Design, synthesis, and biological evaluation of novel trifluoromethyl indoles as potent HIV-1 NNRTIs with an improved drug resistance profile

Applications of intelligent technology in the evaluation of mutagenicity

Bioassays are widely used in assessment of mutagenicity. Alternative methods have also been developed, including "intelligent evaluation", which depends on the quality of data, strategies, and techniques. CISOC-PSMT is an Ames test prediction system. The strategies and techniques for intelligent evaluation and four applications of CISOC-PSMT are presented; roles in pesticide management, environmental protection, drug discovery, and safety management of chemicals are introduced.

Catalyst-free C(sp3)-H functionalization of methyl azaarenes with heteroaromatic trifluoromethyl ketone hydrates: "all-water" synthesis of α-trifluoromethyl tertiary alcohols

An efficient catalyst-free C(sp³)-H bond functionalization of methyl azaarenes with heteroaromatic trifluoromethyl ketone hydrates in neat water has been developed for the synthesis of α-trifluoromethyl tertiary alcohols bearing N-heteroaromatics. This method not only features excellent efficiency, broad substrate scope, catalyst-free conditions, and easy gram-scale preparation but also represents a new and rare example of "all-water" synthesis of trifluoromethylated molecules.

Design, Catalyst-Free Synthesis of New Novel α-Trifluoromethylated Tertiary Alcohols Bearing Coumarins as Potential Antifungal Agents

A new method for the synthesis of α-trifluoromethylated tertiary alcohols bearing coumarins is described. The reaction of 3-(trifluoroacetyl)coumarin and pyrrole provided the target compounds with high yields under catalyst-free, mild conditions. The crystal structure of compound 3fa was investigated by X-ray diffraction analysis. The biological activities, such as in vitro antifungal activity of the α-trifluoromethylated tertiary alcohols against Fusarium graminearum, Fusarium oxysporum, Fusarium moniliforme, Rhizoctonia solani Kuhn, and Phytophthora parasitica var nicotianae, were investigated. The bioassay results indicated that compounds 3ad, 3gd, and 3hd showed broad-spectrum antifungal activity in vitro. Compound 3cd exhibited excellent fungicidal activity against Rhizoctonia solani Kuhn, with an EC₅₀ value of 10.9 μg/mL, which was comparable to that of commercial fungicidal triadimefon (EC₅₀ = 6.1 μg/mL). Furthermore, molecular docking study suggested that 3cd had high binding affinities with 1W9U, like argifin.

Recent Advances in the Catalytic Asymmetric Friedel-Crafts Reactions of Indoles

Functionalized chiral indole derivatives are privileged and versatile organic frameworks encountered in numerous pharmaceutically active agents and biologically active natural products. The catalytic asymmetric Friedel-Crafts reaction of indoles, catalyzed by chiral metal complexes or chiral organocatalysts, is one of the most powerful and atom-economical approaches to access optically active indole derivatives. Consequently, a wide range of electrophilic partners including α,β-unsaturated ketones, esters, amides, imines, β,γ-unsaturated α-keto- and α-ketiminoesters, ketimines, nitroalkenes, and many others have been successfully employed to achieve a plethora of functionalized chiral indole moieties. In particular, strategies for C-H functionalization in the phenyl of indoles require incorporation of a directing or blocking group in the phenyl or azole ring of indole. The discovery of chiral catalysts which can control enantiodiscrimination has gained a great deal of attention in recent years. This review will provide an updated account on the application of the asymmetric Friedel-Crafts reaction of indoles in the synthesis of diverse chiral indole derivatives, covering the timeframe from 2011 to today.

An insight into the recent developments in anti-infective potential of indole and associated hybrids

Prevention, accurate diagnosis, and effective treatment of infections are the main challenges in the overall management of infectious diseases. The best example is the ongoing SARs-COV-2(COVID-19) pandemic; the entire world is extremely worried about at present. Interestingly, heterocyclic moieties provide an ideal scaffold on which suitable pharmacophores can be designed to construct novel drugs. Indoles are amongst the most essential class of heteroaromatics in medicinal chemistry, which are ubiquitous across natural sources. The aforesaid derivatives have become invaluable scaffolds because of their wide spectrum therapeutic applications. Therefore, many researchers are focused on the design and synthesis of indole and associated hybrids of biological relevance. Hence, in the present review, we concisely discuss the indole containing natural sources, marketed drugs, clinical candidates, and their biological activities like antibacterial, antifungal, anti-TB, antiviral, antimalarial, and anti-leishmanial activities. The structure-activity relationships study of indole derivatives is also presented for a better understanding of the identified structures. The literature data presented for the anti-infective agents herein covers largely for the last twelve years.

Visible Light-induced Phosphine-Catalyzed Perfluoroalkylation of Indoles

A photo-induced, catalytic phosphine-promoted perfluoroalkylation reaction of indole molecules is developed. Inexpensive and readily available PPh3 is used in a catalytic amount as the sole reaction initiator in this protocol....

Biological macromolecule binding and anticancer activity of synthetic alkyne-containing L-phenylalanine derivatives

Herein, we described the synthesis of two L-phenylalanines α-derivatized with a terminal alkyne moiety whose structures differed by phenyl ring halogen substitution (two o-Cl in 1 vs. one p-Br in 2) and investigated their effect on biological macromolecules and living cells. We explored their interaction with quadruplex DNA (G4 DNA), using tel₂₆ and c-myc as models, and bovine serum albumin (BSA). By CD spectroscopy, we found that 1 caused minor tel26 secondary structure changes, leading also to a slight thermal stabilization of this hybrid antiparallel/parallel G4 structure, while the c-myc parallel topology remained essentially unchanged upon 1 binding. Other CD evidences showed the ability of 1 to bind BSA, while molecular docking studies suggested that the same molecule could be housed into the hydrophobic cavity between sub-domains IIA, IIB, and IIIA of the protein. Furthermore, preliminary aggregation studies, based on concentration-dependent spectroscopic experiments, suggested the ability of 1 to aggregate forming noncovalent polymeric systems in aqueous solution. Differently from 1, the bromine-modified compound was able to bind Cu(II) ion, likely with the formation of a CuL₂ complex, as found by UV spectroscopy. Finally, cell tests excluded any cytotoxic effect of both compounds toward normal cells, but showed slight antiproliferative effects of 2 on PC3 cancerous cells at 24 h, and of 1 on both T98G and MDA-MB-231 cancer cells at 48 h.

Reaction of indoles with aromatic fluoromethyl ketones: an efficient synthesis of trifluoromethyl(indolyl)phenylmethanols using K2CO3/n-Bu4PBr in water

A new, mild and efficient protocol for the synthesis of trifluoromethyl(indolyl)phenylmethanols by the reaction of indoles with a variety of aromatic fluoromethyl ketones in the presence of K₂CO₃ (15 mol %) and n-Bu₄PBr (15 mol %) in water. The desired products were obtained in good to excellent yields without requiring a column chromatographic purification. The reusability of the catalytic system and large-scale synthesis of indolyl(phenyl)methanols, which would further transform into biological active indole-derived compounds, are further advantages of this protocol.

Brønsted Acid-Catalyzed Asymmetric Friedel-Crafts Alkylation of Indoles with Benzothiazole-Bearing Trifluoromethyl Ketone Hydrates

An efficient Brønsted acid-catalyzed asymmetric Friedel-Crafts alkylation of indoles with benzothiazole-bearing trifluoromethyl ketone hydrates as electrophiles has been developed. The mild organocatalytic reactions proceeded well with low catalyst loading to afford a range of enantioenriched α-trifluoromethyl tertiary alcohols containing both benzothiazole and indole rings with excellent yields and enantioselectivities.

Spectroscopic and SEM evidences for G4-DNA binding by a synthetic alkyne-containing amino acid with anticancer activity

Herein, we present a spectroscopic (CD and UV) and SEM study of a phenylalanine derivative carrying a terminal alkyne moiety and indicated by us CF3IIIPhe, with particular attention to its interaction with Cu(II) cation and some biological macromolecules, as well as a preliminary evaluation of its effect on cancerous cells. CD spectroscopy evidenced the ability of CF3IIIPhe to interact with tel₂₆ and c-myc, two quadruplex DNA (G4 DNA) models explored in this study. Other CD and UV studies revealed the ability of the unnatural amino acid to form aggregates in aqueous solution, to bind Cu(II) cation, and to interact with bovine serum albumin (BSA). Cellular studies demonstrated CF3IIIPhe antiproliferative activity on PC3 cells. Its ability to bind telomeric DNA was verified with tel₂₆ by CD investigation and SEM analysis, that revealed a noteworthy change in DNA morphology (mainly based on nanosphere structures) by CF3IIIPhe, confirming its G4-DNA binding ability already evidenced by spectroscopy.

Simplification of Natural β-Carboline Alkaloids to Obtain Indole Derivatives as Potent Fungicides against Rice Sheath Blight

The increasing resistance of rice sheath blight caused by Rhizoctonia solani highlights the need for highly effective and environmentally benign agents. Natural β-carboline alkaloids were simplified to obtain a series of indole derivatives, and their fungicidal activity and preliminary mode of action against R. solani were also evaluated. The initial hit indole (7) displayed significant fungicidal activity with an EC₅₀ value of 25.56 μg/mL, and was selected for further optimization. Importantly, compound 55, the most active compound, had an EC₅₀ value of 0.62 μg/mL, and approximately 300-fold more potent than validamycin A (EC₅₀ = 183.00 μg/mL). In vivo bioassay also demonstrated that compound 55 showed better fungicidal activities than validamycin A. Moreover, the mechanism studies revealed that compound 55 not only caused remarkable morphological and structural alterations of R. solani hyphae, but also induced the loss of mitochondrial membrane potential and interfered with DNA synthesis. Therefore, compound 55 showed superior fungicidal activity against R. solani, and the elucidated mode of action supported the potential application of compound 55 against rice sheath blight.

An insight into the medicinal perspective of synthetic analogs of indole: A review

Heterocycles occupy a salient place in chemistry due to their wide range of activity in the fields of drug design, photochemistry, agrochemicals, dyes, and so on. Amongst all, indole scaffold is considered as one of the most promising heterocycles found in natural and synthetic sources and has been shown to possess various biological activity, including anti-inflammatory, anti-HIV, antitubercular, antimalarial, anticonvulsant, antidiabetic, antihypertensive, analgesics, antidepressant, anticancer, antioxidant, antifungal, and antimicrobial, etc. All the reported indole molecules bind to multiple receptors with high affinity, thus expedite the research on the development of novel biologically active compounds through the various approach. In this review, we aimed to highlight synthetic and medicinal perspective on the development of indole-based analogs. In addition, structural activity relationship (SAR) study to correlate for their biological activity also discussed.

Medicinal chemistry of indole derivatives: Current to future therapeutic prospectives

Indole is a versatile pharmacophore, a privileged scaffold and an outstanding heterocyclic compound with wide ranges of pharmacological activities due to different mechanisms of action. It is an superlative moiety in drug discovery with the sole property of resembling different structures of the protein. Plenty of research has been taking place in recent years to synthesize and explore the various therapeutic prospectives of this moiety. This review summarizes some of the recent effective chemical synthesis (2014-2018) for indole ring. This review also emphasized on the structure-activity relationship (SAR) to reveal the active pharmacophores of various indole analogues accountable for anticancer, anticonvulsant, antimicrobial, antitubercular, antimalarial, antiviral, antidiabetic and other miscellaneous activities which have been investigated in the last five years. The precise features with motives and framework of each research topic is introduced for helping the medicinal chemists to understand the perspective of the context in a better way. This review will definitely offer the platform for researchers to strategically design diverse novel indole derivatives having different promising pharmacological activities with reduced toxicity and side effects.

Recent Advances in the Design and Development of Non-nucleoside Reverse Transcriptase Inhibitor Scaffolds

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) have always been an important part of the anti-HIV-1 combination therapy known as combination antiretroviral therapy (cART) since 1996. The use of NNRTIs for about 22 years has led to some mutations in the residues that compose the reverse transcriptase active site, resulting in the emergence of drug-resistant viruses. Thus, the search for new potent NNRTIs with an improved safety profile and activity against drug-resistant HIV strains is indispensable, and many hit and lead NNRTIs have been discovered in the last decade. This review provides an overview of the development in this field from 2013 to August 2018.

Synthesis and Evaluation of N-(3-Trifluoroacetyl-indol-7-yl) Acetamides for Potential In Vitro Antiplasmodial Properties

A series of novel N-((2,5-diaryl-3-trifluoroacetyl)-1H-indol-7-yl)acetamides has been prepared via a successive and one-pot reaction sequence involving initial trifluoroacetic acid-mediated Beckmann rearrangement of the oximes derived from the 1-(2,5-diaryl-1H-indol-7-yl)ethanones, followed by trifluoroacetylation of the incipient N-(2,5-diaryl-1H-indol-7-yl)-acetamides with trifluoroacetic anhydride. The prepared compounds were evaluated for potential in vitro antiplasmodial properties. Preliminary results from antiplasmodial activity against the chloroquine-sensitive 3D7 strain of Plasmodium falciparum revealed that a combination of 2-(4-flurophenyl)- and 5-(4-fluorophenyl) or 2-(4-flurophenyl)- and 4-fluorostyryl groups in compounds 3(a,f) and 4(a,g), for example, is required for biological activity for both series of compounds. Their possible mode of action against the plasmodial parasite is explained theoretically through molecular docking of the most active compounds against the parasite lactate dehydrogenase (pLDH). These compounds were docked at the entrance of NAD+ in pLDH presumably hindering entry of lactate to cause the observed inhibition effect of pLDH. The four compounds were found to exhibit low toxicity against monkey kidney Vero cells at the highest concentrations tested.

Substituted indoles as HIV-1 non-nucleoside reverse transcriptase inhibitors: a patent evaluation (WO2015044928)

The invention described in this patent (WO2015044928) is related to compounds based on the substituted indole scaffold, their synthetic process and application to inhibit HIV-1 replication as non-nucleoside reverse transcriptase inhibitors (NNRTIs). Some of the newly claimed compounds presented improved potency against wild-type (WT) HIV-1 strain in comparison to previously disclosed indole-based NNRTIs and were also shown to be effective against common resistant HIV-1 strains. In light of their novel structural characteristics, simple synthetic route and improved anti-HIV activity, these compounds deserve further study as promising NNRTIs.

Synthesis and SARs of indole-based α-amino acids as potent HIV-1 non-nucleoside reverse transcriptase inhibitors

A series of non-nucleoside reverse transcriptase inhibitors derived from indole-based α-amino acids were designed and synthesized. Their inhibitory activities were detected by a TZM-bl cell assay on HIV virus type HIV-1IIIB. The comprehensive understanding of the SAR was obtained by utilizing the variation of the substituents of the indole-based α-amino acids. From the screened compounds, the novel inhibitors 19 and 29 were identified to be highly potent candidates with EC50 values of 0.060 μM and 0.045 μM respectively (CC50 values of 109.545 μM and 49.295 μM and SI values of 1825.8 and 1095.4). In most cases, the variation of substituents at different positions had a significant effect on the potency of activities. The results also indicate that the indole-based α-amino acids as efficient NNRTIs displayed comparable anti-HIV-1 activities to the reference drug NVP. We hope the identification of these indole-based amino acids as efficient NNRTIs of RT could stimulate researchers to develop more diversified anti-HIV drugs.