A helicase-primase drug candidate with sufficient target tissue exposure affects latent neural herpes simplex virus infections

Fluorescent octahydrophenazines as novel inhibitors against herpes simplex viruses

A new series of racemic fluorescent octahydrophenazines (rac-PZ1-11) have been designed and synthesized via the efficient nucleophilic aromatic substitution (SNAr) of tetrafluorobenzenedinitriles (1a-c) and racemic cyclohexane-1,2-diamines (rac-2a and b). The bioactivities of these racemic rac-PZs (20 μM) against herpes simplex virus type-1 (HSV-1) were evaluated by the relative cell viability of Vero cells infected with HSV-1. It was found that rac-PZ3 shows much higher anti-HSV-1 activity than others, with EC50 = 9.2 ± 1.4 μM. Further investigation into the anti-HSV activities of rac-PZ3 and its enantiomers RR- and SS-PZ3 indicates that rac-PZ3 can also efficiently inhibit HSV-2 and even ACV-resistant HSV-2 (EC50 = 11.0 ± 2.3 and 14.9 ± 2.8 μM, respectively), SS-PZ3 has better activities against HSV-1, HSV-2 and ACV-resistant HSV-2 (EC50 = 4.1 ± 1.1, 5.8 ± 1.0 and 7.9 ± 1.2 μM, respectively), but RR-PZ3 has almost no antiviral activities. The primary mechanism study indicates that rac-PZ3 efficiently reverses the HSV-1/2-induced cytopathic effect and suppresses the expression of viral mRNA and proteins. In addition, rac-, RR- and SS-PZ3 possess excellent fluorescence properties with almost the same emission wavelength and high fluorescence quantum yields (ΦF = 90.3-92.3 % in cyclohexane solutions and 54.4-57.3 % in solids) and can target endoplasmic reticulum and cell membrane. The efficient anti-HSV bioactivities and excellent fluorescence of PZ3 prove its potential applications in antiviral therapy and biological imaging.

Ultrathin organosiloxane membrane for precision organic solvent nanofiltration

Promising advances in membrane technology can lead to energy-saving and eco-friendly solutions in industrial sectors. This work demonstrates a highly selective membrane with ultrathin and highly interconnected organosiloxane polymer nanolayers by initiated chemical vapor deposition to effectively separate solutes within the molecular weight range of 150-300 g mol-1. We optimize the poly(1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane) membrane by adjusting both the thickness of the selective layer and the pore sizes of its support membranes. Notably, the 29 nm selective layer imparts a uniformly narrow molecular sieving property, providing a record-high solute-solute selectivity of 39.88 for different-sized solutes. Furthermore, a solute-solute selectivity of 11.04 was demonstrated using the real-world active pharmaceutical ingredient mixture of Acyclovir and Valacyclovir, key components for Herpes virus treatment, despite their molecular weight difference of less than 100 g mol-1. The highly interconnected membrane is expected to meet rigorous requirements for high-standard active pharmaceutical ingredient separation.

Herpes simplex keratitis: A brief clinical overview

The aim of our minireview is to provide a brief overview of the diagnosis, clinical aspects, treatment options, management, and current literature available regarding herpes simplex keratitis (HSK). This type of corneal viral infection is caused by the herpes simplex virus (HSV), which can affect several tissues, including the cornea. One significant aspect of HSK is its potential to cause recurrent episodes of inflammation and damage to the cornea. After the initial infection, the HSV can establish a latent infection in the trigeminal ganglion, a nerve cluster near the eye. The virus may remain dormant for extended periods. Periodic reactivation of the virus can occur, leading to recurrent episodes of HSK. Factors triggering reactivation include stress, illness, immunosuppression, or trauma. Recurrent episodes can manifest in different clinical patterns, ranging from mild epithelial involvement to more severe stromal or endothelial disease. The severity and frequency of recurrences vary among individuals. Severe cases of HSK, especially those involving the stroma and leading to scarring, can result in vision impairment or even blindness in extreme cases. The cornea's clarity is crucial for good vision, and scarring can compromise this, potentially leading to visual impairment. The management of HSK involves not only treating acute episodes but also implementing long-term strategies to prevent recurrences and attempt repairs of corneal nerve endings via neurotization. Antiviral medications, such as oral Acyclovir or topical Ganciclovir, may be prescribed for prophylaxis. The immune response to the virus can contribute to corneal damage. Inflammation, caused by the body's attempt to control the infection, may inadvertently harm the corneal tissues. Clinicians should be informed about triggers and advised on measures to minimize the risk of reactivation. In summary, the recurrent nature of HSK underscores the importance of both acute and long-term management strategies to preserve corneal health and maintain optimal visual function.

Asymmetric synthesis of sulfoximines, sulfonimidoyl fluorides and sulfonimidamides enabled by an enantiopure bifunctional S(VI) reagent

An increased interest to expand three-dimensional chemical space for the design of new materials and medicines has created a demand for isosteric replacement groups of commonly used molecular functionality. The structural and chemical properties of chiral S(VI) functional groups provide unique spatial and electronic features compared with their achiral sulfur- and carbon-based counterparts. Manipulation of the S(VI) centre to introduce structural variation with stereochemical control has remained a synthetic challenge. The stability of sulfonimidoyl fluorides and the efficiency of sulfur fluorine exchange chemistry has enabled the development of the enantiopure bifunctional S(VI) transfer reagent t-BuSF to overcome current synthetic limitations. Here, we disclose a reagent platform that serves as a chiral sulfur fluorine exchange template for the rapid asymmetric synthesis of over 70 sulfoximines, sulfonimidoyl fluorides and sulfonimidamides with excellent enantiomeric excess and good overall yields. Furthermore, the practical utility of the bifunctional S(VI) transfer reagent was demonstrated in the syntheses of enantiopure pharmaceutical intermediates and analogues.

Screening and verification of antiviral compounds against HSV-1 using a method based on a plaque inhibition assay

BACKGROUND

Herpes simplex virus type 1 (HSV-1) infection is a common viral disease that mainly causes oral lesions, but can also cause genital lesions in some instances. Current treatments with nucleoside analogs are limited by the emergence of drug resistance. Therefore, novel anti-HSV-1 drugs are urgently needed.

METHODS

In this study, we screened a library of 2080 compounds for anti-HSV-1 activity using a plaque formation assay. We selected 11 potential inhibitors of HSV-1 and further evaluated their antiviral effects by plaque reduction assay and real-time polymerase chain reaction (qPCR).

RESULTS

Five compounds, namely ginsenoside Rd, brassinolide, rosamultin, 3'-hydroxy puerarin, and clinafloxacin HCl, showed potent anti-HSV-1 activity and completely suppressed plaque formation at a concentration of 10 µM. Among them, clinafloxacin HCl, a fluoroquinolone antibiotic, exhibited a high selectivity index for HSV-1.

CONCLUSIONS

Our findings suggest that these five compounds have potential antiviral properties against HSV-1 and may have different mechanisms of action. Further studies are warranted to elucidate the antiviral mechanisms of these compounds and to explore their therapeutic potential for HSV-1 infection.

Intermittent therapy with helicase-primase inhibitor IM-250 efficiently controls recurrent herpes disease and reduces reactivation of latent HSV

Herpes is a contagious life-long infection with persistently high incidence and prevalence, causing significant disease worldwide. Current therapies have efficacy against active HSV infections but no impact on the latent viral reservoir in neurons. Thus, despite treatment, disease recurs from latency and the infectious potential remains unaffected within patients. Here, efficacy of the helicase-primase inhibitor (HPI) IM-250 against chronic neuronal HSV infections utilizing two classic herpes in vivo latency/reactivation animal models (intravaginal guinea pig HSV-2 infection model and ocular mouse HSV-1 infection model) is presented. Intermittent therapy of infected animals with 4-7 cycles of IM-250 during latency silences subsequent recurrences analyzed up to 6 months. In contrast to common experience, our studies show that the latent reservoir is indeed accessible to antiviral therapy altering the latent viral reservoir such that reactivation frequency can be reduced significantly by prior IM-250 treatment. We provide evidence that antiviral treatment during HSV latency can reduce future reactivation from the latent reservoir, supporting a conceptual shift in the antiviral field, and reframing what is achievable with respect to therapy of latent neuronal HSV infections.

The Impact of Antiviral Resistance on Herpetic Keratitis

ABSTRACT

Herpes simplex keratitis resistance to antiviral treatment presents a growing concern. The herpes simplex virus has many different mechanisms of resistance to antiviral treatment, which have been well described. Resistance to acyclovir occurs because of mutations in the viral thymidylate kinase and DNA polymerase that decrease this enzyme's affinity for its substrate. This article discusses factors that explain the prevalence of this resistance, the ability for recurrences in immunocompromised populations, current treatments for acyclovir-resistant herpes simplex keratitis, and novel therapies for this growing concern.

Synthesis of Sulfoximines and Sulfonimidamides Using Hypervalent Iodine Mediated NH Transfer

The development of NH transfer reactions using hypervalent iodine and simple sources of ammonia has facilitated the synthesis of sulfoximines and sulfonimidamides for applications across the chemical sciences. Perhaps most notably, the methods have been widely applied in medicinal chemistry and in the preparation of biologically active compounds, including in the large-scale preparation of an API intermediate. This review provides an overview of the development of these synthetic methods involving an intermediate iodonitrene since our initial report in 2016 on the conversion of sulfoxides into sulfoximines. This review covers the NH transfer to sulfoxides and sulfinamides, and the simultaneous NH/O transfer to sulfides and sulfenamides to form sulfoximines and sulfonimidamides, respectively. The mechanism of the reactions and the identification of key intermediates are discussed. Developments in the choice of reagents, and in the reaction conditions and setups used are described.

Synthesis of Sulfoximine Propargyl Carbamates under Improved Conditions for Rhodium Catalyzed Carbamate Transfer to Sulfoxides

Sulfoximines provide aza-analogues of sulfones, with potentially improved properties for medicinal chemistry. The sulfoximine nitrogen also provides an additional vector for the inclusion of other functionality. Here, we report improved conditions for rhodium catalyzed synthesis of sulfoximine (and sulfilimine) carbamates, especially for previously low-yielding carbamates containing π-functionality. Notably we report the preparation of propargyl sulfoximine carbamates to provide an alkyne as a potential click handle. Using Rh₂(esp)₂ as catalyst and a DOE optimization approach provided considerably increased yields.

Complete and Prolonged Inhibition of Herpes Simplex Virus Type 1 Infection In Vitro by CRISPR/Cas9 and CRISPR/CasX Systems

Almost all people become infected with herpes viruses, including herpes simplex virus type 1 (HSV-1), during their lifetime. Typically, these viruses persist in a latent form that is resistant to all available antiviral medications. Under certain conditions, such as immunosuppression, the latent forms reactivate and cause disease. Moreover, strains of herpesviruses that are drug-resistant have rapidly emerged. Therefore, it is important to develop alternative methods capable of eradicating herpesvirus infections. One promising direction is the development of CRISPR/Cas systems for the therapy of herpesvirus infections. We aimed to design a CRISPR/Cas system for relatively effective long-term and safe control of HSV-1 infection. Here, we show that plasmids encoding the CRISPR/Cas9 system from Streptococcus pyogenes with a single sgRNA targeting the UL30 gene can completely suppress HSV-1 infection of the Vero cell line within 6 days and provide substantial protection within 9 days. For the first time, we show that CRISPR/CasX from Deltaproteobacteria with a single guide RNA against UL30 almost completely suppresses HSV-1 infection of the Vero cell line for 3 days and provides substantial protection for 6 days. We also found that the Cas9 protein without sgRNAs attenuates HSV-1 infection. Our results show that the developed CRISPR/Cas systems are promising therapeutic approaches to control HSV-1 infections.

Discovery, Chemistry, and Preclinical Development of Pritelivir, a Novel Treatment Option for Acyclovir-Resistant Herpes Simplex Virus Infections

When the nucleoside analogue acyclovir was introduced in the early 1980s, it presented a game-changing treatment modality for herpes simplex virus infections. Since then, work has been ongoing to improve the weaknesses that have now been identified: a narrow time window for therapeutic success, resistance in immunocompromised patients, little influence on frequency of recurrences, relatively fast elimination, and poor bioavailability. The present Drug Annotation focuses on the helicase–primase inhibitor pritelivir currently in development for the treatment of acyclovir-resistant HSV infections and describes how a change of the molecular target (from viral DNA polymerase to the HSV helicase–primase complex) afforded improvement of the shortcomings of nucleoside analogs. Details are presented for the discovery process leading to the final drug candidate, the pivotal preclinical studies on mechanism of action and efficacy, and on how ongoing clinical research has been able to translate preclinical promises into clinical use.

Modular Two-Step Route to Sulfondiimidamides

Sulfur functional groups are common motifs in bioactive molecules. Sulfonamides are most prevalent but related aza-derivatives, in which oxygen atoms are replaced by imidic nitrogens, such as sulfoximines and sulfonimidamides, are gaining attraction. Despite this activity, the double aza-variants of sulfonamides, termed sulfondiimidamides, are almost completely absent from the literature. The reason for this is poor synthetic accessibility. Although a recent synthesis has established sulfondiimidamides as viable motifs, the length of the route and the capricious nature of the key sulfondiimidoyl fluoride intermediates mean that direct application to discovery chemistry is challenging. Herein, we describe a two-step synthesis of sulfondiimidamides, exploiting a hypervalent iodine-mediated amination as the key step. The starting materials are organometallic reagents, an unsymmetrical sulfurdiimide, and amines. The method allowed >40 examples to be prepared, including derivatives of three sulfonamide-based drugs. The operational simplicity, broad scope, and concise nature make this route attractive for discovery chemistry applications.

Comprehensive clinical and virological characterization of three cases of fulminant liver failure owing to HSV1 primary infection

Herpes simplex virus 1 (HSV-1) is a frequently unrecognized, yet deadly cause of acute liver failure (ALF). We, therefore, analysed three cases of fatal HSV-1-induced ALF. All patients shared clinical (extremely elevated transaminases, LDH and AST/LDH ratio < 1) and virological characteristics (ratio of viral load in plasma versus throat swabs: 60-700-fold, lack of anti-HSV-1-IgG antibodies or low IgG-avidity during primary infection), which may help to identify patients at risk. Additionally, in vitro chemosusceptibility assays revealed high efficacy of the helicase-primase inhibitors (HPI), pritelivir and drug-candidate IM-250 compared to acyclovir (ACV) using HSV-1-isolates from two patients; hence, ACV/HPI-combinations might offer new therapeutic options for HSV-induced ALF.

Stereospecific reaction of sulfonimidoyl fluorides with Grignard reagents for the synthesis of enantioenriched sulfoximines

Sulfonimidoyl halides have previously shown poor stability and selectivity in reaction with organometallic reagents. Here we report the preparation of enantioenriched sulfonimidoyl fluorides and their stereospecific reaction at sulfur with Grignard reagents. Notably the first enantioenriched alkyl sulfonimidoyl fluorides are prepared, including methyl. The nature of the N-group is important to the success of the stereocontrolled sequence to sulfoximines.

40 Years after the Registration of Acyclovir: Do We Need New Anti-Herpetic Drugs?

Herpes simplex virus types 1 and 2 HSV1 and 2, namely varicella-zoster VZV and cytomegalovirus CMV, are among the most common pathogens worldwide. They remain in the host body for life. The course of infection with these viruses is often asymptomatic or mild and self-limiting, but in immunocompromised patients, such as solid organ or bone marrow transplant recipients, the course can be very severe or even life-threatening. Unfortunately, in the latter group, the highest percentage of infections with strains resistant to routinely used drugs is observed. On the other hand, frequent recurrences of genital herpes can be a problem even in people with normal immunity. Genital herpes also increases the risk of acquiring sexually transmitted diseases, including HIV infection and, if present in pregnant women, poses a risk to the fetus and newborn. Even more frequently than herpes simplex, congenital infections can be caused by cytomegalovirus. We present the most important anti-herpesviral agents, the mechanisms of resistance to these drugs, and the associated mutations in the viral genome. Special emphasis was placed on newly introduced drugs such as maribavir and brincidofovir. We also briefly discuss the most promising substances in preclinical testing as well as immunotherapy options and vaccines currently in use and under investigation.

A Silyl Sulfinylamine Reagent Enables the Modular Synthesis of Sulfonimidamides via Primary Sulfinamides

A new N-silyl sulfinylamine reagent allows the rapid preparation of a broad range of (hetero)aryl, alkenyl, and alkyl primary sulfinamides, using Grignard, organolithium, or organozinc reagents to introduce the carbon fragment. Treatment of these primary sulfinamides with an amine in the presence of a hypervalent iodine reagent leads directly to NH-sulfonimidamides. This two-step sequence is straightforward to perform and provides a modular approach to sulfonimidamides, allowing ready variation of both reaction components, including primary and secondary amines.

Synthesis and Transformations of NH-Sulfoximines

Recent years have seen a marked increase in the occurrence of sulfoximines in the chemical sciences, often presented as valuable motifs for medicinal chemistry. This has been prompted by both pioneering works taking sulfoximine containing compounds into clinical trials and the concurrent development of powerful synthetic methods. This review covers recent developments in the synthesis of sulfoximines concentrating on developments since 2015. This includes extensive developments in both S-N and S-C bond formations. Flow chemistry processes for sulfoximine synthesis are also covered. Finally, subsequent transformations of sulfoximines, particularly in N-functionalization are reviewed, including N-S, N-P, N-C bond forming processes and cyclization reactions.

Helicase primase inhibitors (HPIs) are efficacious for therapy of human herpes simplex virus (HSV) disease in an infection mouse model

Although the seroprevalence of Herpes simplex virus type 1 (HSV-1) currently amounts to ∼ 67% worldwide, the annual incidence of a severe disease progression, particularly herpes encephalitis, is approximately 2-4 cases per 1,000,000 infections. Nucleoside analogues, such as acyclovir (ACV), valacyclovir (VACV) or famciclovir, are still the therapeutic treatment of choice for HSV infections. However, nucleoside drugs have limited efficacy against severe HSV disease and for treatment of nucleoside-resistant viral strains, alternative therapies such as helicase-primase inhibitors (HPIs) which are highly potent by inhibiting viral replication are under development. In preclinical studies we analyzed the antiviral efficacy of drug candidates of a novel compound class of HPIs for the treatment of HSV to identify the most active eutomer structure in an intranasal infection mouse lethal challenge model. HSV-1 infected BALB/c mice treated with vehicle control developed fatal disease according to humane endpoints after 5-7 days. In contrast, the animals dosed orally once daily with the HPI compounds at 10 or 4 mg/kg/day showed a significantly increased survival (70% and 100% for 10 mg/kg/day; 90% and 100% for 4 mg/kg/day, respectively) compared to the vehicle treatment (0-10%), when therapy was initiated 6 h post HSV-1 inoculation. We observed a significantly improved outcome in clinical parameters and survival over 21 days in the group receiving novel HPI candidates using even the lowest dose of 4 mg/kg/day. With VACV treatment of 75 mg/kg daily survival was also significantly increased (80%-90% for 75 mg/kg/day) but to lesser extent. Initial IM-250 therapy at 10 mg/kg/day could be delayed up to 72 h resulting in significantly increased survival compared to the vehicle control. Furthermore, we detected significantly fewer viral genome copies in the lungs and brains of HPI treated animals compared to vehicle (440-fold reduction for 4 mg/kg/day IM-250 in the brain) or VACV controls by quantitative PCR. In conclusion the preclinical studies of the novel HPI compounds showed superior efficacy in comparison to the current standard HSV treatment represented by VACV with respect to the survival according humane endpoints, the clinical score and virus load in lungs and brains. Thus, candidates of this new drug class are promising antivirals of HSV infections and further translation into clinical trials is warranted.

Overwhelming Evidence for a Major Role for Herpes Simplex Virus Type 1 (HSV1) in Alzheimer's Disease (AD); Underwhelming Evidence against

This review describes investigations of specific topics that lie within the general subject of HSV1's role in AD/dementia, published in the last couple of years. They include studies on the following: relationship of HSV1 to AD using neural stem cells; the apparent protective effects of treatment of HSV1 infection or of VZV infection with antivirals prior to the onset of dementia; the putative involvement of VZV in AD/dementia; the possible role of human herpes virus 6 (HHV6) in AD; the seemingly reduced risk of dementia after vaccination with diverse types of vaccine, and the association shown in some vaccine studies with reduced frequency of HSV1 reactivation; anti-HSV serum antibodies supporting the linkage of HSV1 in brain with AD in APOE-ε4 carriers, and the association between APOE and cognition, and association of APOE and infection with AD/dementia. The conclusions are that there is now overwhelming evidence for HSV1's role-probably causal-in AD, when it is present in brain of APOE-ε4 carriers, and that further investigations should be made on possible prevention of the disease by vaccination, or by prolonged antiviral treatment of HSV1 infection in APOE-ε4 carriers, before disease onset.