Synthesis and antiproliferative activity of sulfonamide-based peptidomimetic calpain inhibitors

The calpains are a conserved family of cysteine proteases that includes several isoforms of which µ–calpain and m-calpain are the most widely distributed in mammalian cells. Calpains have been implicated in normal physiological processes as well as cellular abnormalities such as neurodegenerative disorders, cataract, and cancer. Therefore, calpain inhibitors are of interest as potential therapeutic agents. We have synthesized four new sulfonamide-based peptidomimetic compounds 2–5 as inhibitors of μ-calpain that incorporate (E)-1-(phenyl)-2-phenyldiazene and (E)-1-(phenyl)-2-phenylethene functionalities as the N-terminal capping groups of the inhibitors. Compound 5 with K_i value of 9 nM versus μ-calpain was the most potent member of the group. The compounds were predicted to be more lipophilic compared to MDL28170 based on CLogP estimation. They displayed moderate to good antiproliferative activity versus melanoma cell lines (A-375 and B-16F1) and PC-3 prostate cancer cells in vitro. Additionally, one member of the group (compound 3) inhibited DU-145 cell invasion by 80% at 2 μM concentration in the Matrigel cell invasion assay.     

Polyprenylated polycyclic acylphloroglucinol: Angiogenesis inhibitor from Garcinia multiflora

A new polyprenylated polycyclic acylphloroglucinol, garcimultiflorone K (1), has been isolated from the stems of Garcinia multiflora, together with two known compounds, garcimultiflorone A (2) and garcimultiflorone B (3). The structure of new compound 1 was determined through spectroscopic methods including 1D and 2D NMR and MS analyses. The anti-angiogenic and anti-cancer effects of compounds 1–3 were evaluated in human endothelial progenitor cells (EPCs) and cancer cells. Of these, garcimultiflorone K (1) displayed the most potent anti-angiogenic property by suppressing cell growth and tube formation of EPCs. Compound 1 also exhibited growth-inhibitory activities against human hepatocellular carcinoma cell line SK-Hep-1 and hormone refractory prostate cancer cell line PC-3 with GI₅₀ values of 4.3?±?1.6 and 6.6?±?0.4?μM, respectively.     

Oleanane glycosides from the roots of Alhagi maurorum

Three new oleanane-type triterpene glycosides (1–3), along with four known compounds (4–7) glycosides, were isolated from the roots of Alhagi maurorum. Their structures were elucidated by 1D and 2D-NMR experiments as well as ESI-MS analysis. The antiproliferative activity of the isolated compounds was evaluated against a small panel of cancer cell lines including human breast cancer (MCF-7), human lung adenocarcinoma (A549), human prostate cancer (PC-3) and human leukemia (U937) cell lines. None of the tested compounds, in a range of concentrations between 1 and 50 μM, caused a significant reduction of the cell number.     

Topoisomerase II inhibitors from the roots of Stellera chamaejasme L.

Three new compounds, including one daphnane diterpene (1), one sesquiterpene (6), and one lignan (7) have been isolated from the Stellera chamaejasme L., together with five other known compounds, including four daphnane diterpenenoids (2–5) and one lignan (8). The structures of the new compounds were elucidated by spectroscopic analysis. The cytotoxicities of compounds 1–8 towards human lung adenocarcinoma cells (A549 cells) were evaluated using a sulforhodamine B assay. All of the compounds displayed significant cytotoxicity, with IC₅₀ values in the ranging of 0.2 nM to 2.0 μM. Mechanistic studies revealed that the antitumor activities of compounds 1–3 and 7 were derived from their inhibition of topoisomerase II (Topo II). Furthermore, as a Topo II inhibitor, compound 1 was found to effectively induced G2-M phase cell cycle arrest and apoptosis in cancer cells.     

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.     

Bisstyryl constituents from the leaves of Miliusa sinensis

Miliusa sinensis Finet and Gagnep. have recently been subjected to numerous scientific studies pursuing its structure and biological properties. The chromatographic separation of the components from the methanolic extract of M. sinensis leaves yielded three new bisstyryls, namely, sinenbisstyryls A–C (1–3). The structures of the new compounds were determined via interpretation of their spectroscopic data. Of the isolated compounds, sinenbisstyryl A (1) exhibited cytotoxic activity against the A549 human lung, HepG2 human hepatocyte carcinoma, MCF7 human breast, and DU145 human prostate cancer cell lines, with IC₅₀ values of between 11.46 μM and 19.01 μM in four cases.     

Synthesis of β-ionone derived chalcones as potent antimicrobial agents

A series of chalcones (3a–v) have been synthesized by condensation of β-ionone (1) with a variety of aldehydes (2a–v). The synthesized compounds have been screened for their in vitro antimicrobial activity against five bacterial and five fungal strains, using disc diffusion assay. The evaluated compounds display a wide range of activities, from completely inactive to the highly active compounds. Some of the compounds are also active against methicillin resistant staphylococcus aureus (MRSA).     

N-containing compounds from Hymenocallis littoralis and their cytotoxicity against Hep3B cells

A chemical study focusing on the N-containing constituents of Hymenocallis littoralis was carried out, leading to the isolation of two new alkaloidal flavonoids (1–2) and five known alkaloids (3-7). Structures of the isolated compounds were established mainly by spectroscopic techniques, including NMR spectroscopy and mass spectrometry as well as the CD experiment. These compounds were subjected to the in vitro cytotoxicity assays using Hep3B cells, and among them only the known pancratistatine (3) and lycorine (5) could significantly inhibit the Hep3B cell proliferation.     

Two novel saponins from Cephalaria davisiana (Dipsacaceae)

Two novel hederagenin type triterpene saponins, namely davisianoside A (1) and davisianoside B (2) together with ten known compounds (3–12) were isolated from the aerial parts of Cephalaria davisiana (Dipsacaceae). One new prosapogenin (1a) was also obtained after the alkaline hydrolysis of compound 1. The chemical structures of all compounds were established mainly by 1D-, 2D-NMR and HR-ESI/MS analysis as well as chemical methods.The antibacterial and antifungal effects of compounds 1–2 were evaluated against Gram-positive, Gram-negative bacteria and unicellular yeast C. albicans by MIC method.     

Two new phenolic compounds from the white flower of Impatiens balsamina

During the course of our continuing search for biologically active compounds from Korean medicinal sources, we investigated the white flower of Impatiens balsamina. From the MeOH extract, two new phenolic compounds (1–2) containing a nitrile group and eleven known phenolic compounds (3–13) were isolated. The chemical structures of new compounds (1–2) were determined through NMR, HRMS, and CD data. We tested the isolated compounds (1–13) for their cytotoxic activities by determining their inhibitory effects on human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT15) in vitro using the sulforhodamine B (SRB) assay. We also investigated their neuroprotective activity by determining their effects on nerve growth factor (NGF) secretion in C6 cells, and anti-neuroinflammatory activity by measuring nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated BV-2 cells.     

New ursane-type triterpenes from the root bark of Calotropis procera

As a part of our continuing interest in identifying anticancer drug leads from natural sources, we have investigated the in vitro growth inhibitory effects of the hexane fraction of the root bark of Calotropis procera (Ait) R. Br. (Asclepiadaceae). This study reports the isolation and structure elucidation of four new ursane-type triterpenes named calotroprocerol A (1), calotroproceryl acetate A (2), calotroprocerone A (3) and calotroproceryl acetate B (4) in addition to five known compounds including pseudo-taraxasterol acetate (5), taraxasterol (6), calotropursenyl acetate B (7), stigmasterol (8) and (E)-octadec-7-enoic acid (9). Their structures were established on the basis of 1D and 2D NMR studies (¹H–¹H COSY, HSQC, and HMBC) and HRMS spectral data. The in vitro growth inhibitory activity of the isolated compounds was evaluated against three human cancer cell lines including the A549 non-small cell lung cancer (NSCLC), the U373 glioblastoma (GBM) and the PC-3 prostate cancer cell lines.     

Synthesis and antihyperglycemic evaluation of new 2-hydrazolyl-4-thiazolidinone-5-carboxylic acids having pyrazolyl pharmacophores

In the search of new antihyperglycemic agents and following rational approach of drug designing here new 2-hydrazolyl-4-thiazolidinone-5-carboxylic acids (4a–g) with pyrazolyl pharmacophore have been synthesized via thia Michael addition reaction of 1-((3-(4-substituted phenyl)-1-phenyl-1H-pyrazol-4-yl)methylene)thiosemicarbazides (3a–g) with maleic anhydride. The required precursors, (3a–g) were obtained by condensing known 3-(4-substituted phenyl)-1-phenyl-1H-pyrazole-4-carbaldehydes (1a–g) with thiosemicarbazide in ethanol. The newly synthesized compounds (4a–g) have been evaluated for the antihyperglycemic activity in sucrose loaded rat model and among these compounds 4d, 4f and 4g have displayed significant antihyperglycemic activity.     

Bioactive compounds from sclerotia extract of Poria cocos that control adipocyte and osteoblast differentiation

Poria cocos Wolf confers edible sclerotia also known as ‘Indian bread’ in North America, that have been used for the treatment of various diseases in Asian countries. As part of our ongoing aim to identify biologically new metabolites from Korean edible mushrooms, we investigated the ethanol (EtOH) extract of the sclerotia of P. cocos by applying a comparative LC/MS- and bioassay-based analysis approach, since the EtOH extract reciprocally regulated adipocyte and osteoblast differentiation in mouse mesenchymal stem cells (MSCs). Bioassay-based analysis of the EtOH extract led to the successful isolation of two sterols, ergosterol peroxide (1) and 9,11-dehydroergosterol peroxide (2); three diterpenes, dehydroabietic acid (3), 7-oxocallitrisic acid, (4) and pimaric acid (5); and two triterpenes, dehydroeburicoic acid monoacetate (6) and eburicoic acid acetate (7) from the active hexane-soluble fraction. The isolated compounds (1–7) were examined for their effects on the regulation of MSC differentiation. The two sterols (1 and 2) were able to suppress MSC differentiation toward adipocytes. In contrast, the three diterpenes (3–5) showed activity to promote osteogenic differentiation of MSC. These findings demonstrate that the EtOH extract of P. cocos sclerotia is worth consideration as a new potential source of bioactive compounds effective in the treatment of osteoporosis in the elderly, since the extract contains sterols that inhibit adipogenic differentiation as well as diterpenes that promote osteogenic differentiation from MSCs.     

DFT/B3LYP calculations,in vitro cytotoxicity and antioxidant activities of steroidal pyrimidines and their interaction with HSA using molecular docking and multispectroscopic techniques

As a part of our continuing program on the synthesis of steroidal heterocycles, it has been prepared a series of novel steroidal pyrimidine derivatives 4–6 via TMSCl, steroidal ketones (1c–3c), urea and benzaldehyde. The systems presented here, are novel scaffolds and have not been described before at 6th position of steroidal-6-one (1c–3c). Structural assignment of newly synthesized compounds was performed by DFT/B3LYP calculations as well as spectral and analytical data. The interactions of compounds (4–6) with HSA were studied by fluorescence spectroscopy, DLS, CD and molecular docking, under imitated physiological conditions. The antitumor activity has been tested in vitro against three cancer cell lines MDA-MB231 (breast carcinoma), HeLa (human cervical carcinoma), HepG2 (hepatic carcinoma) and one non-cancer normal cell lines, PBMCs (peripheral blood mononuclear cell) by MTT assay. In addition, in vitro antioxidant activity and apoptosis assay of the synthesized compounds (4–6) have also been investigated.     

Cytotoxic metabolites from the leaves of the mangrove Rhizophora apiculata

One new 8,4’-oxyneolignan (1) and one new 7,8-dihydrobenzofuranone (2), together with twenty-one known compounds (3‒23) were isolated from the methanol extract of Rhizophora apiculata leaves. The structures of new compounds, as well as their absolute configuration, were determined by a combination of spectroscopic methods and quantum chemical calculations of NMR and ECD data. All isolated compounds were evaluated for their cytotoxicity, and only 2,6-dimethoxy-1,4-benzoquinone (8) exhibited inhibitory effects against SK-LU-1, HepG2, and MCF7 cells with IC₅₀ values in the range of 8.33–14.82 μM.     

Isolation,characterization and cytotoxic activity of benzophenone glucopyranosides from Mahkota Dewa (Phaleria macrocarpa (Scheff.) Boerl)

Two benzophenone glucopyranosides have been isolated from the nut shell part of Mahkota Dewa. The structures were identified as 2,4′,6-trihydroxy-4-methoxy-benzophenone-2-O-β-d-glucoside (Mahkoside A) and 2,4′,6-trihydroxy-4-methoxy-6″-acetyl-benzophenone-2-O-β-d-glucoside (Mahkoside B). Mahkoside B was recognized as a novel compound. Furthermore, a series of benzophenone glucopyranoside derivatives (compounds 3–18) were synthesized and their bioactivities were characterized. Our results demonstrated that compound 18 has significant cytotoxicity against two esophageal cancer cell lines, stomach cancer cell line and prostate cancer cell line, with IC₅₀ less than 10 μM, indicating its potential activity against cancer cells.     

New amide linked dimeric 1,2,3-triazoles bearing aryloxy scaffolds as a potent antiproliferative agents and EGFR tyrosine kinase phosphorylation inhibitors

A search for potent antiproliferative agents has prompted to design and synthesize aryloxy bridged and amide linked dimeric 1,2,3-triazoles (7a–j) by using 1,3-dipolar cycloaddition reaction between 2-azido-N-phenylacetamides (4a–e) and bis(prop-2-yn-1-yloxy)benzenes (6a–b) via copper (I)-catalyzed click chemistry approach with good to excellent yields. All the newly synthesized compounds have been screened for their in vitro antiproliferative activities against two human cancer cell lines. The compounds 7d, 7e, 7h, 7i and 7j have revealed promising antiproliferative activity against human breast cancer cell line (MCF-7), whereas, the compounds 7a, 7b, 7c, 7i and 7j were observed as potent antiproliferative agents against human lung cancer cell line (A-549). The active compounds against MCF-7 have been also analysed for their mechanism of action by the enzymatic study, which shows that the compounds 7d, 7h and 7j were acts as active EGFR tyrosine kinase phosphorylation inhibitors. In support to this biological study, the molecular docking as well as in silico ADME properties of all the newly synthesized hybrids were predicted.     

Design,synthesis, and biological evaluation of 1,9-diheteroarylnona-1,3,6,8-tetraen-5-ones as a new class of anti-prostate cancer agents

In search of more effective chemotherapeutics for the treatment of castration-resistant prostate cancer and inspired by curcumin analogues, twenty five (1E,3E,6E,8E)-1,9-diarylnona-1,3,6,8-tetraen-5-ones bearing two identical terminal heteroaromatic rings have been successfully synthesized through Wittig reaction followed by Horner–Wadsworth–Emmons reaction. Twenty-three of them are new compounds. The WST-1 cell proliferation assay was employed to assess their anti-proliferative effects toward both androgen-sensitive and androgen-insensitive human prostate cancer cell lines. Eighteen out of twenty-five synthesized compounds possess significantly improved potency as compared with curcumin. The optimal compound, 78, is 14- to 23-fold more potent than curcumin in inhibiting prostate cancer cell proliferation. It can be concluded from our data that 1,9-diarylnona-1,3,6,8-tetraen-5-one can serve as a new potential scaffold for the development of anti-prostate cancer agents and that pyridine-4-yls and quinolin-4-yl act as optimal heteroaromatic rings for the enhanced potency of this scaffold. Two of the most potent compounds, 68 and 75, effectively suppress PC-3 cell proliferation by activating cell apoptosis and by arresting cell cycle in the G₀/G₁ phase.     

New antiproliferative and immunosuppressive withanolides from the seeds of Datura metel

Two new withanolides baimantuoluoside H (1) and baimantuoluoline K (2), and one known withanolide glycoside (3) were isolated and identified from the ethyl acetate-soluble fraction of ethanol extract of Datura metel seeds. The structures of the new compounds were determined using 1D and 2D NMR spectroscopy, and mass spectrometry. All isolated compounds were evaluated for their antiproliferative activity against human gastric adenocarcinoma (SGC-7901), human hepatoma (Hepg2), and human breast cancer (MCF-7) cells, as well as their immunosuppressive properties. It was determined that compounds 1–3 exhibited medium antiproliferative and potential immunosuppressive effects.     

Chemical constituents of Ligularia alticola Worosch. leaves and their biological activities

Seven eremophilane-type sesquiterpenes (1–7), six cycloartane derivatives (8–13) and α-amyrin acetate (14) were isolated from the leaves of the far-eastern plant Ligularia alticola Worosch. (Family Asteraceae). (4S,5R,8S,10R)-8-Ethoxyeremophil-7(11)-en-12(8)-olide (1), 8α,11-epidioxy-8β-methoxyeremophil-6-ene (2) and 29-norcycloartan-3α-ol (8) have not been previously reported. Fukinone α-epoxide (3) was isolated for the first time from a natural source. The structures of all the compounds were established by the extensive analysis of their 1D and 2D NMR spectra and HR ESI mass spectrometry. The absolute stereochemistry of 1 was determined by comparison of theoretical and experimental ECD spectra with the application of B3LYP-TDDFT and B3LYP-GIAO calculations as well as by NMR spectroscopy. Compound 1 showed cytotoxic action against human cancer HL-60, Raji, and THP-1 cell lines (IC₅₀ 12.6, 6.0 and 6.9 μM, respectively). Compounds 2 and 4 demonstrated significant cytotoxic activities against HL-60 (IC₅₀ 2.8 and 5.8 μM, respectively) and Raji cells (IC₅₀ 2.9 and 4.2 μM, respectively). Compound 6 was cytotoxic against Raji cells (IC₅₀ 4.6 μM). None of tested compounds were cytotoxic against RAW 264.7 cells. Compounds 1 and 4–7 significantly decreased intracellular ROS levels, induced by endotoxic LPS from Escherichia coli in RAW 264.7 murine macrophages.