Synthesis and antitumor properties of novel curcumin analogs

A series of novel curcumin (CC) analogs were synthesized by reacting substituted aldehydes with intermediates 4a and 4b. The inhibitory activities of these CC analogs were investigated on human cancer cells PC3, Bcap-37, and MGC-803 in vitro by MTT assay. The results showed that most of the title compounds displayed moderate to high levels of antitumor activities. Compound 5f, the most active CC analogs, has the IC₅₀ values of 1.34 ± 0.28, 3.90 ± 0.36, and 0.86 ± 0.44 μM against the three human cancer cells assayed, respectively. Furthermore, subsequent fluorescence staining and flow cytometry analysis indicated compound 5f could induce apoptosis in PC3, Bcap-37, and MGC-803 cells, and the apoptosis ratio reachs the peak (27.1 %) in MGC-803 cells at 24 h after treatment at 10 μM.     

Arylnitro monocarbonyl curcumin analogues: Synthesis and in vitro antitubercular evaluation

Curcumin is a natural product that has been reported to exhibit myriad pharmacological properties, one of which is antitubercular activity. It demonstrates antitubercular activity by directly inhibiting Mycobacterium tuberculosis (M.tb) and also enhances immune responses that ultimately lead to the elimination of M.tb by macrophages. This natural product is, however, unstable, and several analogues, noticeably monocarbonyl analogues, have been synthesized to overcome this challenge. Curcumin and its monocarbonyl analogues reported so far exhibit moderate antitubercular activity in the range of 7 to 16 μM. Herein, we report a straightforward synthesis of novel monocarbonyl curcumin analogues, their antitubercular activity, and the structure–activity relationship. The hit compound from this study, 3a , exhibits potent MIC₉₀ values in the range of 0.2 to 0.9 μM in both ADC and CAS media.     

Synthesis and antioxidant activity of curcumin analogs

Numerous biological activities including antioxidant, antitumor, anti-inflammation, and antivirus of the natural product curcumin were reported. However, the clinical application of it was significantly limited by its instability, poor solubility, less body absorbing, and low bioavailability. This review focuses on the structure modification and antioxidant activity evaluation of curcumin. To study the structure–activity relationship (SAR), five series of curcumin analogs were synthesized and their antioxidant activity were evaluated in vitro. The results showed that electron-donating groups, especially the phenolic hydroxyl group are an essential component to improve the antioxidant activity.     

Synthesis, anticancer and antibacterial activities of piperine analogs

A series of piperine analogs were synthesized by the condensation of piperic acid with different aminoacids and substituted aniline. The synthesized compounds (4a–4e) were evaluated for their anticancer activity against human cancer cell lines (MCF-7, Breast Cancer cell line, and Hela cervix cell line) and antibacterial activity against human pathogens (Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, Shigella dysenteriae, Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa). The efficacies of the synthesized compounds were superior to those of piperine in all tested human cancer cell lines. Among the tested conjugates, 4c showed significant anticancer activity against Hela cervix cell line with IC₅₀ of 0.736 μmol and 4a showed significant activity against breast cancer cell line. The antibacterial activity of the tested compounds was also found to be superior to that of piperine. The approach is novel as the abundantly available natural product piperine is utilized as precursor for the synthesis of new potential antimicrobial and anticancer agents.     

Synthesis and anticancer activity of asparagine analogs

A series of 11 asparagines substituted on N4 was prepared and evaluated for their ability to inhibit the growth of L5178Y leukemia cell cultures. These cells require an exogenous source of L-asparagine and should be sensitive to an asparagine antimetabolite. The compounds were prepared by reaction of phthalylaspartic anhydride with a primary or secondary amine, followed by removal of the phthalyl group with hydrazine. One compound, N,N-dibenzylasparagine, showed significant activity. Additional study of asparagine derivatives bearing large, lipophilic groups at N4 is warranted.     

Synthesis and antitumor activity of some curcumin analogs

In this study, four new curcurmin analogs (compounds 1, 2, 17 and 18) were synthesized. 17 [3,5-bis(4-hydroxy-3-methoxy-5-methylcinnamyl)N-methylpiperidone] showed high activity with GI50, TGI, and LC50 MG-MID values of 21.3, 70.7, and 97.7 microM, respectively. 18 [3,5-bis(4-hydroxy-3-methoxy-5-methylcinnamyl)-N-ethylpiperidone] showed the highest activity in this study with GI50, TGI, LC50 MG-MID values of 4.4, 33.8, 89.1 microM, respectively. 18 is even more active than curcumin with GI50, TGI, LC50 MG-MID values of 38.4, 35.6, 66.0 microM; respectively. 8 showed moderate selectivity towards Leukemia cell line-subpanel with a ratio of 5.6 (curcumin ratio: 1.2 for the same subpanel). The in vitro anti-tumor screening reveals that the results go hand in hand with the in vitro free radical scavenging effects. The antioxidant effect of these compounds depends mainly on the stabilization of the formed phenoxy free radical for which the p-hydroxy phenyl moiety is essential. o-substitution by electron-donating groups like the o-methoxy group (and to a even higher degree by the ethoxy group) increases the stability of phenoxy free radical, hence increasing both free scavenging and anti-tumor effects. Increasing the alkyl group chain on the N in the series of substituted N-alkyl piperidones as well as the extension of conjugation, increases the stabilization of phenoxy free radical and thereby the activity towards both free radical scavenging and anti-tumor effects. This may be attributed to an increased positive inductive effect and/or increased lipophilicity of the new compounds, a fact which is proven by the superior activities of compounds 17 and 18.     

Synthesis,X-ray crystal structure and biological properties of acetylenic flavone derivatives

The reactions of iodoflavone with 3-methyl-3-hydroxybut-1-yne and 3-methylbut-3-en-2-yne are described and the antimicrobial and cytotoxic activities of the obtained compounds have been tested. The molecular structures of 6-(3-hydroxy-3-methylbut-1-ynyl)-flavone (1a) and 6-(3-methylbut-3-en-1-ynyl) flavone (1b) have been determined by X-ray crystallography. The planar configuration of the two compounds has been attributed to intramolecular hydrogen bond interactions. In 1a, the presence of the hydroxyl group determines a dimeric arrangement of the molecules. In both compounds in the crystal state, molecular stacking has been observed.     

Synthesis and preliminary anticancer evaluation of 10-hydroxycamptothecin analogs

We have synthesized new 10-hydroxycamptothecin (HCPT) analogs and evaluated their anticancer activity in cell culture and in experimental animal tumor model. Although the new analogs were less potent against L1210 leukemia cells in vitro, some of them were more efficacious against L1210 leukemia in vivo compared to the parent HCPT.     

Synthesis,biological activity and conformational analysis of cyclic GRF analogs

A novel cyclic GRF analog, cyclo(Asp⁸-Lys¹²)-[Asp⁸,Ala¹⁵]-GRF(1-29)-NH₂, i.e. cyclo^8.12[Asp⁸,Ala¹⁵]-GRF(1-29)-NH₂, was synthesized by the solid phase procedure and found to retain significant biological activity. Solid phase cyclization of Asp⁸ to Lys¹² proceeded rapidly (～2h) using the BOP reagent. Substitution of Ala¹² with d -Ala² and/or NH₂-terminal replacement (desNH₂-Tyr¹ or N-MeTyr¹) in the cyclo^8.12[Asp⁸,Ala¹⁵]-GRF(1-29)-NH₂ system resulted in highly potent analogs that were also active in vivo. Conformational analysis (circular dichroism and molecular dynamics calculations based on NOE-derived distance constraints) demonstrated that cyclo^8.12[Asp⁸,Ala¹⁵]-GRF(1-29)-NH₂ contains a long α-helical segment even in aqueous solution. A series of cyclo^8.12 stereoisomers containing d -Asp⁸ and/or d -Lys¹² were prepared and also found to be highly potent and to retain significant α-helical conformation. The high biological activity of cyclo^8.12[N-MeTyr¹,d -Ala²,Asp⁸,Ala¹⁵]-GRF(1-29)-NH₂ may be explained on the basis of retention of a preferred bioactive conformation.     

抗癌药达沙替尼的热稳定性与晶型研究

本文对药物达沙替尼的热稳定性和晶型进行分析与研究。通过差示扫描量热仪(DSC)和热重分析仪(TGA)分析达沙替尼的热稳定性;通过X射线粉末衍射仪(XRD)及其原位高温附件(in situ high temperature)测定达沙替尼试样的多晶型结构及相转变。结果表明,达沙替尼存在两种晶型(分子中分别含1个结晶水和1.5个结晶水),在加热过程中两种晶型都会发生结构变化,失去结晶水后,最终变为相同的晶体结构,其熔点分别为285.68℃和285.50℃。     

Synthesis and anticancer activity of 13-membered cyclic enediynes

We herein describe the synthesis of 15 novel 13-membered cyclic enediyne derivatives using simple and straightforward approach. Representative examples were screened for their anticancer activities on 60 different human tumor cell lines representing various histologies viz. leukemia, melanoma, and cancers of lung, colon, kidney, ovary, breast, prostate, and central nervous system. The enediyne derivatives with halogen substitutions, especially fluorides were found to be active against most of the cell lines. The initial results indicates marginal to good inhibition for the growth of tumor cells for several cell lines, which shows the potential of these class of compound towards anticancer application.     

Synthesis of polyketide natural products and analogs as promising anticancer agents

Recent highlights in the synthesis of polyketide natural products and structural analogs as promising anticancer agents are described, focusing on the halichondrins and eribulin (Eisai), together with recently published research on bryostatin, dictyostatin, spongistatin, peloruside, spirastrellolide, palmerolide, reidispongiolide, spirangien and saliniketals. These examples demonstrate the centrality of bioactive polyketides in current and future anticancer drug discovery, and the increasingly key role of efficient total synthesis in providing a sustainable supply of such compounds for drug development.     

Synthesis and properties of chemotactic peptide analogs

As a part of a research program aimed at studying structure activity relationship in the field of chemotactic peptides, modified analogs of the potent chemoattractant HCO-Met-Leu-Phe-OH (fMLP) of the general formula HCO-Xaa-Leu-Yaa-OMe are examined. 4-Aminotetrahydrothiopyran-4-carboxylic acid (Thp) and 2-aminoindane-2-carboxylic acid (Ain) have been chosen as achiral, conformationally restricted amino acids suitable to mimick the external Met and Phe residues of fMLP-OMe. Studies on a first model, namely [Ain³]fMLP-OMe 1, have already been reported (12). Here the two remaining analogs (Thp¹, Ain³) 2 and [Thp¹] 3 have been synthesized. The conformation in the crystal of the disubstituted analog 2 has been determined and compared with those adopted by the parent fMLP-OMe and by previously studied models. The backbone conformation of 2 is characterized by helical folding centred at each of the three residues with the central Leu presenting helical handedness opposite to those of the two adjacent achiral residues. This conformation presents strong similarities with that adopted in the crystal by fMLP-OMe and resembles the conformation of fMLP bound to immunoglobulin (Bence-Jones dimer). The conformationally restricted analogs 2 and 3 are more active than the parent in the stimulation of directed mobility of human neutrophils but are practically inactive in the superoxide production. Crystals of 2 are orthorhombic, s.g. P 2₁ 2₁ 2₁, with a = 21.934 (8), b = 10.856 (2), c = 10.380 (2) Å. The structure has been refined to R = 0.071 for 2301 independent reflections with I > 1.5 σ.     

Synthesis and immunological properties of bombesin analogs

Bombesin (Bn, pGlu-Gln-Arg-Leu-Gly-Asn-Gln-Trp-Ala-Val-Gly-His-Leu-Met-NH₂) is one of the most potent peptides, possessing a variety of physiological and pharmacological functions. We find from CD spectroscopy that the eight C-terminal residues of bombesin [Bn(7-14)NH₂] have an ordered structure, and replacement of His-12 with Pro of Bn(7-14)NH₂ changes the conformation from ordered to a more unordered form. Antibodies to Bn(7-14)NH₂ cross-react to Bn and gastrin releasing peptide (GRP) in a dose-dependent manner. Antibodies to the Pro-analog do not recognize Bn or GRP. Substitution of the C-terminal amide by isopropylamide [Bn(7-14)NHC₃H₇(i))] makes its antibodies more specific to Bn than to GRP. It appears that this region of the peptide is an important antigenic determinant, which makes these antibodies differentiate between BN and GRP.     

Synthesis and antinociceptive activity of cyclic endomorphin-2 and morphiceptin analogs

Cyclic analogs of the opioid peptides endomorphin-2 and morphiceptin of the type Tyr-X-Phe-Phe-Y-NH2 and Tyr-X-Phe-D-Pro-Y-NH2 (X = Lys or Asp and Y = Lys or Asp), respectively, were synthesized in order to test their structure-activity relationships. Antinociceptive activity of the new analogs was assessed in the hot-plate test after intracerebroventricular administration in mice. The strong analgesic effect was observed for the analogs with Asp in position 2, while the analogs with Lys in the second position were inactive. Antinociception caused by Asp2 analogs was dose-dependent and reversed by the concomitant administration of the universal opioid antagonist naloxone and by the selective kappa antagonist, nor-BNI. However, receptor binding studies revealed poor affinity of all cyclic analogs at the mu-opioid receptor and no affinity at delta- and kappa-opioid receptors. It is most likely that the new cyclic analogs produced their antinociception by the release of dynorphin A, which subsequently acted on the kappa-opioid receptor.     

Synthesis and biological evaluation of new cyclic amidine analogs of chlorambucil

A number of novel cyclic amidine analogs of chlorambucil were synthesized and examined for cytotoxicity in breast cancer cell cultures and for inhibition of topoisomerases I and II. Evaluation of the cytotoxicity of these compounds employing a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and inhibition of [(3)H]-thymidine incorporation into DNA in both MDA-MB-231 and MCF-7 breast cancer cells demonstrated that these compounds were more active than chlorambucil. The degree to which these compounds inhibited cell growth breast cancer cells was directly correlated to DNA-binding affinity. These studies indicate that cyclic amidine analogs of chlorambucil are a potent catalytic inhibitor of topoisomerase II but not topoisomerase I. The highest degree of DNA binding and cytotoxicity in both MDA-MB-231 and MCF-7 breast cancer cells was observed for the compound, which possess a 4,5-dihydro-1H-imidazol moiety.