Anti-AIDS (acquired immune deficiency syndrome) agents. 17. New brominated hexahydroxybiphenyl derivatives as potent anti-HIV agents

Novel Pyrazole Acyl(thio)urea Derivatives Containing a Biphenyl Scaffold as Potential Succinate Dehydrogenase Inhibitors: Design, Synthesis, Fungicidal Activity, and SAR

As part of a program to discover novel succinate dehydrogenase inhibitor fungicides, a series of new pyrazole acyl(thio)urea compounds containing a diphenyl motif were designed and synthesized. Their structures were confirmed by 1H NMR, HRMS, and single X-ray crystal diffraction analysis. Most of these compounds possessed excellent activity against 10 fungal plant pathogens at 50 μg mL-1, especially against Rhizoctonia solani, Alternaria solani, Sclerotinia sclerotiorum, Botrytis cinerea, and Cercospora arachidicola. Interestingly, compounds 3-(difluoromethyl)-1-methyl-N-((3',4',5'-trifluoro-[1,1'-biphenyl]-2-yl)carbamoyl)-1H-pyrazole-4-carboxamide (9b, EC50 = 0.97 ± 0.18 μg mL-1), 1,3-dimethyl-N-((3',4',5'-trifluoro-[1,1'-biphenyl]-2-yl)carbamoyl)-1H-pyrazole-4-carboxamide (9a, EC50 = 2.63 ± 0.41 μg mL-1), and N-((4'-chloro-[1,1'-biphenyl]-2-yl)carbamoyl)-1,3-dimethyl-1H-pyrazole-4-carboxamide (9g, EC50 = 1.31 ± 0.15 μg mL-1) exhibited activities against S. sclerotiorum that were better than the commercial fungicide bixafen (EC50 = 9.15 ± 0.05 μg mL-1) and similar to the positive control fluxapyroxad (EC50 = 0.71 ± 0.11 μg mL-1). These compounds were not significantly phytotoxic to monocotyledonous and dicotyledonous plants. Structure-activity relationships (SAR) are discussed by substituent effects/molecular docking, and density functional theory analysis indicated that these compounds are succinate dehydrogenase inhibitors.

Thyroid and COVID-19: a review on pathophysiological, clinical and organizational aspects

BACKGROUND

Thyroid dysfunction has been observed in patients with COVID-19, and endocrinologists are requested to understand this clinical issue. Pandemic-related restrictions and reorganization of healthcare services may affect thyroid disease management.

OBJECTIVE AND METHODS

To analyze and discuss the relationship between COVID-19 and thyroid diseases from several perspectives. PubMed/MEDLINE, Google Scholar, Scopus, ClinicalTrial.gov were searched for this purpose by using free text words and medical subject headings as follows: "sars cov 2", "covid 19", "subacute thyroiditis", "atypical thyroiditis", "chronic thyroiditis", "hashimoto's thyroiditis", "graves' disease", "thyroid nodule", "differentiated thyroid cancer", "medullary thyroid cancer", "methimazole", "levothyroxine", "multikinase inhibitor", "remdesivir", "tocilizumab". Data were collected, analyzed, and discussed to answer the following clinical questions: "What evidence suggests that COVID-19 may induce detrimental consequences on thyroid function?"; "Could previous or concomitant thyroid diseases deteriorate the prognosis of COVID-19 once the infection has occurred?"; "Could medical management of thyroid diseases influence the clinical course of COVID-19?"; "Does medical management of COVID-19 interfere with thyroid function?"; "Are there defined strategies to better manage endocrine diseases despite restrictive measures and in-hospital and ambulatory activities reorganizations?".

RESULTS

SARS-CoV-2 may induce thyroid dysfunction that is usually reversible, including subclinical and atypical thyroiditis. Patients with baseline thyroid diseases are not at higher risk of contracting or transmitting SARS-CoV-2, and baseline thyroid dysfunction does not foster a worse progression of COVID-19. However, it is unclear whether low levels of free triiodothyronine, observed in seriously ill patients with COVID-19, may worsen the disease's clinical progression and, consequently, if triiodothyronine supplementation could be a tool for reducing this burden. Glucocorticoids and heparin may affect thyroid hormone secretion and measurement, respectively, leading to possible misdiagnosis of thyroid dysfunction in severe cases of COVID-19. High-risk thyroid nodules require a fine-needle aspiration without relevant delay, whereas other non-urgent diagnostic procedures and therapeutic interventions should be postponed.

DISCUSSION

Currently, we know that SARS-CoV-2 could lead to short-term and reversible thyroid dysfunction, but thyroid diseases seem not to affect the progression of COVID-19. Adequate management of patients with thyroid diseases remains essential during the pandemic, but it could be compromised because of healthcare service restrictions. Endocrine care centers should continuously recognize and classify priority cases for in-person visits and therapeutic procedures. Telemedicine may be a useful tool for managing patients not requiring in-person visits.

Antitumor agents. 293. Nontoxic dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylenedioxybiphenyl-2,2'-dicarboxylate (DDB) analogues chemosensitize multidrug-resistant cancer cells to clinical anticancer drugs

Novel dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylenedioxybiphenyl-2,2'-dicarboxylate (DDB) analogues were designed and synthesized to improve their chemosensitizing action on KBvin (vincristine-resistant nasopharyngeal carcinoma) cells, a multidrug resistant cell line overexpressing P-glycoprotein (P-gp). Structure-activity relationship analysis showed that aromatic and bulky aliphatic side chains at the 2,2'-positions effectively and significantly sensitized P-gp overexpressing multidrug resistant (MDR) cells to anticancer drugs, such as paclitaxel (TAX), vincristine (VCR), and doxorubicin (DOX). DDB derivatives 16 and 23 showed 5-10 times more effective reversal ability than verapamil (VRP) for TAX and VCR. Analogue 6 also exhibited five times greater chemosensitizing effect against DOX than VRP. Importantly, no cytotoxicity was observed by the active DDB analogues against both non-MDR and MDR cells, suggesting that DDB analogues serve as novel lead compounds for the development of chemosensitizers to overcome the MDR phenotype. The mechanism of action studies demonstrated that effective inhibition of P-glycoprotein by DDB analogues dramatically elevated the cellular concentration of anticancer drugs.

Cancer preventive agents 11. Novel analogs of dimethyl dicarboxylate biphenyl as potent cancer chemopreventive agents(†)

CONTEXT

Dimethyl dicarboxylate biphenyl (DDB) is a clinically used hepatoprotectant and has also been found to have chemopreventive activity.

MATERIALS AND METHODS

Sixteen novel analogs (5-20) were designed, synthesized, and evaluated for their cancer preventive activity. The 2,2'-bismethyl ester (5-18) and ether (19, 20) DDB analogs were synthesized by insertion of various linear alkyl, short fatty acid, polar, and aromatic groups. All synthesized analogs were evaluated in an in vitro short-term 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced Epstein Barr virus early antigen (EBA-EA) activation assay. Three of the most potent compounds were also tested for inhibitory effects on skin tumor promotion in an in vivo two-stage mouse-skin carcinogenesis test using 7,12-dimethylbenz[a]anthracene (DMBA) as an initiator and TPA as a promoter.

RESULTS

Compound 19 with bisprenyl ethers had the most significant cancer preventive activity (100% inhibition of activation at 1 × 10(3) mol ratio/TPA, 78.4%, 49.7%, and 10.9% inhibition at 5 × 10(2), 1 × 10(2), 1 × 10 mol ratio/TPA, respectively) in vitro. Compound 19 also exhibited a remarkable inhibitory effect on skin tumor promotion in the in vivo two-stage mouse-skin carcinogenesis test.

DISCUSSION AND CONCLUSIONS

Thus, DDB analog 19 could be a valuable candidate as a cancer preventive agent or as a lead for the development of new antitumor promoter drugs.

HIV-1 NNRTIs: structural diversity, pharmacophore similarity, and implications for drug design

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) nowadays represent very potent and most promising anti-AIDS agents that specifically target the HIV-1 reverse transcriptase (RT). However, the effectiveness of NNRTI drugs can be hampered by rapid emergence of drug-resistant viruses and severe side effects upon long-term use. Therefore, there is an urgent need to develop novel, highly potent NNRTIs with broad spectrum antiviral activity and improved pharmacokinetic properties, and more efficient strategies that facilitate and shorten the drug discovery process would be extremely beneficial. Fortunately, the structural diversity of NNRTIs provided a wide space for novel lead discovery, and the pharmacophore similarity of NNRTIs gave valuable hints for lead discovery and optimization. More importantly, with the continued efforts in the development of computational tools and increased crystallographic information on RT/NNRTI complexes, structure-based approaches using a combination of traditional medicinal chemistry, structural biology, and computational chemistry are being used increasingly in the design of NNRTIs. First, this review covers two decades of research and development for various NNRTI families based on their chemical scaffolds, and then describes the structural similarity of NNRTIs. We have attempted to assemble a comprehensive overview of the general approaches in NNRTI lead discovery and optimization reported in the literature during the last decade. The successful applications of medicinal chemistry strategies, crystallography, and computational tools for designing novel NNRTIs are highlighted. Future directions for research are also outlined.

Hydrolyzable tannins (chebulagic acid and punicalagin) target viral glycoprotein-glycosaminoglycan interactions to inhibit herpes simplex virus 1 entry and cell-to-cell spread

Herpes simplex virus 1 (HSV-1) is a common human pathogen that causes lifelong latent infection of sensory neurons. Non-nucleoside inhibitors that can limit HSV-1 recurrence are particularly useful in treating immunocompromised individuals or cases of emerging acyclovir-resistant strains of herpesvirus. We report that chebulagic acid (CHLA) and punicalagin (PUG), two hydrolyzable tannins isolated from the dried fruits of Terminalia chebula Retz. (Combretaceae), inhibit HSV-1 entry at noncytotoxic doses in A549 human lung cells. Experiments revealed that both tannins targeted and inactivated HSV-1 viral particles and could prevent binding, penetration, and cell-to-cell spread, as well as secondary infection. The antiviral effect from either of the tannins was not associated with induction of type I interferon-mediated responses, nor was pretreatment of the host cell protective against HSV-1. Their inhibitory activities targeted HSV-1 glycoproteins since both natural compounds were able to block polykaryocyte formation mediated by expression of recombinant viral glycoproteins involved in attachment and membrane fusion. Our results indicated that CHLA and PUG blocked interactions between cell surface glycosaminoglycans and HSV-1 glycoproteins. Furthermore, the antiviral activities from the two tannins were significantly diminished in mutant cell lines unable to produce heparan sulfate and chondroitin sulfate and could be rescued upon reconstitution of heparan sulfate biosynthesis. We suggest that the hydrolyzable tannins CHLA and PUG may be useful as competitors for glycosaminoglycans in the management of HSV-1 infections and that they may help reduce the risk for development of viral drug resistance during therapy with nucleoside analogues.

An improved method for the synthesis of gamma-DDB

A mild and efficient method for the synthesis gamma-DDB has been developed through anhydride-linker assisted intramolecular Ullmann reaction. Highly regioselective bromination of differentially protected gallate was realized by virtue of the introduction of NBS.

Discovery and development of natural product-derived chemotherapeutic agents based on a medicinal chemistry approach

Medicinal plants have long been an excellent source of pharmaceutical agents. Accordingly, the long-term objectives of the author's research program are to discover and design new chemotherapeutic agents based on plant-derived compound leads by using a medicinal chemistry approach, which is a combination of chemistry and biology. Different examples of promising bioactive natural products and their synthetic analogues, including sesquiterpene lactones, quassinoids, naphthoquinones, phenylquinolones, dithiophenediones, neo-tanshinlactone, tylophorine, suksdorfin, DCK, and DCP, will be presented with respect to their discovery and preclinical development as potential clinical trial candidates. Research approaches include bioactivity- or mechanism of action-directed isolation and characterization of active compounds, rational drug design-based modification and analogue synthesis, and structure-activity relationship and mechanism of action studies. Current clinical trial agents discovered by the Natural Products Research Laboratories, University of North Carolina, include bevirimat (dimethyl succinyl betulinic acid), which is now in phase IIb trials for treating AIDS. Bevirimat is also the first in a new class of HIV drug candidates called "maturation inhibitors". In addition, an etoposide analogue, GL-331, progressed to anticancer phase II clinical trials, and the curcumin analogue JC-9 is in phase II clinical trials for treating acne and in development for trials against prostate cancer. The discovery and development of these clinical trial candidates will also be discussed.

New developments in natural products-based anti-AIDS research

This review discusses anti-HIV natural products from several compound classes, including terpenoids, coumarins, alkaloids, polyphenols, tannins, and flavonoids. Natural products can provide novel anti-AIDS chemotherapeutic leads that are structurally unique or have new mechanisms of action. The drug discovery and development process proceeds from bioactivity-directed isolation and identification of a promising lead natural product, followed by rational design-based structural modification and structure-activity relationship analyses to optimize the lead compound as a drug candidate. This process is notably exemplified by the discovery of the modified betulinic acid derivative, DSB [PA-457], which is currently in Phase II clinical trial and is the first-in-class HIV maturation inhibitor (MI).

A solid-phase approach to DDB derivatives

Since the discovery of 2,2'-dimethoxycarbonyl-4,4-dimethoxy-5,6,5',6'-biomethylenedioxy-biphenyl (DDB) as a potent anti-HBV agent, we have studied the structure-activity relationships of 4,4'-dimethoxy-5,6,5',6'-dimethenedioxy-2-alkyloxycarbonyl-2'-(4-substituted benzyl piperazin-1-yl)carbonyl-biphenyl as anti-HBV agents. Therefore, it is rational to extend this study to the 3,3'-disustituted-4,4'-dimethoxy-5,6,5',6'-dimethenedioxy-2-alkyloxycarbonyl-2'-Serine derivatives. Thus, in an attempt to develop an efficient method for the preparation of a large number of DDB derivatives, the reaction between a DDB acid chloride and serine derivatives on solid support was studied. The structure of resulted compounds was confirmed by LC-MS and (1)H NMR analysis. Compounds 2a, 2d, 2f, 2j showed in vitro anti-HBV activity without significant toxicity up to 100 microM.

Enantiomer separation of dimethyl dicarboxy α-biphenyl (DDB) and its analogues on a covalently bonded cellulose tris-(3,5-dimethylphenyl-carbamate) CSP

Dimethyl dicarboxy alpha-biphenyl (DDB) and its analogues represent atropisomers which have been resolved on the covalently bonded cellulose tris-(3,5-dimethylphenylcarbamate) (CDMPC) CSP. Different kinds of alcohols, tetrahydrofuran (THF), and chloroform were employed as mobile phase modifiers (MPMs), and their influence on the retention and separation of the enantiomers was investigated. Ternary mobile phases (hexane/2-propanol/THF, hexane/2-propanol/chloroform) were employed to investigate the separation of the five enantiomers. The advantages of the broader choice of solvents offered by the covalently bonded CDMPC CSP were discussed. The effect of structural variation of the enantiomers on their retention and separation was investigated.

Efficient synthesis of γ -DDB

Synthesis of gamma-DDB, which is another family member of gamma-DDB (dimethyl 4,4(')-dimethoxy-5,6,5('),6(')- dimethylenedioxybiphenyl-2,2(')-dicarboxylate), is described. The unsymmetric isomer (gamma-DDB) was constructed by a linker-directed intramolecular Ullmann coupling reaction, followed by the cleavage of the linker and re-esterification.

Anti-AIDS agents--XXVI. Structure-activity correlations of gomisin-G-related anti-HIV lignans from Kadsura interior and of related synthetic analogues

Bioactivity-directed fractionation of an ethanolic extract of the stems of Kadsura interior led to the isolation and identification of 12 known lignans (1-12). Seven of these compounds (1, 6, 8-12) were active as anti-HIV agents. Gomisin-G (11) exhibited the most potent anti-HIV activity with EC50 and therapeutic index (TI) values of 0.006 microgram/mL and 300, respectively. Schisantherin-D (6), kadsuranin (8), and schisandrin-C (10) showed good activity with EC50 values of 0.5, 0.8, and 1.2 micrograms/mL, and TI values of 110, 56, and 33.3, respectively. Ten related synthetic biphenyl compounds, five variously substituted bismethylenedioxy, dimethoxy, and dimethoxycarbonyl isomers (18-22) and five brominated derivatives (23-27) also were evaluated for inhibitory activity against HIV-1 replication in acutely infected H9 cells. The total syntheses of two new isomers (21 and 22) are reported for the first time. The anti-HIV data indicated that the relative position and types of substituents on the phenolic hydroxy groups of either the natural lignans or the synthetic biphenyl compounds rather than the numbers of bromine(s) on the aromatic rings are of primary importance. In the cyclooctane ring of the natural lignans, the position and substitution of hydroxy groups are also important to enhanced anti-HIV activity.

Galloyl-Derived Orthoquinones as Reactive Partners in Nucleophilic Additions and Diels-Alder Dimerizations: A Novel Route to the Dehydrodigalloyl Linker Unit of Agrimoniin-Type Ellagitannins

Orthochloranil-mediated oxidation of galloyl monoethers furnishes the derived orthoquinones in excellent yield. These reactive electrophiles participate in a variety of nucleophilic addition reactions with heteroatomic and carbanionic partners. In addition, Lewis acid-mediated dimerization of the orthoquinones provides an efficient route to dehydrodigalloyl-type diaryl ether units characteristic of several ellagitannin natural products. The implications for ellagitannin biosynthesis and gallotannin-protein covalent attachment are discussed.