Psammocindoles A-C: Isolation, Synthesis, and Bioactivity of Indole-γ-lactams from the Sponge Psammocinia vermis.

Psammocindoles A-C (1-3), a new class of indole alkaloids, were isolated from a Psammocinia vermis sponge. By combined spectroscopic analyses, the structures of these compounds were determined to be the indole-γ-lactams derived from three amino acid residues. In addition, an enantiomer psammocindole D (4), and the N-lactam isomers isopsammocindoles A-D (5-8) were also synthesized. These natural products and synthetic analogues were found to significantly stimulate adiponectin secretion in human bone marrow mesenchymal stem cells.

Synthesis and biological activity of selenopsammaplin A and its analogues as antitumor agents with DOT1L inhibitory activity.

Disruptor of telomeric silencing-1 like (DOT1L) is a histone H3 methyltransferase which specifically catalyzes the methylation of histone H3 lysine-79 residue. Recent findings demonstrate that DOT1L is abnormally overexpressed and the upregulated DOT1L evokes the proliferation and metastasis in human breast cancer cells. Therefore, the DOT1L inhibitor is considered a promising strategy to treat breast cancers. Non-nucleoside DOT1L inhibitors, selenopsammaplin A and its analogues, were firstly reported in the present study. Selenopsammaplin A was newly designed and synthesized with 25% overall yield in 8 steps from 3-bromo-4-hydroxybenzaldahyde, and thirteen analogues of selenopsammaplin A were prepared for structure-activity relationship studies of their cytotoxicity against cancer cells and inhibitory activity toward DOT1L for antitumor potential. All synthetic selenopsammaplin A analogues exhibited the higher cytotoxicity compared to psammaplin A with up to 6 - 60 times depending on cancer cells, and most analogues showed significant inhibitory activities against DOT1L. Among the prepared analogues, the phenyl analogue (10) possessed the most potent activity with both cytotoxicity and inhibition of DOT1L. Compound 10 also exhibited the antitumor and antimetastatic activity in an orthotopic mouse metastasis model implanted with MDA-MB-231 human breast cancer cells. These biological findings suggest that analogue 10 is a promising candidate for development as a cancer chemotherapeutic agent in breast cancers.

Inhibition of DOT1L by Half-Selenopsammaplin A Analogs Suppresses Tumor Growth and EMT-Mediated Metastasis in Triple-Negative Breast Cancer.

Due to a lack of hormone receptors, current treatment strategies for triple-negative breast cancer (TNBC) are limited with frequent disease recurrence and metastasis. Recent findings have suggested that aberrant methylation of histone H3 lysine 79 residue (H3K79me) by the histone methyltransferase disruptor of telomeric silencing 1-like (DOT1L) is a potential therapeutic target for TNBC clinical management. Therefore, we developed DOT1L inhibitors as potential antitumor agents against TNBC cells. We reveal that a synthetic half-selenopsammaplin A analog 9l (subsequently known as 9l) exhibited inhibitory activity against DOT1L-mediated H3K79 methylation, and showed antitumor activity in TNBC cells. The analog 9l also significantly inhibited TNBC invasion and migration via the modulation of epithelial-mesenchymal transition (EMT) markers, including N-cadherin and vimentin downregulation and E-cadherin upregulation. In an MDA-MB-231/Luc-implanted orthotopic mouse metastasis model, treatment with 9l effectively inhibited tumor growth and lung metastasis via DOT1L regulatory activity and EMT processes. Taken together, these findings highlight the potential of 9l as a novel therapeutic candidate for treating metastatic TNBC via DOT1L modulation.

Targeting Histone Methyltransferase DOT1L by a Novel Psammaplin A Analog Inhibits Growth and Metastasis of Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is the most intractable cancer in women with a high risk of metastasis. While hyper-methylation of histone H3 catalyzed by disruptor of telomeric silencing 1-like (DOT1L), a specific methyltransferase for histone H3 at lysine residue 79 (H3K79), is reported as a potential target for TNBCs, early developed nucleoside-type DOT1L inhibitors are not sufficient for effective inhibition of growth and metastasis of TNBC cells. We found that TNBC cells had a high expression level of DOT1L and a low expression level of E-cadherin compared to normal breast epithelial cells and non-TNBC cells. Here, a novel psammaplin A analog (PsA-3091) exhibited a potent inhibitory effect of DOT1L-mediated H3K79 methylation. Consistently, PsA-3091 also significantly inhibited the proliferation, migration, and invasion of TNBC cells along with the augmented expression of E-cadherin and the suppression of N-cadherin, ZEB1, and vimentin expression. In an orthotopic mouse model, PsA-3091 effectively inhibited lung metastasis and tumor growth by the regulation of DOT1L activity and EMT biomarkers. Together, we report here a new template of DOT1L inhibitor and suggest that targeting DOT1L-mediated H3K79 methylation by a novel PsA analog may be a promising strategy for the treatment of metastatic breast cancer patients.

Anti-cancer effect of GV1001 for prostate cancer: function as a ligand of GnRHR.

GV1001, a 16-amino acid fragment of the human telomerase reverse transcriptase catalytic subunit (hTERT), has been developed as an injectable formulation of cancer vaccine. Here, we revealed for the first time that GV1001 is a novel ligand for gonadotropin-releasing hormone receptor (GnRHR). The docking prediction for GV1001 against GnRHR showed high binding affinity. Binding of GV1001 to GnRHR stimulated the Gαs-coupled cAMP signaling pathway and antagonized Gαq-coupled Ca2+ release by leuprolide acetate (LA), a GnRHR agonist. Repeated injection of GV1001 attenuated both serum testosterone level and seminal vesicle weight via desensitization of hypothalamic-pituitary-gonadal (HPG) axis. We then tested whether GV1001 has an inhibitory effect on tumor growth of LNCaP cells, androgen receptor-positive human prostate cancer (PCa) cells. GV1001 significantly inhibited tumor growth and induced apoptosis in LNCaP-implanted xenografts. Interestingly, mRNA expressions of matrix metalloproteinase 2 and matrix metalloproteinase 9 were suppressed by GV1001, but not by LA. Moreover, GV1001 significantly inhibited the proliferation and migration of PCa cells and induced apoptosis in a concentration-dependent manner. Our findings suggest that GV1001 functions as a biased GnRHR ligand to selectively stimulate the Gαs/cAMP pathway, with anti-proliferative and anti-migratory effects on human PCa.

An α-quaternary chiral latam derivative, YH-304 as a novel broad-spectrum anticancer agent.

Previously, we reported that α-quaternary chiral lactam derivatives have broad spectrum anticancer activity. However, the underlying molecular mechanisms and its relevance are largely unknown. In the present study, we report progress on α-quaternary chiral lactam analogues that address this, focusing on the novel analogue YH-304 as a candidate to broadly target human cancer cells. The effect of YH-304 on cell transformation was assessed by clonogenic assay in non-small cell lung cancer cells (NSCLCs) A549 and 226B. Proapoptotic activity of YH-304 was determined by TUNEL assay and cleaved PARP, cleaved caspase-9, and Bax as markers for apoptosis. The p53-dependency and therapeutic spectrum of YH-304 was assessed by western blot analysis, real-time PCR, and cell viability assays in cells expressing endogenous wild or mutant p53. The effect of YH-304 on angiogenesis in vivo was examined by bFGF-mediated angiogenesis assay in zebrafish. Finally, the effect of YH-304 on AKT and ERK activation (phosphorylation) as a putative mechanism underlying the effect of YH-304 on bFGF-mediated angiogenesis was assessed using western blotting. We found that YH-304 significantly decreases the colony-forming activities of both A549 and 226B cells, inducing cellular apoptosis. Unlike nutlin-3 (p53 pathway activator), YH-304 did not affect the expression levels of p53 and its target gene such as p21 and thus showed p53-independent anticancer activity with broad spectrum. In addition, YH-304 inhibited bFGF-induced angiogenesis in vivo through mediating AKT and ERK signaling pathway, which plays an important role in bFGF activation and angiogenesis. Taken together, our data indicate that YH-304 may represent a novel therapeutic option for the treatment of cancer in a p53-independent manner.

Determination and validation of psammaplin A and its derivatives in rat plasma by liquid chromatography-tandem mass spectrometry and its application in pharmacokinetic study.

A liquid chromatography-tandem mass (LC-MS/MS) method was developed for the determination of psammaplin A (PsA) and its newly synthesized derivatives (PsA 107, PsA 109, and PsA 123) in rat plasma using bupropion as an internal standard (IS). The plasma samples were deproteinized with acetonitrile. Chromatographic separation was performed on hydro-RP column (75×2.0mm, 80Å, 4µm) with isocratic elution using 5mM ammonium formate buffer/acetonitrile (30:70, v/v) at a flow rate of 0.4mL/min and the total run time was 5min. Mass spectrometric detection was performed with positive electrospray ionization (ESI) in multiple reaction monitoring (MRM) mode. The ion transitions monitored were m/z 663.2→331.0, 687.2→343.1, 587.3→293.1, 563.3→281.0, and 240.0→184.0 for PsA, PsA 107, PsA 109, PsA 123, and IS, respectively. All analytes showed good linearity over the concentration range of 5.00-5000ng/mL (r(2)≥0.994). The lower limit of quantification was 5ng/mL for PsA and its three PsA derivatives. Within- and between-run precisions (relative standard deviation, RSD) were less than 9.66% and accuracy (relative error, RE) ranged from -9.34% to 7.25%. Established method was successfully applied to the investigation of pharmacokinetic properties of PsA and its derivatives in rats after intravenous administration at a dose of 2mg/kg.

Efficient synthesis and biological activity of Psammaplin A and its analogues as antitumor agents.

We describe a new concise method for the synthesis of psammaplin A and its analogues, and antitumor activity of psammaplin A analogues. Psammaplin A was obtained with 41% yield in 5 steps from 3-bromo-4-hydroxybenzaldahyde and ethyl acetoacetate via Knoevenagel condensation and α-nitrosation as key steps. Twenty eight analogues of psammaplin A were prepared employing the new synthetic approach. Structure-activity relationship study against cytotoxicity reveal that the free oxime group and disulfide functional group were responsible for high cytotoxicity. Also the bromotyrosine component was relatively tolerable and hydrophobic aromatic groups preserved the cytotoxicity. The cytotoxicity of aromatic group is dependent on the size and spatial geometry. Among them, five compounds showed comparable cytotoxicity to psammaplin A. Compound 30 exhibited potential HDAC inhibitory activity and in vivo antitumor activity.

RORα decreases oxidative stress through the induction of SOD2 and GPx1 expression and thereby protects against nonalcoholic steatohepatitis in mice.

AIMS: Increased hepatic oxidative stress and inflammation is the main cause of exacerbating nonalcoholic steatohepatitis (NASH). Retinoic acid-related orphan receptor α (RORα) regulates diverse target genes associated with lipid metabolism, and its expression level is low in the liver of patients with NASH. Here, we investigated the role of RORα in regulating hepatic oxidative stress and inflammation. RESULTS: First, cholesterol sulfate (CS), an agonist of RORα, lowered oxidative stress that was induced by 1.5 mM oleic acid in the primary cultures of hepatocytes. Second, exogenously introduced RORα or CS treatment induced the mRNA level of antioxidant enzymes, superoxide dismutase 2 (SOD2) and glutathione peroxidase 1 (GPx1), through the RORα response elements located in the upstream promoters of Sod2 and Gpx1. Third, RORα significantly decreased reactive oxygen species levels and mRNA levels of tumor necrosis factor α (TNFα) and interleukin-1ß that were induced by lipopolysaccharide or TNFα in Kupffer cells. Finally, the administration of JC1-40 decreased the signs of liver injury, lipid peroxidation, and inflammation in the MCD diet-induced NASH mice. INNOVATION AND CONCLUSION: We showed for the first time that RORα and its ligands protect NASH in mice by reducing hepatic oxidative stress and inflammation. Further, the molecular mechanism of the protective function of RORα against oxidative stress in the liver was revealed. These findings may offer a rationale for developing therapeutic strategies against NASH using RORα ligands.

Asymmetric synthesis and evaluation of α-quaternary chiral lactam derivatives as novel anticancer agents.

Asymmetric synthesis of α-quaternary chiral lactam derivatives as novel anticancer agents and evaluation of their cytotoxic potentials and spectrums are reported. Among the developed lactam derivatives, the most active new compounds (S)-4m and (S)-4n synthesized via asymmetric phase-transfer catalytic alkylation in very high optical yields (98 % ee) show promising in vitro anticancer activities with low micromolar IC50 values against colon, uterus, lung, and breast human cancer cells.

N-methylthioureas as new agonists of retinoic acid receptor-related orphan receptor.

Thirty two thiourea derivatives were prepared and their agonistic activities on the retinoic acid receptor-related orphan receptor α (RORα) were evaluated. The replacement of the 3-allyl-2-imino-thiazolidin-4-one moiety of the lead compound CGP52608 (1) with various functional group substituted aromatic rings, improved the agonistic activity of RORα. Among the prepared derivatives, 1-methyl-3-(4-phenoxy-benzyl)-thiourea (32) showed 2.6-fold higher agonistic activity than CGP52608 in the RORα-activation assay.

Retinoic acid receptor-related orphan receptor α-induced activation of adenosine monophosphate-activated protein kinase results in attenuation of hepatic steatosis.

UNLABELLED: There is increasing evidence that the retinoic acid receptor-related orphan receptor α (RORα) plays an important role in the regulation of metabolic pathways, particularly of fatty acid and cholesterol metabolism; however, the role of RORα in the regulation of hepatic lipogenesis has not been studied. Here, we report that RORα attenuates hepatic steatosis, probably via activation of the adenosine monophosphate (AMP)-activated protein kinase (AMPK) and repression of the liver X receptor α (LXRα). First, RORα and its activator, cholesterol sulfate (CS), induced phosphorylation of AMPK, which was accompanied by the activation of serine-threonine kinase liver kinase B1 (LKB1). Second, the activation of RORα, either by transient transfection or CS treatment, decreased the TO901317-induced transcriptional expression of LXRα and its downstream target genes, such as the sterol regulatory element binding protein-1 (SREBP-1) and fatty acid synthase. RORα interacted physically with LXRα and inhibited the LXRα response element in the promoter of LXRα, indicating that RORα interrupts the autoregulatory activation loop of LXRα. Third, infection with adenovirus encoding RORα suppressed the lipid accumulation that had been induced by a free-fatty-acid mixture in cultured cells. Furthermore, we observed that the level of expression of the RORα protein was decreased in the liver of mice that were fed a high-fat diet. Restoration of RORα via tail-vein injection of adenovirus (Ad)-RORα decreased the high-fat-diet-induced hepatic steatosis. Finally, we synthesized thiourea derivatives that activated RORα, thereby inducing activation of AMPK and repression of LXRα. These compounds decreased hepatic triglyceride levels and lipid droplets in the high-fat-diet-fed mice. CONCLUSION: We found that RORα induced activation of AMPK and inhibition of the lipogenic function of LXRα, which may be key phenomena that provide the beneficial effects of RORα against hepatic steatosis.

Enantioselective synthesis of (R)- and (S)-alpha-alkylcysteines via phase-transfer catalytic alkylation.

We reported efficient enantioselective synthetic methodologies for (R)-alpha-alkylcysteines and (S)-alpha-alkylcysteines. The phase-transfer catalytic alkylation of 2-phenyl-2-thiazoline-4-carboxylic acid tert-butyl ester and 2-o-biphenyl-2-thiazoline-4-carboxylic acid tert-butyl ester, in the presence of chiral catalysts (1 or 2), gave the corresponding alkylated products, which could be hydrolyzed to provide (R)-alpha-alkylcysteines (67->99% ee) and (S)-alpha-alkylcysteines (66-88% ee), respectively.

Asiatic acid derivatives enhance cognitive performance partly by improving acetylcholine synthesis.

Thirty-six semi-synthesized derivatives of asiatic acid were examined to determine if they had cognitive-enhancing activity in a passive avoidance test. Among the compounds tested, AS-2, AS-2-9-006 and AS-9-006 significantly alleviated scopolamine-induced memory impairment at doses of 1 and 10 mg kg(-1). Furthermore, AS-2 and AS-2-9-006 (1 mg kg(-1) administered four times daily) enhanced cognitive performance as determined in a water maze test. These three asiatic acid derivatives did not show any significant effect on the learning process in active avoidance tests. AS-2, AS-2-9-006 and AS-9-006 enhanced cholineacetyltransferase activity in a cholinergic neuroblastoma cell line, S-20Y, in-vitro. Therefore, AS-2, AS-2-9-006 and AS-9-006 may have therapeutic value in alleviating certain memory impairment observed in dementia.

First asymmetric total synthesis of (-)-antofine by using an enantioselective catalytic phase transfer alkylation.

[structure: see text] The first asymmetric total synthesis of a potential antitumor phenanthroindolizidine alkaloid, (-)-antofine, is described. An important feature of this synthesis is the creation of a stereogenic center by using enantioselective catalytic phase transfer alkylation, affording an unnatural alpha-amino acid derivative, together with a ring closing metathesis for pyrrolidine ring construction.

Synthesis of 6-formyl-pyridine-2-carboxylate derivatives and their telomerase inhibitory activities.

Twenty-one pyridine-2-carboxylate derivatives were prepared by the coupling of 6-formyl-2-carboxylic acid with the corresponding phenol, thiophenol, and aniline, substituted with various functional groups. Among them, the 3,4-dichlorothiophenol ester (9p) showed the highest in vitro telomerase inhibitory activity and quite significant in vivo tumor suppression activity.