Natural products-based insecticidal agents 7. Semisynthesis and insecticidal activity of novel 4α-alkyloxy-2-chloropodophyllotoxin derivatives against Mythimna separata Walker in vivo

In continuation of our program aimed at the discovery and development of natural products-based insecticidal agents, 16 novel 4α-alkyloxy-2-chloropodophyllotoxin derivatives were semisynthesized from podophyllotoxin, and preliminarily evaluated for their insecticidal activity against the pre-third-instar larvae of Mythimna separata Walker in vivo. Among all the tested derivatives, especially compounds 4b, 4e, 4g, and 4p exhibited more promising and pronounced insecticidal activity than toosendanin, a commercial insecticide derived from Melia azedarach. Generally, it was obviously demonstrated that the length of straight-chain or branched-chain alkyloxy, and heteroatom-containing cycloalkyloxy at the C-4 position of 2-chloropodophyllotoxin were very important for the insecticidal activity.     

Natural products-based insecticidal agents 11. Synthesis and insecticidal activity of novel 4α-arylsulfonyloxybenzyloxy-2β-chloropodophyllotoxin derivatives against Mythimna separata Walker in vivo

In continuation of our program aimed at the discovery and development of natural products-based insecticidal agents, 14 novel 4α-arylsulfonyloxybenzyloxy-2β-chloropodophyllotoxin derivatives were stereoselectively semisynthesized from podophyllotoxin, and preliminarily evaluated for their insecticidal activity against the pre-third-instar larvae of Mythimna separata Walker in vivo. Especially compounds 9c' and 9g' exhibited the most promising and pronounced insecticidal activity than toosendanin, a commercial insecticide derived from Melia azedarach at 1mg/mL. Generally, it was preliminarily demonstrated that arylsulfonyloxy groups at the C-2 position of benzyloxy moiety and the length of the side chain on the benzenesulfonyloxy group of 4α-arylsulfonyloxybenzyloxy-2β-chloropodophyllotoxins might be important for the insecticidal activity.     

Synthesis of some ester derivatives of 4′-demethoxyepipodophyllotoxin/2′-chloro-4′-demethoxyepipodophyllotoxin as insecticidal agents against oriental armyworm,Mythimna separata Walker

Podophyllotoxin is a naturally occurring non-alkaloid toxin isolated from the roots and rhizomes of Podophyllum peltatum and P. hexandrum. In continuation of our program aimed at the discovery and development of natural product-based insecticides, two series of ester derivatives of 4′-demethoxyepipodophyllotoxin/2′-chloro-4′-demethoxyepipodophyllotoxin were prepared. The structures of the target compounds were well characterized by 1H NMR, IR, optical rotation and mp. The precise three-dimensional structural information of 8j was further determined by single-crystal X-ray diffraction. Their insecticidal activity was tested against Mythimna separata Walker. These compounds showed delayed insecticidal activity. Among all derivatives, some compounds showed more potent insecticidal activity than toosendanin against M. separata; especially compounds 8k and 9k exhibited the most potent activity with the final mortality rates of 71.4%. Their structure–activity relationships were discussed.     

Synthesis of 4β-acyloxypodophyllotoxin analogs modified in the C and E rings as insecticidal agents against Mythimna separata Walker

To discover the new natural-product-based insecticidal agents, four series of sixty novel 4β-acyloxypodophyllotoxin analogs modified in the C and E rings were prepared, and their insecticidal activity was tested against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at the concentration of 1 mg/mL. It demonstrated that the position of the dioxo group on the E-ring of 4′-demethylepipodophyllotoxin was regioselectively controlled by the chlorine atom at its C-2′ position when 2′-chloro-4′-demethylepipodophyllotoxin was oxidized by sodium periodate. Among all the derivatives, IIIi exhibited the best potent insecticidal activity with the final mortality rate of 63.3%. To alkylacyloxy series, the proper length of the side chain at the C-4 position of Ia–g, IIa–g and IIIa–g was important for their insecticidal activity.     

Design,synthesis and structure–activity relationship of novel diphenylamine derivatives

Diphenylamine derivatives have been reported with good fungicidal, insecticidal, acaricidal, rodenticidal and/or herbicidal activities. To find new lead compound of this kind, a series of novel diphenylamine derivatives were designed and synthesized by the approach of Intermediate Derivatization Methods. All compounds were identified by ¹H NMR and elemental analysis. Bioassays demonstrated that some compounds substituted at 2,4,6-positions or 2,4,5-positions of phenyl ring B exhibited excellent fungicidal activities. The optimal compounds P30 and P33 showed 80% and 85% control respectively against cucumber downy mildew at 12.5 mg L⁻¹, both 100% control against rice blast at 0.3 mg L⁻¹ and both 100% control against cucumber gray mold at 0.9 mg L⁻¹. The relationship between structure and fungicidal activities was discussed as well.     

Design,synthesis and antioxidant activity evaluation of novel β-elemene derivatives

Forty β-elemene derivatives were prepared and their antioxidant activity in H₂O₂-treated human umbilical vein endothelial cells (HUVECs) was first investigated. Among which, the dimer compounds 5r and 5s exhibited the most potent antioxidant activity against reactive oxygen species production. Meanwhile, 5r and 5s led to a significant increase in superoxide dismutase and nitric oxide levels and decrease in malonyldialdehyde and lactate dehydrogenase contents. Furthermore, MTT assay showed that 5r and 5s did not produce obvious cytotoxicity and had significantly cytoprotective effects against oxidative damage on HUVECs.     

Design,synthesis and α-amylase inhibitory activity of novel chromone derivatives

Quercetin is one of the naturally occurring polyphenol flavonoid predominantly known for antidiabetic activity. In the present study, by considering the structural requirements, twenty two novel chromone derivatives (5–26) as α-amylase inhibitor were designed and subsequently in silico evaluated for drug likeness behavior. Designed compounds were synthesized, characterized by spectral analysis and finally evaluated for the inhibition of α-amylase activity by in vitro assay. Tested compounds exhibited significant to weak activity with IC₅₀ range of 12–125 µM. Among the tested compounds, analogues 5, 8, 12, 13, 15, 17 and 22 exhibited significant human α-amylase inhibitory activity with IC₅₀ values <25 µM, which can be further explored as anti-hyperglycemic agents. Putative binding mode of the significant and least active α-amylase inhibitors with the target enzyme was also explored by the docking studies.     

Preparation of 5′-deoxy-5′-amino-5′-C-methyl adenosine derivatives and their activity against DOT1L

From a readily available 5-C-Me ribofuranoside, we have realized a reliable route to valuable 5′-deoxy-5′-amino-5′-C-methyl adenosine derivatives at gram scale with confirmed stereochemistry. These adenosine derivatives are useful starting materials for the preparation of 5′-deoxy-5′-amino-5′-C-methyl adenosine derivatives with higher complexity. From one of the new adenosine derivatives, some 5′-deoxy-5′-amino-5′-C-methyl adenosine DOT1L inhibitors were prepared in several steps. Data from DOT1L assay indicated that additional 5′-C-Me group improved the enzyme inhibitory activity.     

Design,synthesis, antimicrobial activity and anti-HIV activity evaluation of novel hybrid quinazoline–triazine derivatives

Abstract

A series of novel hybrid quinazoline–triazine derivatives was designed and synthesized from cyanuric chloride and anthranilic acid through sequential reactions, which contain different pharmacophores like quinazoline and substituted diaryl triazine (DATA) linked with ethylene diamine. All the newly synthesized compounds were characterized by infrared, ¹H-NMR, ¹³C-NMR, MS and elemental analysis. Further, we evaluated the in vitro anti-HIV activity of the newly synthesized compounds against HIV-1 (III_B) and HIV-2 (ROD) viral strains and as well as in vitro antimicrobial activity against four bacteria (Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, Klebsiella pneumoniae) and two fungi (Aspergillus clavatus, Candida albicans) using the paper agar streak dilution method. The bioassay results indicate that four compounds namely 7d, 7n, 7r and 7s could be considered as possible potential agents.     

Synthesis,characterization and biological evaluation of novel 4′-fluoro-2′-hydroxy-chalcone derivatives as antioxidant,anti-inflammatory and analgesic agents

Abstract

In an effort to develop safe and potent anti-inflammatory agents, a series of novel 4′-fluoro-2′-hydroxychalcones 5a–d and their dihydropyrazole derivatives 6a–d was prepared. It was synthesized via aldol condensation of 4′-fluoro-2′-hydroxyacetophenone with appropriately substituted aldehydes followed by cyclization with hydrazine hydrate. All the synthesized compounds were evaluated for their antioxidant, anti-inflammatory, cyclooxygenase inhibition selectivity and analgesic activities. The dimethoxychalcone 5a and its dihydropyrazole derivative 6a showed the highest antioxidant activity, while the monomethoxychalcone 5d and its dihydropyrazole derivative 6d showed the highest analgesic and anti-inflammatory activities. It was also found that there is a close correlation between 4′-fluoro-2′-hydroxychalcones 5a–d and their dihydropyrazole derivatives 6a–d in the screened biological activities. To explain the correlation between the synthesized chalcones and their dihydropyrazole derivatives, especially for the anti-inflammatory activity, docking studies were performed.     

Design,synthesis and anti-Alzheimer’s activity of novel 1,2,3-triazole-chromenone carboxamide derivatives

Alzheimer’s disease (AD) is a well-known neurodegenerative disorder affecting millions of old people worldwide and the corresponding epidemiological data highlights the significance of the disease. As AD is a multifactorial illness, various single-target directed drugs that have reached clinical trials have failed. Therefore, various factors associated with outset of AD have been considered in targeted drug discovery and development. In this work, a wide range of 1,2,3-triazole-chromenone carboxamides were designed, synthesized, and evaluated for their cholinesterase inhibitory activity. Among them, N-(1-benzylpiperidin-4-yl)-7-((1-(3,4-dimethylbenzyl)-1H-1,2,3-triazol-4-yl)methoxy)-2-oxo-2H-chromene-3-carboxamide (11b) showed the best acetylcholinesterase inhibitory activity (IC₅₀ = 1.80 µM), however, it was inactive toward butyrylcholinesterase. It should be noted that compound 11b was evaluated for its BACE1 inhibitory activity and calculated IC₅₀ = 21.13 µM confirmed desired inhibitory activity. Also, this compound revealed satisfactory neuroprotective effect against H₂O₂-induced cell death in PC12 neurons at 50 µM as well as metal chelating ability toward Fe²⁺, Cu²⁺, and Zn²⁺ ions.     

Design,synthesis and anti-P. falciparum activity of pyrazolopyridine–sulfonamide derivatives

Ten 1-phenyl-1H-pyrazolo[3,4-b]pyridine derivatives connected by a linker group to benzenesulfonamide moieties with different substituents in the 4-position were synthesized and assayed against Plasmodium falciparum. These ten compounds exhibited activity in vitro against the chloroquine-resistant clone W2 with IC₅₀ values ranging from 3.46 to 9.30 μM. The most active derivatives with substituent R₂ = Cl or CH₃ at the benzenesulfonamide moiety exhibited the lowest IC₅₀. Compounds with an R₁ = CO₂Et substituent at the 5-position of the 1H-pyrazolo[3,4-b]pyridine ring presented lower activity than those with a CN substituent. The 1H-pyrazolo[3,4-b]pyridine system appears to be promising for further studies as an antimalarial for overcoming the burden of resistance in P. falciparum.     

Symmetrical α-bromoacryloylamido diaryldienone derivatives as a novel series of antiproliferative agents. Design,synthesis and biological evaluation

In a continuing study of hybrid compounds containing the α-bromoacryloyl moiety as potential anticancer drugs, we synthesized a novel series of hybrids 4a–h, in which this moiety was linked to a 1,5-diaryl-1,4-pentadien-3-one system. Many of the conjugates prepared (4b, 4c, 4e and 4g) demonstrated pronounced, submicromolar antiproliferative activity against four cancer cell lines. Moreover, compound 4b induced apoptosis through the mitochondrial pathway and activated caspase-3 in a concentration-dependent manner.     

Synthesis of novel 2-amino-4-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-6-aryl-4H-pyran-3-carbonitrile derivatives as antimicrobial and antioxidant agents

As a part of systematic investigation of synthesis and biological activities of indole analogues linked to various heterocyclic systems, we have synthesized new compounds viz., 2-amino-4-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-6-aryl-4H-pyran-3-carbonitriles (2a–i), 4,5-diamino-6-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-8-aryl-2-oxo-2,6-dihydrodipyrano [2,3-b:3,2-e]pyridine-3-carbonitriles (3a–i), 4-amino-5-(5′-substituted 2′-phenyl-1H-indol-3-yl)-7-aryl-1H-pyrano[2,3-d]pyrimidin-2(5H)-ones (4a–i), 4-amino-5-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-7-aryl-1H-pyrano[2,3-d]pyrimidin-2(5H)-thiones (5a–i), 4-(5′-subtituted 2′-phenyl-1H-indol-3′-yl)-6-aryl-1,4-dihydropyrano[2,3-c]pyrazol-3-amines (6a–i) and 5-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-7-aryl-3H-pyrano[2,3-d]pyrimidin-4(5H)-ones (7a–i). Antibacterial activity results revealed that, compound 6a showed promising activity versus Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae. Compound 6d exhibited good activity against S. aureus, K. pneumoniae and Pseudomonas aeruginosa. Antifungal activity results indicated that, compound 4d exhibited maximum zone of inhibition against Aspergillus oryzae and Aspergillus flavus. In case of antioxidant activity, compound 4a showed promising radical scavenging activity, ferric ions (Fe³⁺) reducing antioxidant power (FRAP) and metal chelating activity.     

Design,synthesis and biological evaluation of benzylisoquinoline derivatives as multifunctional agents against Alzheimer’s disease

A novel series of benzylisoquinoline derivatives were designed, synthesized, and evaluated as multifunctional agents against Alzheimer’s disease (AD). The screening results showed that most of the compounds significantly inhibited cholinesterases (ChEs), human cholinesterases (h-ChEs) and self-induced β-amyloid (Aβ) aggregation. In particular, compound 9k showed the strongest acetylcholinesterase (AChE) inhibitory activity, being 1000-fold and 3-fold more potent than its precursor benzylisoquinoline (10) and the positive control galanthamine, respectively. In addition, 9k was a moderately potent inhibitor for h-ChEs. Compared with precursor benzylisoquinoline (36.0% at 20 μМ), 9k (78.4% at 20 μМ) could further inhibit Aβ aggregation. Moreover, 9k showed low cell toxicity in human SH-SY5Y neuroblastoma cells. Therefore, compound 9k might be a promising lead compound for AD treatment.     

Design,synthesis, biological evaluation and molecular docking studies of novel benzofuran–pyrazole derivatives as anticancer agents

This study deals with design and synthesis of novel benzofuran–pyrazole hybrids as anticancer agents. Eight compounds were chosen by National Cancer Institute (NCI), USA to evaluate their in vitro antiproliferative activity at 10⁻⁵ M in full NCI 60 cell panel. The preliminary screening of the tested compounds showed promising broad-spectrum anticancer activity. Compound 4c was further assayed for five dose molar ranges in full NCI 60 cell panel and exhibited remarkable growth inhibitory activity pattern against Leukemia CCRF-CEM, MOLT-4, Lung Cancer HOP-92, Colon Cancer HCC-2998, CNS Cancer SNB-75, Melanoma SK-MEL-2, Ovarian Cancer IGROV1, Renal Cancer 786-0, RXF 393, Breast Cancer HS 578T and T-47D (GI₅₀: 1.00–2.71 μM). Moreover, enzyme assays were carried out to investigate the possible antiproliferative mechanism of action of compound 4c. The results revealed that compound 4c has good c-Src inhibitory activity at 10 μM. In addition, molecular docking studies showed that 4c could bind to the ATP Src pocket sites. Fulfilling the Lipinskiís rule of five in addition to its ADME profile and the biological results, all strongly suggest that 4c is a promising Src kinase inhibitor.     

Bronchial mucosal and kidney cortex affinity of 4- and 4,4′-substituted sulphur-containing derivatives of 2,2′-5,5′-tetrachlorobiphenyl in mice

In order to evaluate further the structural requirements previously proposed for accumulation of polychlorinated biphenyls (PCB) and their sulphur-containing metabolites in the respiratory tract of mice, 4-methylthio-, 4-methylsulphonyl and 4,4′-bis(methylthio)-2,2′,5,5′-[¹⁴C]tetrachlorobiphenyl were studied by whole body autoradiography. All the compounds gave rise to a strong accumulation of radioactivity in the mucosa of the bronchi, trachea and larynx. The first two substances were also concentrated in the mucosa of the nasal cavities. At the longer post-injection times all the compounds studied were localized in distinct sites of the kidney cortex. However, while the uptake of the monosubstituted sulphur-containing tetrachlorobiphenyl metabolites there was comparatively weak, the bis(methylthio) derivative showed a remarkable accumulation and retention in the kidney cortex. The study makes it possible to formulate the structural requirements for bronchial accumulation on the basis of the structure of the compounds that are accumulated rather than on the structure of the unmetabolized polychlorobiphenyls. Also with regard to the uptake in the kidney cortex a specific structure-dependency seems to exist.     

Chemical synthesis and biological activity of novel brominated 7-deazaadenosine-3′,5′-cyclic monophosphate derivatives

Synthetic derivatives of cyclic adenosine monophosphate, such as halogenated or other more hydrophobic analogs, are widely used compounds, to investigate diverse signal transduction pathways of eukaryotic cells. This inspired us to develop cyclic nucleotides, which exhibit chemical structures composed of brominated 7-deazaadenines and the phosphorylated ribosugar. The synthesized 8-bromo- and 7-bromo-7-deazaadenosine-3′,5′-cyclic monophosphates rank among the most potent activators of cyclic nucleotide-regulated ion channels as well as cAMP-dependent protein kinase. Moreover, these substances bind tightly to exchange proteins directly activated by cAMP.     

Design, synthesis and cytotoxic activities of novel β-amino alcohol derivatives

Three series of novel β-amino alcohols possessing an N-anthranyl group have been obtained using tryptophan as the major starting material. These compounds were screened for cytotoxic activity against five human cancer cell lines in vitro by MTT assay, and some of them exhibited potential ability to be anticancer agents. Structure-activity relationship was carefully investigated. Only the compounds possessing small substituents (H or CH₃) at C-6 position showed the same activity as cisplatin (DDP) did.