Synthesis and biological evaluation of 1,2,3-triazole linked aminocombretastatin conjugates as mitochondrial mediated apoptosis inducers

A series of 1,2,3-triazole linked aminocombretastatin conjugates were synthesized and evaluated for cytotoxicity, inhibition of tubulin polymerization and apoptosis inducing ability. Most of the conjugates exhibited significant anticancer activity against some representative human cancer cell lines and two of the conjugates 6d and 7c displayed potent cytotoxicity with IC₅₀ values of 53 nM and 44 nM against A549 human lung cancer respectively, and were comparable to combretastatin A-4 (CA-4). SAR studies revealed that 1-benzyl substituted triazole moiety with an amide linkage at 3-position of B-ring of the combretastatin subunit are more active compared to 2-position. G2/M cell cycle arrest was induced by these conjugates 6d and 7c and the tubulin polymerization assay (IC₅₀ of 1.16 μM and 0.95 μM for 6d and 7c, respectively) as well as immunofluorescence analysis showed that these conjugates effectively inhibit microtubule assembly at both molecular and cellular levels in A549 cells. Colchicine competitive binding assay suggested that these conjugates bind at the colchicine binding site of tubulin as also observed from the docking studies. Further, mitochondrial membrane potential, ROS generation, caspase-3 activation assay, Hoechst staining and DNA fragmentation analysis revealed that these conjugates induce cell death by apoptosis.     

Quinazolino linked 4β-amidopodophyllotoxin conjugates regulate angiogenic pathway and control breast cancer cell proliferation

A series of new conjugates of quinazolino linked 4β-amidopodophyllotoxins 10aa–af and 10ba–bf were synthesized and evaluated for their anticancer activity against human pancreatic carcinoma (Panc-1) as well as breast cancer cell lines such as MCF-7 and MDA-MB-231 by employing MTT assay. Among these conjugates, some of them like 10bc, 10bd, 10be and 10bf exhibited high potency of cytotoxicity. Flow cytometric analysis showed that these conjugates arrested the cell cycle in the G2/M phase and caused the increase in expression of p53 and cyclin B1 protein with concomitant decrease in Cdk1 thereby suggesting the inhibitory action of these conjugates on mitosis. Interestingly, we observed a decrease in expression of proteins that control the tumor micro environment such as VEGF-A, STAT-3, ERK1/2, ERK-p, AKT-1 ser 473 phosphorylation in compounds treated breast cancer cells. Further, these effective conjugates have exhibited inhibitory action on integrin (αVβIII). Furthermore, the MCF-7 cells that were arrested and lost the proliferative capacity undergo mitochondrial mediated apoptosis by activation of caspases-9. Thus these conjugates have the potential to control breast cancer cell growth by effecting tumor angiogenesis and invasion.     

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.     

Quinazolinone linked pyrrolo[2,1-c][1,4]benzodiazepine (PBD) conjugates: Design,synthesis and biological evaluation as potential anticancer agents

A series of novel quinazolinone linked pyrrolobenzodiazepine (PBD) conjugates were synthesized. These compounds 4a–f and 5a–f were prepared in good yields by linking C-8 of DC-81 with quinazolinone moiety through different alkane spacers. These conjugates were tested for anticancer activity against 11 human cancer cell lines and found to be very potent anticancer agents with GI₅₀ values in the range of <0.1–26.2 μM. Among all the PBD conjugates, one of the conjugate 5c was tested against a panel of 60 human cancer cells. This compound showed activity for individual cancer cell lines with GI₅₀ values of <0.1 μM. The thermal denaturation studies exhibited effective DNA binding ability compared to DC-81 and these results are further supported by molecular modeling studies. The detailed biological aspects of these conjugates on A375 cell line were studied. It was observed that compounds 4b and 5c induced the release of cytochrome c, activation of caspase-3, cleavage of PARP and subsequent cell death. Further, these compounds when treated with A375 cells showed the characteristic features of apoptosis like enhancement in the levels of p53, p21 and p27 inhibition of cyclin dependent kinase-2 (CDK2) and suppression of NF-κB. Moreover, these two compounds 4b and 5c control the cell proliferation by regulating anti-apoptotic genes like (B-cell lymphoma 2) Bcl-2. Therefore, the data generated suggests that these PBD conjugates activate p53 and inhibit NF-κB and thereby these compounds could be promising anticancer agents with better therapeutic potential for the suppression of tumours.     

Design,synthesis and biological evaluation of novel β-pinene-based thiazole derivatives as potential anticancer agents via mitochondrial-mediated apoptosis pathway

A series of novel β-pinene-based thiazole derivatives were synthesized and characterized by HRMS, ¹H NMR, and ¹³C NMR analyses as potential antineoplastic agents. Derivatives were evaluated for their anticancer activities in vitro, and the data manifested that most target compounds showed potent anti-proliferative activities against three human cancer cell lines. Especially, compound 5g displayed excellent cytotoxic activity against Hela, CT-26, and SMMC-7721 cell lines with IC₅₀ values of 3.48 ± 0.14, 8.84 ± 0.16, and 6.69 ± 0.15 µM, respectively. To determine the underlying mechanism of compound 5g on cell viability, DAPI staining, Annexin-V/PI staining, JC-1 staining, DCFDA staining, and Western blot analysis were performed. Our data showed that compound 5g inhibited cell proliferation by inducing apoptosis and cell cycle arrest of Hela cells at the G0/G1 phase in a dose dependent manner. Further studies revealed that compound 5g enhanced levels of reactive oxygen species (ROS), caused a decrease in mitochondrial membrane potential, increased the release of mitochondrial cytochrome C, and affected the expression of Bax, Bcl-2, caspase-3 and caspase-9. Thus, our findings indicated that compound 5g induced apoptosis in Hela through ROS-mediated mitochondrial dysfunction signaling pathways.     

Synthesis and antitumor activities of novel α-aminophosphonates dehydroabietic acid derivatives

A series of novel α-aminophosphonate derivatives containing DHA structure were designed and synthesized as antitumor agents. In vitro antitumor activities of these compounds against the NCI-H460 (human lung cancer cell), A549 (human lung adenocarcinoma cell), HepG2 (human liver cancer cell) and SKOV3 (human ovarian cancer cell) human cancer cell lines were evaluated and compared with commercial anticancer drug 5-fluorouracil (5-FU), employing standard MTT assay. The pharmacological screening results revealed that many compounds exhibited moderate to high levels of antitumor activities against the tested cancer cell lines and that most demonstrated more potent inhibitory activities compared with the commercial anticancer drug 5-FU. The action mechanism of representative compound 7c was preliminarily investigated by acridine orange/ethidium bromide staining, Hoechst 33258 staining, JC-1 mitochondrial membrane potential staining and flow cytometry, which indicated that the compound can induce cell apoptosis in NCI-H460 cells. Cell cycle analysis showed that compound 7c mainly arrested NCI-H460 cells in G1 stage.     

Concise syntheses of 7-anilino-indoline-N-benzenesulfonamides as antimitotic and vascular disrupting agents

Described herein is the development of a novel series of 7-anilino-indoline-N-benzenesulfonamides, derived from ABT751 (1), as potent anticancer agents. Amongst the synthesized series, compounds 6, 12, 13, and 14 have shown comparable to better anticancer activity on comparing with compound 1. 7-(4-Cyanophenylamino)-1-(4-methoxybenzenesulfonyl)indoline (13) was found to be the most potent one with up to 6 fold better activity against KB, HT29, and MKN45 cancer cell lines with IC₅₀ values of 49.7, 149, and 92 nM, respectively. Compound 13 was also found inhibiting multidrug resistant cancer cell lines, blocking cell cycle at G2/M phase, and inhibiting tubulin polymerization. Capillary disruption assay results revealed that compound 13 was able to disrupt formed capillaries in a concentration-dependent manner without affecting cell viability.     

Synthesis,cytotoxicity, DNA binding and topoisomerase II inhibition of cassiarin A derivatives

Four series of cassiarin A derivatives with alkanoyl (3a–3d), aroyl (4a–4d), hydroxy/amino-substituted ethylene glycol (5a–5c) and selenium-containing (6a) side chains were synthesized. Their antitumor activities were evaluated against BT474, CHAGO, HepG2, KATO-III, SW620 and CaSki cancer cell lines. Preliminary results demonstrated that 5b had moderate activities against HepG2 and KATO-III cell lines, while 5c showed moderate to high cytotoxicity against most tested cell lines. In addition, 6a exhibited moderate cytotoxicity against cervical cells, CaSki. DNA-binding and ethidium bromide displacement experiments suggested that 5c and 5b binds to DNA via an intercalative mode, whereas 6a did not. However, the selenium-containing cassiarin A derivative 6a inhibited topoisomerase II with more than 95% inhibition at the concentration of 50 μM. These cassiarin A derivatives showed lower toxicity to normal cells, WI-38 than amonafide therefore they are potential lead compounds to be further developed as new anticancer agents.     

Synthesis and anticancer activity studies of indolylisoxazoline analogues

A new library of thirteen indolylisoxazolines 6a–m has been synthesized by the treatment of indolylchalcones with hydroxylamine hydrochloride. Evaluation of anticancer activity of indolylisoxazolines 6a–m led to the identification of potent compounds 6c–d, 6i and 6l, with IC₅₀ ranging 2.5–5.0?µM against the tested cancer cell lines. Using a number of complementary techniques such as acridine orange/ethidium bromide staining, PARP1 cleavage and DNA strand breaks assay, we show that the compounds 6c and 6i induce apoptosis in highly aggressive C4-2 cells. Our data further revealed that 6c and 6i inhibited C4-2 cells proliferation without inducing reactive oxygen species (ROS). Finally, we show that compounds 6c and 6i also potently inhibit cell migration, indicating these compounds have the potential to serve as effective anti-cancer agents.     

Design,synthesis and biological evaluation of 2-(3,4-dimethoxyphenyl)-6 (1,2,3,6-tetrahydropyridin-4-yl)imidazo[1,2-a]pyridine analogues as antiproliferative agents

Two series of forty five novel 2-(3,4-dimethoxyphenyl)-6-(1,2,3,6-tetrahydropyridin-4-yl) imidazo[1,2-a]pyridine analogues (IPA 1–22, IPS 1–22 and IP-NH) have been designed, synthesized and structures confirmed by ¹H NMR, ¹³C NMR, mass spectrometry. Furthermore, single crystal was developed for IPS-13. All the final derived conjugates were evaluated for their in vitro antiproliferative activity against a panel of diverse cancer cell lines viz., A549 (lung cancer), HeLa (cervical cancer), B16F10 (melanoma) and found to show potent anticancer activity on the tested cell lines. Many of them showed the IC₅₀ values in the range 2.0–20.0 µM. The most active compounds (IPA 5,6,8,9,12,16,17,19 and IPS 7,8,9,22) from IPA and IPS series were screened to determine their cytotoxicity on HEK-293 (human embryonic kidney) normal cell line and were found to be nontoxic to normal human cells. The molecular interactions of the derivatised conjugates were also supported by molecular docking simulations. These derivatives may serve as lead structures for development of novel potential anticancer drug candidates.     

Click chemistry-assisted synthesis of novel aminonaphthoquinone-1,2,3-triazole hybrids and investigation of their cytotoxicity and cancer cell cycle alterations

A series of 12 novel 1,4-naphthoquinone-1,2,3-triazole hybrids were designed and synthesized through copper-catalyzed click reaction of 2-(prop-2-ynylamino)naphthalene-1,4-dione (3) and different azidomethyl-benzene derivatives. The synthesized compounds were assessed for their anticancer activity against three cancer cell lines (MCF-7, HT-29 and MOLT-4) by MTT assay. The results showed that the majority of the synthesized compounds displayed cytotoxic activity. Derivatives 6f and 6h, bearing 4-trifluoromethyl-benzyl and 4-tert-butyl-benzyl groups, respectively, as well as intermediate 3 demonstrated good cytotoxic potential against all tested cancer cell lines, among which compound 6f showed the highest activity. Flow cytometric analysis revealed that compounds 3, 6f and 6h arrested cell cycle at G0/G1 phase in MCF-7 cells. Therefore, synthesized aminonaphthoquinone-1,2,3-triazole derivatives can be introduced as promising molecules for further development as potential anticancer agents.     

Synthesis,characterization and biological studies of diosgenyl analogues

A series of optical amino acid diosgenyl esters and diosgenyl salicylate conjugates were designed and synthesized to develop new anticancer and anti-inflammatory agents. The analogue 9c that contains an 6-aminohexanoic acid residue at C-3 of diosgenin exhibits higher potency against all three tumor cell lines with IC₅₀ values ranging from 4.7 μM in C26 cells to 14.6 μM in Hep G2 cells. In addition, seven of newly synthesized compounds significantly inhibit xylene-induced ear edema and exhibit comparable or better anti-inflammatory activities than those of diosgenin and aspirin. Furthermore, preliminary structure–activity relationship studies demonstrate that diosgenyl salicylate conjugates have stronger anti-inflammatory activities than amino acid diosgenyl esters.     

Imidazopyridine linked triazoles as tubulin inhibitors,effectively triggering apoptosis in lung cancer cell line

A library of new imidazopyridine linked triazole hybrid conjugates (8a-r) were designed, synthesized and evaluated for their cytotoxicity against four cancer cell lines namely, human lung (A549), human prostate (DU-145), human colon (HCT-116) and breast (MDA-MB 231) cancer. These conjugates exhibited good to moderate activity against the tested human cancer cell lines. Two of the conjugates (8g and 8j) showed significant antitumor activity against human lung cancer cell line (A549) with IC₅₀ values of 0.51 µM and 0.63 µM respectively. Flow cytometry analysis revealed that these conjugates arrested the cell cycle at G₂/M phase in human lung cancer cell line (A549). Immune-histochemistry and tubulin polymerization assay suggest inhibition of tubulin. Hoechst staining, annexin V and DNA fragmentation by tunnel assay suggested that these compounds induce cell death by apoptosis. Overall, the current study demonstrates that the synthesis of imidazopyridine linked triazole conjugates as promising anticancer agents causing G₂/M arrest and apoptotic-inducing ability.     

Synthesis and in vitro evaluation of 3-(4-nitrophenyl)coumarin derivatives in tumor cell lines

Coumarins are naturally-occurring compounds that have attracted considerable interest due to their numerous biological activities depending on their pattern of substitution on the coumarin molecule. In this present investigation, we synthesized 3-(4-nitrophenyl)coumarin derivatives (9a–e) and evaluated their in vitro cytotoxic effect on human lung (A549), breast (MDA-MB-231) and prostate (PC3) cancer cell lines for 48 h using crystal violet dye binding assay. Cytotoxic effects of the most active compound on normal human lung (MRC-9) and breast (MCF-10A) cell lines, cell cycle analysis using flow cytometry and mitochondrial membrane potential (MMP) using Tetramethyl Rhodamine Methyl Ester (TMRM; rhodamine-123) fluorescent dye were also examined. Among the compounds that were evaluated, 9c showed cytotoxic effect (active), caused significant cells arrest (p < 0.05) in G₀/G₁ and S phases of cell cycle and loss of MMP in A459, MDA-MB-231 and PC3 cell lines. Additionally, the cytotoxic effect of 9c was compared to reference drugs (Coumarin and Docetaxel) for comparative study. These results further demonstrate that acetoxy group at C-7 and C-8 positions of 9c are responsible for the observed cytotoxic effect in these cancer cell lines.     

Design,synthesis, and mechanism of action of 2-(3-hydroxy-5-methoxyphenyl)-6-pyrrolidinylquinolin-4-one as a potent anticancer lead

New 6- (or 6,7-) substituted 2-(hydroxyl substituted phenyl)quinolin-4-one derivatives were synthesized and screened for antiproliferative effects against cancer cell lines. Structure–activity relationship correlations were established and the most promising compound 2-(3-hydroxy-5-methoxyphenyl)-6-pyrrolidin-1-ylquinolin-4-one (6h) exhibited strong inhibitory activity against various human cancer cell lines, particularly non-small cell lung cancer NCI-H522. Additional studies suggested a mechanism of action resembling that of the antimitotic drug vincristine. The presence of a C-ring OH group in 6h will allow this compound to be converted readily to a water soluble and physicochemically stable hydrophilic prodrug. Compound 6h is proposed as a new anticancer lead compound.     

Design and synthesis of 2-(3-alkylaminophenyl)-6-(pyrrolidin-1-yl)quinolin-4-ones as potent antitumor agents

2-(3-Alkylaminophenyl)-6-(pyrrolidin-1-yl)quinolin-4-ones 1–3 were synthesized and screened for anti-proliferative activity against three human cancer cell lines, as well as the normal cell line Detroit 551. All of the synthesized target compounds 1–3 demonstrated potent cytotoxic activity against the cancer cell lines, but weak inhibitory activity toward the normal cell line. 2-(3-Methyl aminophenyl)-6-(pyrrolidin-1-yl)quinolin-4-one (1), one of the potent compounds in vitro, was also tested in an in vivo Hep3B xenograft nude mice model, and its significant anticancer activity was reconfirmed. Therefore, compound 1 merits further investigation as an antitumor clinical trial candidate and potential anticancer agent.     

Synthesis of pyrazolo[1,5-a]pyrimidine linked aminobenzothiazole conjugates as potential anticancer agents

A series of pyrazolo[1,5-a]pyrimidine linked 2-aminobenzothizole conjugates (6a–t) were synthesized and evaluated for their anticancer activity against five human cancer cell lines. Among them two compounds 6p and 6m showed significant anticancer activity with IC₅₀ values ranging from 2.01 to 7.07 and 1.94–3.46 μM, respectively. Moreover, cell cycle arrest in G₂/M and reduction in Cdk1 expression level were observed upon treatment of these compounds and they also induced caspase-3 dependent apoptosis. This was further confirmed by staining as well as DNA fragmentation analysis.     

Anticancer properties of N-alkyl-2, 4-diphenylimidazo [1, 2-a] quinoxalin-1-amine derivatives; kinase inhibitors

Structure activity correlation revealed that the quinoxaline ring is a satisfactory backbone for anticancer activity and a specific functional group at position 1 and 2 can improve the activity. In this basis, besides quinoxaline, imidazoles as potential anticancer agents were used as a supplementary agents for cancer treatment.In this paper, a new series of N-alkyl-2, 4-diphenylimidazo [1, 2-a] quinoxalin-1-amine derivatives were synthesized in a simple and efficient step. The products are fully characterized by 1H NMR, ¹³C NMR, FT-IR, HRMS, and CHN elemental analysis. Several starting materials with different functionalities have been used for the synthesis of the final products with high isolated yields. The biological activities of the synthesized compounds were evaluated in kinase inhibition and cytotoxic activity in several cancerous cell lines. All compounds (6) were evaluated for inhibition of the cell proliferation using 4 cancerous cell lines. Five of the more active compounds were studied for determination of IC50_%. Compounds 6(32–34) showed good activity on some of cancerous cell lines.The results showed that compound 6–32 has the highest biological activity (IC₅₀% 9.77 for K562 cell line). An IC₅₀% value of 15.84 µM was observed for 6–34. Furthermore 6–34 exhibited inhibition of ABL1 and c-Src kinases with an IC50% value of 5.25 µM and 3.94 µM respectively. Docking simulation was performed to position active synthesized compounds 6–32, 6–33, and 6–34 over the ABL1 active site in two different wild-type (DFG-in and DFG-out motif conformer) and T315I mutant to determine the probable binding orientation, conformation and mode of interaction. According to docking study, the docked location in wild type forms is similar and can be found near the P-loop region while in the case of T315I mutant form, the compounds have a distinct docked location which is close to the αC helix and activation loop. Also, it concluded the role of R₁ substituent on phenyl ring produced higher interaction energy. Additionally, the detailed inter-molecular energy and types of non-bonding interaction of these compounds over the wild-type and mutant form of ABL1.     

Antitumor agents 270. Novel substituted 6-phenyl-4H-furo[3,2-c]pyran-4-one derivatives as potent and highly selective anti-breast cancer agents

6-Phenyl-4H-furo[3,2-c]pyran-4-one derivatives based on neo-tashinlactone (1) were synthesized and evaluated as novel anti-breast cancer agents. Compounds 10–13, 23, 25, and 27 showed potent inhibition against the SK-BR-3 breast cancer cell line. Importantly, 25 and 27 showed the highest cancer cell line selectivity, being approximately 100–250-fold more potent against SK-BR-3 (ED₅₀ 0.28 and 0.44 μM, respectively) compared with other cancer cell lines tested. In addition, 25 displayed low cytotoxicity against normal breast cell lines 184A1 and MCF10A. Compounds 25 and 27 merit further investigation in our continuing program to generate and develop selective anti-breast cancer agents.     

Synthesis and biological evaluation of benzo[b]furo[3,4-e][1,4]diazepin-1-one derivatives as anti-cancer agents

A new series of novel Podophyllotoxin-like benzo[b]furo[3,4-e][1,4]diazepin-1-ones possessing structural elements of 4-aza-2,3-didehydropodophyllotoxins with central diazepine ring was designed and synthesized as anti-cancer agents. In initial assessment, the cytotoxic activity of the synthesized compounds was evaluated against three cancer cell lines including MCF-7, PC3 and B16-F10 employing the MTT assay. Some of compounds (12h, 13a, 13c and 14b) showed significant cytotoxic activity. So, we investigated the cytotoxicity of compounds 12h, 13a, 13c and 14b, along with podophyllotoxin as the reference drug in different cancer cell lines including A549, A2780, DU145, HeLa, and normal Huvec cell line. Among these four compounds, 13c showed promising antiproliferative activity against all cancer cells stronger than the other compounds and comparable to reference drug podophyllotoxin in some cancer cells. All these four compounds did not show significant cytotoxicity on normal Huvec cell line. The flow cytometry analysis of the MCF-7, PC3 and A2780 human cancer cell lines treated with 13c showed that 13c, induced apoptosis in the MCF-7, PC3 and A2780 human cancer cell lines, which is in good agreement to its cytotoxic activity as well. Compound 13c did not show significant influence on tubulin assembly and exert its cytotoxic effects via induction of apoptosis and has potent and selective cytotoxic effects in cancer cells.