Synthesis and anti-H5N1 activity of chiral gossypol derivatives and its analogs implicated by a viral entry blocking mechanism

A series of chiral gossypol derivatives and its analogs were synthesized and tested in vitro for their anti-H₅N₁ activity. Interestingly, (+)-gossypol derivatives and its analogs were more active against H₅N₁ than the corresponding (?)-gossypol derivatives and its analogs. Through a simple chemical modification with amino acids, less active chiral gossypol could be converted into more active derivatives, and most of chiral gossypol derivatives were more potent against H₅N₁ than 1-adamantylamine. With regard to the mechanism of action, chiral gossypol derivatives and its analogs might impair the virus entry step of cell infection, likely targeting to HA2 protein.     

Design,synthesis and evaluation of carbamate-modified (−)-N1-phenethylnorphysostigmine derivatives as selective butyrylcholinesterase inhibitors

We synthesized carbamate-modified (?)-N¹-phenethylnorphysostigmine derivatives 3a–u and evaluated their anti-cholinesterase activities. In vitro evaluation showed that cyclohexylmethylcarbamate derivative 3u potently and selectively inhibits butyrylcholinesterase.     

Anti-cancer activity of m-carborane-containing trimethoxyphenyl derivatives through tubulin polymerization inhibition

m-Carborane-containing compound 1a was identified as a cell growth inhibitor from a random screening of a boron compound library. As 1a is a mixture of diastereomers due to the presence of two chiral carbons, we designed achiral derivatives 2–4 and studied the structure-activity relationships of the methoxy groups on the benzene ring. 3,4,5-Trimethoxybenzyl derivative 2a and 3,4,5-trimethoxybenzoyl derivative 3a showed more potent anti-cancer activity against the human breast cancer cell line MDA-MB-453 than lead compound 1a. Compound 3a inhibited tubulin polymerization in a dose-dependent manner.     

C-3 benzoic acid derivatives of C-3 deoxybetulinic acid and deoxybetulin as HIV-1 maturation inhibitors

A series of C-3 phenyl- and heterocycle-substituted derivatives of C-3 deoxybetulinic acid and C-3 deoxybetulin was designed and synthesized as HIV-1 maturation inhibitors (MIs) and evaluated for their antiviral activity and cytotoxicity in cell culture. A 4-subsituted benzoic acid moiety was identified as an advantageous replacement for the 3′3′-dimethylsuccinate moiety present in previously disclosed MIs that illuminates new aspects of the topography of the pharmacophore. The new analogs exhibit excellent in vitro antiviral activity against wild-type (wt) virus and a lower serum shift when compared with the prototypical HIV-1 MI bevirimat (1, BVM), the first MI to be evaluated in clinical studies. Compound 9a exhibits comparable cell culture potency toward wt virus as 1 (WT EC₅₀ = 16 nM for 9a compared to 10 nM for 1). However, the potency of 9a is less affected by the presence of human serum, while the compound displays a similar pharmacokinetic profile in rats to 1. Hence 9a, the 4-benzoic acid derivative of deoxybetulinic acid, represents a new starting point from which to explore the design of a 2nd generation MI.     

A pair of new tetrahydro-naphthalenone enantiomers from Eremurus altaicus (Pall.) Stev.

A new racemic mixture of a 4-hydroxytetralone derivative, altaicusin A (1), was isolated from the whole plant of Eremurus altaicus (Pall.) Stev., together with three anthraquinones (compounds 2–4) and two naphthalene derivatives (5–6). The racemic altaicusin A (1) was further purified by chiral HPLC to yield a pair of enantiomers, (+)-(4S)-altaicusin A (1a) and (−)-(4R)-altaicusin A (1b). Their structures were established on the basis of spectroscopic analysis, including IR, HR-TOF-MS, and NMR. The absolute configurations of compounds 1a and 1b were elucidated by quantum chemical ECD calculations. Compounds 3 and 6 exhibited inhibitory activity against protein tyrosine phosphatase 1B (PTP1B).     

[2-(4-Phenyl-4-piperidinyl)ethyl]amine based CCR5 antagonists: derivatizations at the N-terminal of the piperidine ring

Several series of CCR5 antagonists have been discovered by derivatization at the N-terminal of the piperidine ring of the core template 2. Some derivatives exhibited potent inhibition against HIV-1infection. The pharmacokinetic properties of the lead compounds 11a, 14a, 15b, and 16b have been evaluated in vivo.     

Synthesis of dammarane-type triterpene derivatives and their ability to inhibit HIV and HCV proteases

We synthesized dammarane-type triterpene derivatives and evaluated their ability to inhibit HIV-1 and HCV proteases to understand their structure–activity relationships. All of the mono- and di-succinyl derivatives (5a–5f) were powerful inhibitors of HIV-1 protease (IC₅₀ < 10 μM). However, only di-succinyl (5e) and 2,3-seco-2,3-dioic acid (3b) derivatives similarly inhibited HCV protease (IC₅₀ < 10 μM). A-nor dammarane-type triterpenes (4a and 4b, IC₅₀ 10.0 and 29.9 μM, respectively) inhibited HIV-1 protease moderately or strongly, but were inactive against HCV protease. All compounds that powerfully inhibited HIV-1 or HCV protease did not appreciably inhibit the general human proteases, renin and trypsin (IC₅₀ > 1000 μM). These findings indicated that the mono-succinyl dammarane type derivatives (5a–5d) selectively inhibited HIV-1 protease and that the di-succinyl (5e, 5f) as well as 2,3-seco-2,3-dioic acid (3b) derivatives preferably inhibited both viral proteases.     

Fused heterocyclic compounds bearing bridgehead nitrogen as potent HIV-1 NNRTIs. Part 1: Design,synthesis and biological evaluation of novel 5,7-disubstituted pyrazolo[1,5-a]pyrimidine derivatives

In our continuous efforts to identify novel potent HIV-1 NNRTIs, a novel class of 5,7-disubstituted pyrazolo[1,5-a]pyrimidine derivatives were rationally designed, synthesized and evaluated for their anti-HIV activities in MT4 cell cultures. Biological results showed that most of the tested compounds displayed excellent activity against wild-type HIV-1 with a wide range of EC₅₀ values from 5.98 to 0.07 μM. Among the active compounds, 5a was found to be the most promising analogue with an EC₅₀ of 0.07 μM against wild-type HIV-1 and very high selectivity index (SI, 3999). Compound 5a was more effective than the reference drugs nevirapine (by 2-fold) and delavirdine (by 2-fold). In order to further confirm their binding target, an HIV-1 RT inhibitory assay was also performed. Furthermore, SAR analysis among the newly synthesized compounds was discussed and the binding mode of the active compound 5a was rationalized by molecular modeling studies.     

Leucoflavonine,a new bioactive racemic flavoalkaloid from the leaves of Leucosceptrum canum

A new flavoalkaloid racemate, leucoflavonine (1), together with its flavonoid precursor pectolinarigenin (2), was isolated from the leaves of Leucosceptrum canum collected from Tibet. Its structure was established by comprehensive spectroscopic analysis. Chrial separation of the enantiomers of 1 was achieved, and their absolute configurations were determined as S-(+)- and R-(?)-leucoflavonines ((+)-1a and (?)-1b) by comparison of their computational and experimental optical rotations. Biological assays indicated that both (+)-1a and (?)-1b exhibited inhibitory activity against acetylchlorinesterase (AChE) in vitro (IC₅₀?=?68.0?±?8.6 and 18.3?±?1.8?μM, respectively). Moreover, (?)-1b displayed cytotoxicity against human hepatoma cells HepG2 (IC₅₀?=?52.9?±?3.6?μM), and inhibited the production of interleukelin-2 (IL-2) in Jurkat cells (IC₅₀?=?16.5?±?0.9?μM), while (+)-1a showed no obvious activity in these assays.     

Synthesis and antimicrobial activity of 2,3-bis(bromomethyl)quinoxaline derivatives

We synthesized 12 derivatives of 2,3-bis(bromomethyl)quinoxaline with substituents at the 6- and/or 7-positions, and evaluated their activities against bacteria and fungi. Of the 12 compounds, nine (1a-h, 1j, and 1k) showed antibacterial activity. The derivative 1g, which bears a trifluoromethyl group at the 6-position, showed the highest activity against Gram-positive bacteria, while 1c, which has a fluoro-group at the 6-position, showed the widest antifungal activity spectrum. However, only the derivative with an ethyl ester substitution, 1k showed activity against Gram-negative bacteria.     

Synthesis,spectroscopic and molecular docking studies on new schiff bases,nucleosides and α-aminophosphonate derivatives as antibacterial agents

New Nucleosides, analogues derived from 1, 3, 4-oxadiazole, arylidene analogues and α-aminophosphonate were prepared. Infrared (IR), elemental analysis and ¹HNMR elucidated nucleosides; arylidines and phosphonate derivatives. The prepared derivatives were purified and allowed to test against bacteria strains. Phosphonate derivative 12a showed the higher antibacterial against E. coli with inhibition zone 35 mm, P. aeruginosa with inhibition zone 30 and S. aureus with inhibition zone 22 while compounds 4, 6d, 9a, 9c and 12c showed moderate to weak activity against these bacteria species with inhibition zones ranged from 12 mm to 24 mm. The molecular docking studies was applied on compound 12a, which showed the binding at the active DNA Gyrase.     

Synthesis,and anti-proliferative,Pim-1 kinase inhibitors and molecular docking of thiophenes derived from estrone

Heterocyclization of steroids were reported to give biologically active products where ring D modification occured. Estrone (1) was used as a template to develop new heterocyclic compounds. Ring D modification of 1 through its reaction with cyanoacetylhydrazine and elemental sulfur gave the thiophene derivative 3. The latter compound reacted with acetophenone derivatives 4a-c to give the hydrazide-hydrazone derivatives 5a-c, respectively. In addition, compound 3 formed thiazole derivatives through its first reaction with phenylisothiocyanate to give the thiourea derivative 9 followed by the reaction of the later with α-halocarbonyl compounds. In the present work a series of novel estrone derivatives were designed, synthesized and evaluated for their in vitro biological activities against c-Met kinase, and six typical cancer cell lines (A549, H460, HT-29, MKN-45, U87MG and SMMC-7721). The most promising compounds 5b, 5c, 11a, 13c, 15b, 15c, 15d, 17a and 17b were further investigated against the five tyrosine kinases c-Kit, Flt-3, VEGFR-2, EGFR, and PDGFR. Compounds 5b, 15d, 17a and 17b were selected to examine their Pim-1 kinase inhibition activity where compounds 15d and 17b showed high activities. Molecular docking of some of the most potent compounds was demonstrated.     

Synthesis and biological evaluation of α-1-C-4′-arylbutyl-l-arabinoiminofuranoses,a new class of α-glucosidase inhibitors

A series of α-1-C-4′-arylbutyl-l-arabinoiminofuranoses 3 with functional groups attached to the phenyl ring, which are potential α-glycosidase inhibitors, was designed and synthesized by using a Negishi cross-coupling reaction as the key reaction. Arylbutyl derivatives 3a–e showed potent inhibitory activities against intestinal maltase. Among them, difluorophenylbutyl derivative 3e showed good inhibition activities against intestinal isomaltase and sucrase as compared to those of 1 and commercial drugs.     

Design,synthesis and anti-HIV-1 RT evaluation of 2-(benzyl(4-chlorophenyl)amino)-1-(piperazin-1-yl)ethanone derivatives

In this study, using molecular hybridization approach, fourteen novel 2-(benzyl(4-chlorophenyl)amino)-1-(piperazin-1-yl)ethanone derivatives (7a–n) were designed as inhibitor of HIV-1 RT. The binding affinity of the designed compounds with HIV-1 RT as well as their drug-likeness behavior was predicted using in-silico studies. All the designed compounds were synthesized, characterized and in-vitro evaluated for HIV-1 RT inhibitory activity, in which tested compounds displayed significant to weak potency against the selected target. Moreover, best active compounds of the series, 7k and 7m inhibited the activity of RT with IC₅₀ values 14.18 and 12.26 μM respectively. Structure Activity Relationship (SAR) studies were also performed in order to predict the influence of substitution pattern on the RT inhibitory potency. Anti-HIV-1 and cytotoxicity studies of best five RT inhibitor (7a, 7d, 7k, 7L and 7m) revealed that, except compound 7d other compounds retained significant anti-HIV-1 potency with good safety index. Best scoring pose of compound 7m was analysed in order to predict its putative binding mode with wild HIV-1 RT.     

Synthesis,cytotoxicity, DNA binding and topoisomerase II inhibition of cassiarin A derivatives

Four series of cassiarin A derivatives with alkanoyl (3a–3d), aroyl (4a–4d), hydroxy/amino-substituted ethylene glycol (5a–5c) and selenium-containing (6a) side chains were synthesized. Their antitumor activities were evaluated against BT474, CHAGO, HepG2, KATO-III, SW620 and CaSki cancer cell lines. Preliminary results demonstrated that 5b had moderate activities against HepG2 and KATO-III cell lines, while 5c showed moderate to high cytotoxicity against most tested cell lines. In addition, 6a exhibited moderate cytotoxicity against cervical cells, CaSki. DNA-binding and ethidium bromide displacement experiments suggested that 5c and 5b binds to DNA via an intercalative mode, whereas 6a did not. However, the selenium-containing cassiarin A derivative 6a inhibited topoisomerase II with more than 95% inhibition at the concentration of 50 μM. These cassiarin A derivatives showed lower toxicity to normal cells, WI-38 than amonafide therefore they are potential lead compounds to be further developed as new anticancer agents.     

Synthesis of novel forskolin isoxazole derivatives with potent anti-cancer activity against breast cancer cell lines

Forskolin C₁-isoxazole derivatives (3,5-regioisomers) (11a–e, 14, 15a–h and 15, 16a–g) were synthesized regioselectively by adopting 1,3-dipolar cycloadditions. These derivatives were tested using estrogen receptor positive breast cancer cell lines MCF-7 and BT-474. Majority of the compounds exhibited activity against the p53-positive MCF-7 breast cancer cells but not against the p53-negative BT-474 breast cancer cells. Among forskolin derivatives, compounds 11a, 11c, 14a, 14f, 14g, 14h, 15b, 16g and 17b exhibited higher anti-cancer activity against MCF-7 cell line with an IC₅₀ ≤ 1 µM. The derivative 14f exhibited highest activity in both p53-positive (MCF-7) and p53-negative (BT-474) breast cancer cell lines with an IC₅₀ of 0.5 µM.     

3-Anhydro-6-hydroxy-ophiobolin A,a new sesterterpene inhibiting the growth of methicillin-resistant Staphylococcus aureus and inducing the cell death by apoptosis on K562, from the phytopathogenic fungus Bipolaris oryzae

A new ophiobolin derivative, 3-anhydro-6-hydroxy-ophiobolin A (1), as well as two known ophiobolin derivatives 3-anhydro-ophiobolin A (2) and 3-anhydro-6-epi-ophiobolin A (3) were isolated from the PDB culture of a phytopathogenic fungus Bipolaris oryzae. The structure of 1 was elucidated through 2D NMR and other spectroscopic techniques. Compound 1 exhibited strong antimicrobial activity against Bacille Calmette–Guerin, Bacillus subtilis, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus with MIC value of 12.5 μg/mL, and potent antiproliferative activity against cell lines HepG2 and K562 with IC₅₀ of 6.49 μM and 4.06 μM, respectively. Further studies on the cytotoxicity of compound 1 against K562 cells demonstrated that it induced apoptosis, observed by flow cytometric method. Preliminary structure–activity relationships of these ophiobolins and the mechanism of apoptosis induced by 1 were analyzed.     

Rational design,synthesis, anti-HIV-1 RT and antimicrobial activity of novel 3-(6-methoxy-3,4-dihydroquinolin-1(2H)-yl)-1-(piperazin-1-yl)propan-1-one derivatives

In the present study, fifteen novel 3-(6-methoxy-3,4-dihydroquinolin-1(2H)-yl)-1-(piperazin-1-yl)propan-1-one (6a-o) derivatives were designed as inhibitor of HIV-1 RT using ligand based drug design approach and in-silico evaluated for drug-likeness properties. Designed compounds were synthesized, characterized and in-vitro evaluated for RT inhibitory activity against wild HIV-1 RT strain. Among the tested compounds, four compounds (6a, 6b, 6j and 6o) exhibited significant inhibition of HIV-1 RT (IC₅₀ ⩽ 10 μg/ml). All synthesized compounds were also evaluated for anti-HIV-1 activity as well as cytotoxicity on T lymphocytes, in which compounds 6b and 6l exhibited significant anti-HIV activity (EC₅₀ values 4.72 and 5.45 μg/ml respectively) with good safety index.Four compounds (6a, 6b, 6j and 6o) found significantly active against HIV-1 RT in the in-vitro assay were in-silico evaluated against two mutant RT strains as well as one wild strain. Further, titled compounds were evaluated for in-vitro antibacterial (Escherichia coli, Pseudomonas putida, Staphylococcus aureus and Bacillus cereus) and antifungal (Candida albicans and Aspergillus niger) activities.     

Synthesis of highly functionalized 2,4-diaminoquinazolines as anticancer and anti-HIV agents

Novel polyhalo 2,4-diaminoquinazolines 3a–3d were prepared by reacting polyhaloisophthalonitriles with guanidine carbonate under solvent-free conditions and in the absence of a catalyst with good yields (74–95%). A series of highly functionalized 2,4-diaminoquinazolines 4–5 were then synthesized based on 3a–3c. The anticancer activities of compounds 3–5 were evaluated in vitro against human cell lines such as Skov-3, HL-60, A431, A549, and HepG-2. Some of the compounds showed excellent cytotoxic activity and 5a was found to be the most potent derivative, with an IC₅₀ value lower than 2.5 μg/mL against the five tumor cell lines, making it more active than cisplatin. Representative compounds were also preliminarily evaluated as HIV-1 inhibitors in vitro, and 3c showed the most potent anti-HIV-1 activity with EC₅₀ values of 0.6 and 1.6 μg/mL, and TI values of >59.6 and 66.6, respectively.     

Synthesis of C-2 and C-3 substituted quinolines and their evaluation as anti-HIV-1 agents

A plenty of natural products and synthetic derivatives containing quinoline moiety have been reported to possess various pharmacological activities. Quinolines such as 2-styrylquinolines and 8-hydroxyquinolines are extensively studied for their anti-HIV-1 activity and found to act mainly through HIV-1 integrase enzyme inhibition. In continuation of our efforts to search for newer anti-HIV-1 molecules, thirty-one quinoline derivatives with different linkers to ancillary phenyl ring were synthesized and evaluated for in vitro anti-HIV-1 activity using TZM-bl assays. Compound 31 showed higher activity in TZM-bl cell line against HIV-1_VB59 and HIV-1_UG070 cell associated virus (IC₅₀ 3.35 ± 0.87 and 2.57 ± 0.71 μM) as compared to other derivatives. Compound 31 was further tested against cell free virus HIV-1_VB59 and HIV-1_UG070 (IC₅₀ 1.27 ± 0.31 and 2.88 ± 1.79 μM, TI 42.20 and 18.61, respectively). This lead molecule also showed good activity in viral entry inhibition assay and cell fusion assay defining its mode of action. The activity of compound 31 was confirmed by testing against HIV-1_VB51 in activated peripheral blood mononuclear cells (PBMCs). Binding interactions of 31 were compared with known entry inhibitors.