Effects of Corchorusoside C on NF-κB and PARP-1 Molecular Targets and Toxicity Profile in Zebrafish

The present study aims to continue the study of corchorusoside C (1), a cardenolide isolated from Streptocaulon juventas, as a potential anticancer agent. A mechanistic study was pursued in a zebrafish model and in DU-145 prostate cancer cells to investigate the selectivity of 1 towards NF-κB and PARP-1 pathway elements. Compound 1 was found to inhibit the expression of IKKα and NF-κB p65 in TNF-α induced zebrafish and inhibit the expression of NIK in vitro. The protein expression levels of XRCC-1 were increased and p53 decreased in DU-145 cells. XIAP protein expression was initially decreased after treatment with 1, followed by an increase in expression at doses higher than the IC50 value. The activity of caspase-1 and the protein expression levels of IL-18 were both decreased following treatment of 1. The binding interactions for 1 to NIK, XRCC-1, p53, XIAP, and caspase-1 proteins were explored in molecular docking studies. Additionally, the toxicity profile of 1 in zebrafish was favorable in comparison to its analog digoxin and other anticancer drugs at the same MTD in zebrafish. Overall, 1 targets the noncanconical NF-κB pathway in vivo and in vitro, and is well tolerated in zebrafish supporting its potential in the treatment of prostate cancer

Isolation, Structure Elucidation, and Biological Evaluation of 16,23-Epoxycucurbitacin Constituents from <i>Eleaocarpus chinensis</i>

Eight new 16,23-epoxycucurbitacin derivatives, designated as elaeocarpucins A–H (<b>1</b>–<b>8</b>), and five known cucurbitacins (<b>9</b>–<b>13</b>) were isolated from the chloroform-soluble partitions of separate methanol extracts of the fruits and stem bark of <i>Elaeocarpus chinensis</i> collected in Vietnam. Isolation work was facilitated using a LC/MS dereplication procedure, and bioassay-guided fractionation was monitored using HT-29 human cancer cells. The structures of compounds <b>1</b>–<b>8</b> were determined on the basis of spectroscopic data interpretation, with the absolute configurations of isomers <b>1</b> and <b>2</b> established by the Mosher ester method. Compounds <b>1</b>–<b>13</b> were evaluated in vitro against the HT-29 cell line and using a mitochondrial transmembrane potential assay. Elaeocarpucin C (<b>3</b>), produced by partial synthesis from 16α,23α-epoxy-3β,20β-dihydroxy-10α<i>H</i>,23β<i>H</i>-cucurbit-5,24-dien-11-one (<b>13</b>), was found to be inactive when evaluated in an in vivo hollow fiber assay using three different cancer cell types (dose range 0.5–10 mg/kg/day, ip)

Caeruleanone A, a Rotenoid with a New Arrangement of the D‑Ring from the Fruits of <i>Millettia caerulea</i>

Caeruleanone A (<b>1</b>), a novel rotenoid with an unprecedented arrangement of the D-ring, was isolated with another two new analogues, caeruleanones B (<b>2</b>) and C (<b>3</b>), together with 11 known rotenoids from the fruits of <i>Millettia caerulea</i>. The structures of the new compounds were determined by spectroscopic data analysis, with that of <b>1</b> being confirmed by single-crystal X-ray diffraction. Compounds <b>2</b> and <b>3</b> displayed potent mitochondrial transmembrane potential inhibitory and quinone reductase induction activities

Bioactive Flavaglines and Other Constituents Isolated from <i>Aglaia perviridis</i>

Eight new compounds, including two cyclopenta­[<i>b</i>]­benzopyran derivatives (<b>1</b>, <b>2</b>), two cyclopenta­[<i>b</i>]­benzofuran derivatives (<b>3</b>, <b>4</b>), three cycloartane triterpenoids (<b>5</b>–<b>7</b>), and an apocarotenoid (<b>8</b>), together with 16 known compounds, were isolated from the chloroform-soluble partitions of separate methanol extracts of a combination of the fruits, leaves, and twigs and of the roots of <i>Aglaia perviridis</i> collected in Vietnam. Isolation work was monitored using human colon cancer cells (HT-29) and facilitated with an LC/MS dereplication procedure. The structures of the new compounds (<b>1</b>–<b>8</b>) were determined on the basis of spectroscopic data interpretation. The Mosher ester method was employed to determine the absolute configurations of <b>5</b>–<b>7</b>, and the absolute configuration of the 9,10-diol unit of compound <b>8</b> was established by a dimolybdenum tetraacetate [Mo₂(AcO)₄] induced circular dichroism procedure. Seven known rocaglate derivatives (<b>9</b>–<b>15</b>) exhibited significant cytotoxicity against the HT-29 cell line, with rocaglaol (<b>9</b>) being the most potent (ED₅₀ 0.0007 μM). The new compounds <b>2</b>–<b>4</b> were also active against this cell line, with ED₅₀ values ranging from 0.46 to 4.7 μM. The cytotoxic compounds were evaluated against a normal colon cell line, CCD-112CoN. In addition, the new compound perviridicin B (<b>2</b>), three known rocaglate derivatives (<b>9</b>,<b> 11</b>, <b>12</b>), and a known sesquiterpene, 2-oxaisodauc-5-en-12-al (<b>17</b>), showed significant NF-κB (p65) inhibitory activity in an ELISA assay

Sphenostylisins A–K: Bioactive Modified Isoflavonoid Constituents of the Root Bark of Sphenostylis marginata ssp. erecta

Sphenostylisins A–C (<b>1</b>–<b>3</b>), three complex dimeric compounds representing two novel carbon skeletons, along with an additional eight new compounds, sphenostylisins D–K (<b>4</b>–<b>11</b>), were isolated from the active chloroform-soluble extract of the root bark of Sphenostylis marginata ssp. erecta using a bioactivity-guided isolation approach. The structures were elucidated by means of detailed spectroscopic analysis, including NMR and HRESIMS analysis, and tandem MS fragmentation was utilized to further support the structures of <b>1</b>–<b>3</b>. The absolute configuration of sphenostylisin C (<b>3</b>) was established by electronic circular dichroism analysis. Plausible biogenetic relationships between the modified isoflavonoids <b>1</b>–<b>11</b> are proposed, and a cyclization reaction of <b>9</b> was conducted to support one of the biogenetic proposals made. All of these pure isolates were evaluated against a panel of in vitro bioassays, and among the results obtained, sphenostylisin A (<b>1</b>) was found to be a very potent NF-κB inhibitor (IC₅₀ = 6 nM)

Discovery of anticancer agents of diverse natural origin

Abstract: A collaborative multidisciplinary research project is described in which new natural product anticancer drug leads are obtained from a diverse group of organisms, constituted by tropical plants, aquatic cyanobacteria, and filamentous fungi. Information is provided on how these organisms are collected and processed. The types of bioassays are indicated in which crude extracts of these acquisitions are tested. Progress made in the isolation of lead bioactive secondary metabolites from three tropical plants is discussed. Keywords: natural products; plants; cyanobacteria; fungi; anticancer activity. Article: INTRODUCTION Cancer is responsible for about one in every four deaths in the United States and is therefore a major public health burden. The American Cancer Society projects that in 2008, there will be over 1.4 million new cases of invasive cancer diagnosed and over 565 000 deaths from cancer, or more than 1500 deaths each day. The major cancer mortalities in the United States result from cancers of the lung and bronchus, prostate, and colon and rectum in men, and of the lung and bronchus, breast, and colon and rectum in women Natural product compounds have substantial structural diversity and frequently afford new mechanisms of biological activity. As a result, natural products are used widely in cancer chemotherapy western countries and Japan, it was revealed that of 155 compounds in total ever introduced since the 1940s, 47.1 % were either unmodified natural products (25 compounds, 16.1 %) or semi-synthetic derivatives of natural products (48 compounds, 31.0 %) In this short review, we will describe a new multi-institutional collaborative project funded by the U.S. National Cancer Institute (NCI), National Institutes of Health (NIH), Bethesda, Maryland, through the &quot;program project&quot; (P01) mechanism. This is a successor to a previous &quot;National Cooperative Drug Discovery Groups&quot; (NCDDG) project (U01/U19 mechanism), also funded by NCI, NIH, and involves the same four partners, namely, two academic groups (The Ohio State University and the University of Illinois at Chicago), a private, nonprofit research institute (Research Triangle Institute, North Carolina), and an industrial partner (Bristol-Myers Squibb, Pharmaceutical Research Institute, Princeton, New Jersey). In this new project, however, there is now the participation of a biotechnology company, Mycosynthetix, Inc. (Hillsborough, North Carolina). Descriptions of our collaborative work on the former NCDDG project have been published previously For over a decade, members of four major groups of plant-derived anticancer agents have been available in the United States and elsewhere, including the vinca (Catharanthus) bisindole alkaloids, the epipodophyllotoxin analogs, the taxanes, and the camptothecins Cyanobacteria (blue-green algae) have been identified as a promising source of novel bioactive metabolites A number of fungal compounds have been investigated for anticancer activity COLLECTION AND PROCESSING OF ORGANISMS A continued search for anticancer agents from tropical plants, aquatic cyanobacteria, and filamentous fungi should pay dividends, both in terms of the potential discovery of further examples of antitumor agents of natural origin and the favorable prospects of generating specific molecular probes germane to the biology of cancer. The strategies being used to collect and process these three basic types of organisms in our program project will be discussed briefly in turn. In our former NCDDG project, the entire focus was on the discovery of plant-derived anticancer agents from understudied endemic species of tropical rainforest plants The approaches taken in plant collection have been discussed previously, inclusive of the development of benefit-sharing agreements, the use of the NAPRALERT database to select under-investigated endemic plants for subsequent laboratory study, and the types and numbers of plant parts collected per species In this collaborative work, aquatic cyanobacteria are being collected in part in the field, with some samples obtained from commercial sources. The latter group is represented by the Culture Collection of Algae at the University of Texas at Austin (UTEX), the Provasoli-Guillard National Center for the Culture of Marine Phytoplankton (CCMP), and the Culture Collection of Algae at the University of Gottingen (SAG). All taxonomic orders of cyanobacteria (viz., Chroococcales, Nostocales, Oscillatoriales, Pleurocapsales, and Stigonematales) are present in our culture collection, which currently consists of over 300 cyanobacterial strains. Obstacles in studying the bioactive secondary metabolites of cyanobacteria are the slow growth rate and low biomass yield of these organisms in culture. To overcome these limitations, we use the recently developed micro-analytical technique of segmented flow analysis (SFA) microcoil NMR The program project has access to a library of over 55 000 filamentous fungi, housed at Mycosynthetix, Inc. Although acquisitions in this collection have been examined for drug leads for several different pharmaceutical and agrochemical applications in the past, this library has never been examined systematically as anticancer leads. It has been estimated that 1.5 million species of fungi exist in the world Mycosynthetix has developed approaches to culturing fungi that supports the production of unusual metabolites, including the use of both liquid and solid media. In many instances, it has been observed that a particular metabolite is produced specifically under only one set of conditions. Diverse growth conditions are utilized to optimize the chances of discovering promising biological activity. This ability to culture and optimize the growth conditions of an organism presents a means to re-supply a large quantity of a promising lead compound. Prior to initial biological screening, fungal specimens are subjected to a two-stage culturing procedure, in both liquid seed and grain-based solid media. For initial biological testing, cultures are extracted with 1:1 chloroform-methanol, with organic and aqueous partitions being produced, and the organic extract partitioned into 1:1 acetonitrile-hexane. BIOLOGICAL EVALUATION OF SAMPLES Once initial crude extracts are prepared from tropical plants, aquatic cyanobacteria, and filamentous fungi, they are subjected to evaluation in a battery of cell-and mechanism-based assays housed at the various locations where the laboratory work in our program project is carried out. Cytotoxicity assays using selected cancer cell lines are conducted at The Ohio State University In an earlier review on our collaborative work on anticancer agents from natural sources, a detailed account was given as to how the in vivo hollow fiber assay is used We have found the biological testing resources available through the NCI to be highly complementary to our research efforts. For example, the NCI 60-cell line panel provides data on potency and selectivity against various leukemias and solid types of cancer in cell culture PROGRAM PROJECT ORGANIZATION An organizational scheme of our program project research collaboration is shown in EXAMPLES OF COMPOUNDS RECENTLY ISOLATED AND EVALUATED To exemplify compounds isolated in this collaboration in our ongoing work, compounds from three tropical plant leads that have shown some in vivo activity are briefly reviewed below. In each case, a valid benefitssharing agreement has been in place prior to plant collection. The examples have been chosen to complement those mentioned in the last review article on this project Alvaradoins E-N from Alvaradoa haitensis In 1999, four compounds in the &quot;alvaradoin&quot; series, alvaradoins A-D, were isolated and characterized from the aerial parts of Alvaradoa jamaicensis Benth., but these were not investigated for their potential anticancer activity In an initial investigation carried out at The Ohio State University, four new compounds with a C-9 hydroxy group, aculeatols A-D, were isolated from the leaves of A. aculeatum collected in Indonesia, along with aculeatins A (3) and B (4) Accordingly, aculeatin A (3) was selected for testing in the in vivo hollow fiber assay at the University of Illinois at Chicago. When evaluated against three cancer cells in hollow fibers (Lu1, LNCaP, and MCF-7), the compound inhibited the growth only of MCF-7 cells by 10-60 % at the dose range 6.25-50 mg/kg body weight, when administered at the intraperitoneal site Silvestrol and episilvestrol from Aglaia foveolata Our collaborative group has investigated the fruits and twigs of Aglaia foveolata Pannell (Meliaceae; originally misidentified as Aglaia silvestris), collected in Kalimantan, Indonesia, initially as part of our former NCDDG project [79]. (-)-Silvestrol (7; These in vitro studies were followed by analysis of silvestrol (7) in vivo [79]. When silvestrol was tested in the hollow fiber assay at the University of Illinois at Chicago at doses up to 5 mg/kg, silvestrol inhibited proliferation of all cell lines, particularly the LNCaP human prostate cancer line (up to 83 % inhibition with ip administration), showing no detectable gross toxicity to the mice [79]. Silvestrol was also tested in the P388 murine lymphocytic leukemia model at Bristol-Myers Squibb and found to be active at its maximum tolerated dose of 2.5 mg/kg when administered as five daily ip injections. A maximum increase in lifespan corresponding to a T/C ratio of 150 % was achieved. When silvestrol was injected intravenously twice daily for five days in the P388 model, a T/C ratio of 129 % was obtained at a cumulative dose of 2 mg/kg/day [79]. Two cytotoxic and antineoplastic compounds with the same NMR spectroscopic properties as silvestrol and episilvestrol have been reported in the patent literature from the bark of a Malaysian plant, Aglaia leptantha Miq., with one of the compounds found to inhibit the growth of PC3 human prostate cancer cells in a xenograft study At the University of Illinois at Chicago, studies have been conducted to elucidate the cellular mechanism of action of silvestrol Moreover, cell-cycle arrest induced by silvestrol (7) led to cell death by apoptosis Pelletier and colleagues have shown recently that silvestrol (7) can inhibit translation in eukaryotic cells and enhance the sensitivity of lymphoma cells to doxorubicin Recent studies by Grever and Lucas at The Ohio State University Medical Center, outside the scope of our current program project, have suggested that the cytotoxicity of silvestrol ACKNOWLEDGMENT