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Herein, we evaluated the anti-cancer effect and molecular mechanisms of a novel betulinic acid (BA) derivative, SYK023, by using two mouse models of lung cancer driven by KrasG12D or EGFRL858R. We found that SYK023 inhibits lung tumor proliferation, without side effects in vivo or cytotoxicity in primary lung cells in vitro. SYK023 triggered endoplasmic reticulum (ER) stress. Blockage of ER stress in SYK023-treated cells inhibited SYK023-induced apoptosis. In addition, we found that the expression of cell cycle-related genes, including cyclin A2, B1, D3, CDC25a, and CDC25b decreased but, while those of p15INK4b, p16INK4a, and p21CIP1 increased following SYK023 treatment. Finally, low doses of SYK023 significantly decreased lung cancer metastasis in vitro and in vivo. Expression of several genes related to cell migration, including synaptopodin, were downregulated by SYK023, thereby impairing F-actin polymerization and metastasis. Therefore, SYK023 may be a potentially therapeutic treatment for metastatic lung cancer.

Podophyllotoxin (PPT), as well as its congeners and derivatives, exhibits pronounced biological activities, especially antineoplastic effects. Its strong inhibitory effect on tumor cell growth led to the development of three of the most highly prescribed anticancer drugs in the world, etoposide, teniposide, and the water-soluble prodrug etoposide phosphate. Their clinical success as well as intriguing mechanism of action stimulated great interest in further modification of PPT for better antitumor activity. The C-4 position has been a major target for structural derivatization aimed at either producing more potent compounds or overcoming drug resistance. Accordingly, numerous PPT derivatives have been prepared via hemisynthesis and important structure-activity relationship (SAR) correlations have been identified. Several resulting compounds, including GL-331, TOP-53, and NK611, reached clinical trials. Some excellent reviews on the distribution, sources, applications, synthesis, and SAR of PPT have been published. This review focuses on a second generation of new etoposide-related drugs and provides detailed coverage of the current status and recent development of C-4-modified PPT analogs as anticancer clinical trial candidates., (© 2014 Wiley Periodicals, Inc.)

Twelve novel 20-sulfonylamidine derivatives (9a-9l) of camptothecin (1) were synthesized via a Cu-catalyzed three-component reaction. They showed similar or superior cytotoxicity compared with that of irinotecan (3) against A-549, DU-145, KB, and multidrug-resistant (MDR) KBvin tumor cell lines. Compound 9a demonstrated better cytotoxicity against MDR cells compared with that of 1 and 3. Mechanistically, 9a induced significant DNA damage by selectively inhibiting Topoisomerase (Topo) I and activating the ATM/Chk related DNA damage-response pathway. In xenograft models, 9a demonstrated significant activity without overt adverse effects at 5 and 10 mg/kg, comparable to 3 at 100 mg/kg. Notably, 9a at 300 mg/kg (i.p.) showed no overt toxicity in contrast to 1 (LD50 56.2 mg/kg, i.p.) and 3 (LD50 177.5 mg/kg, i.p.). Intact 9a inhibited Topo I activity in a cell-free assay in a manner similar to that of 1, confirming that 9a is a new class of Topo I inhibitor. 20-Sulfonylamidine 1-derivative 9a merits development as an anticancer clinical trial candidate.

Structural optimizations of the prior lead 1a led to the discovery of a series of N-aryl-6-methoxy-1,2,3,4-tetrahydroquinoline derivatives as a novel class of tubulin polymerization inhibitors targeted at the colchicine binding site. The most active compound 6d showed extremely high cytotoxicity against a human tumor cell line panel (A549, KB, KBvin, and DU145) with GI50 values ranging from 1.5 to 1.7 nM, significantly more potent than paclitaxel, especially against the drug-resistant KBvin cell line, in the same assays. Analogs 5f, 6b, 6c, and 6e were also quite potent, with a GI50 range of 0.011-0.19 μM. In further studies, active compounds 6b-e and 5f significantly inhibited tubulin assembly, with IC50 values of 0.92-1.0 μM and strongly inhibited colchicine binding to tubulin, with inhibition rates of 75-99% (at 5 μM), comparable with or more potent than combretastatin A-4 (IC50 0.96 μM). Current studies included design, synthesis, and biological evaluations of 24 new compounds (series 3-6). Related SAR analysis, molecular modeling, and evaluation of essential drug-like properties, i.e. water solubility, log P, and in vitro metabolic stability, were also performed., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Twenty new acyl thiourea derivatives of podophyllotoxin and 4'-demethylepipodophyllotoxin were prepared and screened for their cytotoxicity against four human tumor cell lines, A-549, DU-145, KB, and KBvin. With IC50 values of 0.098-1.13 μM, compounds 13b, 13c, and 13o displayed much better cytotoxic activity than the control etoposide. Most importantly, 13b and 13o exhibited promising cytotoxicity against the drug resistant tumor cell line KBvin with IC50 values of 0.098 and 0.13 μM, respectively, while etoposide lost activity completely. Structure-activity relationship (SAR) correlations of the new derivatives have been established. Compounds 13b and 13o merit further development as a new generation of epipodophyllotoxin-derived antitumor clinical trial candidates., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Eighteen novel spin-labeled 18β-glycyrrhetinic acid (GA) derivatives were designed, synthesized, and evaluated for cytotoxicity against four human tumor cell lines (A-549, DU-145, KB and KBvin). Most of the derivatives showed more significant cytotoxicity than that of the parent compound GA. The best compound, 6j, with a tryptophan amino moiety and piperidine nitroxyl radical showed GI(50) values of 13.7-15.0 μM, and was fivefold more potent than GA. In a mechanism of action study, compound 7a was confirmed as a 20S proteasome inhibitor in both in vitro and cell-based assays. These findings support further optimization efforts based on 18β-GA as a lead compound to develop potential anticancer drug candidates., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Based on a shared structural core of diarylamine in several known anticancer drugs as well as a new cytotoxic hit 6-chloro-2-(4-cyanophenyl)amino-3-nitropyridine (7), 30 diarylamines and diarylethers were designed, synthesized, and evaluated for cytotoxic activity against A549, KB, KB-vin, and DU145 human tumor cell lines (HTCL). Four new leads 11e, 12, 13a, and 13b were discovered with GI(50) values ranging from 0.33 to 3.45μM. Preliminary SAR results revealed that a diarylamine or diarylether could serve as an active structural core, meta-chloro and ortho-nitro groups on the A-ring (either pyridine or phenyl ring) were necessary and crucial for cytotoxic activity, and the para-substituents on the other phenyl ring (B-ring) were related to inhibitory selectivity for different tumor cells. In an investigation of potential biological targets of the new leads, high thoughput kinase screening discovered that new leads 11e, 12 and 13b especially inhibit Mer tyrosine kinase, a proto-oncogene associated with munerous tumor types, with IC(50) values of 2.2-3.0μM. Therefore, these findings provide a good starting point to optimize a new class of compounds as potential anticancer agents, particularly targeting Mer tyrosine kinase., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Thirty-five S- and O-substituted 7-mercaptocoumarin (9-23) and 7-hydroxy- or 7-mercapto-chromone (24-43) analogs were designed, synthesized and evaluated in vitro against four human tumor cell lines [KB (nasopharyngeal), KB-vin (vincristine-resistant subline), A549 (lung) and DU145 (prostate)] with paclitaxel as the positive control. Many of the synthesized compounds exhibited potent cytotoxic activity. Among them, compounds 10 and 18 showed broad spectrum activity with GI(50) values ranging from 0.92 to 2.11 μM and 2.06-14.07 μM, respectively. However, 33, a 3-brominated compound, displayed significant and selective inhibition against MDR KB-vin with a GI(50) of 5.84 μM. Regardless of the size of the 7-alkoxy group, 2-α-bromoethyl-8-bromomethyl compounds (40-43) exhibited increased cytotoxicity compared with 2-ethyl-8-bromomethyl compounds (36-39). Moreover, in a preliminary pharmacological study, 10 not only remarkably increased cellular apoptosis in a concentration-dependent manner, but also clearly induced A549 cell cycle arrest at the G2/M phase. Thus, these coumarin derivatives merit investigation as novel potential antitumor agents with further structural modification to produce an optimal lead compound and elucidate the detailed pharmacological mechanism(s)., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

Chalcones have a distinctive 1,3-diarylpropenone skeleton and exert numerous biological effects. Using a one-step Claisen-Schmidt condensation, we synthesized eleven bis-chalcones (3-13) and three acetyl chalcones (14-16) from substituted aldehydes and diacetylresorcinol. The compounds were tested for in vitro cytotoxic activity against four human cancer cell lines (A549, DU145, KB, and KB-VIN) and inhibition of NO production in lipopolysaccharide (LPS)-activated microglial cells. Among them, four compounds (3, 5, 6, and 13) showed significant cytotoxic activity with EC(50) values ranging from 1.57 to 5.14 μM, and seven compounds (3, 5-8, 10, and 13) displayed potent anti-inflammatory activity by inhibiting NO production with IC(50) values ranging from 0.95 to 8.65 μM. A mechanism of action study of active compounds 6 and 7 discovered that these compounds down-regulated iNOS expression by inhibiting p65 NF-κB activation/nuclear translocation due to prevention of IκBα degradation. Structure-activity relationship (SAR) findings are also discussed., (Crown Copyright © 2011. Published by Elsevier Masson SAS. All rights reserved.)

In this study, 22 new betulinic acid (BA) derivatives were synthesized and tested for their inhibition of the chymotrypsin-like activity of 20S proteasome. From the SAR study, we concluded that the C-3 and C-30 positions are the pharmacophores for increasing the proteasome inhibition effects, and larger lipophilic or aromatic side chains are favored at these positions. Among the BA derivatives tested, compounds 13, 20, and 21 showed the best proteasome inhibition activity with IC(50) values of 1.42, 1.56, and 1.80 μM, respectively, which are three to fourfold more potent than the proteasome inhibition controls LLM-F and lactacystin., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

A series of novel bichalcone analogs were synthesized and evaluated in lipopolysaccharide (LPS)-activated microglial cells as inhibitors of nitric oxide (NO) and for in vitro anticancer activity using a limited panel of four human cancer cell lines. All analogs inhibited NO production. Compounds 4 and 11 exhibited optimal activity with IC(50) values of 0.3 and 0.5 μM, respectively, and were at least 38-fold better than the positive control. A mechanism of action study showed that both compounds significantly blocked the nuclear translocation of NF-κB p65 and up-regulation of iNOS at 1.0 μM. Compound 4 and three other analogs (3, 20, and 23) exerted significant in vitro anticancer activity GI(50) values ranging from 0.70 to 13.10 μM. A mode of action study using HT-29 colon cancer cells showed that 23 acts by inducing apoptosis signaling., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Ten new triterpenoids, camphoratins A-J (1-10), along with 12 known compounds were isolated from the fruiting body of Taiwanofungus camphoratus. Their structures were established by spectroscopic analysis and chemical methods. Compound 10 is the first example of a naturally occurring ergosteroid with an unusual cis-C/D ring junction. Compounds 2-6 and 11 showed moderate to potent cytotoxicity, with EC(50) values ranging from 0.3 to 3 μM against KB and KB-VIN human cancer cell lines. Compounds 6, 10, 11, 14-16, 18, and 21 exhibited anti-inflammatory NO-production inhibition activity with IC(50) values of less than 5 μM, and were more potent than the nonspecific NOS inhibitor N(ω)-nitro-L-arginine methyl ester.

Our previous exploration of 2-phenylquinolin-4-ones (2-PQs) has led to an anticancer drug candidate 2-(2-fluorophenyl)-6,7-methylenedioxyquinolin-4-one monosodium phosphate (CHM-1-P-Na). In order to develop additional new drug candidates, novel 2-PQs were designed, synthesized, and evaluated for cytotoxic activity. Most analogues, including 1b, 2a,b, 3a,b, 4a,b, and 5a,b, exhibited significant inhibitory activity (IC(50) of 0.03-8.2 μM) against all tested tumor cell lines. As one of the most potent analogue, 2-(3-fluorophenyl)-5-hydroxy-6-methoxyquinolin-4-one (3b) selectively inhibited 14 out of 60 cancer cell lines in a National Cancer Institute (NCI) evaluation. Preliminary mechanism of action study suggested that 3b had a significant effect on the tyrosine autophosphorylation of insulin-like growth factor-1 receptor (IGF-1R). Safety pharmacology profiling of 3b showed no significant effect on normal biological functions of most enzymes tested. Furthermore, sodium 2-(3-fluorophenyl)-6-methoxy-4-oxo-1,4-dihydroquinolin-5-yl phosphate (15), the monophosphate of 3b, exceeded the activity of doxorubicin and was comparable to CHM-1-P-Na in a Hep3B xenograft nude mice model. In summary, 15 is a promising clinical candidate and is currently under preclinical study.

To discover the anti-tumoral indoles a series of benzyl 1,2,3,5,11,11a-hexahydro-3,3-dimethyl-1-oxo-6H-imidazo[3',4':1,2]pyridin[3,4-b]indole-2-substituted acetates (2a-n) are prepared via one-pot-preparation. The IC(50) values of 2a-n in vitro against human lung carcinoma, prostate cancer, nasopharyngeal carcinoma, vincristine-resistant KB subline and human breast carcinoma cells range from 40 nM to 60 microM. On Sarcoma 180 (S180) tumor-bearing mouse model four of them (2e,g,h,i) significantly inhibited the tumor growth. At the dose of 0.1mg/kg the efficacy of the most potent 2h was equal to that of 1.0mg/kg of doxorubicin. In contrast to doxorubicin, at 1.0mg/kg of dose 2e,g,h,i did not induce the treated S180 mice to have organ atrophy and body emaciation. The healthy mice receiving 10, 100 and 500 mg/kg of 2e,g,h,i gave no any neurotoxic response. Even up to the dose of 500 mg/kg the healthy mice occurred no death. The interaction of 2a-n with DNA was confirmed by the fluorescence quenching experiments and automated flexible ligand docking. By 3D QSAR analysis the IC(50) values of 2a-n against prostate cancer cells were correlated with the structures and conformations of their side chains. To increase the data related to their physical-chemical properties the experimental LogP values were also provided., (Copyright 2010 Elsevier Ltd. All rights reserved.)

CHM-1 [2-(2-fluorophenyl)-6,7-methylenedioxyquinolin-4-one] (1) has a unique antitumor mechanism of action. However, because 1 has relatively low hydrophilicity, it was evaluated only via ip administration, which is not clinically acceptable. In this study, we synthesized the monosodium phosphate salt (CHM-1-P-Na, 4) of 1 as a hydrophilic prodrug. Compound 4 was rapidly converted into 1 following iv and po administration and also possessed excellent antitumor activity in a SKOV-3 xenograft nude mice model. Compound 4 also had clear-cut pharmacological effects on enzymes related with tumor cells. Neither 4 nor 1 significantly affected normal biological function in a safety pharmacology profiling study. Compound 1 caused apoptotic effects in breast carcinoma cells via accumulation of cyclin B1, and importantly, the endogenous levels of the mitotic spindle checkpoint proteins BubR1 directly correlated with cellular response to microtubule disruption. With excellent antitumor activity profiles, 4 is highly promising for development as an anticancer clinical trials candidate.

Sixteen novel N-(3-carboxyl-9-benzyl-beta-carboline-1-yl)ethylamino acids (6a-p) were synthesized as intercalating lead compounds. In the in vitro cytotoxic assay their IC(50) values against five human carcinoma cell lines ranged from 10.95 microM to about 400 microM. On S180 mouse model eight of them exhibited anti-tumor action, four of them showed the same anti-tumor potency as that of cytarabine. The preliminary toxicity evaluation revealed that the LD(50) values of 6a-p should be more than 500 mg/kg. With CT DNA as model system an intercalating mechanism was explored. Using 3D QSAR analysis the relationship of the in vivo anti-tumor activity and the structure was quantitatively described. By docking 6a-p onto d(CGATCG)(2) oligonucleotides the intercalation was demonstrated.

Acid-catalyzed transacetalation of dimethyl (2R,3S)-2,3-dimercapto-succinate and 1,1,3,3-tetramethoxypropane provided cis-4,5-dimethoxycarbonyl-2-(2',2'-dimethoxyethyl)-1,3-dithiolane (2) in 77% yield. The esterification of 2 and l-amino acids provided 18 active antitumor cis-2-carbonylmethyl-4,5- di(l-aminoacyloxymethyl)-1,3-dithiolane analogs (5a-r). Five compounds (5b,c,e,k,p) exhibited remarkable antitumor activity in in vivo assays. The in vivo antitumor potency of 5e,k,p at 44.64micromol/kg was similar to that of cytarabine at 89.28micromol/kg. Several different assay systems, including UV-vis of CT DNA with or without the representative compound 5d and CD spectra of CT DNA with or without representative compounds 5b,f,i demonstrated that DNA is the target of 5a-r. A 3D QSAR model was established to elucidate quantitative relationships between in vivo antitumor activity and analog structures. An equation with r(2) equal to 0.992 was built to predict antitumor activity of unknown cis-2,4,5-trisubstituted-1,3-dithiolane analogs.

As part of our continuing investigation of azo-flavonoid derivatives as potential anticancer drug candidates, a series of 2-aryl-6,7-methylenedioxyquinolin-4-one analogues was designed and synthesized. The design combined structural features of 2-(2-fluorophenyl)-6,7-methylenedioxyquinolin-4-one (CHM-1), a previously discovered compound with potent in vivo antitumor activity, and 2-arylquinolin-4-ones, identified by CoMFA models. The newly synthesized analogues were evaluated for cytotoxicity against seven human cancer cell lines, and structure-activity relationship (SAR) correlations were established. Analogues 1, 37, and 39 showed potent cytotoxicity against different cancer cell lines. Compound 1 demonstrated selective cytotoxicity against Hep 3B (hepatoma) cells. Compound 37 was cytotoxic against HL-60 (leukemia), HCT-116 (colon cancer), Hep 3B (hepatoma), and SK-MEL-5 (melanoma) cells. Compound 39 exhibited broad cytotoxicity against all seven cancer cell lines, with IC50 values between 0.07 and 0.19 microM. Results from mechanism of action studies revealed that these new quinolone derivatives function as antitubulin agents.

Abstract: Epiceanothic acid (1) is a naturally occurring, but very rare pentacyclic triterpene with a unique pentacyclic triterpene (PT) structure. An efficient synthesis of 1 starting from betulin (3) has been accomplished in 12-steps with a total yield of 10% in our study. Compound 1 and selected synthetic intermediates were further evaluated as anti-HIV-1 agents, inhibitors of glycogen phosphorylase (GP), and cytotoxic agents. Compound 1 exhibited moderate HIV-1 inhibition. Most importantly, compound 5, with an opened A-ring, showed significant GP inhibitory activity with an IC50 of 0.21μM, suggesting a potential for development as an anti-diabetic agent. On the other hand, compound 12, with a closed A-ring, showed potent cytotoxicity against A549 and MCF-7 human tumor cell lines, with IC50 values of 0.89 and 0.33μM, respectively. These results suggest that the A-ring of PTs is an important pharmacophore that could be modified to involve different biological activities. [Copyright &y& Elsevier]

Abstract: Five new benzenoids, benzocamphorins A–E (1–5), and 10 recently isolated triterpenoids, camphoratins A–J (16–25), together with 23 known compounds including seven benzenoids (6–12), three lignans (13–15), and 13 triterpenoids (26–38) were isolated from the fruiting body of Taiwanofungus camphoratus. Their structures were established by spectroscopic analysis. Selected compounds were examined for cytotoxic and anti-inflammatory activities. Compounds 9 and 21 showed moderate cytotoxicity against MCF-7 and Hep2 cell lines with ED50 values of 3.4 and 3.0μg/mL, respectively. Compounds 21, 25, 26, 29–31, 33, and 36 demonstrated potent anti-inflammatory activity by inhibiting lipopolysaccharide (LPS)-induced nitric oxide (NO) production with IC50 values of 2.5, 1.6, 3.6, 0.6, 4.1, 4.2, 2.5, and 1.5μM, respectively, which were better than those of the nonspecific nitric oxide synthase (NOS) inhibitor N-nitro-l-arginine methyl ester (l-NAME) (IC50: 25.8μM). These results may substantiate the use of T. camphoratus in traditional Chinese medicine (TCM) for the treatment of inflammation and cancer-related diseases. The newly discovered compounds deserve further development as anti-inflammatory candidates. [ABSTRACT FROM AUTHOR]