Polyacetylenes from a marine sponge Petrosia sp. inhibit DNA replication at the level of initiation

Acetylenic Aquatic Anticancer Agents and Related Compounds

Although acetylenes are common as components of terrestrial plants, it is only within the last 30 years that biologically active polyacetylenes having unusual structural features have been reported from aquatic organisms: cyanobacteria, algae, fungi, invertebrates, and other sources. Naturally occurring aquatic acetylenes are of particular interest since many of them display important biological activities and possess antitumor, antibacterial, antimicrobial, antifouling, antifungal, pesticidal, phototoxic, HIV inhibitory, and immuno-suppressive properties. There is no doubt that they are of great interest, especially for the medicinal and/or pharmaceutical industries. This review presents structures and describes cytotoxic and anticancer activities of more than 230 acetylenic metabolites isolated from aquatic organisms. With the computer program PASS some additional biological activities are also predicted, which point toward possible new applications of these compounds. This review emphasizes the role of aquatic acetylenic compounds as an important source of leads for drug discovery.

Two new thiophene polyacetylene glycosides from Atractylodes lancea

Phytochemical investigation on the rhizomes of Atractylodes lancea led to the isolation of two new thiophene polyacetylene glycosides (1 and 2) and six known compounds (3-8). Their structures were elucidated based on the extensive spectroscopic data (UV, IR, 1D and 2D NMR, and HRESIMS). The absolute configurations of new compounds were established by calculated and experimental circular dichroism. All the compounds were assessed on the lipopolysaccharide-induced NO production in BV2 cells and compounds 3, 7, and 8 showed moderate inhibitory activities.

Chiral alkynylcarbinols from marine sponges: asymmetric synthesis and biological relevance

Covering: up to March 2014. Previous review on the topic: B. W. Gung, C. R. Chim., 2009, 12, 489-505. Chiral α-functional lipidic propargylic alcohols extracted from marine sponges, in particular of the pacific genus Petrosia, constitute a class of acetylenic natural products exhibiting remarkable in vitro biological activities, especially anti-tumoral cytotoxicity. These properties, associated to functionalities that are uncommon among natural products, have prompted recent projects on asymmetric total synthesis. On the basis of a three-sector structural typology, three main sub-types of secondary alkynylcarbinols (with either alkyl, alkenyl, or alkynyl as the second substituent) can be identified as the minimal pharmacophoric units. Selected natural products containing these functionalities have been targeted using previously known or on purpose-designed procedures, where the stereo-determining step can be: (i) a C-C bond forming reaction (e.g. the Zn-mediated addition of alkynyl nucleophiles to aldehydes in the presence of chiral aminoalcohols), (ii) a functional layout (e.g. the asymmetric organo- or metallo-catalytic reduction of ynones), or (iii) an enantiomeric resolution (e.g. a lipase-mediated kinetic resolution via acetylation). The promising medicinal importance of these targets is finally surveyed, and future investigation prospects are proposed, such as: (i) further total synthesis of known or future extraction products; (ii) the synthesis of non-natural analogues, with simpler lipophilic environments of the alkynylcarbinol-based pharmacophoric units; (iii) the variation and optimization of both the pharmacophoric units and their lipophilic environment; and (iv) investigations into the biological mode of action of these unique structures.

On terminal alkynylcarbinols and derivatization thereof

The chemistry of three prototypes of secondary alkynylcarbinols (ACs), recently highlighted as challenging targets in anti-tumoral medicinal chemistry, is further documented by results on n-alkyl, alkynyl and alkenyl representatives. The N-naphthyl carbamate of an n-butyl-AC is thus characterized by X-ray crystallography. A novel dialkynylcarbinol (DAC) with synthetic potential is described, namely the highly dissymmetrical triisopropylsilyl-protected version of diethynylmethanol. The latter is shown to act as a dipolarophile in a selective Huisgen reaction with benzyl azide under CuAAC click conditions, giving an alkenyl-AC, where the alkene unsaturation is embedded in a 1,4-disubstituted 1,2,3-triazole ring, as confirmed by X-ray crystallography.

Identification of chiral alkenyl- and alkynylcarbinols as pharmacophores for potent cytotoxicity

Illumination by acetylene: Systematic structural variations in a series of archetypal acetylenic lipids derived from the naturally occurring (S,E)-icos-4-en-1-yn-3-ol allowed the discovery of a series of 3R-like 1,4-di-unsaturated carbinol units with a significant and systematic enantiomeric effect on cytotoxicity.

Structure, synthesis, and biological activity of a C-20 bisacetylenic alcohol from a marine sponge Callyspongia sp

An optically inactive C-20 bisacetylenic alcohol, (4E,16E)-icosa-4,16-diene-1,19-diyne-3,18-diol, was isolated from a marine sponge Callyspongia sp. as a result of screening of antilymphangiogenic agents from marine invertebrates. An optical resolution using chiral-phase HPLC gave each enantiomer, (-)-1 and (+)-2. Because the natural and synthetic enantiomers 1 and 2 showed different biological properties, we investigated the structure-activity relationships of bisacetylenic alcohols using 11 synthetic derivatives, and it is clarified that the essential structural unit for antiproliferative activity is the "1-yn-3-ol" on both termini and that there is a minimum chain length that connects the "1-yn-3-ol" moieties.

The Apoptotic Activity of one VLC Fraction of the Sponge Petrosia tuberosa on Human Cervical Cells and the Subsequent Isolation of a Bioactive Polyacetylene

As part of our ongoing studies on bioactive natural products from marine sponges, we investigated the cytotoxic potential of extracts from the new sponge Petrosia tuberosa sampled from Mauritius waters. Bioguided fractionation of the ethyl acetate extract by vacuum liquid chromatography (VLC) revealed two fractions, namely VLC (6-9) and (13-17) showing cell deaths of 86 ± 1% and 88 ± 4%, respectively, at 50 μg/mL on HeLa cells. At 10 μg/mL, only VLC (13-17) displayed a significant cell death (56 ± 7%) compared with VLC (6-9) (8 ± 1 %). The cytotoxic activity of VLC (13-17) was also determined on nine other human cancer cell lines. Clonogenic assay, mitochondrial membrane potential change, DNA fragmentation and microscopic analysis of fraction VLC (13-17) revealed distinct features of apoptosis on HeLa cells. Further fractionation and purification of this fraction by chromatographic techniques resulted in isolation of one known secondary metabolite, petrosynol. Its structure was determined by 1H and 13C-NMR analyses.

Cytotoxic activities of hexane, ethyl acetate and butanol extracts of marine sponges from Mauritian Waters on human cancer cell lines

The ocean is an exceptional source of natural products with many of them exhibiting novel structural features and bioactivity. As one of the most interesting phylum with respect to pharmacological active marine compounds, Poriferas have been investigated widely in the last few decades. A total of 60 organic extracts (hexane, ethyl acetate and butanol) from 20 species of marine sponges from Mauritius were screened at 50μg/ml in an in vitro screening assay against 9 human cancer cell lines. From these tested extracts, many exhibited pronounced cytotoxic effect at least in one of the cell lines and cell type cytotoxic specificity was observed. 27% of ethyl acetate, 11% of hexane and 2% of butanol extracts were found to possess a cytotoxicity ≥75% on 9 different cancer cell lines with the sponges Petrosia sp. 1, Petrosia sp. 2, Pericharax heteroraphis and Jaspis sp. being the most active. Overall, the HL-60cells were much more sensitive to most of the extracts than the other cell lines. We further evaluated the properties of the ethyl acetate (JDE) and hexane extract (JDH) of one sponge, Jaspis sp. on KB cells. JDE displayed a smaller IC(50) than JDH. Clonogenic assay confirmed the antiproliferative effect of both extracts while mitochondrial membrane potential change and microscopic analysis demonstrated extracts-induced apoptosis. Treatment with 100ng/ml of JDE led to a significant increase of cells (24h: 4.02%; 48h: 26.23%) in sub-G1 phase. The cytotoxic properties of the tested extracts from these sponges suggest the presence of compounds with pharmacological potential and are currently undergoing fractionation to isolate the active constituents.

Bioactive chemicals from carrot (Daucus carota) juice extracts for the treatment of leukemia

Overwhelming evidence indicates that consumption of fruits and vegetables with antioxidant properties correlates with reduced risk for cancers, including leukemia. Carrots contain beneficial agents, such as β-carotene and polyacetylenes, which could be effective in the treatment of leukemia. This study investigated the effect of carrot juice extracts on myeloid and lymphoid leukemia cell lines together with normal hematopoietic stem cells. Leukemia cell lines and nontumor control cells were treated with carrot juice extracts for up to 72 hours in vitro. Induction of apoptosis was investigated by using annexin V/propidium iodide staining followed by flow cytometric analysis, and results were confirmed by using 4'-6-diamidino-2-phenylindole morphology. Effects on cellular proliferation were investigated via cell cycle analysis and cell counts. Treatment of leukemia cell lines with carrot juice extract induced apoptosis and inhibited progression through the cell cycle. Lymphoid cell lines were affected to a greater extent than were myeloid cell lines, and normal hematopoietic stem cells were less sensitive than most cell lines. This study has shown that extracts from carrots can induce apoptosis and cause cell cycle arrest in leukemia cell lines. The findings suggest that carrots may be an excellent source of bioactive chemicals for the treatment of leukemia.

Assignment of the structure of petrocortyne A by mixture syntheses of four candidate stereoisomers

Two different mixture synthesis routes have been used to make the four stereoisomers of petrocortyne A. A first quick and dirty route provided a mixture of the four isomers in nonselective fashion. Mosher and 2-naphthylmethoxyacetic acid (NMA) ester methods were developed to identify the components, and the mixture was partially resolved on analytical chiral HPLC to give the two pure enantiomers of petrocortyne A and the racemate of its diastereomer. A second fluorous mixture synthesis produced all four isomers of petrocortyne A in individual pure form. Comparison of spectra of Mosher derivatives of the synthetic isomers with two supposedly different natural products showed that both natural samples were instead identical and had the (3S,14S) configuration. Likewise, petrocortynes B, D, and F-H are (3S,14S) and petrocortyne D is (3R,14S). Having access to all possible candidate isomers of both petrocortyne A and its Mosher derivatives provided a secure structure assignment not so much because one of the isomers matched the natural product, but because all of the other isomers did not.

Endangered medicinal species of the Indian Ocean: radical need for conservation

Life originated in the Oceans, which are also the most fertile source of chemically distinctive natural products that are mainly accumulated in living organisms. Several of these compounds show pharmacological activities, and are helpful for the invention and discovery of bioactive compounds, primarily for several fatal diseases. The Indian Ocean is home to several exotic species of flora and fauna. Several environmental and man-made factors are responsible for deterioration of several precious biodiversity areas of the Ocean. The author, while highlighting the medicinal importance of these organisms, underlines the need for comprehensive conservatory measures on the part of the international community to be taken in order to maintain the rich Oceanic biodiversity.

Investigation of the anti-inflammatory and analgesic effects from an extract of Aplysina caissara, a marine sponge

A variety of biologically active compounds with pharmacological applications has been reported to occur in marine sponges. The present study was undertaken to provide a set of data about an extract from Aplysina caissara, a Brazilian marine sponge. The antinociceptive and anti-inflammatory effects were investigated against different experimental models in mice. When evaluated against writhing test intraperitoneally (60 and 90 mg/kg), the extract significantly inhibited abdominal constriction by 33.7% and 41.4% respectively. In the formalin test (60 and 90 mg/kg), the extract of sponge inhibited 43.6% and 51.6% in the first phase and 98.2% and 97.2% in the second phase respectively. When evaluated against the hot plate test, both doses demonstrated activity. An increase in the hot plate latency was observed after 60 min. The anti-inflammatory effect was evaluated by formalin-induced mice paw edema. Extract from A. caissara (60 and 90 mg/kg) significantly reduced hind paw swelling. Mortality increased with increasing doses, with LD(50) of 212.2 mg/kg for intraperitoneal administration. These results demonstrated that the extract of the marine sponge A. caissara possesses antinociceptive and anti-edematogenic effects.

A "shortcut" Mosher ester method to assign configurations of stereocenters in nearly symmetric environments. Fluorous mixture synthesis and structure assignment of petrocortyne A

A "shortcut" of the advanced Mosher rule for use in assigning stereocenters in molecules with elements of local symmetry is proposed. A single Mosher ester is made, and the chemical shifts of pairs of resonances related by local symmetry are subtracted from each other (rather than from analogous resonances in the isomeric Mosher ester) to provide the configuration. Fluorous mixture synthesis is used to make a stereoisomer library of the four isomers of petrocortyne A. These samples and the derived Mosher esters are used to assign the (3S,14S) configuration to petrocortyne A and to validate both the standard and shortcut Mosher methods for use in the petrocortyne family of dialkynyl carbinols.

First Total Synthesis of the Potent Anticancer Natural Product Dideoxypetrosynol A: Preparation of the "Skipped" (Z)-Enediyne Moiety by Oxidative Coupling of Homopropargyl Phosphonium Ylide

Dideoxypetrosynol A is a C30 polyacetylenic alcohol with C2 symmetry. The first total synthesis of both enantiomers of the potent anti-cancer natural product (+)- and (-)-dideoxypetrosynol A is reported. The key step is an oxidative coupling of a homopropargyl phosphonium ylide to prepare the "skipped" (Z)-enediyne moiety. The natural dideoxypetrosynol A was isolated as a racemic mixture as shown in structure 1. The absolute configurations of the chiral centers are established for the (+)- and (-)-enantiomers using Burgess' enzymatic resolution procedure with Pseudomonas AK lipase.

Anticancer activity of natural and synthetic acetylenic lipids

This review is a comprehensive survey of acetylenic lipids and their derivatives, obtained from living organisms, that have anticancer activity. Acetylenic metabolites belong to a class of molecules containing triple bond(s). They are found in plants, fungi, microorganisms, and marine invertebrates. Although acetylenes are common as components of terrestrial plants, fungi, and bacteria, it is only within the last 30 years that biologically active polyacetylenes having unusual structural features have been reported from plants, cyanobacteria, algae, invertebrates, and other sources. Naturally occurring aquatic acetylenes are of particular interest since many of them display important biological activities and possess antitumor, antibacterial, antimicrobial, antifouling, antifungal, pesticidal, phototoxic, HIV-inhibitory, and immunosuppressive properties. There is no doubt that they are of great interest, especially for the medicinal and/or pharmaceutical industries. This review presents structures and describes cytotoxic and anticancer activities only for more than 300 acetylenic lipids and their derivatives isolated from living organisms.

Marine pharmacology in 2001-2: antitumour and cytotoxic compounds

During 2001 and 2002, marine antitumour pharmacology research aimed at the discovery of novel antitumour agents was published in 175 peer-reviewed articles. The purpose of this paper is to present a structured Review of the antitumour and cytotoxic properties of 97 marine natural products, many of them novel compounds that belong to diverse structural classes, including polyketides, terpenes, steroids, and peptides. The organisms yielding these bioactive compounds comprise a taxonomically diverse group of marine invertebrate animals, algae, fungi and bacteria. Antitumour pharmacological studies were conducted with 30 structurally characterised natural marine products in a number of experimental and clinical models which further defined their mechanisms of action. Particularly potent in vitro cytotoxicity data generated with murine and human tumour cell lines was reported for 67 novel marine chemicals with as yet undetermined mechanisms of action. Noteworthy, is the fact that marine anticancer research was sustained by a collaborative effort, involving researchers from Australia, Brazil, Canada, Denmark, Egypt, France, Germany, Italy, Japan, Netherlands, New Zealand, The Philippines, Russia, Singapore, South Korea, Thailand, Taiwan, Turkey, Spain, Switzerland, Taiwan, Thailand, Turkey, and the United States. Finally, this 2001-2 overview of the marine pharmacology literature highlights the fact that the discovery of novel marine antitumour agents has continued at the same pace as during 1998, 1999 and 2000.

In vitro anti-inflammatory and pro-aggregative effects of a lipid compound, petrocortyne A, from marine sponges

(3 S,14 S)-Petrocortyne A, a lipid compound (a C(46) polyacetylenic alcohol), from marine sponges ( Petrosia sp.) is potently cytotoxic against several solid tumour cells. In this study, we investigated in vitro anti-inflammatory and pro-aggregative effects of petrocortyne A at non-cytotoxic concentrations on various cellular inflammatory phenomena using the macrophage and monocytic cell lines RAW264.7 and U937. Petrocortyne A blocked tumour necrosis factor-alpha (TNF-alpha) production strongly and concentration-dependently in lipopolysaccharide (LPS)-activated RAW264.7 cells and phorbol 12-myristate 13-acetate (PMA)/LPS-treated U937 cells. It also blocked NO production concentration-dependently in LPS- or interferon (IFN)-gamma-treated RAW264.7 cells. Among the migration factors tested, the compound selectively blocked the expression of hepatocyte growth factor/scatter factor (HGF/SF). On the other hand, as assessed by a cell-cell adhesion assay, petrocortyne A did not block the activation of adhesion molecules induced by aggregative antibodies to adhesion molecules, but suppressed PMA-induced cell-cell adhesion significantly. Intriguingly, petrocortyne A induced U937 homotypic aggregation following long exposure (2 and 3 days), accompanied by weak induction of pro-aggregative signals such as tyrosine phosphorylation of p132 and phosphorylation of extracellular signal-related kinase 1 and 2 (ERK 1/2). Petrocortyne A may thus inhibit cellular inflammatory processes and immune cell migration to inflamed tissue.