274-7 www.springer.com/12250 (0123456789().,-volV)(0123456789().,-volV) RESEARCH ARTICLE Identification of Aristolactam Derivatives That Act as Inhibitors of Human Immunodeficiency Virus Type 1 Infection and Replication by Targeting Tat-Mediated Viral Transcription 1 2 2 1 2 1 YoungHyun Shin • Chul Min Park • Hong Gi Kim • Dong-Eun Kim • Min Suk Choi • Jeong-ah Kim • 1 1 Byeong-Sun Choi • Cheol-Hee Yoon Received: 15 May 2020 / Accepted: 28 June 2020 Ó Wuhan Institute of Virology, CAS 2020 Abstract Despite the success of antiretroviral therapy (ART), efforts to develop new classes of antiviral agents have been hampered by the emergence of drug resistance. Dibenzo-indole-bearing aristolactams are compounds that have been isolated from various plants species and which show several clinically relevant effects, including anti-inflammatory, antiplatelet, and anti- mycobacterial actions. However, the effect of these compounds on human immunodeficiency virus type 1 (HIV-1) infection has not yet been studied. In this study, we discovered an aristolactam derivative bearing dibenzo[cd,f]indol-4(5H)-one that had a potent anti-HIV-1 effect. A structure-activity relationship (SAR) study using nine synthetic derivatives of aristolactam identified the differing effects of residue substitutions on the inhibition of HIV-1 infection and cell viability. Among the compounds tested, 1,2,8,9-tetramethoxy-5-(2-(piperidin-1-yl)ethyl)-dibenzo[cd,f]indol-4(5H)-one (Compound 2) exhibited the most potent activity by inhibiting HIV-1 infection with a half-maximal inhibitory concentration (IC50) of 1.03 lmol/L and a half-maximal cytotoxic concentration (CC50) of 16.91 lmol/L (selectivity index, 16.45). The inhibitory effect of the compounds on HIV-1 infection was linked to inhibition of the viral replication cycle. Mode-of-action studies showed that the aristolactam derivatives did not affect reverse transcription or integration; instead, they specifically inhibited Tat-mediated viral transcription. Taken together, these findings show that several aristolactam derivatives impaired HIV-1 infection by inhibiting the activity of Tat-mediated viral transcription, and suggest that these derivatives could be antiviral drug candidates. Keywords Human immunodeficiency virus type 1 (HIV-1) Á Aristolactam Á Antiviral activity Á HIV-1 transcription Introduction with highly active antiretroviral therapy (HAART) main- tains viral levels below the level of detection and extends a Human immunodeficiency virus type 1 (HIV-1) is the patient’s lifespan, these treatments are limited by increas- major causative agent of acquired immunodeficiency syn- ingly frequent drug-resistant mutations, adverse side drome (AIDS) (Mitsuya et al. 1985). Although treatment effects, and the high cost of long-term HAART (Gibson et al. 2019; Margolis et al. 2014). In addition, latent reservoirs of HIV-1-infected cells can persist in a patient, YoungHyun Shin and Chul Min Park have contributed equally to this which prevents clearance of the virus even during HAART work. (Churchill et al. 2016). Therefore, efforts are under way to develop new agents that target key steps in the HIV-1 life & Cheol-Hee Yoon cycle. [email protected] Numerous naturally derived products have been sug- 1 Division of Viral Disease Research, Center for Infectious gested as inhibitors of HIV-1 infection, including calano- Disease Research, Korea National Institute of Health, lides (reverse transcriptase (RT) inhibitors), kuwanon-L Heungdeok-gu, Cheongju-si, Chungbuk 28159, Republic of (an RT and integrase (IN) inhibitor), patentiflorin A (an RT Korea and IN inhibitor), and betulinic acid (a viral maturation 2 Center for Convergent Research of Emerging Virus Infection, inhibitor) (Cary and Peterlin 2018). Despite the high Korea Research Institute of Chemical Technology, Yuseong-gu, Daejeon 34114, Republic of Korea potency of these natural products against HIV-1, their use 123 Virologica Sinica as therapeutics could be restricted due to the difficulty of derivatives was identified as inhibition of Tat-mediated high-yield purification or large-scale synthesis. In the field viral transcription rather than inhibition of viral reverse of synthetic organic chemistry, unique structure-bearing transcription or integration. purine-based compounds, such as seliciclib (also called R-roscovitine or CYC202) (Agbottah et al. 2005), and several purine derivatives bearing aryl groups (Yuan et al. Materials and Methods 2007) are known to inhibit HIV-1 infection; therefore, to improve their anti-HIV-1 activity, derivatives of these Cells, Virus, and Reagents compounds have been explored. Some derivatives bearing an indole core (which is structurally similar to purine) have The inhibition of HIV-1 infection by aristolactam deriva- been investigated as anti-HIV-1 agents (Xu and Lv 2009). tives was tested in TZM-bl cells, which contain long ter- The benzodiazepine derivative (Ro 5-3335) containing minal repeat (LTR)-driven firefly luciferase and lacZ (b- benzene has been intensively investigated as a potent anti- galactosidase), and express human CD4, CXCR4, and HIV-1 agent (Hsu et al. 1991). Interestingly, both purine CCR5, in order to facilitate HIV-1 infection, as described and the benzene-based compounds described above have previously (Platt et al. 1998). bl-DTR (TZM-bl-derived been observed to impede HIV-1 infection by inhibiting dual Tat reporter) cells were generated from TZM-bl cells Tat-dependent viral transcription (Mousseau and Valente by transforming two doxycycline-inducible lentiviral 2012), which is a pivotal step in viral replication. There- expression cassettes encoding flag-tagged tat and Renila- fore, this step is considered to be a potential target for luciferase genes; these cells were then used to determine blocking HIV replication. As such, numerous studies have Tat-mediated HIV-1 transcriptional activity, as described attempted to identify Tat-dependent transcriptional inhibi- previously (Shin et al. 2017). TZM-bl and bl-DTR cells tors such as Durhamycin A (Jayasuriya et al. 2002), beta- were cultured in Dulbecco’s modified Eagle’s medium carboline derivatives (Yu et al. 2004) and Didehydro- supplemented with 1% penicillin–streptomycin and 10% Cortistatin A (dCA) (Mousseau et al. 2012) from naturally (v/v) heat-inactivated fetal bovine serum (all obtained from derived compounds. Although individual structures con- Gibco-BRL, Gaithersburg, MD, USA). The bl-DTR cells taining either indole or benzene substituents have anti- were additionally supplemented with 1 lg/mL puromycin HIV-1 effects, the potential anti-HIV-1 effects of com- and 200 lg/mL zeocin. Peripheral blood mononuclear cells pounds containing hybrid benzene–indole cores, such as (PBMCs) were purchased from AllCells (Alameda, CA, aristolactams, have not yet been investigated. USA) and cultured, as described previously (Yoon et al. Aristolactams bearing unique dibenzo-indole cores are 2015). HIV-1 clones pNL4-3 and AD8, as well as TZM-bl recognized as an important family of alkaloids due to their and A3.01 cells, were obtained from the National Institute potent biological activities, including anti-inflammatory, of Health’s AIDS Research and Reference Reagent Pro- antiplatelet, anti-mycobacterial, neuro-protective, and anti- gram (NIH, Bethesda, MD, USA). Organic chemical tumor effects. Aristolactams have been isolated from sev- compounds were provided by the Korea Research Institute eral plant species and used as traditional medicines (Chia of Chemical Technology (KRICT) (Choi et al. 2009). The et al. 2000; Kim et al. 2004; Kumar et al. 2003; Tsai chemicals were renamed as follows: (1-(2-(dimethy- et al. 2005; Zhang et al. 2007). Several aristolactam lamino)ethyl)-9-methoxybenzo[6,7]oxepino[4,3,2-cd]isoin- derivatives have been successfully synthesized, and some dol-2(1H)-one (ID 262860): 1,2,8,9-tetramethoxy-5-(2- of these have exhibited potent biological activity; Struc- (pyrrolidin-1-yl)ethyl)dibenzo[cd,f]indole-4(5H)-one \ Com- ture-activity relationship studies have explored the chem- pound 1 [ : 1,2,8,9- tetramethoxy-5-(2-(piperidin-1-yl)ethyl)- istry needed to attain specific biological activities in an dibenzo[cd,f]indole-4(5H)-one \ Compound 2 [: 5-(2-(diethy- effort to advance clinical applications (Bedini et al. 2005; lamino)ethyl)-tetramethoxydibenzo[cd,f]indole-4(5H)-one \ Choi et al. 2009; Reddy and Jeganmohan 2017; Yao and Compound 3 [ : 5-(2-(diethylamino)ethyl)-1,2-dimethoxy- Larock 2005). Despite the multi-potent activity of aristo- dibenzo[cd,f]indole-4(5H)-one \ Compound 4 [ : 1,2,9-tri- lactams, their potential anti-HIV-1 effects, including the methoxy-5-(2-(piperidin-1-yl)ethyl)dibenzo[cd,f]indole-4(5H) contribution of their unique structural feature—the -one \ Compound 5 [ : 1,2-dimethoxy-5-(2-piperidin-1- dibenzo-indole core—have not yet been elucidated. yl)ethyl)dibenzo[cd,f]indole-4(5H)-one \ Compound 6 [ : For the purposes of this study, we identified an aristo- 2-amino-5-(2-piperidin-1-yl)ethyl)dibenzo[cd,f]indole-4(5H)- lactam derivative from a synthetic organic compound one \ Compound 7 [ : 8-fluoro-1,2-dimethoxy-5-(2-piper- library that inhibited HIV-1 infection. The effect of sub- idin-1-yl)ethyl) dibenzo[cd,f]indole-4(5H)-one \ Compound stituting side chains on the aristolactam derivative on anti- 8[ : 8-cloro-1,2-dimethoxy-5-(2-piperidin-1-yl)ethyl) dibenzo- HIV-1 activity and cytotoxicity was investigated. In addi- [cd,f]indole-4(5H)-one \ Compound 9 [ . tion, the mode of anti-HIV-1 action of the aristolactam 123 Y. Shin et al.: Aristolactam Derivatives Inhibit HIV-1 Infection Seliciclib, azidothymidine (AZT), adefovir (ADV), ral- compounds was determined using a Bright Glo luciferase tegravir (RAL), and elvitegravir (ELV) were purchased assay kit (Promega). The infectivity data are presented as a from Sigma Aldrich (St. Louis, MO, USA). percentage relative to the DMSO control (vehicle). The inhibitory effects of the compounds on viral repli- Inhibition of HIV-1 Infection cation were determined, as described previously (Shin et al.