Simultaneous Measurement of HDAC1 and HDAC6 Activity in HeLa Cells Using UHPLC-MS

The search for new histone deacetylase (HDAC) inhibitors is of increasing interest in drug discovery. Isoform selectivity has been in the spotlight since ...

Universités des Geneva–Lausanne (EPGL)

Investigation of the aerial parts of Schizanthus tricolor yielded seven isomeric tropane alkaloids: 3alpha-(1-methylitaconyl)-6beta-senecioyloxytropane (1), 3alpha-(1-methylitaconyl)-6beta-angeloyloxytropane (2), 3alpha-(1-methylmesaconyl)-6beta-senecioyloxytropane (3), 3alpha-(1-methylmesaconyl)-6beta-angeloyloxytropane (4), 3alpha-(1-methylmesaconyl)-6beta-tigloyloxytropane (5), 3alpha-(1-methylcitraconyl)-6beta-senecioyloxytropane (6), and 3alpha-(1-methylcitraconyl)-6beta-angeloyloxytropane (7). Their structures were established by NMR including (1)H, (13)C NMR, HSQC, HMBC, COSY, and NOESY experiments, UV, IR, and mass spectrometry. Compounds 1, 6, and 7 are new to the literature. Alkaloids 1, 3, 4, and 5 and a mixture of 3, 4, and 5 were evaluated for in vitro antiplasmodial and cytotoxic activity. Compounds 1, 4, and 5 showed marginal inhibition of Plasmodium falciparum strain K1 with IC(50) values of 22.8, 24.8, and 36.0 microM and displayed no cytotoxicity on MRC-65 cells (CC(50) > 64 microM). Alkaloid 3 was inactive (IC(50) 63.5 microM). The alkaloid mixture exhibited slightly higher activity (IC(50) 17.0 microM) than the pure compounds, indicating some synergy between the different isomers.

Isomeric tropane alkaloids from the aerial parts of Schizanthus tricolor.

Aristotelia chilensis leaves (Elaeocarpaceae) are used in Chilean folk medicine to treat pain and inflammation. A bioguided study was carried out on serial extracts (hexane, dichloromethane, methanol, aqueous extract (INFU) and a crude mixture of alkaloids (ALK-MIX). All extracts were evaluated for (1) topical administration against both arachidonic acid and 12-deoxyphorbol-13-decanoate (TPA)-induced inflammation in mice and (2) per-os administration against inflammation by λ-carrageenan-induced paw oedema in guinea-pigs and (3) topical analgesia in tail flick and formalin models and per-os writhing test in mice.

Chemical study and anti-inflammatory, analgesic and antioxidant activities of the leaves of Aristotelia chilensis (Mol.) Stuntz, Elaeocarpaceae.

Schizanthus grahamii is an endemic Chilean plant that is known to contain tropane alkaloids. Five new alkaloids, grahamines A-E (1-5), were isolated and characterized by extensive spectroscopic analysis. Their structures were determined to be 2-{[(3α-hydroxytropo-6β-yl)oxy]carbonyl}-2-methyl-3-{[((6β-angeloyloxy)-3α-yl)oxy]carbonyl}-4-phenylcyclobutanecarboxylic acid (1), 2-{[(3α-hydroxytropo-6β-yl)oxy]carbonyl}-2-methyl-3-{[((6β-tigloyloxy)-3α-yl)oxy]carbonyl}-4-phenylcyclobutanecarboxylic acid (2), 1-methyl-2-{[(3α-hydroxytropo-6β-yl)oxy]carbonyl}-4-{[((6β-angeloyloxy)-3α-yl)oxy]carbonyl}-3-phenylcyclobutanecarboxylic acid (3), 1,2-bis{[(3α-hydroxytropo-6β-yl)oxy]carbonyl}-2-methyl-3-{[((6β-angeloyloxy)-3α-yl)oxy]carbonyl}-4-phenylcyclobutanecarboxylate (4), and 1-{[(3α-mesaconyloxytropo-6β-yl)oxy]carbonyl}-2-{[(3α-hydroxytropo-6β-yl)oxy]carbonyl}-2-methyl-3-{[((6β-angeloyloxy)-3α-yl)oxy]carbonyl}-4-phenylcyclobutanecarboxylate (5).

Grahamines A-E, cyclobutane-centered tropane alkaloids from the aerial parts of Schizanthus grahamii.

A series of twelve analogs carrying fluoro, chloro, bromo and iodo halogens on the ortho, meta and para positions of a benzoyloxytropane skeleton were synthesized by a simple acylation of 8-methyl-8-aza-bicyclo[3.2.1]octan- 3α-ol by halogenobenzoyl chlorides. The compounds were evaluated in vitro against Plasmodium falciparum (P. f.), Trypanosoma brucei brucei (T. b. b.), Trypanosoma cruzi (T. c.) and Leishmania infantum (L. i.). This study shows that the presence of a halogenated atom and its position on the aromatic ring are important for in vitro activity. Compounds 4 (IC50 = 3.6 µM), 8 (IC50 = 6.7 µM), 5 (IC50 = 8.1 µM) and 7 (IC50 = 9.5 µM) were found the most active against P. f., whereas compounds 12 (IC50 = 5.1 µM), 11 (IC50 = 5.6 µM) and 9 (IC50 = 5.8 µM) exhibited the most pronounced activity against T. b. b. This series of compounds can be considered as non-toxic to the human cell line MRC-5.

Synthesis and in vitro evaluation of tropane halogenated-derivatives against malaria, sleeping sickness, Chagas disease and leishmaniasis.

Chemical investigation of the dichloromethane root extract of Waltheria indica led to the isolation and characterization of 10 quinoline alkaloids, namely, 8-deoxoantidesmone (1), waltheriones E-L (2-9), and antidesmone (10). Among these, compounds 2-9 have not yet been described in the literature. Their chemical structures were established by means of spectroscopic data interpretation including (1)H and (13)C NMR, HSQC, HMBC, COSY, and NOESY experiments and UV, IR, and HRESIMS. The absolute configurations of the compounds were established by comparison of experimental and TDDFT-calculated ECD spectra. In addition, the isolated constituents were evaluated for their in vitro antitrypanosomal activity. Compounds 4, 5, and 8 showed potent and selective growth inhibition toward Trypanosoma cruzi with IC50 values between 0.02 and 0.04 μM. Cytotoxicity for mouse skeletal L-6 cells was also determined for these compounds.

Antitrypanosomal quinoline alkaloids from the roots of Waltheria indica.

Six extracts from the roots and the aerial parts of Waltheria indica L. (Malvaceae) were screened for their in vitro antitrypanosomal activity towards Trypanosoma brucei brucei STIB 427 strain, T. brucei rhodesiense STIB 900 and Trypanosoma cruzi Tulahuen C4. The dichloromethane extract from the roots showed the highest activity against T. cruzi (IC50=0.74 μg/mL) as well as a good selectivity index (SI value of 35). Based on these results, this extract was fractionated and led to the isolation of three alkaloids (adouetin X (1), waltheriones A (2) and C (3)) and three pentacyclic triterpene derivatives (betulinic acid (4), 3β-acetoxy-27-trans-caffeoyloxyolean-12-en-28-oic acid methyl ester (5) and 3β-acetoxy-27-cis-caffeoyloxyolean-12-en-28-oic acid methyl ester (6)) identified by 1D and 2D NMR, UV, IR and MS analyses. Among these, waltherione C exhibited the highest and selective antitrypanosomal activity towards T. cruzi (IC50=1.93 μM) with low cytotoxicity (IC50=101.23 μM), resulting in a selectivity index value of 52. Waltherione C conforms to hit activity criteria with respect to T. cruzi as required by the WHO/TDR.

Chemical constituents from Waltheria indica exert in vitro activity against Trypanosoma brucei and T. cruzi.

Chemical investigation of a dichloromethane extract of the aerial parts of Waltheria indica led to the isolation and characterization of five polyhydroxymethoxyflavonoids, namely, oxyanin A (1), vitexicarpin (3), chrysosplenol E (4), flindulatin (5), 5-hydroxy-3,7,4'-trimethoxyflavone (6), and six quinolone alkaloids, waltheriones M-Q (2, 7, 8, 10, 11) and 5(R)-vanessine (9). Among these, compounds 2, 7, 8, 10, and 11 have not yet been described in the literature. Their chemical structures were established by means of spectroscopic data interpretation including (1)H and (13)C, HSQC, HMBC, COSY, and NOESY NMR experiments and UV, IR, and HRESIMS. The absolute configurations of the compounds were established by ECD. The isolated constituents and 10 additional quinoline alkaloids previously isolated from the roots of the plant were evaluated for their in vitro antifungal activity against the human fungal pathogen Candida albicans, and 10 compounds (7, 9, 11-16, 18, 21) showed growth inhibitory activity on both planktonic cells and biofilms (MIC ≤ 32 μg/mL). Their spectrum of activity against other pathogenic Candida species and their cytotoxicity against human HeLa cells were also determined. In addition, the cytological effect of the antifungal isolated compounds on the ultrastructure of C. albicans was evaluated by transmission electron microscopy.

Antifungal Quinoline Alkaloids from Waltheria indica.

At the early drug discovery stage, the high-throughput parallel artificial membrane permeability assay is one of the most frequently used in vitro models to predict transcellular passive absorption. While thousands of new chemical entities have been screened with the parallel artificial membrane permeability assay, in general, permeation properties of natural products have been scarcely evaluated. In this study, the parallel artificial membrane permeability assay through a hexadecane membrane was used to predict the passive intestinal absorption of a representative set of frequently occurring natural products. Since natural products are usually ingested for medicinal use as components of complex extracts in traditional herbal preparations or as phytopharmaceuticals, the applicability of such an assay to study the constituents directly in medicinal crude plant extracts was further investigated. Three representative crude plant extracts with different natural product compositions were chosen for this study. The first extract was composed of furanocoumarins (Angelica archangelica), the second extract included alkaloids (Waltheria indica), and the third extract contained flavonoid glycosides (Pueraria montana var. lobata). For each medicinal plant, the effective passive permeability values Pe (cm/s) of the main natural products of interest were rapidly calculated thanks to a generic ultrahigh-pressure liquid chromatography-UV detection method and because Pe calculations do not require knowing precisely the concentration of each natural product within the extracts. The original parallel artificial membrane permeability assay through a hexadecane membrane was found to keep its predictive power when applied to constituents directly in crude plant extracts provided that higher quantities of the extract were initially loaded in the assay in order to ensure suitable detection of the individual constituents of the extracts. Such an approach is thus valuable for the high-throughput, cost-effective, and early evaluation of passive intestinal absorption of active principles in medicinal plants. In phytochemical studies, obtaining effective passive permeability values of pharmacologically active natural products is important to predict if natural products showing interesting activities in vitro may have a chance to reach their target in vivo.

Prediction of the Passive Intestinal Absorption of Medicinal Plant Extract Constituents with the Parallel Artificial Membrane Permeability Assay (PAMPA).

Natural products are generally ingested as part of traditional herbal decoctions or in the current diet. However, in natural product research, the bioavailability of secondary metabolites is often poorly investigated. In this work, a systematic study was carried out in order to highlight the physicochemical parameters that mainly influence the passive intestinal absorption of natural products. For this, a representative set of natural products including alkaloids, coumarins, flavonoid aglycones and glycosides, and carboxylic acids was selected and their physicochemical properties were predicted using relevant Volsurf+ descriptors. The chemical space obtained with this unbiased method was then correlated with experimental passive intestinal permeability data, which highlighted the main influence of lipophilicity, global hydrophilicity, size, and the ionisation state on passive intestinal absorption of natural products. Since the pH range encountered in the intestine is wide, the influence of the ionisation was investigated deeper experimentally. The ionisation state of weakly ionisable natural products, such as flavonoid aglycones, alkaloids, and carboxylic acids, was found to prevent the passive intestinal absorption of such natural products completely. In addition, the impact of solubility issues on passive permeability results was evaluated in cases of poorly water-soluble natural products, such as flavonoid aglycones and coumarins. The biomimetic fasted state simulated fluid-version 2 was found to improve the apparent solubility of such poorly soluble natural products without influencing their permeability behaviours. The use of such a solubilising buffer was found to be well adapted to the hexadecane membrane-parallel artificial membrane permeability assay and can circumvent the solubility issues encountered with poorly soluble natural products in such an assay.

Passive Intestinal Absorption of Representative Plant Secondary Metabolites: A Physicochemical Study.

Waltheria indica L. is traditionally used in several countries against inflammatory related diseases and cancer, mainly as a decoction of the aerial parts.

Cancer chemopreventive activity of compounds isolated from Waltheria indica.

Multiple myeloma is characterized by the accumulation of malignant plasma cells in the bone marrow. Multiple myeloma is the second most frequently diagnosed hematological malignancy, predominantly affecting the elderly. Despite recent advances in the development of novel therapies, multiple myeloma remains an incurable malignancy where the majority of patients relapse, develop resistance, and eventually die from the disease. This has been attributed to the fact that conventional therapy currently in use targets mainly the bulk of tumor cells, but not the tumor-initiating cancer stem cells. Cancer stem cells are a highly resistant subpopulation of cells believed to be responsible for the initiation, progression, metastasis, and relapse of cancer. Enormous efforts have been invested in the characterization of cancer stem cells. These efforts led to the characterization of key cellular signaling pathways responsible for conferring stem cell characteristics including self-renewal, differentiation, migratory, survival, and intracellular detoxification capabilities. Targeting these protective mechanisms offers a valuable strategy that may help combat a major driving force behind cancers. The use of natural products offers a promising therapeutic approach for targeting cancer stem cells. In this review, recent advances achieved in the characterization of cancer stem cells derived from hematological malignancies, with a particular focus on multiple myeloma, are discussed and major natural products that target cancer stem cells are presented. As natural products remain an essential source of novel chemical structures and medicinal leads, the exploitation of this immense reservoir is used to draw lessons in targeting multiple myeloma-cancer stem cells.

Targeting Multiple Myeloma Cancer Stem Cells with Natural Products - Lessons from Other Hematological Malignancies.

A new bibenzyl derivative (4), together with two glycosylated flavonoids (1 and 2), batatasin III (3) and the phenanthrene isohircinol (5) were isolated from the aerial parts of Gavilea lutea. Their structures were elucidated on the basis of spectroscopic studies including 1D and 2D NMR, UV, IR and HRESIMS. All isolated compounds were evaluated for their antifungal activity towards Candida albicans. The new compound 4 showed inhibitory activity with a MIQ of 50 μg. In addition, compound 4 exhibited a selective activity (IC50 = 2.3 μg/mL) against Leishmania donovani.

Sylvian Cretton

Section des Sciences Pharmaceutiques

Universités des Geneva–Lausanne (EPGL)

Simultaneous Measurement of HDAC1 and HDAC6 Activity in HeLa Cells Using UHPLC-MS

Sylvian Cretton

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Section des Sciences Pharmaceutiques

Universités des Geneva–Lausanne (EPGL)

Simultaneous Measurement of HDAC1 and HDAC6 Activity in HeLa Cells Using UHPLC-MS

Section des Sciences Pharmaceutiques