Cherry L. Herald

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.

Demonstration of sub-nanomolar affinity of bryostatin 1 for the phorbol ester receptor in rat brain

The effect of bryostatin 1 on [26-3H]phorbol 12,13-dibutyrate [( 3H]PDBu) binding to a washed particulate preparation from rat brain was examined. Bryostatin 1 inhibited phorbol ester binding at concentrations considerably lower than previously reported. As would be expected for a ligand of high affinity, the apparent displacing potency of bryostatin 1 was dependent on the concentration of tissue/binding sites included in the assay. Decreasing the concentration of [3H]PDBu binding sites to the picomolar detection limit resulted in apparent bryostatin displacing potencies in the picomolar range with these values representing an upper estimate of the true affinity. When included in saturation studies with [3H]PDBu, bryostatin 1 displayed mixed competitive/non-competitive inhibition. Using either repetitive washing or dialysis of the membrane preparation, it was not possible to reverse the inhibition produced by bryostatin 1. The greater affinity of bryostatin 1 compared to other classes of agents that act directly on protein kinase C and the stability of its association may contribute to the unique biological properties of the bryostatins.

Isolation and structure of bryostatins 14 and 15

Abstract Further investigation of constituents from the marine bryozoan Bugula neritina employing new 1,000 kg recollections from the Gulf of Mexico and Eastern Pacific Ocean (California) has led to isolation and structural determination of two previously undetected members of the bryostatin (1-13) series, bryostatins 14 (14) and 15 (15). Structural analyses were conducted primarily with high field (400 MHz) NMR and high resolution mass spectral techniques. Both new bryostatins significantly inhibited growth of the P388 lymphocytic leukemia.

Antineoplastic agents 293. The exceptional human cancer cell growth inhibitors spongistatins 6 and 7

Abstract A twenty year investigation of the South African marine sponge Spirastrella spinispirulifera (Carter, 1879) for antineoplastic constituents has now led to discovery of spongistatin 6 (1e) and 7 (2b) in 3.5 × 10−7% and 2.2 × 10−7% yields. Structural elucidations were based on detailed analyses of high field (400 and 500 MHz) 2D-NMR and high resolution mass spectra. Spongistatins 6 and 7 were exceptionally potent against a subset of human cancer cell lines in the NCI screening panel which are characteristically sensitive to cellular microtubule interactive antimitotics.

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.

A broad-spectrum antifungal from the marine sponge Hyrtios erecta

Spongistatin 1, a macrocyclic lactone polyether from the marine sponge Hyrtios erecta, was fungicidal for a variety of opportunistic yeasts and filamentous fungi, including strains resistant to amphotericin B, ketoconazole and flucytosine. In broth macrodilution assays, MICs ranged from 0.195 to 12.5 microg/ml, and minimum fungicidal concentrations ranged from 3.12 to 25 microg/ml. Initial disk diffusion screens with six related macrocyclic lactone polyethers from H. erecta and Spirastrella spinispirulifera, revealed that these polyethers were also antifungal. The fungicidal activity of spongistatin 1 was confirmed in killing kinetics studies, where killing of Candida albicans and Cryptococcus neoformans occurred within 6 and 12 h, respectively. During the killing kinetics experiments, non-treated C. albicans maintained the yeast morphology. However, elongated forms resembling germ tubes were the predominant morphologic form in spongistatin 1-treated C. albicans cultures. The spongistatins show promise as potential antifungal agents and as probes to study fungal morphogenesis and nuclear division.

Conformational analysis of a marine antineoplastic macrolide, bryostatin 10☆

Abstract Conformation of bryostatin 10, a marine antineoplastic macrolide, in CDCl3 was analyzed by the spectroscopic and computational chemical methods. A combination of homonuclear two-dimensional NMR techniques at 600 MHz have enabled us to perform complete assignment of the 1H signals of bryostatin 10 in CDCl3. The conformation of its solution form was elucidated by a phase sensitive ROESY spectrum, temperature effect on OH proton and 3J vicinal coupling constants. Restrained molecular-dynamics simulation led to a well defined conformation of the compound in solution, which was found to be homologous to that of bryostatin 2 observed in the solid state.

Isolation and structure of the remarkable human cancer cell growth inhibitors spongistatins 2 and 3 from an eastern indian ocean Spongia sp.

A black Spongia sp. In the Porifera class Demospongiae had been found to contain two new and exceptionally potent cell (human cancer) growth inhibitors named spongistatins 2 (1b) and 3 (1c)

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.

Isolation and structure of the powerful human cancer cell growth inhibitors spongistatins 4 and 5 from an African Spirastrella spinispirulifera(porifera)

The Southwest Indian Ocean marine sponge Spirastrella spinispirulifera has been found to contain (in 10–7% yields) two extraordinarily potent (Gl50ca. 10–8µg ml–1) human cancer cell line inhibitors designated spongistatins 4 1d and 5 2.