Synthesis of Guaianolide Analogues with a Tunable α-Methylene-γ-lactam Electrophile and Correlating Bioactivity with Thiol Reactivity.

α-Methylene-γ-lactones are present in ∼3% of known natural products, and compounds comprising this motif display a range of biological activities. However, this reactive lactone limits informed structure-activity relationships for these bioactive molecules. Herein, we describe chemically tuning the electrophilicity of the α-methylene-γ-lactone by replacement with an α-methylene-γ-lactam. Guaianolide analogues having α-methylene-γ-lactams are synthesized using the allenic Pauson-Khand reaction. Substitution of the lactam nitrogen with electronically different groups affords diverse thiol reactivity. Cellular NF-κB inhibition assays for these lactams were benchmarked against parthenolide and a synthetic α-methylene-γ-lactone showing a positive correlation between thiol reactivity and bioactivity. Cytotoxicity assays show good correlation at the outer limits of thiol reactivity but less so for compounds with intermediate reactivity. A La assay to detect reactive molecules by nuclear magnetic resonance and mass spectrometry peptide sequencing assays with the La antigen protein demonstrate that lactam analogues with muted nonspecific thiol reactivities constitute a better electrophile for rational chemical probe and therapeutic molecule design.

Recent Patents on Anti-Cancer Potential of Helenalin.

BACKGROUND: Arnica montana, containing helenalin as its principal active constituent, is the most widely used plant to treat various ailments. Recent studies indicate that Arnica and helenalin provide significant health benefits, including anti-inflammatory, neuroprotective, antioxidant, cholesterol-lowering, immunomodulatory, and most important, anti-cancer properties. OBJECTIVE: The objective of the present study is to overview the recent patents of Arnica and its principal constituent helenalin, including new methods of isolation, and their use in the prevention of cancer and other ailments. METHODS: Current prose and patents emphasizing the anti-cancer potential of helenalin and Arnica, incorporated as anti-inflammary agents in anti-cancer preparations, have been identified and reviewed with particular emphasis on their scientific impact and novelty. RESULTS: Helenalin has shown its anti-cancer potential to treat multiple types of tumors, both in vitro and in vivo. It has also portrayed synergistic effects when given in combination with other anti- cancer drugs or natural compounds. New purification/isolation techniques are also developing with novel helenalin formulations and its synthetic derivatives have been developed to increase its solubility and bioavailability. CONCLUSION: The promising anti-cancer potential of helenalin in various preclinical studies may open new avenues for therapeutic interventions in different tumors. Thus clinical trials validating its tumor suppressing and chemopreventive activities, particularly in conjunction with standard therapies, are immediately required.

Integration of dry-column flash chromatography with NMR and FTIR metabolomics to reveal cytotoxic metabolites from Amphoricarpos autariatus.

Metabolomics generate a profile of small molecules from plant extracts, which could be directly responsible for bioactivity effects. Using dry-column flash chromatography enabled a rapid and inexpensive method for the very efficient separation of plant extract with a high resolution. This separation method coupled to NMR and FTIR-based metabolomics is applied to identify bioactive natural products. OPLS multivariate analysis method, was used for correlation the chemical composition of the plant extracts, Amphoricarpos autariatus, with the results of cytotoxic activity against Human cervical adenocarcinoma cell line (HeLa) and epithelial lung cancer cell line (A549). In this way, the highest contribution to the cytotoxic activity was recorded for the guaianolide sesquiterpene lactones named amphoricarpolides. The compounds indicated as bioactive after metabolomics analysis were tested, and their cytotoxic activity were confirmed.

Preparation and Phytotoxicity Evaluation of 11,13-Dehydro seco-Guaianolides.

11,13-Dehydro seco-guaianolides, a particular type of sesquiterpene lactones, were synthesized from the commercially available α-santonin (11) using a facile strategy involving a high-yielding photochemical reaction. Natural products 10 and 17 from Artemisia gorgonum were synthesized in good yields. Specifically, compound 10 was obtained in five steps with an overall yield of 17%. The sesquiterpene lactones were tested in the etiolated wheat coleoptile bioassay, and the most active compounds were assayed on standard target species. Guaianolide 13 showed the highest phytotoxic activities when compared with the known herbicide Logran.

Synthesis and structure-activity relationships of guaiane-type sesquiterpene lactone derivatives with respect to inhibiting NO production in lipopolysaccharide-induced RAW 264.7 macrophages.

A guaiane framework was scaffolded by photochemical rearrangement reactions using α-santonin 1 as a starting material. Then, using a series of reactions, we synthesized the guaiane-type sesquiterpene lactone 5 in high yield. The inhibitory activities of compound 5 and of a series of derivatives on nitric oxide (NO) release were evaluated in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Compounds 6g, 7h, 7i, 7k and 8g, exhibited significant inhibitory effects on NO production, with IC50 values of 14.8, 22.3, 18.3, 17.4 and 7.0 µM, respectively. Their cytotoxicities were also estimated using an MTT assay. The structure-activity relationships of these compounds were also discussed.

Japonicone A suppresses growth of Burkitt lymphoma cells through its effect on NF-κB.

PURPOSE: NF-κB, a transcriptional regulator of diverse genes involved in cell survival, proliferation, adhesion, and apoptosis, has been implicated in various malignancies. We discovered a potent natural NF-κB inhibitor, Japonicone A, from the traditional herb Inula japonica Thunb, evaluated its preclinical pharmacology and therapeutic activity, and investigated the underlying mechanisms of action for its antitumor activity. EXPERIMENTAL DESIGN: Various types of cancer and normal cells were exposed to Japonicone A for cytotoxicity screening, followed by determination of cell apoptosis and cell-cycle arrest. Western blotting, immunostaining, and gene reporter assay were used to analyze NF-κB activity. Two xenograft models were used for therapeutic efficacy evaluation. RESULTS: Japonicone A killed cancer cells but had low cytotoxicity to normal cells. Burkitt lymphoma cells were particularly sensitive. Japonicone A inhibited the growth and proliferation of Raji, BJAB, and NAMALWA lymphoma cells and resulted in G2-M phase arrest and apoptosis. Furthermore, exposure of cells to Japonicone A caused inactivation of the TNF-α-TAK1-IKK-NF-κB axis and inhibition of TNF-α-stimulated NF-κB activity and nuclear translocation, followed by downregulation of NF-κB target genes involved in cell apoptosis (Bcl-2, Bcl-xL, XIAP, TRAF2) and in the cell cycle and growth (cyclin D, c-Myc). Moreover, Japonicone A inhibited local growth and dissemination of cancer cells to multiple organs in vivo. CONCLUSION: Japonicone A exerts significant anticancer effects on Burkitt lymphoma cells in vitro and in vivo through targeting of the NF-κB signaling cascade. These results highlight the potential of Japonicone A as a chemotherapeutic agent and warrant its development as a therapy for lymphomas.

An unusual dimeric guaianolide with antiprotozoal activity and further sesquiterpene lactones from Eupatoriumperfoliatum.

The CH(2)Cl(2) extract of aerial parts of Eupatorium perfoliatum L. exhibits antiprotozoal activity under in vitro conditions, especially against Plasmodium falciparum (IC(50)=2.7µg/ml). The search for active compounds yielded seven sesquiterpene lactones: Four structurally similar guaianolides, one dimeric guaianolide, and two germacranolides. The guaianolides differ in the degree of oxidation at C-14, ranging from a hydroxyl group up to a free carboxylic acid. The dimeric guaianolide, structurally closely related to the monomers, displays an unusual type of interguaianolide linkage between C-14 and C-4. Except for the germacranolide euperfolitin, all STLs described here were hitherto unknown. Furthermore, the flavonoid aglycones eupafolin, hispidulin, patuletin, and kaempferol were identified in the extract, which, except for kaempferol, have not been described as constituents of E. perfoliatum before. The dimeric guaianolide was shown to be the most active constituent against Plasmodium falciparum (IC(50) = 2.0µM) and was less cytotoxic against rat skeletal myoblasts (IC(50) = 16.2µM, selectivity index of about 8).

Antileishmanial activity of a guaianolide from Tanacetum parthenium (L.) Schultz Bip.

Leishmaniasis is one of the major infectious diseases affecting the poorest regions of the world. The present study evaluated the antileishmanial activity of a guaianolide purified from the hydroalcoholic extract of aerial parts of Tanacetum parthenium (L.) Schultz Bip. The isolated compound showed activity against the promastigote form of Leishmania amazonensis, with 50% inhibition (IC(50)) of cell growth at a concentration of 2.6 µg/ml. For the intracellular amastigote form, this guaianolide reduced by 10% the survival index of parasites in macrophages when it was used at 20.0 µg/ml. The selective index (SI) ratio (CC(50) for J774G8 cells/IC(50) for protozoans) was 385, showing that it is more selective against the parasite than mammalian cells. Morphological alterations of protozoans treated with IC(50) included changes in size, shape, and structure (more than one nucleus and flagellum) under both light and scanning electron microscopies.

A cytotoxic and apoptosis-inducing sesquiterpenoid isolated from the aerial parts of Artemisia princeps PAMPANINI (Sajabalssuk).

Repeated silica gel and octadecyl silica gel (ODS) column chromatography of the aerial parts of Artemisia princeps PAMPANINI (Sajabalssuk) led to the isolation of a new sesquiterpenoid, 3-((S)-2-methylbutyryloxy)-costu-1(10),4(5)-dien-12,6 alpha-olide (2), along with two previously reported sesquiterpenoids: 8 alpha-angeloyloxy-3beta,4 beta-epoxy-6 beta H,7 alpha H,8 beta H-guaia-1(10),11(13)-dien-12,6 alpha-olide (1, carlaolide B) and 3beta,4 beta-epoxy-8 alpha-isobutyryloxy-6 beta H,7 alpha H,8 beta H-guaia-1(10),11(13)-dien-12,6 alpha-olide (3, carlaolide A). The structure of compound 2 was elucidated by spectroscopic data analysis, including one dimensional (1D) and two dimensional (2D) nuclear magnetic resonance (NMR) experiments. Of the isolates, compound 2 exhibited potent cytotoxicity against human cervix adenocarcinoma cells and induced apoptosis.

Cytotoxic versus anti-inflammatory effects in HeLa, Jurkat T and human peripheral blood cells caused by guaianolide-type sesquiterpene lactones.

Four guaianolide type sesquiterpene lactones (SL), namely the new 1,2-dihydro-3-oxo-costic acid guaianyl ester 3beta-O-(1,2-didehydro-3-oxo-costoyloxy)-4beta,10beta-dihydroxy-guaia-1(2)-en-6beta,12-olide (1) and 3beta-O-(1,2-didehydro-3-oxo-costoyloxy)-4beta,10beta-dihydroxy-guaia-1(2)-en-6alpha,12-olide (2), as well as the known moroccolide A [5alphaH-2beta,4-epoxy-3beta-hydroxy-guaia-1(10),11(13)-dien-6beta,12-olide, 3] and 3beta-O-(2-methylbutyryl)-moroccolide A [5alphaH-2beta,4-epoxy-3beta-(2-methylbutyryloxy)-guaia-1(10),11(13)-dien-6beta,12-olide, 4] were examined for their cytotoxic and anti-inflammatory effects in HeLa, Jurkat T and human peripheral blood mononuclear cells. Compounds 1, 2 and 4 were found to exert a strong cytotoxicity similar in potency in all investigated cell types, whereas 3 was significantly less active. Along with the cytotoxic effect compounds 1 and 4 showed a potent and comparable down-regulation of the mRNAs of the house-keeping genes beta-actin and GAP-DH in PBMCs after 20 h. In contrast, the down-regulation of the PMA-induced mRNA levels of the NF-kappaB-driven pro-inflammatory genes IL-2, IL-6, GM-CSF, TNF-alpha, and IL-1beta in PBMCs is significantly stronger with compound 4. Compound 3 did not significantly modulate cytokine mRNAs levels at biochemically relevant concentrations. The electromobility shift assay (EMSA), revealed a stronger inhibition of NF-kappaB for 1 (IC(50) 2.5 microM) than for 4 (IC(50) 5 microM). Both compounds were also subjected to an IL-6 luciferase reporter gene assay and showed IC(50) values of 1.0 (1) and 1.2 microM (4). Thus, the NF-kappaB inhibition measured by EMSA, as well as the IL-6 luciferase assay did not reflect the differential modulation of pro-inflammatory genes measured with RT-rt-PCR.