New secondary metabolites from the mangrove-derived fungus Aspergillus sp. AV-2

Chemical investigation of the mangrove-derived fungus Aspergillus sp. AV-2 following fermentation on solid rice medium led to the isolation of a new phenyl pyridazine derivative (1) and a new prenylated benzaldehyde derivative, dioxoauroglaucin (2), together with fourteen known compounds (3-16). Chemical structures of the new compounds were unambiguously determined based on HRESIMS and extensive 1D and 2D NMR spectroscopic analyses. Compounds 2-7, 8 and 13 were assessed for their antiproliferative activity against Caco-2 cell lines, where flavoglaucin (6) revealed the most potent cytotoxicity with IC₅₀ of 2.87 μM.     

Novel semisynthetic derivatives of betulin and betulinic acid with cytotoxic activity

A series of new imidazole carboxylic esters (carbamates) and N-acylimidazole derivatives of betulin and betulinic acid (14–29) have been synthesized. The new compounds were screened for in vitro cytotoxicity activity against human cancer cell lines HepG2, Jurkat and HeLa. A number of compounds have shown IC₅₀ values lower than 2 μM against the cancer cell lines tested and the vast majority has shown a better cytotoxicity profile than betulinic acid, including the betulin derivatives. N-Acylimidazole derivatives 26 and 27 (IC₅₀ 0.8 and 1.7 μM in HepG2 cells) and the C-3 carbamate derivative 16 (IC₅₀ 2.0 μM in HepG2 cells) were the most promising compounds. Based on the observed cytotoxicity, structure–activity relationships have been established.     

Synthesis and proapoptotic activity of oleanolic acid derived amides

Thirty-one different 3-O-acetyl-OA derived amides have been prepared and screened for their cytotoxic activity. In the SRB assays nearly all the carboxamides displayed good cytotoxicity in the low μM range for several human tumor cell lines. Low EC₅₀ values were obtained especially for the picolinylamides 14–16, for a N-[2-(dimethylamino)-ethyl] derivative 27 and a N-[2-(pyrrolinyl)-ethyl] carboxamide 28. These compounds were submitted to an extensive biological testing and proved compound 15 to act mainly by an arrest of the tumor cells in the S phase of the cell cycle. Cell death occurred by autophagy while compounds 27 and 28 triggered apoptosis.     

Design,synthesis, in silico and in vitro studies of novel 4-methylthiazole-5-carboxylic acid derivatives as potent anti-cancer agents

Since inhibitors of mucin onco proteins are potential targets for breast cancer therapy, a series of novel 4-methylthiazole-5-carboxylic acid (1) derivatives 3a–k were synthesized by the reaction of 1 with SOCl₂ followed by different bases/alcohols in the presence of triethylamine. Once synthesized and characterized, their binding modes with MUC1 were studied by molecular docking analysis using Aruglab 4.0.1 and QSAR properties were determined using HyperChem. All synthesized compounds were screened for in vitro anti-breast cancer activity against MDA-MB-231 breast adenocarcinoma cell lines by Trypan-blue cell viability assay and MTT methods. Compounds 1, 3b, 3d, 3e, 3i and 3f showed good anti-breast cancer activity. Since 1 and 3d exhibited high potent activity against MDA-MB-231 cell lines, they show could be effective mucin onco protein inhibitors.     

Synthesis and biological evaluation of purine-pyrazole hybrids incorporating thiazole,thiazolidinone or rhodanine moiety as 15-LOX inhibitors endowed with anticancer and antioxidant potential

Novel purine-pyrazole hybrids combining thiazoles, thiazolidinones and rhodanines, were designed and tested as 15-LOX inhibitors, potential anticancer and antioxidant agents. All tested compounds were found to be potent 15-LOX inhibitors with IC₅₀ ranging from 1.76 to 6.12 µM. The prepared compounds were evaluated in vitro against five cancer cell lines: A549 (lung), Caco-2 (colon), PC3 (prostate), MCF-7 (breast) and HepG-2 (liver). Compounds 7b and 8b displayed broad spectrum anticancer activity against the five tested cell lines (IC₅₀ = 18.5–95.39 µM). While, compound 7h demonstrated moderate anticancer activity against lung A549 and colon Caco-2 cell lines. Antioxidant screening revealed that six compounds (5a, 5b, 6b, 7b, 7h and 8b) with IC₅₀ ranging from 0.93 to 14.43 µg/ml were found to be more potent scavengers of 2,2- diphenyl-1-picrylhydrazyl (DPPH) than the reference ascorbic acid with IC₅₀ value of 15.34 µg/ml. Compounds 7b, 7h and 8b, when evaluated for their antioxidant activity, where found to be potent DPPH scavengers. Moreover, compound 7b displayed twice the potency of ascorbic acid as NO scavenger. Docking study was performed to elucidate the possible binding mode of the most active compounds with the active site of 15-LOX enzyme. Collectively, the purine-pyrazole hybrids having thiazoline or thizolidinone moieties (7b, 7h and 8b) constitute a promising scaffold in designing more potent 15-LOX inhibitors with anticancer and antioxidant potential.     

2-Thienyl-4-furyl-6-aryl pyridine derivatives: Synthesis,topoisomerase I and II inhibitory activity,cytotoxicity, and structure–activity relationship study

Designed and synthesized 60 2-thienyl-4-furyl-6-aryl pyridine derivatives were evaluated for their topoisomerase I and II inhibitory activities at 20 μM and 100 μM and cytotoxicity against several human cancer cell lines. Compounds 8, 9, 11–29 showed significant topoisomerase II inhibitory activity and compounds 10 and 11 showed significant topoisomerase I inhibitory activity. Most of the compounds (7–21) possessing 2-(5-chlorothiophen-2-yl)-4-(furan-3-yl) moiety showed higher or similar cytotoxicity against HCT15 cell line as compared to standards. Most of the selected compounds displayed moderate cytotoxicity against MCF-7, HeLa, DU145, and K562 cell lines. Structure–activity relationship study revealed that 2-(5-chlorothiophen-2-yl)-4-(furan-3-yl) moiety has an important role in displaying biological activities.     

Synthesis and evaluation of 3-salicyloylpyridine derivatives as cytotoxic mitochondrial apoptosis inducers

A series of novel 3-salicyloylpyridines (4a–h) were synthesized with good yield by modified Knoevenagel–Stobbel method; o-allylation with allyl bromide lead to formation of compounds (5a–h). The synthesized compounds were characterized by spectroscopic techniques and evaluated for cytotoxic activity against human cancer cell lines. Compounds bearing hydroxyl group displayed high cytotoxicity (4a–h) as compared to o-allylated molecules (5a–h). The most active compound 4b was selected for further investigation to look for mechanism of cell death in prostate cancer (PC-3) cells. The apoptotic bodies induced by 4b in PC-3 cells were scanned by confocal microscopy and confirmed by scanning electron microscopy (SEM). Further results obtained from spectrofluorimetric determination of mitochondrial membrane potential (ΔΨm) and intracellular reactive oxygen species (ROS) in treated PC-3 cells revealed that mitochondria dependent apoptosis was involved in the cell death.     

Novel 9-(2-(1-arylethylidene)hydrazinyl)acridine derivatives: Target Topoisomerase 1 and growth inhibition of HeLa cancer cells

A series of 9-(2-(1-arylethylidene)hydrazinyl)acridine and its analogs were designed, synthesized and evaluated for biological activities. Various biochemical assays were performed to determine the free radical scavenging capacity of synthesized compounds (4a–4j). Anticancer activity of these compounds was assessed against two different human cancer cell lines viz cervical cancer cells (HeLa) and liver cancer cells (HepG2) as well as normal human embryonic kidney cell line (HEK 293). Compounds 4b, 4d and 4e showed potential anti-proliferative effects on HeLa cells. Based on results obtained from antioxidant and cytotoxicity studies, 4b, 4d and 4e were further studied in detail for different biological activities. 4b, 4d and 4e reduced the cell growth, inhibited metastatic activity and declined the potential of cell migration in HeLa cell lines. Topoisomerase1 (Top1) treated with compounds 4b, 4d and 4e exhibited inhibition of Top1 and prevented DNA replication. Molecular docking results validate that interaction of compounds 4b, 4d and 4e with Top1-DNA complex, which might be accountable for their inhibitory effects. Further it was concluded that compounds 4b, 4d and 4e arrests the cells at S phase and consequently induces cell death through DNA damage in HeLa cells.     

Synthesis and in vitro cytotoxicity of andrographolide-19-oic acid analogues as anti-cancer agents

The synthesis of a series of andrographolide-19-oic acid derivatives was described and their in vitro anti-tumor activity against two human cell lines was evaluated. Most compounds were found to exhibit significant cytotoxicity, better than andrographolide, and compounds 9d and 9b were identified as the most potent with IC₅₀ values of 1.18 and 6.28 μm against HCT-116 and MCF-7 cell lines, respectively. The preliminary results indicated that the oxidation of C-19-hydroxyl group of andrographolide to corresponding carboxyl group and the subsequent esterification of the formed carboxylic acid led to considerable improvement in cytotoxicity against the cancer cells.     

Synthesis and evaluation of novel sulfonamide analogues of 6/7-aminoflavones as anticancer agents via topoisomerase II inhibition

A series of new sulfonamide analogues of 6/7-aminoflavones were synthesized by using molecular hybridization approach. These new sulfonamide analogues were screened for antiproliferative activity against human hepatocellular carcinoma (HepG-2), human lung cancer cell line (A-549), human colorectal adenocarcinoma (Caco-2) cancer cell lines. Compounds 5p, 5q, 5t, 5v, 5w and 5x exhibited good anticancer activity against selected cancer cell lines. These compounds were further evaluated to predict their ability to inhibit topoisomerase-II enzyme. Compound 5x has shown potent antiproliferative activity (IC₅₀ value 0.98 µM) as compared to standard drug Adriamycin (IC₅₀ = 0.94 µM) indicating that these compounds exhibits anticancer activity via inhibition of topoisomerase-II enzyme. Docking results also have supported above observations by indicating that compounds are held in the active pocket by combination of various hydrogen and hydrophobic interactions with Top II-DNA-etoposide enzyme.     

In vitro cytotoxicity of novel 2,5,7-tricarbo-substituted indoles derived from 2-amino-5-bromo-3-iodoacetophenone

A series of novel 2,5,7-tricarbo-substituted indoles were prepared via sequential Sonogashira and Suzuki–Miyaura cross-coupling of 2-amino-5-bromo-3-iodoacetophenone with terminal acetylenes and aryl/styrylboronic acids followed by palladium chloride-mediated heteroannulation of the incipient 5-aryl/styryl-substituted 2-amino-3-(arylalkynyl)acetophenones. These polycarbo-substituted indole derivatives were evaluated for potential in vitro antiproliferative activity against the human breast adenocarcinoma (MCF-7) and human cervical cancer (HeLa) cell lines. Compounds 6f, 6i, 6k, 6m and 6n were found to exhibit significant cytotoxicity and selectivity against the HeLa cells. Compounds 6i and 6m were chosen as representative examples to evaluate their pro-apoptotic efficacy against the HeLa cell line. The compounds induced apoptosis through cell membrane alteration and DNA fragmentation caspase-dependent pathways.     

Synthesis and evaluation of novel α-substituted chalcones with potent anti-cancer activities and ability to overcome multidrug resistance

A series of forty α-substituted chalcones were synthesized and screened for their antiproliferative activities against HCT116 (colorectal) and HCC1954 (breast) cancer cell lines. Compounds 5a and 5e were found to be the most potent compounds with GI₅₀ values of 0.63 µM and 0.725 µM in HCC1954 cell line and 0.69 µM and 1.59 µM in HCT116 cell line, respectively. Both compounds induced a G2/M cell cycle arrest and caused apoptotic cell death in HCT116 cells as shown by the induction of PARP cleavage. The compounds also stabilized p53 in a dose-dependent manner in HCT116 cells following 24-hour treatment. Furthermore, both 5a and 5e were able to overcome multidrug resistance in two MDR-1 overexpressing multidrug resistant cell lines.     

Design and synthesis of mono-and di-pyrazolyl-s-triazine derivatives,their anticancer profile in human cancer cell lines,and in vivo toxicity in zebrafish embryos

s-Triazine is considered a privileged structure, as it is found in several FDA-approved drugs. In the framework of our ongoing medicinal chemistry project based on the use of s-triazine as a scaffold, we synthesized a series of mono- and di-pyrazolyl-s-triazine derivatives and tested them against four human cancer cell lines, namely Human breast carcinoma (MCF 7 and MDA-MB-231), hepatocellular carcinoma (HepG2), colorectal carcinoma (LoVo), and leukemia (K562). The cell viability assay revealed that most of the s-triazine compounds induced cytotoxicity in all four types of human cancer cell lines, however, compounds 4a, and 6g, both of them have a piperidine moiety in their structure were most effective. These two compounds affected the cell viability of cancer cells, with IC₅₀ values within the range between 5 to 9 µM. The cell cycle analysis showed that 4a and 6g induced S and G2/M phase cell cycle arrest in K562 cells. This could be the mechanism by which these molecules induced cytotoxicity in tested cancer cells. The prepared compounds were tested in zebrafish embryos to evaluate in vivo and developmental toxicity of the pyrazolyl-s-triazine derivatives in animals. None of the derivatives were lethal in the concentration range tested.     

Cytotoxicity and topoisomerase I/II inhibition of glycosylated 2-phenyl-indoles, 2-phenyl-benzo[b]thiophenes and 2-phenyl-benzo[b]furans

A panel of glycosylated DNA binding agents (1-12) designed as functional anthracycline mimics was screened against three solid-tumor cell lines (MCF-7, HT 29 and HepG2/C3A) and three non-tumor cell lines by the MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) cell viability assay. Several compounds showed better in vitro cytotoxicity and selectivity against MCF-7 cells than daunomycin and doxorubicin, two known DNA binding agents that are clinically-used anti-cancer agents. Although the selectivity for HT 29 and HepG2/C3A cells is generally lower, the IC₅₀ values of some analogs against these two cancer cell lines were of the same magnitude as doxorubicin. Because there was no correlation between DNA binding affinity and cytotoxicity, and because topoisomerase (Topo) inhibition is another biological mechanism of action of most anthracycline drugs, Topo I/II inhibition assays with 1-12 were performed. Some of the compounds showed strong inhibition against these enzymes at 100 ??M, but there was no clear correlation between cytotoxicity and Topo I/II inhibition ability. Topo I/II inhibition mode assays were also performed, which verified that these compounds are topoisomerase suppressors, not poisons. Based on these results, we conclude that although DNA binding and/or topoisomerase inhibition may contribute to the observed cytotoxicity of 1-12, other mechanisms of action are also likely to be important.     

New 2-arylbenzofurans with selective cytotoxicity from Morus wittiorum

Four new 2-arylbenzofuran derivatives wittifurans O, N, K and L (1–4) were isolated from the stem bark of Morus wittiorum. Their structures were elucidated on the basis of spectroscopic analysis. Compounds 1–3 were evaluated for their cytotoxicity against five human cancer cell lines. Compounds 1 and 2 exhibited selective cytotoxicity against human ovarian cancer cell line A2780 with IC₅₀ (μM) values of 1.80 and 1.32, respectively.     

Identification of spirobisnaphthalene derivatives with anti-tumor activities from the endophytic fungus Rhytidhysteron rufulum AS21B

The cultivation of the mangrove-derived fungus Rhytidhysteron rufulum AS21B in acidic condition changed its secondary metabolite profile. Investigation of the culture broth extract led to the isolation and identification of two new spirobisnaphthalenes (1 and 2) together with eleven known compounds (3–13) from the crude extract of the fungus grown under an acidic condition as well as six known compounds (4, 10, 14–17) were isolated from the crude extract of the fungus grown under a neutral condition. Their structures were elucidated on the basis of extensive spectroscopic data. The isolated compounds were evaluated for their cytotoxicity against two human cancer cell lines, Ramos lymphoma and drug resistant NSCLC H1975. Compounds 2 and 10 displayed the most promising anti-tumor activity against both cancer cell lines.     

Synthesis and cytotoxicity of A-homo-lactam derivatives of cholic acid and 7-deoxycholic acid

Using cholic acid and deoxycholic acid as starting materials, a series of 3-aza-A-homo-4-one bile acid and 7-deoxycholic acid derivatives were synthesized by the esterification, oxidation, reduction, oximation and Beckman rearrangement etc. The cytotoxicity of the synthesized compounds against MGC 7901 (human ventriculi carcinoma cell line), hela (human cervical carcinoma cell line), SMMC 7404 (human liver carcinoma cell line) were investigated. The results showed that bile acid and 7-deoxycholic-acid derivatives with 3-aza-A-homo-4-one configuration bearing a 6-hydroximino or 12-hydroximino group displayed a distinct cytotoxicity to Hela tumor cell line. In particular, the IC₅₀ values of the compounds 6 and 13 were 14.3 and 24.3  μmol/L against Hela human tumor cell line respectively. The information obtained from the studies may be useful for the design of novel chemotherapeutic drugs.     

Benzofuran–appended 4-aminoquinazoline hybrids as epidermal growth factor receptor tyrosine kinase inhibitors: synthesis,biological evaluation and molecular docking studies

A series of 2-arylbenzo[b]furan–appended 4-aminoquinazoline hybrids were prepared and evaluated for cytotoxicity in vitro against the human lung cancer (A549), colorectal adenocarcinoma (Caco-2), hepatocellular carcinoma (C3A) and cervical cancer (HeLa) cell lines. Compounds 10d and 10j exhibited significant cytotoxicity against the C3A and Caco-2 cell lines and induced apoptosis in these cell lines. Likewise, compounds 10d and 10e exhibited significant inhibitory activity towards epidermal growth factor receptor-tyrosine kinase phosphorylation (IC₅₀ values of 29.3?nM and 31.1?nM, respectively) against Gefitinib (IC₅₀?=?33.1?nM). Molecular docking of compounds 10 into EGFR-TK active site suggests that they bind to the region of EGFR like Gefitinib does.

     

Design and synthesis of the novel oleanolic acid-cinnamic acid ester derivatives and glycyrrhetinic acid-cinnamic acid ester derivatives with cytotoxic properties

Oleanolic acid (OA) and glycyrrhetinic acid (GA) are natural products with anticancer effects. Cinnamic acid (CA) and its derivatives also exhibited certain anticancer activity. In order to improve the anticancer activity of OA and GA, we designed and synthesized a series of novel OA-CA ester derivatives and GA-CA ester derivatives by using molecular hybridization approach. The 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay was used to assess their in vitro cytotoxicity on three cell lines (HeLa (cervical cancer), MCF-7 (breast cancer) and L-O2 (a normal hepatic cell)). Among the evaluated compounds, 3o presented the strongest selective cytotoxicity on HeLa cells (IC₅₀ = 1.35 μM) and showed no inhibitory activity against MCF-7 cells (IC₅₀ > 100 μM) and L-O2 cells (IC₅₀ > 100 μM), and 3e presented the strongest selective inhibition of the MCF-7 cells (IC₅₀ = 1.79 μM). What’s more, compound 2d also showed very strong selective inhibitory activity against HeLa cells (IC₅₀ = 1.55 μM). The further research using Hoechst 33342, AO/EB dual-staining, flow cytometric analysis and DCFH-DA fluorescent dye staining assay presented that 2d and 3o could induce HeLa cells apoptosis and autophagy.     

In vitro studies on the inhibition of colon cancer by amino acid derivatives of bromothiazole

The investment in cancer research is critical to find more and better treatments, but essentially to save lives. Here, we describe the synthesis and characterization on new bromothiazole derivatives with amino acids and with core of nitazoxanide, an FDA-approved antiprotozoal drug. Using a human adenocarcinoma-derived cell line (the Caco-2 cell line), we then investigated the antiproliferative (³H-thymidine incorporation) and cytotoxic (extracellular lactate dehydrogenase activity) effect of these derivatives. All the derivatives caused a concentration–dependent decrease in cell proliferation and viability. At their highest concentration, all compounds were able to reduce ³H-thymidine incorporation by more than 80%, corresponding to a more marked antiproliferative effect than butyrate. As to their cytotoxic effect, it was comparable to that of butyrate. The ability of bromo substituent in thiazole ring with new sequences of amino acids in inducing cell death and apoptosis in Caco-2 cells (and other cell lines) is now being studied.