Novel anti-viability ceramide analogs: Design,synthesis, and structure–activity relationship studies of substituted (S)-2-(benzylideneamino)-3-hydroxy-N-tetradecylpropanamides

A group of novel l-serinamides, substituted (S)-2-(benzylideneamino)-3-hydroxy-N-tetradecylpropanamides (3a–o) and substituted (S)-2-(benzylamino)-3-hydroxy-N-tetradecyl propanamides (4c, 4i, 4l, and 4o), were synthesized as potential anti-tumor lead compounds. In vitro cell viability assay results indicate treatment with 3a–o compounds resulted in significant inhibition of cell viability in the chemoresistant breast cancer cell line, MCF-7TN-R. Compounds 3i and 3l, both ortho-substituted analogs, show the greatest efficacy with IC₅₀ values of 10.3 μM and 12.5 μM, respectively. The SAR analysis indicate that the imine functional group of 3a–o is critical for the cellular anti-viability effect, and the partial atomic charge (PAC) value of imine C atom is a valuable structural parameter for predicting the activity of these ceramide analogs.     

Angoline: A selective IL-6/STAT3 signaling pathway inhibitor isolated from Zanthoxylum nitidum

STAT3 signaling pathway is an important target for human cancer therapy. Thus, the identification of small-molecules that target STAT3 signaling will be of great interests in the development of anticancer agents. The aim of this study was to identify novel inhibitors of STAT3 pathway from the roots of Zanthoxylum nitidum (Roxb.) DC. The bioassay-guided fractionation of MeOH extract of Z. nitidum using a STAT3-responsive gene reporter assay led to the isolation of angoline (1) as a potent and selective inhibitor of the STAT3 signaling pathway (IC₅₀ = 11.56 μM). Angoline inhibited STAT3 phosphorylation and its target gene expression and consequently induced growth inhibition of human cancer cells with constitutively activated STAT3 (IC₅₀ = 3.14–4.72 μM). This work provided a novel lead for the development of anti-cancer agents targeting the STAT3 signaling pathway.     

Synthesis and cytotoxic activity of new azepino[3′,4′:4,5]pyrrolo[2,1-a]isoquinolin-12-ones

A series of azepino[3′,4′:4,5]pyrrolo[2,1-a]isoquinolin-12-ones (3a–f), that were conformationally restricted analogs of lead compound 2, were designed as potential cytotoxic compounds and synthesized using a radical oxidative aromatic substitution reaction as the key step. Compounds 3a–f were tested on five tumor cell lines to determine the conformational requirements for biological activity of compound 2. The results show that conformational restrictions on compound 2, generating the derivatives 3a–f, do not appreciably reduce the cytotoxic activity of 2, although compound 3d (R = Br) showed good activity against U-251 cells. Preliminary structure–activity relationship studies with these compounds revealed the importance of halogens bonded to the isoquinoline moiety. Additionally, derivatives 3f (R = NO₂) and 3b (R = F) were cytotoxic to PC-3 and K-562 cells. However, none of the azepino[3′,4′:4,5]pyrrolo[2,1-a]isoquinolinones inhibited the enzymatic activity of CDK1/cyclin B, CDK5/p25, or GSK-3.     

Cytotoxic pterosins from Pteris multifida roots against HCT116 human colon cancer cells

Two new pterosin glycosides, (2S,3S)-pterosin C 3-O-β-d-(4′-(E)-caffeoyl)-glucopyranoside (1) and (2S,3S)-pterosin C 3-O-β-d-(6′-(E)-p-coumaroyl)-glucopyranoside (2), were isolated from Pteris multifida (Pteridaceae) roots along with ten known pterosin compounds (3–12). The chemical structures of the isolated compounds were elucidated by extensive analysis of the 1D, 2D NMR, HRESIMS, and CD spectroscopic data. The cytotoxicities of 1–12 against HCT116 human colorectal cancer cell line were evaluated. Among the isolates, compound 1 showed moderate antiproliferative activity in HCT116 cells with an IC₅₀ value of 8.0 ± 1.7 μM. Additionally, 1 induced the upregulation of the caspase-9 and procaspase-9 levels in Western blots and increased the annexin V/propidium iodide (PI)-positive cell population in flow cytometry.     

Synthesis,structure–activity relationships and biological evaluation of barbigerone analogues as anti-proliferative and anti-angiogenesis agents

A series of barbigerone analogues (7a–7w, 13a–13x) were designed, synthesized and biologically evaluated for their anti-proliferative and anti-angiogenic activities. Among these compounds, compound 13a exhibited the most potent inhibitory effect on the proliferation of HUVECs, HepG2, A375, U251, B16, and HCT116 cells (IC₅₀ = 3.80, 0.28, 1.58, 3.50, 1.09 and 0.68 μM, respectively). Compound 13a inhibited the angiogenesis in zebrafish embryo assay in a concentration-dependent manner. Furthermore, 13a also effectively inhibited the migration and capillary like tube formation of human umbilical vein endothelial cell in vitro. These results support the further investigation of this class of compounds as potential anti-proliferative and anti-angiogenesis agents.     

A new megastigmane from Kalanchoe tubiflora (Harvey) Hamet

One new megastigmane, (6S,7R,8R,9S)-6-oxaspiro-7,8-dihydroxymegastigman-4-en-3-one (1) (tubiflorone, 1), and ten known compounds were isolated and characterized from the EtOH extract of Kalanchoe tubiflora (Harvey) Hamet. Structures of these isolates were assigned based on spectroscopic analyses that included 1D and 2D NMR techniques, such as HMQC, HMBC, and NOESY. The anti-inflammatory activities of selected isolated compounds (1–6 and 9–11) were evaluated as inhibitory activities against lipopolysaccharide (LPS) induced nitric oxide (NO) production in RAW264.7 cell lines. Compounds 1–4, 6, 9, and 11 possessed nitric oxide inhibitory activity with IC₅₀ values ranging from 15.1 ± 0.9 to 98.9 ± 1.3 μM.     

Anti-inflammatory components of Euphorbia humifusa Willd.

Two new compounds, euphorbinoside (1) and dehydropicrorhiza acid methyl diester (2), along with 24 known compounds (3–26) were isolated from Euphorbia humifusa Willd. The effects of these compounds on soluble epoxide hydrolase (sEH) inhibitory activity were evaluated. Flavonoid compounds (10–21) exhibited high sEH inhibitory activity. Among them, compounds 12, 13, and 19 greatly inhibited sEH enzymatic activity, with IC₅₀ values as low as 18.05 ± 1.17, 18.64 ± 1.83, and 17.23 ± 0.84 μM, respectively. In addition, the effects of these compounds on lipopolysaccharide (LPS)-induced nitric oxide (NO) and tumor necrosis factor alpha (TNF-α) production by RAW 264.7 cells were investigated. Compounds 3–6, 8, 18, 20–23, and 25–26 inhibited the production of both NO and TNF-α, with IC₅₀ values ranging from 11.1 ± 0.9 to 45.3 ± 1.6 μM and 14.4 ± 0.5 to 44.5 ± 1.2 μM, respectively.     

Synthesis and antimicrobial activity of novel amphiphilic aromatic amino alcohols

We report in this work the preparation and in vitro antimicrobial evaluation of novel amphiphilic aromatic amino alcohols synthesized by reductive amination of 4-alkyloxybenzaldehyde with 2-amino-2-hydroxymethyl-propane-1,3-diol. The antibacterial activity was determined against four standard strains (Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa) and 21 clinical isolates of methicillin-resistant Staphylococcus aureus. The antifungal activity was evaluated against four yeast (Candida albicans, Candida tropicalis, Candida glabrata and Candida parapsilosis). The results obtained showed a strong positive correlation between the lipophilicity and the antibiotic activity of the tested compounds. The best activities were obtained against the Gram-positive bacteria (MIC = 2–16 μg ml^?1) for the five compounds bearing longer alkyl chains (4c–g; 8–14 carbons), which were also the most active against Candida (MIC = 2–64 μg ml^?1). Compound 4e exhibited the highest levels of inhibitory activity (MIC = 2–16 μg ml^?1) against clinical isolates of MRSA. A concentration of twice the MIC resulted in bactericidal activity of 4d against 19 of the 21 clinical isolates.     

Secondary metabolites produced by the fungus Monascus pilosus and their anti-inflammatory activity

A detailed phytochemical study of the n-BuOH-soluble fraction of the 95% EtOH extract of red yeast rice fermented with the fungus Monascus pilosus BCRC 38072 (Eurotiaceae) revealed a new azaphilone derivative, namely monascusazaphilol (1) (rel-(3S,3aR,9aR)-3-(1-hydroxydecyl)-9a-methyl-6-((E)-propenyl)-3a,4,8,9a-tetrahydro-3H-furo[3,2-g]isochromene-2,9-dione), along with ten known compounds (2–11). Their structures were established by direct interpretation of their spectral data, mainly high resolution electrospray ionization mass spectrometry (HR-ESI-MS), 1D and 2D NMR (COSY, ROESY, HSQC and HMBC), and comparison of the spectroscopic data with those reported for structurally related compounds. We also evaluated the inhibitory effects of some isolates on the production of tumor necrosis factor (TNF-α) induced by lipopolysaccharide (LPS). Among the isolates, compounds 1–3 inhibited TNF-α production in U937 cells in vitro, and the IC₅₀ values were 1.24, 2.35 and 3.75 μg/ml, respectively.     

Cytotoxicity and modes of action of three naturally occurring xanthones (8-hydroxycudraxanthone G,morusignin I and cudraxanthone I) against sensitive and multidrug-resistant cancer cell lines

BackgroundResistance of cancer to chemotherapy remains a challenging issue for scientists as well as physicians. Naturally occurring xanthones possess a variety of biological activities such as anti-inflammatory, anti-bacterial, and anti-cancer effects. The present study was aimed at investigating the cytotoxicity and the modes of action of three naturally occurring xanthones namely, morusignin I (1), 8-hydroxycudraxanthone G (2) and cudraxanthone I (3) against a panel of nine cancer cell lines, including various sensitive and drug-resistant phenotypes.MethodsThe cytotoxicity of the compounds was determined using a resazurin reduction assay, whereas the caspase-Glo assay was used to detect the activation of caspases 3/7, caspase 8 and caspase 9 in cells treated with compounds 3. Flow cytometry was used for cell cycle analysis and detection of apoptotic cells, analysis of mitochondrial membrane potential (MMP) as well as measurement of reactive oxygen species (ROS).ResultsCompounds 1 and 3 inhibited the proliferation of all tested cancer cell lines including sensitive and drug-resistant phenotypes. Compound 2 was active on 8/9 cell lines with the IC₅₀ values ranging from 16.65 μM (against leukemia CCRF-CEM cells) to 70.38 μM (against hepatocarcinoma HepG2 cells). The IC₅₀ value ranged from 7.15 μM (against CCRF-CEM cells) to 53.85 μM [against human glioblastoma U87MG.ΔEGFR cells] for compound 1, and from 2.78 μM (against breast cancer MDA-MB231 BCRP cells) to 22.49 μM (against U87MG cells) for compound 3. P-glycoprotein expressing CEM/ADR5000 cells were cross-resistant to compounds 1 and 2 (4.21- to 610-fold) while no cross-resistance or even collateral cross-sensitivity were observed in other drug-resistant cell lines to the three compounds. Normal AML12 liver cells were more resistant to the three compounds than HepG2 liver cancer cells. Compounds 3 arrested the cell cycle between G0/G1 and S phases, strongly induced apoptosis via caspases 3/7, caspase 8, caspase 9 activation and disrupted the MMP in CCRF-CEM cells.ConclusionsThe cytotoxicity of the studied xanthones and especially compound 3 deserve more detailed exploration in the future to develop novel anticancer drugs against sensitive and otherwise drug-resistant phenotypes.     

Phytochemical and cytotoxic studies on the leaves of Calotropis gigantea

A new lignan, 9′-methoxypinoresinol (1), and two new glycosylated 5-hydroxymethylfurfurals, calofurfuralside A (2), and calofurfuralside B (3), together with nine known compounds (4–12) have been isolated from the active fractions, CHCl₃ (IC₅₀, 0.32 μg mL^?1) and EtOAc (IC₅₀, 0.55 μg mL^?1) fractions of the leaves of Calotropis gigantea. Their structures were elucidated based on NMR and MS data. Among the isolated compounds, compounds 1 and 9 exhibited potent cytotoxicity against PANC-1 human pancreatic cancer cell line under the normoglycemic condition with IC₅₀ values of 3.7 and 3.3 μM, respectively. 9′-Methoxypinoresinol (1) significantly inhibited the colony formation of PANC-1 cells in a concentration-dependent manner.     

Cytotoxic and apoptosis-inducing activities against human lung cancer cell lines of cassaine diterpenoids from the bark of Erythrophleum fordii

A phytochemical investigation into the bark of Erythrophleum fordii yielded four new compounds, two new cassaine diterpenoids (erythrofordin T and U, 1 and 2) and two new cassaine diterpenoid amines (erythroformine A and B, 6 and 7), as well as nine known compounds. We report for the first time the isolation of erythrofordin V (3) from a natural source and that of the remaining eight known diterpenoids (4–5, 8–13) from E. fordii. All structures were elucidated using spectroscopic analysis. Cytotoxic activity of the isolated compounds (1–13) was examined in vitro against three non-small cell lung cancer cell lines (A549, NCI-H1975, and NCI-H1229) using the MTT assay. Cassaine diterpene amines (6–10, 12, 13) exhibited potent cytotoxic activity against all three cell lines with IC₅₀ values between 0.4 μM and 5.9 μM. Erythroformine B (7) significantly induced apoptosis in all three cancer cells in a concentration-dependent manner.     

Synthesis of dammarane-type triterpene derivatives and their ability to inhibit HIV and HCV proteases

We synthesized dammarane-type triterpene derivatives and evaluated their ability to inhibit HIV-1 and HCV proteases to understand their structure–activity relationships. All of the mono- and di-succinyl derivatives (5a–5f) were powerful inhibitors of HIV-1 protease (IC₅₀ < 10 μM). However, only di-succinyl (5e) and 2,3-seco-2,3-dioic acid (3b) derivatives similarly inhibited HCV protease (IC₅₀ < 10 μM). A-nor dammarane-type triterpenes (4a and 4b, IC₅₀ 10.0 and 29.9 μM, respectively) inhibited HIV-1 protease moderately or strongly, but were inactive against HCV protease. All compounds that powerfully inhibited HIV-1 or HCV protease did not appreciably inhibit the general human proteases, renin and trypsin (IC₅₀ > 1000 μM). These findings indicated that the mono-succinyl dammarane type derivatives (5a–5d) selectively inhibited HIV-1 protease and that the di-succinyl (5e, 5f) as well as 2,3-seco-2,3-dioic acid (3b) derivatives preferably inhibited both viral proteases.     

Activity of three cytotoxic isoflavonoids from Erythrina excelsa and Erythrina senegalensis (neobavaisoflavone,sigmoidin H and isoneorautenol) toward multi-factorial drug resistant cancer cells

IntroductionResistance of cancer cells to chemotherapy has become a worldwide concern. Naturally occuring isoflavonoids possess a variety of biological activities including anti-cancer effects. The present study was aimed at investigating the cytotoxicity and the modes of action of three naturally occuring isoflavonoids, neobavaisoflavone (1), sigmoidin H (2) and a pterocarpan that is a special type of isoflavonoid, isoneorautenol (3) against a panel of nine cancer cell lines, including various sensitive and drug-resistant phenotypes.MethodsThe cytotoxicity of the compounds was determined using a resazurin reduction assay, whereas the caspase-Glo assay was used to detect the activation of caspases 3/7, caspase 8 and caspase 9 in cells treated with compounds 3. Flow cytometry was used for cell cycle analysis and detection of apoptotic cells, analysis of mitochondrial membrane potential (MMP) as well as measurement of reactive oxygen species (ROS).ResultsCompounds 3 showed significant cytotoxicity toward sensitive and drug-resistant cancer cell lines. Compounds 1 and 2 were selectively active, and IC50 values below 115 μM were obtained on 6/9 and 4/9 cell lines respectively with values ranging from 42.93 μM (toward CCRF-CEM cells) to 114.64 μM [against HCT116 (p53^+/+) cells] for 1 and 25.59 μM (toward U87MG) to 110.51 μM [against HCT116 (p53^+/+) cells] for 2. IC50 values ranging from 2.67 μM (against MDA-MB 237BCRP cells) to 21.84 (toward U87MG) were measured for compound 3 and between 0.20 μM (toward CCRF-CEM cells) and 195.12 μM (toward CEM/ADR5000 cells) for doxorubicin as control drug. BCRP-transfected MDA-MB-231 cells, HCT116 (p53^+/+) and U87MG.ΔEGFR cells were hypersensitive (collateral sensitive) to compound 3 as compared to their counterpart cell lines. Compound 3 induced apoptosis in CCRF-CEM cells via activation of caspases 3/7, 8 and 9 as well as the loss of MMP and increased ROS production.ConclusionsThe cytotoxicity of the studied isoflavonoids and especially the pterocarpan 3 deserve more detailed exploration in the future to develop novel anticancer drugs against sensitive and otherwise drug-resistant phenotypes.     

Bioactive chemical constituents from the root bark of Morus australis

Two new pyranoflavonoids, morustralins A (1) and B (2), a new natural benzene derivative, one benzenoid (Z)-1-hydroxy-4-(2-nitroethenyl)benzene (3), and thirty known compounds were isolated and characterized from the root bark of Morus australis. The structures of the new compounds were established from spectroscopic and spectrometric analyses. Ten isolates (1–10) were examined for inhibitory effects on adenosine diphosphate (ADP)-, arachidonic acid (AA)-, and platelet-aggregating factor (PAF)-induced platelet aggregation. Among the tested compounds, compound 3 displayed the most significant inhibition of ADP- and AA-induced platelet aggregation with IC₅₀ values of 9.76 ± 5.54 and 9.81 ± 2.7 μM, respectively. In addition, eight purified compounds (3–10) were examined for inhibition of nitric oxide (NO) production in RAW 264.7 cells and six compounds (3–8) displayed significant inhibitory effects with IC₅₀ values ranging from 2.1 ± 0.3 to 6.3 ± 0.6 μM.     

Limonoids from the leaves of Soymida febrifuga and their insect antifeedant activities

Three new phragmalin-type limonoids (1–3) were isolated from the leaves of Soymida febrifuga together with thirteen known limonoids. The structures of these compounds were established on the basis of spectroscopic data. All these isolates were evaluated for their anti-feedant activities in tobacco caterpillar (Spodoptera litura) and castor semilooper (Achaea janata) using a no-choice laboratory bioassay. Among the tested, compounds 9 and 15 demonstrated the potent anti-feedant index (76.46 μg/cm², 66.61 μg/cm² against A. janata, and 61.69 μg/cm², 51.93 μg/cm²against S. litura).     

Synthesis and bio-evaluation of alkylaminoaryl phenyl cyclopropyl methanones as antitubercular and antimalarial agents

A series of 4-alkylaminoaryl phenyl cyclopropyl methanones (6a–6u and 8a–8c) were synthesized from 4-fluorochalcones (3a and 3b) by cyclopropanation of double bond followed by nucleophilic substitution of F with different amines. The compounds were screened for their antitubercular and antimalarial activities against Mycobacterium tuberculosis H37Rv and Plasmodium falciparum 3D7 strains in vitro respectively. Several compounds (6a, 6d–6h, 6p, 6q and 8a–8c) exhibited good in vitro antitubercular activities with MIC values 3.12–12.5 μg/mL and preferentially inhibited the growth of P. falciparum in vitro (4a, 4c, 6a–6d, 6f, 6s, 8a and 8c) with IC₅₀ as low as 0.080 and 0.035 μg/mL and SI values 4975 and 6948, respectively. Molecular docking studies and in vitro evaluation against FAS-II enzymes using reporter gene assays were carried out to elucidate the mode of action of these molecules. Two compounds 4a and 6g showed significant inhibition at 25 μM concentration of the compound.     

Acylated iridoid glycosides and acylated rhamnopyranoses from Gmelina arborea flowers

Nine acylated iridoid glycosides (1–9), five acylated rhamnopyranoses (10–14) and verbascoside (15) were isolated from Gmelina arborea flowers, including 5 new compounds (1, 2, and 10–12). The cytoprotective activity of 11 selected compounds (1–8, 10, 11, and 15) against CCl₄-induced cytotoxicity on liver was determined. Compounds 1, 2, 4, 7, 8 and 15 displayed hepatoprotective activity. 6-O-α-l-(2″, 3″-di-O-trans-p-hydroxycinnamoyl)rhamnopyranosylcatalpol (2) exhibited the most potent cytoprotective effect with an EC₅₀ value of 42.5 μM (SI = 19.3) compared with biphenyldimethylesterate (DDB, EC₅₀ = 277.3 μM, SI = 9.8) and bicylo-ethanol (EC₅₀ = 279.2 μM, SI = 12.2). Among the acylated iridoid glycosides, the compounds (2 and 8) containing phenolic hydroxy groups were more active than were those lacking them.     

Synthesis,in vitro antiproliferative activity and kinase profile of new benzimidazole and benzotriazole derivatives

Protein kinase 2 (CK2), a member of the serine/threonine kinase family, has been established as a promising target in anticancer therapy. New derivatives of known CK2 inhibitors 4,5,6,7-tetrabromo-1H-benzimidazole (TBBi) and 4,5,6,7-tetrabromo-1H-benzotriazole (TBBt) bearing azide or substituted triazole groups were synthesized. Their influence on the activity of human recombinant CK2α and cytotoxicity against normal and cancer cell lines were evaluated. TBBi derivatives with triazole substituted with carboxyl substituent (7 and 10) exhibited the most potent inhibitory activity against CK2 with K_i value in the range of 1.96–0.91 μM, respectively. New TBBi derivatives 2, 3, 5 and 9 have demonstrated the EC₅₀, in the range of 12–25 μM and 13–29 μM respectively towards CCRF-CEM and MCF-7 cells. Derivatives TBBi decreased viability of cancer cells more efficiently than BALB cells and the biggest differences were observed for the azide substituted compounds 3 and 5. The effect of the most active compounds on the activity of eight off-target kinases was evaluated. Inhibitory efficiency of CK2-mediated p65 phosphorylation was demonstrated for the TBBi and compound 12.     

Cytotoxic abietane-derivative diterpenoids of Salvia lachnostachys

A bioassay-guided fractionation of Salvia lachnostachys Benth leaf extract led to the isolation of three known diterpenes, namely fruticuline A (1), fruticuline B (2) and 7,20-dihydrofruticuline A (3), together with two new compounds, 4 and 5. The structures were mainly elucidated by 1D and 2D NMR spectroscopy and HRESIMS. The cytotoxic activity of the crude ethanol extract, the semi-purified fractions (A-E) and compounds 1, 2 and 4 were evaluated against seven human cancer cell lines and the normal cell line HaCat. The ethanol extract showed activity against all tested cell lines (GI₅₀ 25.0⿿44.0 μg/mL). Among the fractions, the greatest activity was exhibited by fraction A (eluted with hexane), which inhibited the growth of all tested cell lines with GI₅₀ of 3.9⿿19.5 μg/mL. Compounds 1 and 4 were the most active, inhibiting the growth of U251, MCF-7, NCI-ADR/RES, 786.0, NCI-H460, PC-3, OVCAR-03 and HaCat cell lines with GI₅₀ < 10 μM. Compound 2 showed moderate activity against MCF-7, NCI-H460, OVCAR-03, K562 and HaCat, with GI₅₀ varying 19.9⿿29.3 μM.