Jean Charles Chapuis

Isolation of dolastatins 10–15 from the marine mollusc dolabella auricularia

Abstract A twenty year pursuit of the cell growth inhibitory and antineoplastic constituents of the Western Indian Ocean (Mauritius) sea hare Dolabella auricularia has resulted in the discovery of fifteen structurally unique peptide, cyclopeptide, depsipeptide, and cyclodepsipeptide type-substances designated dolastatins 1–15. Solution of the difficult isolation problems leading to discovery of dolastatins 10–15 in 10−6 to 10−7% yields required 1,600 kg of Dolabella aurlcularia. To date, this represents the largest scale separation of sea hare components. Of these dolastatin 10 (4) has displayed unprecedented potency in experimental antineoplastic and tubulin assembly systems. Dolastatin 15 (9), and to a lesser extent dolastatin 14 (8) were also found to exhibit unusually strong antineoplastic activity. Both dolastatina 10 and 15 are in advanced preclinical development. Details of the isolation strategies and structural summaries for dolastatins 10–15 have been recorded. Intensive Study of the cell growth inhibition and antineoplastic constituents of the sea hare Dolabella auricularia provided the structurally unique peptides designated dolastatins 1-15.

Antineoplastic agents 338. The cancer cell growth inhibitory. Constituents of Terminalia arjuna (Combretaceae)

By means of bioassay-guided separation methods, the cancer cell growth inhibitory constituents residing in the bark, stem and leaves of the Mauritius medicinal plant Terminalia arjuna (Combretaceae) were examined. The cancer cell line active components were found to be gallic acid, ethyl gallate, and the flavone luteolin. Only gallic acid was previously known to occur in this plant. Luteolin has a well established record of inhibiting various cancer cell lines and may account for most of the rationale underlying the use of T. arjuna in traditional cancer treatments. Luteolin was also found to exhibit specific activity against the pathogenic bacterium Neisseria gonorrhoeae.

Carbohydrate Dependent Targeting of Cancer Cells by Bleomycin−Microbubble Conjugates

Biotinylated bleomycin A(5) was attached to streptavidin-derivatized microbubbles, and a solution containing the conjugate was passed over a monolayer of cultured MCF-7 cells. The bleomycin-derivatized microbubbles adhered to the MCF-7 cells, and the association could be monitored by the use of a microscope. Three other cancer cell lines gave similar results. The bleomycin-microbubble conjugate did not bind to a normal breast cell line (MCF-10A) or to the matched noncancer cell lines corresponding to the other cancer cell lines targeted by bleomycin. No binding to any tested cell line was observed when the microbubbles lacked conjugated bleomycin A(5) or when the microbubble contained a bleomycin A(5) analogue lacking the carbohydrate moiety.

Antineoplastic agents. 536. New sources of naturally occurring cancer cell growth inhibitors from marine organisms, terrestrial plants, and microorganisms(1a,).

Bioassay-guided fractionation of extracts of various plants, marine organisms, and microorganisms has led to the discovery of new natural sources of a number of known compounds that have significant biological activity. The isolation of interesting and valuable cancer cell growth inhibitors including majusculamide C ( 1), axinastatin 5 ( 5), bengazoles A ( 6), B ( 7), and E ( 8), manzamine A ( 10), jaspamide ( 11), and neoechinulin A ( 19) has been summarized.

Screening for cytotoxic activity of plants used in traditional medicine

A total of 260 extracts have been prepared from 75 medicinal plant species collected in Africa, Panama and Mauritius. Three different concentrations of each extract have been screened in vitro for cytotoxic activity using a colorimetric assay to determine cell survival of human colon carcinoma Co115 cells. Fifteen plants showed ED50 values between 10.0 and 1.0 micrograms/ml but more significant activities were obtained in 11 (ED50 range 1.0-0.1 micrograms/ml) and 3 (ED50 range 0.1-0.01 micrograms/ml) plant specimens. Identification of new active substances may well be aided by pre-selecting plants known to be used empirically by traditional healers.

E-Combretastatin and E-resveratrol structural modifications: Antimicrobial and cancer cell growth inhibitory β-E-nitrostyrenes

As part of a broad-based SAR investigation of E-resveratrol (strong sirtuin activator and antineoplastic) and the anticancer vascular-targeting combretastatin-type stilbenes, a series of twenty-three beta-E-nitrostyrenes was synthesized in order to evaluate potential antineoplastic, antitubulin, and antimicrobial activities. The beta-E-nitrostyrenes evaluated ranged from monosubstituted phenols to trimethoxy and 3-methoxy-4,5-methylenedioxy derivatives. Two of the beta-nitrostyrenes were synthesized as water-soluble sodium phosphate derivatives (4t, 4v). All except four (4r, 4s, 4t, 4u) of the series significantly inhibited a minipanel of human cancer cell lines. All but eight led to an IC(50) of <10 microM for inhibition of tubulin polymerization, and all except three (4l, 4t, 4v) displayed antimicrobial activity.

Cyclotrimerization approach to unnatural structural modifications of pancratistatin and other amaryllidaceae constituents - Synthesis and biological evaluation

The phenanthridone core of pancratistatin lacking all aromatic oxygenation was prepared by cyclotrimerization of acetylene-containing scaffolds 30 and 41, reflecting the natural and the C-1 epi configuration, re- spectively, of the amino inositol moiety. The cobalt-catalyzed formation of the aromatic core led to bisTMS derivatives 39 and 48, as well as bisacetyl derivative 51. The effectiveness of cyclotrimerization of the natural or trans series was compared with that of the cis series. In addition, the yields of cyclotrimerization were compared for propargylic amines and propargylic amides. Eleven derivatives, including the fully hydroxylated phenantridone 39, were tested against seven cancer cell lines. Three of the compounds displayed activities only an order of magnitude less than those of 7- deoxypancratistatin. Full experimental and spectral details are provided for all key compounds and future projections for the preparation of unnatural analogs of Amaryllidaceae constituents are advanced, along with some new insight into the minimum pharmacophore of pancratistatin.

Antineoplastic agents 470. Absolute configuration of the marine sponge bromopyrrole agelastatin A

Two bromopyrrole marine alkaloids were isolated from the Mexican sponge, Agelas sp.: hymenidin (1) and agelastatin A (2). The structures were elucidated by analysis of their spectroscopic data and found to correspond to those in the literature. The absolute configuration of agelastatin A (2) was elucidated by single-crystal X-ray diffraction methods. Agelastatin A (2) exhibited strong activity against a panel of human cancer cell lines as well as human umbilical vein endothelial cells.

Antineoplastic agents. 558. Ampelocissus sp. cancer cell growth inhibitory constituents

An investigation of the Phillippine Ampelocissus sp. roots for cancer cell growth inhibitory components led to the isolation of a new acetogenin characterized as 22-epicalamistrin (1) employing primarily 2D NMR and high-resolution mass spectral analysis. Two other antineoplastic constituents proved to be the known acetogenin uvaribonin (2) and chalcone 3. Constituents 1-3 were all found to show significant cancer cell growth inhibitory activity against a panel of human cancer cell lines.

Synthesis and biological evaluation of a spongistatin AB-spiroketal analogue.

The synthesis of a simplified analogue of the potent, cytotoxic tubulin-depolymerizing agent spongistatin 1, based on the AB spiroketal framework, is presented. The new structural analogue is an extension of a recently described spongistatin congener reported to disrupt microtubules in breast cancer cells in vitro and to alter the microtubule assembly reaction. Cytotoxicity data on the new structural analogue, as well as the parent congener, are reported. We found no significant cytotoxic or antitubulin activity with either compound.