Synthesis and Biological Evaluation of a Series of Novel Celastrol Derivatives with Amino Acid Chain

The synthesis of celastrol analogues containing amino acid ester at the C(29) position and their evaluation for cytotoxic activities in vitro were reported. The MTT test showed that a set of derivatives with lower IC₅₀ values than that of the positive control group cisplatin and the parent compound celastrol, which exhibited greater antiproliferative activities. The most potent title compounds 2a and 2e exhibited cytotoxic activities in vitro against HeLa and A549 cell lines with IC₅₀ values of 0.371 and 0.237 μm , 0.235 and 0.109 μm , respectively. The apoptosis assay demonstrated that 2a and 2e can induces of A549 cell apoptosis in low concentrations. These results showed that 2a and 2e may be promising for further research as antitumor agents.     

Semi-synthesis and anti-tumor activity of novel 25-OCH3-PPD derivatives incorporating aromatic moiety

Previously we have reported that 25-OCH₃-PPD could suppress the reproduction of cancer cells and cause apoptosis without obvious toxicity. Herein, we aimed to enhance its bioactivity by introducing aromatic groups to its dammarane-type skeleton. These synthesized derivatives were tested for their inhibitory activities against five cancer cell lines. Of them, compounds 3a, 14a and 18a had the strongest antiproliferative activities against tumor cells (IC₅₀?<?15?µM, 5-fold to 10-fold increases than 25-OCH₃-PPD). Especially compound 14a displayed the most potent activity against DU145, MCF-7 and HepG2 cells (IC₅₀?=?6.7?±?0.8, 4.3?±?0.8 and 5.8?±?0.6?µM, respectively). Structure-activity relationships demonstrated that having aromatic ester at the C3 position could improve the bioactivity. The data provided new insights into exploring novel antiproliferative lead compounds.     

The red wine component ellagic acid induces autophagy and exhibits anti‐lung cancer activity in vitro and in vivo

Red wine consists of a large amount of compounds such as resveratrol, which exhibits chemopreventive and therapeutic effects against several types of cancers by targeting cancer driver molecules. In this study, we tested the anti‐lung cancer activity of 11 red wine components and reported that a natural polyphenol compound ellagic acid (EA) inhibited lung cancer cell proliferation at an efficacy approximately equal to that of resveratrol. EA markedly increased the expression of the autophagosomal marker LC3‐II as well as inactivation of the mechanistic target of rapamycin signalling pathway. EA elevated autophagy‐associated cell death by down‐regulating the expression of cancerous inhibitor of protein phosphatase 2A (CIP2A), and CIP2A overexpression attenuated EA‐induced autophagy of lung cancer cells. Treating tumour‐bearing mice with EA resulted in significant inhibition of tumour growth with suppression of CIP2A levels and increased autophagy. In addition, EA potentiated the inhibitory effects of the natural compound celastrol on lung cancer cells in vitro and in vivo by enhancing autophagy and down‐regulating CIP2A. These findings indicate that EA may be a promising chemotherapeutic agent for lung cancer, and that the combination of EA and celastrol may have applicability for the treatment of this disease.     

Synthesis and biological activity of some rigid analogues of flavone-8-acetic acid

Some rigid analogues of flavone-8-acetic acid are described. Direct in vitro toxicity of the synthesised compounds was evaluated towards four tumoral cell lines and the ability of these compounds to stimulate mouse peritoneal macrophages in culture to become tumoricidal (indirect toxicity) was also studied. All compounds were able to induce direct cytotoxicity only at very high concentrations but showed a remarkable indirect activity. In particular compound 4d was able to significantly increase macrophage lytic properties and has been selected for further investigations.     

Treatment of myeloid leukemic cells with the phosphatase inhibitor okadaic acid induces cell cycle arrest at either G1/S or G2/M depending on dose.

The phosphatase inhibitor okadaic acid was found to induce cell cycle arrest of human myeloid leukemic cell lines HL-60 and U937 in a concentration- and time-dependent manner. Exposure to low concentrations of okadaic acid (2-8nM) for 24-48 hr caused greater than 70% of cells to arrest at G2/M, with up to 40% of the cells arrested in early mitosis. Cell viability decreased rapidly after 48 hr of treatment, and morphological and DNA structure analysis indicated that this was primarily due to the induction of apoptosis. The cells arrested in mitosis by 8 nM okadaic acid could be highly enriched by density gradient centrifugation and underwent apoptosis when further cultured either with or without okadaic acid, indicating that the effects of okadaic acid were irreversible. In contrast to the effects of low concentrations of okadaic acid, high concentrations (500 nM), inhibited proliferation in less than 3 hr. Remarkably, the majority of cells also entered a mitosis-like state characterized by dissolution of the nuclear membrane and condensation and partial separation of chromosomes. However, these cells had a diploid content of DNA, indicating that the cell cycle arrest occurred at G1/S with premature chromosome condensation (PCC), rather than at G2/M. If cells were first blocked at G1/S with hydroxyurea and then treated with okadaic acid, greater than 90% developed PCC in less than 3 hr without replicating their DNA. Caffeine was not able to induce PCC in these cells, either with or without prior inhibition of DNA synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Novel 1,2,4-triazole and imidazole derivatives of L-ascorbic and imino-ascorbic acid: synthesis, anti-HCV and antitumor activity evaluations

Several novel 1,2,4-triazole and imidazole L-ascorbic acid (1, 2, 3, 5, 6 and 9) and imino-ascorbic acid (4, 7 and 8) derivatives were prepared and evaluated for their inhibitory activity against hepatitis C virus (HCV) replication and human tumour cell proliferation. Compounds 6 and 9 exerted the most pronounced cytostatic effects in all tumour cell lines tested, and were highly selective for human T-cell acute lymphoblastic leukaemia cells (CEM/0) with IC(50)s of 10 ± 4 and 7.3 ± 0.1 μM, respectively. Unlike compound 9, compound 6 showed no toxicity in human diploid fibroblasts. One of the possible mechanisms of action of compound 6 accounting for observed cytostatic activity towards haematological malignancies might be inhibition of inosine monophosphate dehydrogenase (IMPDH) activity, a key enzyme of de novo purine nucleotide biosynthesis providing the cells with precursors for DNA and RNA synthesis indispensable for cell growth and division, which has emerged as an important target for antileukemic therapy. In addition, this compound proved to be the most potent inhibitor of the hepatitis C virus replication as well. However, observed antiviral effect was most likely associated with the effect that the compound exerted on the host cell rather than with selective effect on the replication of the virus itself. In conclusion, results of this study put forward compound 6 as a potential novel antitumor agent (IMPDH inhibitor) for treating leukaemia. Its significant biological activity and low toxicity in human diploid fibroblasts encourage further development of this compound as a lead.     

Synthesis and characterisation of celastrol derivatives as potential anticancer agents

In the present study, three series of novel celastrol derivatives were designed and synthesised by modifying the carboxylic acid at the 20th position with amino acid, amine, and triazole derivatives. All the synthesised compounds were screened for their anticancer activities using MTT assay against AGS, MGC-803, SGC-7901, HCT-116, A549, HeLa, BEL-7402, and HepG-2 cell lines. Most of the synthesised compounds exhibited potent antiproliferative effects. The most promising compound 3-Hydroxy-9β,13α-dimethyl-2-oxo-24,25,26-trinoroleana-1(10),3,5,7-tetraen-29-oic amide, N-(R)-methyl-3-(1H-indol-2-yl)propanoate (11) showed considerable high anticancer activity against AGS cell lines, with an IC₅₀ value of 0.44?μM, and considerably higher activities against HCT-116, BEL-7402, and HepG-2 cell lines, with IC₅₀ values of 0.78, 0.63, and 0.76?μM, respectively. The results of apoptosis tests and molecular docking study of compound 11 binding to Caspase-3 revealed that its mechanism of action with antiproliferative was possibly involved in inducing apoptosis by inducing the activation of caspase-3.     

Constituents in Easter lily flowers with medicinal activity

Easter lily (Lilium longiflorum) flowers have been used in traditional medicine for alleviating many ailments. However, the chemical basis of its bioactivity has not been investigated. We have determined bioactive components in Easter lily flowers using lipid peroxidation and cyclooxygenase enzyme inhibitory assays and found to be kaempferol (1), kaempferol glycosides (2, 3, 4, 8, 9 and 10), quercetin glycosides (5, 6 and 7), a regaloside (11), a chalcone (12) and a fatty acid fraction (13). The structures of compounds were determined by NMR, IR, UV/VIS and mass spectroscopic studies. Compound 1 showed the highest COX-1 inhibition (94.1%) followed by 3, 8 and 12 with 38.7, 30.8 and 32.4%, respectively. Only compound 1 inhibited COX-2 enzyme by 36.9% at 80 ppm. In lipid peroxidation inhibitory assay, kaempferol showed 37 and 100 % inhibitions at 1 and 10 ppm, respectively. At 10 ppm, more than 20% inhibition was observed for compounds 4, 7, 10, 11 and 12 and 53% for compound 3. The compounds reported in here are isolated for the first time from Easter lily flowers including novel compounds 10, 11 and 12. Our results suggest that kaempferol and quercetin flavonoids contributed to the anecdotal medicinal properties of Easter lily flowers.     

Psoralen activity and binding sites in melanotic and amelanotic human melanoma cells

The biological activity and specific binding sites of 8-methoxypsoralen (8-MOP) are assayed using two human melanoma cell lines, melanotic SK-Mel 28 and amelanotic C32TG. Long-term (72 hr) treatment with 8-MOP at a concentration of 10(-4)M results in an increase in melanogenesis and a decrease in proliferation, similar in both cell lines. Daily exposure of these cells to ultraviolet A (UVA) irradiation (1.28 mJ/cm(2)) does not enhance the response to the compound. Daily pulse application (30 min daily) of 8-MOP does not promote any response. However, in combination with UVA, 8-MOP pulse treatment becomes as effective as the long-term treatment. A decrease in cell proliferation in the constant presence of 8-MOP is not coupled with apoptosis, since no increase in the number of apoptotic nuclei was observed after the treatment. The flow cytometry indicates that 8-MOP arrests the cells at the G0/G1 phase, irrespective of the presence or absence of UVA light. In view of the lack of epidermal growth factor (EGF) receptors in both cell lines, it is not likely that such an arrest is associated with the down-regulation of EGF receptors by 8-MOP. It is noted that this compound elicits a biphasic cell response, since cell proliferation increases after the first 24-hr treatment, whereas it decreases in the subsequent 48 hr and thereafter. Competition binding assays using 3H-8-MOP disclosed: 1) the specific binding of the compound in both cell lines occurs in the presence or absence of UVA light, and 2) a higher binding rate at low concentrations of the compound is in SK-Mel 28 (72%) rather than C32TG (58%) cells. The competition assays in the presence of UVA suggest a possible occurrence of covalent bindings between psoralen and receptor, as DNA covalent binding accounted to only 3-5% of the total binding in both cell lines.     

NF-Kappa B Modulation Is Involved in Celastrol Induced Human Multiple Myeloma Cell Apoptosis

Celastrol is an active compound extracted from the root bark of the traditional Chinese medicine Tripterygium wilfordii Hook F. To investigate the effect of celastrol on human multiple myeloma cell cycle arrest and apoptosis and explore its molecular mechanism of action. The activity of celastrol on LP-1 cell proliferation was detected by WST-8 assay. The celastrol-induced cell cycle arrest was analyzed by flow cytometry after propidium iodide staining. Nuclear translocation of the nuclear factor kappa B (NF-κB) was observed by fluorescence microscope. Celastrol inhibited cell proliferation of LP-1 myeloma cell in a dose-dependent manner with IC50 values of 0.8817 µM, which was mediated through G1 cell cycle arrest and p27 induction. Celastrol induced apoptosis in LP-1 and RPMI 8226 myeloma cells in a time and dose dependent manner, and it involved Caspase-3 activation and NF-κB pathway. Celastrol down-modulated antiapoptotic proteins including Bcl-2 and survivin expression. The expression of NF-κB and IKKa were decreased after celastrol treatment. Celastrol effectively blocked the nuclear translocation of the p65 subunit and induced human multiple myeloma cell cycle arrest and apoptosis by p27 upregulation and NF-kB modulation. It has been demonstrated that the effect of celastrol on NF-kB was HO-1-independent by using zinc protoporphyrin-9 (ZnPPIX), a selective heme oxygenase inhibitor. From the results, it could be inferred that celastrol may be used as a NF-kB inhibitor to inhibit myeloma cell proliferation.     

Newly synthesized bis-benzimidazole derivatives exerting anti-tumor activity through induction of apoptosis and autophagy

In this study, a new series of bis-benzimidazole derivatives were designed and synthesized. Most of these new compounds showed significant anti-tumor activity in vitro compared to Hoechst 33258. Among them, the most potent compound 8 had the IC₅₀ values of 0.56 μM for HL60 (Human promyelocytic leukemia cells) tumor cell line and 0.58 μM for U937 (Human leukemic monocyte lymphoma cells) tumor cell line. Subsequent toxicity study on human peripheral blood mononuclear cells (PBMC) showed that compound 8 exhibited less toxicity than 5-FU. We also found that apoptosis and autophagy were simultaneously induced by compound 8 in HL60 cells, and inhibition of autophagy by 3-MA decreased compound 8-induced apoptosis, indicating that they acted in synergy to exert tumor cell death.     

Synthesis of 3- and 29-substituted celastrol derivatives and structure-activity relationship studies of their cytotoxic activities

A series of 3-carbamate and 29-ester celastrol derivatives (compounds 1–26) were designed and synthesized. These analogues were evaluated for their cytotoxic activities against several cancer cell lines. Cytotoxicity data revealed that the properties of substituents and substitution position had important influence on cytotoxic activity. Modification of C-3 hydroxyl with size-limited groups did not reduce the activity obviously. The introduction of polarity group like piperazine could improve the solubility. Compound 23 was chosen to further evaluate anti-tumor efficacy in vivo. It showed higher inhibition rate and better safety than celastrol during in vivo experiment by intragastric administration. The preliminary antitumor studies of compound 23in vivo showed that it might be promising for the development of new antitumor agents.     

Natural daucane sesquiterpenes with antiproliferative and proapoptotic activity against human tumor cells

Plants of the genera Ferula and Ferulago are known for their complex content in bioactive secondary metabolites such as coumarins, phenylpropanoids, and sesquiterpenes. We used the ground parts of Ferula communis subsp. communis, Ferula glauca subsp. glauca and Ferulago campestris as natural sources for the isolation of four coumarins (CU-1 to CU-4), two phenylpropanoids (PE-1 and PE-2), one polyacetylene (PA-1) and 16 daucane esters (DE-1 to DE-16). The cytotoxic activity of the isolated compounds was evaluated against a panel of seven human tumor cell lines. Fourteen of the daucane derivatives showed antiproliferative activity at least against one of the human tumor cell lines tested, four compounds (DE-5, DE-8, DE-11, and DE-16) were active against all the tested cell lines. Among them DE-11 was the most cytotoxic compound against HeLa (4.4 ± 0.7 μM), A549 (2.8 ± 1.4 μM), HL-60 (2.6 ± 0.4 μM), K562 (26.5 ± 6.0 μM) RS 4;11 (1.7 ± 0.3 μM) and SEM (2.4 ± 0.1 μM) cell lines, while DE-8 was the most active against Jurkat (3.3 ± 0.8 μM). Preliminary structure-activity relationship suggests that the most active compounds in the daucane series present the trans fusion of the penta- and hepta-atomic cycles, and lipophylic ester groups linked to position 6. Isomeric derivatives such as DE-8 and DE-9 or DE-3, DE-4, and DE-5 exhibited significant differences in their IC(50) supporting that the β orientation for the ester group in the position 2 enhances the cytotoxic activity. Furthermore, the pro-apoptotic effect of the most active compounds evaluated in Jurkat cell line showed that these compounds are able to induce apoptosis in a time and concentration-dependent manner. Our findings suggest the potential role of daucane derivatives as models for the development of proapoptotic compounds.     

Synthesis,in vitro and in vivo antitumor and antiviral activity of novel 1-substituted benzimidazole derivatives

Abstract

A novel series of 5-nitro-1H-benzimidazole derivatives substituted at position 1 by heterocyclic rings was synthesized. Cytotoxicity and antiviral activity of the new compounds were tested. Compound 3 was more active than doxorubicin against A-549, HCT-116 and MCF-7. However, compound 3 showed no activity against human liver carcinoma Hep G-2 cell line. Compounds 9 and 17b (E) showed potency near to doxorubicin against the four cell lines. The acute toxicity of compound 9 on liver cancer induced in rats was determined in vivo. Interestingly, it showed restoration activity of liver function and pathology towards normal as compared to the cancer-bearing rats induced by DENA. Compounds 17a (Z), 17b (E) and 18a (Z) were the most promising compounds for their antiviral activity against rotavirus Wa strain.     

Semisynthesis of some novel thiourea and carbamimidothioic acid derivatives using natural alkaloid L-norephedrine and their anticancer activity

A novel series of thiourea and carbamimidothioic acid derivatives was synthesized using natural alkaloid L-norephedrine as a starting material. Structures of the newly synthesized compounds were confirmed by analytical and spectral data. The synthesized compounds were evaluated in vitro for anticancer activity against the human breast (MCF-7), human liver (HEPG2), and human colon (HCT116) cancer cell lines. Best activity of the synthesized compounds was expressed against HEPG2, however, none of the compounds exceeded the IC₅₀ of doxorubicin. The corresponding N-(1-(2-chloroacetoxy)-1-phenylpropan-2-yl)-N′-p-tolylcarbamimidothioic acid was the most potent compound and exhibited higher cytotoxic activity against the human colon cancer cell line (HCT116) when compared with the reference drug doxorubicin. Also, this compound was the most active against the MCF-7 cell line but less active than the positive control.     

Synthesis,selective cytotoxicities and probable mechanism of action of 7-methoxy-3-arylflavone-8-acetic acids

Thirteen new analogues of flavone-8-acetic acid, that is, compounds 10a–m bearing a methoxy group at the 7-position and diverse subsitiuents on the benzene ring at the 2- and 3-positions of flavone nucleus, were synthesized and evaluated for their direct antiproliferative effects on two human tumor cell lines and for their indirect antiproliferative activities in the transwell co-culture system. The results indicated that most of compounds 10a–m showed moderate direct cytotoxicities. Among them, compound 10i exhibited higher direct cytotoxicity and selectivity for both cell lines over BJ human foreskin fibroblast cells than 5,6-dimethylxanthenone-4-acetic acid (DMXAA). Interestingly, compared with DMXAA, compound 10e showed comparable indirect cytotoxicity and higher selectivity. In addition, compound 10e was found to be able to induce tumor necrosis factor α (TNF-α) production in human peripheral blood mononuclear cells.     

Inhibition of mammary carcinoma growth by retinoidal benzoic acid derivatives

The growth of many breast carcinoma cell lines is inhibited by vitamin A, and derivatives as well as synthetic retinoids. New retinoidal derivatives have recently been synthesized. These retinoidal benzoic acid derivatives displayed enhanced potency in their ability to reverse hamster tracheal keratinization and inhibit ornithine decarboxylase induction in mouse epidermis. We therefore screened a series of analogues of these compounds for their ability to inhibit human breast carcinoma cell proliferation utilizing three estrogen receptor-positive and two estrogen receptor-negative cell lines. The compound (E)-4-2-(5,6,7,8)tetrahydro-5,5,8,8-tetramethyl-2-naphtalenyl)prop enyl benzoic acid (Ro 1374-10) was approximately 2-3 orders of magnitude more potent than all-trans-retinoic acid in inhibiting breast carcinoma cell proliferation while the compound SRI-6409-40, which differs from Ro 1374-10 only by the position of a methyl group, was 50-fold more potent than Ro 1374-10. All of the compounds tested displayed were inactive against the estrogen receptor-negative breast carcinoma lines.     

Beta-3-Oxindolylalanine: The main intermediate in tryptophan degradation occurring in acid hydrolysis of protein.

Under hydrolytic conditions using 6 M HCl, tryptophan reacted separately with dithiodiglycolic acid and cystine to give beta-3-oxindolylalanine (beta-[3-(2-indolinone)]alanine) as the main product. A compound, which eluted in the amino acid analyzer at the same position as beta-3-oxindolylalanine, was found in the acid hydrolyzate of lysozyme. The identicalness of these two compounds was established by comparison of their ultraviolet absorption spectra, elution positions on ion exchange chromatograms, etc. The "acid degradation product of tryptophan", which is known to be produced upon acid hydrolysis of tryptophan-containing proteins, must also be the same compound.     

Toxicity of N-substituted aromatics to acetoclastic methanogenic activity in granular sludge.

N-substituted aromatics are important priority pollutants entering the environment primarily through anthropogenic activities associated with the industrial production of dyes, explosives, pesticides, and pharmaceuticals. Anaerobic treatment of wastewaters discharged by these industries could potentially be problematical as a result of the high toxicity of N-substituted aromatics. The objective of this study was to examine the structure-toxicity relationships of N-substituted aromatic compounds to acetoclastic methanogenic bacteria. The toxicity was assayed in serum flasks by measuring methane production in granular sludge. Unacclimated cultures were used to minimize the biotransformation of the toxic organic chemicals during the test. The nature and the degree of the aromatic substitution were observed to have a profound effect on the toxicity of the test compound. Nitroaromatic compounds were, on the average, over 500-fold more toxic than their corresponding aromatic amines. Considering the facile reduction of nitro groups by anaerobic microorganisms, a dramatic detoxification of nitroaromatics towards methanogens can be expected to occur during anaerobic wastewater treatment. While the toxicity exerted by the N-substituted aromatic compounds was closely correlated with compound apolarity (log P), it was observed that at any given log P, N-substituted phenols had a toxicity that was 2 orders of magnitude higher than that of chlorophenols and alkylphenols. This indicates that toxicity due to the chemical reactivity of nitroaromatics is much more important than partitioning effects in bacterial membranes.