Biological screening of cucurbitacin inspired estrone analogs targeting mitogen‐activated protein kinase (MAPK) pathway

Assembly of cucurbitacin inspired estrone analogs has been previously synthesized and screened against melanoma cell lines. Further synthetic optimization was executed via installation of Azide polar functional moiety across 23, 24 α, β‐unsaturated ketone side chain using Michael addition reaction. This was followed by biological screening against melanoma cell lines employing MTT assay, in‐cell‐based ELISA assay, and Western blot analysis to monitor the potential of the synthesized analogs to inhibit the phosphorylated ERK levels. This resulted in evolution of MH‐4 possessing IC₅₀ of 3.59 μm with significant decrease in the p‐ERK and targeting MAPK pathway.     

One‐Pot Laccase‐Catalysed Synthesis of 5,6‐Dihydroxylated Benzo[b]furans and Catechol Derivatives,and Their Anticancer Activity

A commercial laccase, Suberase® from Novozymes, was used to catalyse the synthesis of 5,6‐dihydroxylated benzo[b]furans and catechol derivatives. The yields were, in some cases, similar to or better than that obtained by other enzymatic, chemical or electrochemical syntheses. The synthesised derivatives were screened against renal (TK10), melanoma (UACC62), breast (MCF7) and cervical (HeLa) cancer cell lines. GI₅₀, TGI and LC₅₀ are reported for the first time. Anticancer screening showed that the cytostatic effects of the 5,6‐dihydroxylated benzo[b]furans were most effective against the melanoma (UACC62) cancer cell line with several compounds exhibiting potent growth inhibitory activities (GI₅₀ = 0.77–9.76 µM), of which two compounds had better activity than the anticancer agent etoposide (GI₅₀ = 0.89 µM). One compound exhibited potent activity (GI₅₀ = 9.73 µM) against the renal (TK10) cancer cell line and two exhibited potent activity (GI₅₀ = 8.79 and 9.30 µM) against the breast (MCF7) cancer cell line. These results encourage further studies of the 5,6‐dihydroxylated benzo[b]furans for their potential application in anticancer therapy.     

Synthesis and cytotoxicity studies of novel 2-Hydrazonylpyrido[2,3-b]pyrazin-3(4H)-ones

In an attempt to develop potent antitumor agents, a series of novel 2‐hydrazonylpyrido[2,3‐b]pyrazin‐3(4H)‐one derivatives were designed and synthesized. All the prepared compounds were screened for their cytotoxic activities against A549, MDA‐MB‐231 and HT‐29 cell lines in vitro. Pharmacological data indicated that five of the target compounds showed cytotoxicity against A549 cell line below a concentration of 1 µM. Compound 15g was the most potent one with IC₅₀ values of 0.19, 2.11 and 2.15 µM against A549, MDA‐MB‐231 and HT29 cell lines, respectively.     

Synthesis and anticancer activity of Indolin-2-one derivatives bearing the 4-thiazolidinone moiety

A novel series of indolin‐2‐one derivatives containing the 4‐thiazolidinone moiety ( 5a—5p ) was synthesized and the cytotoxicity of these derivatives was evaluated in vitro against three human cancer cell lines (HT‐29, H460 and MDA‐MB‐231) by standard MTT assay. Some prepared compounds exhibited significant cytotoxicity against different human cancer cell lines. Several potent compounds were further evaluated against one normal cell line (WI‐38). In particular, the promising compound 5h showed remarkable cytotoxicity and selectivity against the HT‐29 and H460 cancer cell lines (IC₅₀ = 0.016 µmol/L, 0.0037 µmol/L, respectively).     

The application of tandem aza-wittig reaction to synthesize artemisinin-guanidine hybrids and their anti-tumor activity

Three series of novel artemisinin–guanidine hybrids 4a–4f , 8a–8h and 9a–9h have been facilely synthesized via four‐component reaction (aza‐Wittig reaction) and evaluated for their anti‐tumor activities against A549, HT‐29 and MDA‐MB‐231 cell lines in vitro. All of the tested compounds showed enhanced anti‐tumor activities with IC₅₀ values ranging from 0.02 µM to 12.0 µM as compared to DHA (dihydroartemisinin). Among them, artemisinin derived dimers, compounds 9b (IC₅₀ = 0.05 µM), 9d (IC₅₀ = 0.06 µM) and 9f (IC₅₀ = 0.02 µM) were found to be most active against HT29 cells.     

Synthesis,biology, NMR and conformation studies of the topographically constrained δ‐opioid selective peptide analogs of [β‐iPrPhe3]deltorphin I

Abstract: Replacement of Phe³ in the endogenous δ‐opioid selective peptide deltorphin I with four optically pure stereoisomers of the topographically constrained, highly hydrophobic novel amino acid β‐isopropylphenylalanine (β‐iPrPhe) produced four pharmacologically different deltorphin I peptidomimetics. Radiolabeled ligand‐binding assays and in vitro biological evaluation indicate that the stereoconfiguration of the iPrPhe residue plays a crucial role in determining the binding affinity, bioactivity and selectivity of [β‐iPrPhe³]deltorphin I analogs: a (2S,3R) configuration of the iPrPhe³ residue in [β‐iPrPhe³]deltorphin I provided the most desirable biological properties with binding affinity (IC₅₀ = 2 n m ), bioassay potency (IC₅₀ = 1.23 n m in MVD assay) and exceptional selectivity for the δ‐opioid receptor over the µ‐opioid receptor (30 000). Further conformational studies based on two‐dimensional NMR and computer‐assisted molecular modeling suggested a model for the possible bioactive conformation in which the Tyr¹ and (2S,3R)‐β‐iPrPhe³ residues adopt trans side‐chain conformations, and the linear peptide backbone favors a distorted β‐turn conformation.     

Design and synthesis of 2-iminothiazolidin-4-one moiety-containing compounds as potent antiproliferative agents

A new series of 2,5‐diaryliminothiazolidin‐4‐ones were designed and synthesized as potent antiproliferative agents. The antiproliferative activities of the 25 target compounds were evaluated against three cancer cell lines (A549, H460 and HT29) by MTT assay. Pharmacological data indicated that most of the compounds possessed moderate activity, some showed remarkable activity against one or more cell lines. As the most promising compound, 8s (with IC₅₀ values of 1.1, 0.01 and 1.3 µM against the A549, H460 and HT29 cell lines) was 1.1‐ to 270‐fold more potent than the reference drug sorafenib. Furthermore, preliminary structure–activity relationships (SARs) were summarized to provide guidance for further design and discovery of 2‐iminothiazolidin‐4‐one‐based antiproliferative agents.     

Design,synthesis, and docking study of new quinoline derivatives as antitumor agents

New quinolines substituted with various heterocycles and chalcone moieties were synthesized and evaluated as antitumor agents. All the synthesized compounds were in vitro screened against 60 human cancer cell lines. Compound 13 showed the highest cytotoxicity toward 58 cell lines, exhibiting distinct growth inhibition values (GI₅₀) against the majority of them, including SR, HL‐60 (TB) strains (leukemia), and MDA‐MB‐435 strains (melanoma), with GI₅₀ values of 0.232, 0.260, and 0.300 µM, respectively. It exhibited great selectivity toward cancer cell lines, with less toxic effect against normal cells represented by skin fibroblast (BJ) and breast epithelial cell lines (MCF‐10F). The enzyme inhibitory activity of compound 13 was evaluated against topoisomerase 1 (Topo 1), epidermal growth factor receptor and vascular endothelial growth factor receptor 2, where it displayed worthy Topo 1 inhibition activity with an IC₅₀ value of 0.278 µM compared with camptothecin as a reference drug (IC₅₀ 0.224 µM). Docking studies were performed to investigate the recognition profile of compound 13 with the Topo 1 enzyme binding site.     

Synthesis and Antitumor Activity of Novel Nitrogen Mustard‐Linked Chalcones

A series of nitrogen mustard‐linked chalcones were synthesized and evaluated for their antitumor activity in vitro against the K562 and HepG2 cell lines. The aldol condensation of [N,N‐bis(chloroethyl)‐3‐amino]‐acetophenone ( 2 ) with aromatic aldehydes afforded the nitrogen mustard‐linked chalcones. Among the analogs tested, compounds 5e and 5k exhibited significant anti‐proliferation activities against K562 cells with IC₅₀ values of 2.55 and 0.61 µM, respectively, which revealed higher cell toxicity than the standard drugs cisplatin (IC₅₀ > 200 µM) and adriamycin (IC₅₀ = 14.88 µM). The methoxyl and N,N‐dimethyl groups on the B‐ring of the chalcone frame enhanced the inhibitory activities against both the K562 and HepG2 cell lines. The structure–activity relationship study indicated that the inhibitory activities significantly varied with the position(s) and species of the substituted group(s).     

Synthesis and evaluation of potential affinity labels derived from endomorphin‐2

Abstract: In an attempt to identify potential peptide‐based affinity labels for opioid receptors, endomorphin‐2 (Tyr‐Pro‐Phe‐PheNH₂), a potent and selective endogenous ligand for µ‐opioid receptors, was chosen as the parent peptide for modification. The tetrapeptide analogs were prepared using standard Fmoc‐solid phase peptide synthesis in conjunction with incorporation of Fmoc‐Phe(p‐NHAlloc) and modification of the p‐amino group. The electrophilic groups isothiocyanate and bromoacetamide were introduced into the para position on either Phe³ or Phe⁴; the corresponding free amine‐containing peptides were also prepared for comparison. The peptides bearing an affinity label group and their free amine analogs were evaluated in a radioligand‐binding assay using Chinese hamster ovary (CHO) cells expressing µ‐ and δ‐opioid receptors. Modification on Phe⁴ was better tolerated than on Phe³ for µ‐receptor binding. Among the analogs tested, [Phe(p‐NH₂)⁴]endomorphin‐2 showed the highest affinity (IC₅₀ = 37 nm ) for µ‐receptors. The Phe(p‐NHCOCH₂Br)⁴ analog displayed the highest µ‐receptor affinity (IC₅₀ = 158 nm ) among the peptides containing an affinity label group. Most of the compounds exhibited negligible binding affinity for δ‐receptors, similar to the parent peptide.     

Design,synthesis, and biological evaluation of novel 1,2‐diaryl‐4‐substituted‐benzylidene‐5(4H)‐imidazolone derivatives as cytotoxic agents and COX‐2/LOX inhibitors

A new series of 1,2‐diaryl‐4‐substituted‐benzylidene‐5(4H)‐imidazolone derivatives 4a–l was synthesized. Their structures were confirmed by different spectroscopic techniques (IR, ¹H NMR, DEPT‐Q NMR, and mass spectroscopy) and elemental analyses. Their cytotoxic activities in vitro were evaluated against breast, ovarian, and liver cancer cell lines and also normal human skin fibroblasts. Cyclooxygenase (COX)‐1, COX‐2 and lipoxygenase (LOX) inhibitory activities were measured. The synthesized compounds showed selectivity toward COX‐2 rather than COX‐1, and the IC₅₀ values (0.25–1.7 µM) were lower than that of indomethacin (IC₅₀ = 9.47 µM) and somewhat higher than that of celecoxib (IC₅₀ = 0.071 µM). The selectivity index for COX‐2 of the oxazole derivative 4e (SI = 3.67) was nearly equal to that of celecoxib (SI = 3.66). For the LOX inhibitory activity, the new compounds showed IC₅₀ values of 0.02–74.03 µM, while the IC₅₀ of the reference zileuton was 0.83 µM. The most active compound 4c (4‐chlorobenzoxazole derivative) was found to have dual COX‐2/LOX activity. All the synthesized compounds were docked inside the active site of the COX‐2 and LOX enzymes. They linked to COX‐2 through the N atom of the azole scaffold, while C?O of the oxazolone moiety was responsible for the binding to amino acids inside the LOX active site.

     

Facile Synthesis and In‐Vitro Antitumor Activity of Some Pyrazolo[3,4‐b]pyridines and Pyrazolo[1,5‐a]pyrimidines Linked to a Thiazolo[3,2‐a]benzimidazole Moiety

The key precursor E‐3‐(N,N‐dimethylamino)‐1‐(3‐methylthiazolo[3,2‐a]benzimidazol‐2‐yl)prop‐2‐en‐1‐one 4 was synthesized in good yield using Gold's reagent. The reaction of enaminone 4 with 5‐amino‐3‐aryl‐1‐phenylpyrazoles 5a , b in refluxing acetic acid in the presence of sulphuric acid, yielded pyrazolo[3,4‐b]pyridines 7a , b . Similarly, pyrazolo[1,5‐a]pyrimidines 10a , b and 14a – f were prepared by reaction of enaminone 4 with 5‐amino‐1H‐pyrazoles 8a , b and 12a – f , respectively. The structure of pyrazolo[1,5‐a]pyrimidine 10b was determined by X‐ray diffraction. The synthesized compounds were tested for their in‐vitro antitumor activity against the colon cancer cell line CaCo‐2; their cytotoxicity against the normal fibroblast cell line BHK was explored as well. Some of the tested compounds exhibited cell growth inhibitory activity. The significant antitumor activity of compound 14f against the CaCo‐2 cell line (IC₅₀ = 0.5 μg/mL) was coupled with a lower toxicity against BHK (IC₅₀ = 2.3 μg/mL).     

Some Hydrazones of 2‐Aroylamino‐3‐methylbutanohydrazide: Synthesis,Molecular Modeling Studies,and Identification as Stereoselective Inhibitors of HIV‐1

In accordance with our antiviral drug development attempt, acylhydrazone derivatives bearing amino acid side chains were synthesized for the evaluation of their antiviral activity against various types of viruses. Among these compounds, 8 _S , 11 _S , and 12 _S showed anti‐HIV‐1 activity with a 50% inhibitory concentration (IC₅₀) = 123.8 µM (selectivity index, SI > 3), IC₅₀ = 12.1 µM (SI > 29), IC₅₀ = 17.4 µM (SI > 19), respectively. Enantiomers 8 _R , 11 _R , and 12 _R were inactive against the HIV‐1 strain III_B. Hydrazones 8 _S , 11 _S , and 12 _S which were active against HIV‐1 wild type showed no inhibition against a double mutant NNRTI‐resistant strain (K103N;Y181C). Molecular docking calculations of R‐ and S‐enantiomers of 8 , 11 , and 12 were performed using the hydrazone‐bound novel site of HIV‐1 RT.     

Synthesis and cytotoxic evaluation of some new phthalazinylpiperazine derivatives

A new series of 1,4‐disubstituted phthalazinylpiperazine derivatives 7a–f , 12a–f and 20a–f were designed and synthesized in order to develop potent and selective antitumor agents. The target compounds were screened for their cytotoxic activities against A549, HT‐29 and MDA‐MB‐231 cancer cell lines in vitro. Among them, compounds 7a–f exhibited excellent selectivity for MDA‐MB‐231 with IC₅₀ values ranging from 0.013 µM to 0.079 µM. The most promising compound, 7e (IC₅₀ = 2.19 µM, 2.19 µM, 0.013 µM), was 9.3, 10, and 4.9 × 10³ times more active than vatalanib (IC₅₀ = 20.27 µM, 21.96 µM, 63.90 µM), respectively.     

Synthesis and Evaluation of Benzophenone O‐Glycosides as α‐Glucosidase Inhibitors

The first total synthesis of benzophenone O‐glycosides (iriflophenone 2‐O‐α‐L ‐rhamnopyranoside: 1 and aquilarisinin: 2 ) isolated from the leaves of Aquilaria sinensis and related new derivatives ( 3 – 12 ) was accomplished through suitable protecting group manipulations and glycosylation starting from commercially available L ‐rhamnose, D ‐glucose, D ‐galactose, D ‐mannose, D ‐xylose, and 1,3,5‐trihydroxybenzene. All synthesized benzophenone O‐glycosides were evaluated for their inhibitory activities against α‐glucosidase. Of these, benzophenone O‐glycosides 4 and 10 exhibited the most potent inhibitory activity in vitro against α‐glucosidase with IC₅₀ values of 168.7 ± 13.9 and 210.1 ± 23.9 µM, respectively, when compared with that of the positive control acarbose with an IC₅₀ value of 569.3 ± 49.7 µM.     

Synthesis and cytostatic properties of structure-simplified analogs of dolastatin 15*

Abstract: The linear peptide dolastatin 15 ( 1 ), a potent antineoplastic constituent from the shell-less mollusk Dolabella auricularia, has been selected as the lead compound for developing novel antitumor drugs. Recently LU103793 ( 2 ), a synthetic and structure-simplified analog of dolastatin 15, has been demonstrated to be highly cytotoxic [IC₅₀ = 0.1 nm ; M. De Arruda, C.A. Cocchiaro, C.M. Nelson, C. M. Grinnel, B. Janssen, A. Haupt & T. Barlozzari (1995) Cancer Res. 55 , 3085–3092]. Both compounds have been undergoing human cancer clinical trials in Europe and North America. Based on the novel structure of LU103793, a series of analogs modified at the N-terminal dolavalyl moiety and -Pro-Pro-benzylamide unit was developed. These synthesized analogs were tested using a sulforhodamine B (SRB) assay for the drug-screening program at NCI on a variety of human cancer cell lines. As expected, most analogs exhibited potent and selective growth inhibition against leukemia. Analog 18 was specifically active against HL-60 and K-562 cell lines (GI₅₀s: 0.05 µm and 0.07 µm , respectively) while analogs 14 and 17 were selectively potent against prostate and breast cancer cell lines (GI₅₀s at micromolar levels). However, all analogs were less potent than 2 as growth inhibitors of some breast and colon cancer cell lines (e.g. MDA-MB-435 and HT-29). We believe that modification of novel marine natural products as synthetic analogs might show particular promise for developing novel anticancer candidates with moderate specificity.     

Novel benzimidazo[2,1-c][1,4]thiazinone derivatives with potent activity against HSV-1

The synthesis of new 2‐carboxymethylsulfanylmethyl‐1H‐benzimidazole and 1,3‐dihydro‐4H‐benzo[4′,5′]imidazo[2,1‐c][1,4]thiazine‐4‐one‐8‐carboxylic acid derivatives was investigated. The antiviral activity of compounds 1–14 was tested against the herpes simplex virus 1. Compounds 5 and 14 showed potent activity as they inhibited virus propagation by 94.7% and 91.3% at a dose of 50 µg, respectively. Compounds 5 and 14 showed higher potency than Acyclovir at doses of 20 µg and 50 µg.     

Actions of a series of PPADS analogs at P2X1 and P2X3 receptors

Seven PPADS ( P yridoxal‐5′‐ P hosphate 6‐ A zophenyl 2′,4′‐ D i S ulfonate) analogs were investigated at Group 1 P2X receptors expressed in Xenopus oocytes. All seven analogs potently inhibited P2X₁ (IC₅₀ range, 5–32 nM) and P2X₃ (IC₅₀ range, 22–345 nM), the two Group I P2X receptor subtypes. Analogs showed greater inhibitory activity where the pyridoxal moiety of PPADS contained a 5′‐phosphonate group, rather than a 5′‐phosphate group. Analogs also showed greater potency where disulfonate groups were removed from, or substituted at, the azophenyl moiety. The most active analog was MRS 2257 (pyridoxal‐5′‐phosphonate 6‐azophenyl 3′,5′‐bismethylenephosphonate) at P2X₁ (IC₅₀, 5 nM) and P2X₃ (IC₅₀, 22 nM) receptors, being 14‐fold and 10‐fold more potent than PPADS itself. MRS 2257 produced a nonsurmountable inhibition when tested against a range of ATP concentrations, although blockade was reversed by about 85% after 20 minutes of washout. TNP‐ATP and Ip₅I were equipotent with MRS 2257 at P2X₁ receptors, whereas TNP‐ATP was 64‐fold more potent than MRS 2257 at P2X₃ receptors. In conclusion, the PPADS template can be altered at the pyridoxal and phenyl moieties to produce P2X₁ and P2X₃ receptor antagonists showing higher potency and greater degree of reversibility than the parent compound at these Group I P2X receptors. Drug Dev. Res. 53:281–291, 2001. © 2001 Wiley‐Liss, Inc.     

Design, synthesis, and biological evaluation of bromophenol derivatives as protein tyrosine phosphatase 1B inhibitors

3‐Bromo‐4,5‐bis(2,3‐dibromo‐4,5‐dihydroxybenzyl)‐1,2‐benzenediol (BDB) is a bromophenol purified from the marine red alga Rhodomela confervoides and exhibits potent protein tyrosine phosphatase 1B (PTP1B) inhibition (IC₅₀ = 1.7 µmol/L). In an effort to improve the PTP1B inhibitory activity, a series of derivatives were designed, synthesized, and evaluated in vitro. The preliminary structure–activity relationship indicated that the tricyclic scaffold and multi‐bromine atoms (four to five) attached to the aryl rings are important for PTP1B inhibition. Among these, compound 26 exhibited remarkable inhibitory activity against PTP1B with an IC₅₀ of 0.89 µmol/L, which was approximately two‐fold more potent than the initial lead compound BDB.     

Anticancer activity of gallic acid template‐based benzylidene indanone derivative as microtubule destabilizer

Benzylidene indanones have been designed and synthesized from gallic acid, a plant phenolic acid as possible anticancer agent. The best analogue of the series, that is, 3‐(3′,4′,5′‐trimethoxyphenyl)‐4,5,6‐trimethoxy‐2‐(4?‐nitrobenzylidene)‐indan‐1‐one ( 8 ) exhibited potent cytotoxicity (IC₅₀=3–10 μm ) against several human cancer cell lines through microtubule destabilization (IC₅₀=1.54 μm ) after occupying colchicine‐binding site of β‐tubulin. In cell cycle analysis, compound 8 exerted G2/M phase arrest in both MCF‐7 and MDA‐MB‐231 cells and induced apoptosis. It reduced 34.8% solid tumor in in vivo Ehrlich ascite carcinoma in Swiss albino mice at 30 mg/kg dose. In acute oral toxicity experiment, it was tolerable up to 300 mg/kg doses in Swiss albino mice. The lead compound 8 needs to be optimized for better activity.