Design,synthesis and biological evaluation of 3-benzyloxy-linked pyrimidinylphenylamine derivatives as potent HIV-1 NNRTIs

A novel series of 3-benzyloxy-linked pyrimidinylphenylamine derivatives (8a–8s) was designed, synthesized and evaluated for their in vitro anti-HIV activity in MT-4 cell cultures. Most of the compounds inhibited wild-type (wt) HIV-1 replication in the lower micromolar concentration range (EC₅₀ = 0.05–35 μM) with high selectivity index (SI) values (ranged from 10 to >4870). In particular, 8h and 8g displayed excellent antiretroviral activity against wt HIV-1 with low cytotoxicity (EC₅₀ = 0.07 μM, CC₅₀ >347 μM, SI >4870; EC₅₀ = 0.05 μM, CC₅₀ = 42 μM, SI = 777, respectively), comparable to that of the marked drug nevirapine (EC₅₀ = 0.113 μM, CC₅₀ >15 μM, SI >133). In order to confirm the binding target, 8h was selected to perform the anti-HIV-1 RT assay. Additionally, preliminary structure activity relationship (SAR) analysis and molecular docking studies of newly synthesized compounds were also discussed, as well as the predicted physicochemical properties.     

Design,synthesis and in vitro anti-mycobacterial evaluation of gatifloxacin-1H-1,2,3-triazole-isatin hybrids

A set of novel gatifloxacin-1H-1,2,3-triazole-isatin hybrids 6a-l was designed, synthesized and evaluated for their in vitro anti-mycobacterial activities against M. tuberculosis (MTB) H₃₇Rv and MDR-TB as well as cytotoxicity. The results showed that all the targets (MIC: 0.025–3.12 μg/mL) exhibited excellent inhibitory activity against MTB H₃₇Rv and MDR-TB, but were much more toxic (CC₅₀: 7.8–62.5 μg/mL) than the parent gatifloxacin (GTFX) (CC₅₀: 125 μg/mL). Among them, 61 (MIC: 0.025 μg/mL) was 2–32 times more potent in vitro than the references INH (MIC: 0.05 μg/mL), GTFX (MIC: 0.78 μg/mL) and RIF (MIC: 0.39 μg/mL) against MTB H₃₇Rv. The most active conjugate 6 k (MIC: 0.06 μg/mL) was 16–>2048 times more potent than the three references (MIC: 1.0–>128 μg/mL) against MDR-TB. Both of the two hybrids warrant further investigations.     

Synthesis and biological evaluation of novel 2-(substituted phenylaminocarbonylmethylthio)-6-(2,6-dichlorobenzyl)-pyrimidin-4(3H)-ones as potent HIV-1 NNRTIs

A series of novel 2-(phenylaminocarbonylmethylthio)-6-(2,6-dichlorobenzyl)-pyrimidin-4(3H)-ones have been designed and synthesized. All of the new compounds were evaluated for their anti-HIV activities in MT-4 cells. Most of these new compounds showed moderate to potent activities against wild-type HIV-1 with an EC₅₀ ranging from 4.48 μM to 0.18 μM. Among them, 2-[(4-bromophenylamino)carbonylmethylthio]-6-(2,6-dichlorobenzyl)-5-methylpyrimidin-4(3H)-one 4b3 was identified as the most promising compound (EC₅₀ = 0.18 ± 0.06 μM, CC₅₀ >243.56 μM, SI >1326). The structure–activity relationship (SAR) of these new congeners is discussed.     

Synthesis,activity, and pharmacokinetic properties of a series of conformationally-restricted thiourea analogs as novel hepatitis C virus inhibitors

A series of novel conformationally-restricted thiourea analogs were designed, synthesized, and evaluated for their anti-HCV activity. Herein we report the synthesis, structure–activity relationships (SARs), and pharmacokinetic properties of this new class of thiourea compounds that showed potent inhibitory activities against HCV in the cell-based subgenomic HCV replicon assay. Among compounds tested, the fluorene compound 4b was found to possess the most potent activity (EC₅₀ = 0.3 μM), lower cytotoxicity (CC₅₀ > 50 μM), and significantly better pharmacokinetic properties compared to its corresponding fluorenone compound 4c.     

Bacterial Peptide deformylase inhibition of cyano substituted biaryl analogs: Synthesis,in vitro biological evaluation,molecular docking study and in silico ADME prediction

Herein, we report the synthesis and screening of cyano substituted biaryl analogs 5(a–m) as Peptide deformylase (PDF) enzyme inhibitors. The compounds 5a (IC₅₀ value = 13.16 μM), 5d (IC₅₀ value = 15.66 μM) and 5j (IC₅₀ value = 19.16 μM) had shown good PDF inhibition activity. The compounds 5a (MIC range = 11.00–15.83 μg/mL), 5b (MIC range = 23.75–28.50 μg/mL) and 5j (MIC range = 7.66–16.91 μg/mL) had also shown potent antibacterial activity when compared with ciprofloxacin (MIC range = 25–50 μg/mL). Thus, the active derivatives were not only potent PDF inhibitors but also efficient antibacterial agents. In order to gain more insight on the binding mode of the compounds with PDF, the synthesized compounds 5(a–m) were docked against PDF enzyme of Escherichia coli and compounds exhibited good binding properties. In silico ADME properties of synthesized compounds were also analyzed and showed potential to develop as good oral drug candidates.     

Design,synthesis, antiviral and cytostatic activity of ω-(1H-1,2,3-triazol-1-yl)(polyhydroxy)alkylphosphonates as acyclic nucleotide analogues

The efficient synthesis of a new series of polyhydroxylated dibenzyl ω-(1H-1,2,3-triazol-1-yl)alkylphosphonates as acyclic nucleotide analogues is described starting from dibenzyl ω-azido(polyhydroxy)alkylphosphonates and selected alkynes under microwave irradiation. Selected O,O-dibenzylphosphonate acyclonucleotides were transformed into the respective phosphonic acids. All compounds were evaluated in vitro for activity against a broad variety of DNA and RNA viruses and for cytostatic activity against murine leukemia L1210, human T-lymphocyte CEM and human cervix carcinoma HeLa cells. Compound (1S,2S)-16b exhibited antiviral activity against Influenza A H3N2 subtype (EC₅₀ = 20 μM—visual CPE score; EC₅₀ = 18 μM—MTS method; MCC >100 μM, CC₅₀ >100 μM) in Madin Darby canine kidney cell cultures (MDCK), and (1S,2S)-16k was active against vesicular stomatitis virus and respiratory syncytial virus in HeLa cells (EC₅₀ = 9 and 12 μM, respectively). Moreover, compound (1R,2S)-16l showed activity against both herpes simplex viruses (HSV-1, HSV-2) in HEL cell cultures (EC₅₀ = 2.9 and 4 μM, respectively) and feline herpes virus in CRFK cells (EC₅₀ = 4 μM) but at the same time it exhibited cytotoxicity toward uninfected cell (MCC ⩾ 4 μM). Several other compounds have been found to inhibit proliferation of L1210, CEM as well as HeLa cells with IC₅₀ in the 4–50 μM range. Among them compounds (1S,2S)- and (1R,2S)-16l were the most active (IC₅₀ in the 4–7 μM range).     

Discovery of diphenylmethane analogs as anti-bovine diarrhea viral agents

Based on antiviral screening of our diphenylmethane derivatives prepared as steroid substitutes, we identified a 1,1-diphenylcyclobutane analog (9) and two diethyldiphenylsilane analogs (12 and 13) as superior lead compounds with potent anti-bovine viral diarrhea virus (BVDV) activity, having 50% effective concentration (EC₅₀: based on reduction of BVDV replication-induced cell destruction) and 50% cytotoxic concentration (CC₅₀: based on reduction of viable cell number) values of 6.2–8.4 μM and >100 μM, respectively, in Madin–Darby bovine kidney (MDBK) cells infected with BVDV.     

Design,synthesis, and docking studies of phenylpicolinamide derivatives bearing 1H-pyrrolo[2,3-b]pyridine moiety as c-Met inhibitors

Four series of phenylpicolinamide derivatives bearing 1H-pyrrolo[2,3-b]pyridine moiety (12a–e, 13a–f, 14a–f and 15a–i) were designed, synthesized and evaluated for the IC₅₀ values against three cancer cell lines (A549, PC-3 and MCF-7) and c-Met kinase. Five selected compounds (13b, 15b, 15d, 15e and 15f) were further evaluated for the activity against HepG2 and Hela cell lines. Eighteen of the compounds showed excellent cytotoxicity activity and selectivity with the IC₅₀ valuables in single-digit μM to nanomole range. Seven of them are equal to more active than positive control Foretinib against one or more cell lines. The most promising compound 15f showed superior activity to Foretinib, with the IC₅₀ values of 1.04 ± 0.11 μM, 0.02 ± 0.01 μM and 9.11 ± 0.55 μM against A549, PC-3 and MCF-7 cell lines, which were 0.62 to 19.5 times more active than Foretinib (IC₅₀ values: 0.64 ± 0.26 μM, 0.39 ± 0.11 μM, 9.47 ± 0.22 μM), respectively. Structure–activity relationships (SARs) and docking studies indicated that replacement of quinoline nucleus of the previous active compounds with 1H-pyrrolo[2,3-b]pyridine moiety maintained even improved the potent cytotoxic activity. The results suggested that the introduction of fluoro atoms to the aminophenoxy part of target compounds or the phenyl group of pyrimidine substituted on C-4 position was benefit for the activity.     

Derivatives (halogen,nitro and amino) of 8-hydroxyquinoline with highly potent antimicrobial and antioxidant activities

8-Hydroxyquinoline (8HQ) compounds have been reported to possess diverse bioactivities. In recent years, drug repositioning has gained considerable attention in drug discovery and development. Herein, 8HQ (1) and its derivatives (2–9) bearing various substituents (amino, nitro, cyano and halogen) were investigated for their antimicrobial against 27 microorganisms (agar dilution method) and antioxidant (DPPH method) activities. The parent 8HQ (1) exerted a highly potent antimicrobial activity against Gram-positive bacteria including diploid fungi and yeast with MIC values in the range of 3.44–13.78 μM. Moreover, the halogenated 8HQ, especially 7-bromo-8HQ (4) and clioquinol (6), displayed a high antigrowth activity against Gram-negative bacteria compared with the parent compound (1). Apparently, the derivatives with a relatively high safely index, e.g., nitroxoline (2), exhibited strong antibacterial activity against Aeromonas hydrophila (MIC=5.26 μM) and selectively inhibited the growth of P. aeruginosa with the MIC value of 84.14 μM; cloxyquin (3) showed a strong activity against Listseria monocytogenes and Plesiomonas shigelloides with MIC values of 5.57 and 11.14 μM, respectively. Most compounds displayed an antioxidant activity. Specifically, 5-amino-8HQ (8) was shown to be the most potent antioxidant (IC₅₀=8.70 μM) compared with the positive control (α-tocopherol) with IC₅₀ of 13.47 μM. The findings reveal that 8HQ derivatives are potential candidates to be further developed as antimicrobial and antioxidant agents.     

4′-Substituted pyrimidine nucleosides lacking 5′-hydroxyl function as potential anti-HCV agents

Hepatitis C virus (HCV) infection is one of the major health problems worldwide. If left untreated, it leads to liver cirrhosis, liver cancer and death. Herein, we report synthesis and anti-HCV activity of a new class of pyrimidine nucleosides possessing a 4′-carboxymethyl (9–16, 21 and 23) or 4′-carboxamide function (17–19 and 24). Among these, 10–12 (EC₅₀ = 33.1–42.4 μM), 14 and 21 (EC₅₀ = 43.4–59.5 μM) exhibited potent activity in HCV-1a replicon cells without any toxicity to parent Huh-7 cells (CC₅₀ = >829–1055 μM). The anti-HCV activities demonstrated by this unusual class of compounds were superior to that of ribavirin (EC₅₀ = 81.9 μM). Further, the most active analog, 12, was found to interact synergistically with ribavirin to inhibit HCV RNA replication.     

Design,synthesis, and biological evaluation of 4-(5-nitrofuran-2-yl)prop-2-en-1-one derivatives as potent antitubercular agents

Based on stereoelectronic feature analysis using density functional theory (DFT) at B3LYP/3-211G level, a series of 4-(5-nitrofuran-2-yl)prop-2-en-1-one derivatives with low LUMO energies (<?0.10 eV); concentrated over the nitro group, furan moiety and α,β-unsaturated carbonyl bridge were envisaged as potential antitubercular agents. The target compounds were prepared by condensation of 5-nitro-2-furaldehyde with various ketones under acidic condition. The compounds were evaluated for antitubercular activity against Mycobacterium tuberculosis H37Rv and their cytotoxicity in VERO cell line. Several synthesized compounds showed good antitubercular activity of <5 μM along with low cytotoxicity. In particular, compound ((E)-3-(5-nitrofuran-2-yl)-1-(4-(piperidin-1-yl)phenyl)prop-2-en-1-one) (3v) was found to be very potent (MIC: 0.19 μM) with good selectivity index (MIC₉₀/CC₅₀: >1800). Thus, this study shows the potential of stereoelectronic property analysis in developing improved nitroaromatics as antitubercular agents.     

Triterpenes from the roots of Lantana montevidensis with antiprotozoal activity

Bioassay guided fractionation of the roots of Lantana montevidensis (Verbenaceae) has resulted in the isolation and identification of three new triterpenoids; 13β-hydroxy-3-oxo-olean-11-en-28-oic acid (1), 12β,13β-dihydroxyolean-3-oxo-28-oic acid (2) and 12β,13β,22β-trihydroxyolean-3-oxo-28-oic acid (3) in addition to nine known compounds: oleanonic acid (4), oleanolic acid (5), 3β,25β-dihydroxy-olean-12-en-28-oic acid (6), lantadene A (7), 19α-hydroxy-3-oxo-olean-12-en-28-oic acid (8) pomolic acid (9), camaric acid (10) together with β-sitosterol (11) and β-sitosterol-3-O-β-d-glucoside (12). The structures of the isolated metabolites were elucidated based on comprehensive 1D and 2D NMR spectroscopic data as well as HR-ESI–MS. The extracts and the isolated metabolites were evaluated for their antiprotozoal and antimicrobial activities. Compound 2 showed antibacterial activity against Staphylococcus aureus and methicillin resistant S. aureus with IC₅₀ values against both organisms of 2.1 μM and compound 10 showed activity against same organisms with IC₅₀ values 8.74 and 8.09 μM, respectively, compared to the positive control ciprofloxacin (IC₅₀ = 0.3 μM against S. aureus and MRSA). Compounds 1, 4, 5, 6, and 10 showed moderate antileishmanial activity with IC₅₀ values ranging between (2.54–14.95 μM) and IC₉₀ values ranging between (11.90–19.47 μM), using pentamidine as a control (IC₅₀ values 2.09 ≥ 16.8 μM) and IC₉₀ values ranging between (4.72 ≥ 16.8 μM). These compounds also showed highly potent antitrypanosomal activity with IC₅₀ values ranging between (0.39–7.12 μM) and IC₉₀ values ranging between (1.91–10.51 μM), which are more efficient than the DFMO, the antitrypanosomal drug employed as positive control (IC₅₀ and IC₉₀values 11.82 and 30.82 μM).     

Nitric oxide inhibitory principles from Derris trifoliata stems

Nine rotenoids were isolated from the hexane and dichloromethane extracts of Derris trifoliata stems and were tested for nitric oxide (NO) inhibitory activity using RAW264.7 cells. The result indicated that 12a-hydroxyrotenone (7) possessed very potent NO inhibitory activity with an IC₅₀ value of 0.002 μM, followed by 1 (deguelin, IC₅₀=0.008 μM), 9 (12a-hydroxyelliptone, IC₅₀=0.010 μM) and 2 (α-toxicarol, IC₅₀=0.013 μM), respectively. In addition, the DPPH scavenging activity of rotenoids was also investigated. It was found that 6a,12a-dehydrodeguelin (5) possessed the highest activity against DPPH with an IC₅₀ value of 7.4 μM, followed by deguelin (1, IC₅₀=27.4 μM). All compounds did not show any cytotoxicity at their IC₅₀ values for NO inhibitory activity.Structure–activity relationships (SARs) of these rotenoids against NO release are as follows: (1) hydroxylation at C12a dramatically increased activity, (2) prenylation at furan ring increased activity markedly and (3) hydrogenation of a double bond at C6a–C12a conferred higher activity. For the DPPH radical scavenging effect, it was found that (1) introduction of a double bond at C6a–C12a increased activity and (2) hydroxylation of C11 at the D-ring decreased activity. As regards active compounds of Derris trifoliata stems, the isolated compounds are responsible for the NO inhibitory effect, especially 7, 1, 9 and 2, whereas 5 and 1 are those for the DPPH scavenging activity.     

Isolation,structural characterization and neuraminidase inhibitory activities of polyphenolic constituents from Flos caryophylli

Neuraminidase (NA) is one of the key surface proteins of the influenza virus, which is an important target for anti-influenza therapy. In the present study, bioassay-guided fractionation led to isolation of two new compounds, rhamnetin-3-O-β-d-glucuronide-6″-methyl ester (1) and rhamnazin-3-O-β-d-glucuronide-6″-methyl ester (2), along with seventeen known compounds (3-19), from the MeOH extract of Flos Caryophylli using in vitro NA inhibition assay. These isolated compounds exhibited significantly inhibitory effects on the NA with IC₅₀ values ranging from 8.4 to 94.1 μM and were found to protect MDCK cells from A (H1N1) influenza infections (EC₅₀ = 1.5–84.7 μM) with very low cytotoxicity to the host cells (CC₅₀ = 374.3–1266.9 μM)), with selective index (SI) ranging from 7 to 297. The primary structure-relationships of these isolates were also discussed.     

Antitubercular activity of quinolizidinyl/pyrrolizidinylalkyliminophenazines

Novel riminophenazine derivatives, characterized by the presence of the basic and cumbersome quinolizidinylalkyl and pyrrolizidinylethyl moieties, have been synthesized and tested (Rema test) against Mycobacterium tuberculosis H₃₇R_v and H₃₇R_a, and six clinical isolates of Mycobacterium avium and Mycobacterium tuberculosis. Most compounds exhibited potent activity against the tested strains, resulting more active than clofazimine, isoniazid and ethambutol.The best compounds (4, 5, 12 and 13) exhibited a MIC in the range 0.82–0.86 μM against all strains of Mycobacterium tuberculosis and, with the exception of 4 a MIC around 3.3 μM versus M. avium. The corresponding values for clofazimine (CFM) were 1.06 and 4.23 μM, respectively. Cytotoxicity was evaluated against three cell lines and compound 4 displayed a selectivity index (SI) versus the human cell line MT-4 comparable with that of CFM (SI = 5.23 vs 6.4). Toxicity against mammalian Vero 76 cell line was quite lower with SI = 79.     

Structure based medicinal chemistry approach to develop 4-methyl-7-deazaadenine carbocyclic nucleosides as anti-HCV agent

The structure-based approaches were implemented to design and rationally select the molecules for synthesis and anti-HCV activity evaluation. The systematic structure–activity relationships of previously discovered molecules (types I, II, III) were analyzed to design new molecules (type IV) by bioisosteric replacement of the amino group. The ligand conformation, binding mode studies and drug like properties were major determinant for selection of molecules for final synthesis. The replacement of amino group with methyl restored the interactions with RNA-template (Tem 799) through bifurcated weak H-bond (C–H…O). This is an interesting finding observed from molecular modeling studies. It was found that 6c–e has anti-HCV activity (EC₅₀ in 37–46 μM) while 6a, 6b and 6g were inactive. The compound 6f (EC₅₀ 28 μM) was the most active among the series however it also showed some cytotoxicity (CC₅₀ 52.8 μM). Except 6f, none of the compounds were found to be cytotoxic (CC₅₀ > 100 μM). The present study discloses structure–based approach for novel anti-HCV lead discovery and opens a future scope of lead optimization.     

Studies on the anti-hepatitis C virus activity of newly synthesized tropolone derivatives: Identification of NS3 helicase inhibitors that specifically inhibit subgenomic HCV replication

We synthesized new tropolone derivatives substituted with cyclic amines: piperidine, piperazine or pyrrolidine. The most active anti-helicase compound (IC₅₀ = 3.4 μM), 3,5,7-tri[(4′-methylpiperazin-1′-yl)methyl]tropolone (2), inhibited RNA replication by 50% at 46.9 μM (EC₅₀) and exhibited the lowest cytotoxicity (CC₅₀) >1 mM resulting in a selectivity index (SI = CC₅₀/EC₅₀) >21. The most efficient replication inhibitor, 3,5,7-tri[(4′-methylpiperidin-1′-yl)methyl]tropolone (6), inhibited RNA replication with an EC₅₀ of 32.0 μM and a SI value of 17.4, whereas 3,5,7-tri[(3′-methylpiperidin-1′-yl)methyl]tropolone (7) exhibited a slightly lower activity with an EC₅₀ of 35.6 μM and a SI of 9.8.     

Flavonoids and other bioactive constituents from Ficus thonningii Blume (Moraceae)

Continued interest in the chemistry of Ficus spp. led to the investigation of the figs and the roots of Ficus thonningii Blume. Two new flavonoids, thonningiol (1) and thonningiisoflavone (2) along with nineteen known compounds were isolated. β-Isoluteone (13) was isolated here for the first time from a natural source. Their structures were elucidated on the basis of spectroscopic evidence. Interestingly, thonningiisoflavone (2) and hydroxyalpinumisoflavone (21) showed strong DPPH radical scavenging activity with IC₅₀ = 65.50 μM and 68.20 μM respectively compared to the standard BHA with IC₅₀ = 44.20 μM. The methanolic extract of figs, taxifolin (14), conrauiflavonol (17) and shuterin (19) exhibited moderate antimicrobial activity against six micro-organisms with MIC below 1.5 mg/mL.     

A regio- and stereoselective 1,3-dipolar cycloaddition for the synthesis of new-fangled dispiropyrrolothiazoles as antimycobacterial agents

A series of dispiropyrrolothiazoles compounds were synthesized using 1,3-dipolar cycloaddition and were screened for antimycobacterial activity against Mycobacterium tuberculosis H₃₇Rv and INH resistant M. tuberculosis strains. Two of them were showing good activity with MIC of less than 1 μM. Compound (5f) was found to be the most active with MIC of 0.210 and 8.312 μM respectively.     

POMA analyses as new efficient bioinformatics’ platform to predict and optimise bioactivity of synthesized 3a,4-dihydro-3H-indeno[1,2-c]pyrazole-2-carboxamide/carbothioamide analogues

A series of 43, 3a,4-dihydro-3H-indeno[1,2-c]pyrazole-2-carboxamide/carbothioamide analogues (D01–D43) were analysed using Petra, Osiris, Molinspiration and ALOGPS (POMA) to identify pharmacophore, toxicity prediction, lipophilicity and bioactivity. All the compounds were evaluated for anti-HIV activity. 3-(4-Chlorophenyl)-N-(4-fluorophenyl)-6,7-dimethoxy-3a,4-dihydro-3H-indeno[1,2-c]pyrazole-2-carboxamide (D07) was found to be the most active with IC₅₀ > 4.83 μM and CC₅₀ 4.83 μM. 3-(4-Fluorophenyl)-6,7-dimethoxy-3a,4-dihydro-3H-indeno[1,2-c]pyrazole-2-carbothioamide (D41) was found to be the most active compound against bacterial strains with MIC of 4 μg/ml, comparable to the standard drug ciprofloxacin while 3-(4-methoxyphenyl)-6,7-dimethoxy-3a,4-dihydro-3H-indeno[1,2-c]pyrazole-2-carboxamide (D38) was found to be the most active compound against fungal strains with MIC 2–4 μg/ml, however less active than standard fluconazole. Toxicities prediction by Osiris were well supported and experimentally verified with exception of some compounds. In anticonvulsant screening, 3-(4-fluorophenyl)-N-(4-chlorophenyl)-6,7-dimethoxy-3a,4-dihydro-3H-indeno[1,2-c]pyrazole-2-carboxamide (D09) showed maximum activity showing 100% (4/4, 0.25–0.5 h) and 75% (3/4, 1.0 h) protection against minimal clonic seizure test without any toxicity.