Hideyuki Shigemori

Purealidins B and C, new bromotyrosine alkaloids from the okinawan marine sponge Psammaplysilla purea

New bromotyrosine-derived alkaloids, purealidins B (1) and C (2), have been isolated from the Okinawan marine sponge Psammaplysilla purea and their structures elucidated on the basis of spectroscopic data. Purealidin B (1) showed antibacterial activity, while purealidin C (2) exhibited antifungal and antineoplastic activities.

Taxuspines A ∼ C, new taxoids from Japanese yew Taxus cuspidata inhibiting drug transport activity of P-glycoprotein in multidrug-resistant cells

Abstract Three new taxoids, taxuspines A ∼ C (1 ∼ 3), possessing different skeletons from usual taxane diterpenoids consisting of a 6/8/6-membered ring system have been isolated together with known taxoids (4 ∼ 12) from stems of the Japanese yew Taxus cuspidata Sieb. et Zucc. and the structures elucidated on the basis of spectroscopic data. Most of the taxoids increased cellular accumulation of vincristine in multidrug-resistant tumor cells, while taxol (12) did not show such an activity. The taxoids (1 ∼ 11) showed no or weak cytotoxicity and among them, 2 and 6 reduced appreciably CaCI2-induced depolymerization of microtubules. These results suggest that some taxoids may be useful for overcoming multidrug resistance in tumor cells.

Fellutamides A and B, cytotoxic peptides from a marine fish-possessing fungus Penicillium fellutanum

Abstract Two cytotoxic peptides, fellutamides A and B, have been isolated from the cultured fungus Penicillium fellutanum Biourge which was isolated from the gastrointestine of the marine fish Apogon endekataenia Bleeker, and the structures were elucidated to be 1 and 2 by two-dimensional NMR and FAB MS/MS data.

Hymenamides A and B, new proline-rich cyclic heptapeptides from the Okinawan marine sponge Hymeniacidon sp.

Abstract New cyclic heptapeptides, hymenamides A and B, with a prolyproline segment have been isolated from the Okinawan marine sponge Hymeniacidon sp. and the structures elucidated on the basis of 2D NMR and FAB MS/MS data.

Nakijiquinones C and D, new sesquiterpenoid quinones with a hydroxy amino acid residue from a marine sponge inhibiting c-erbB-2 kinase

Abstract Nakijiquinones C (1) and D (2), new sesquiterpenoid quinones with a serine or a threonine residue, respectively, have been isolated from an Okinawan marine sponge of the family Spongiidae and the structures were determined by spectroscopic data and chemical correlations with a known compound, isospongiaquinone (5). Nakijiquinones and synthetic related compounds exhibited inhibitory activity against c-erbB-2 kinase.

Effects of taxoids from Taxus cuspidata on microtubule depolymerization and vincristine accumulation in MDR cells

Abstract Among new taxoids, taxuspines A ∼ H and J ∼ T ( 1 ∼ 19 ), and known taxoids 20 ∼ 56 containing taxol ( 56 ) and taxol-type compounds 37 ∼ 44 with an N -acylphenylisoserine group at C-13 and an oxetane ring at C-4 and C-5 isolated from stems and leaves of the Japanese yew Taxus cuspidata Sieb. et Zucc., non-taxol-type compounds 4 and 32 remarkably reduced CaCl 2 -induced depolemerization of microtubules. Furthermore, some non-taxol-type compounds 2 , 3 , 9 , 24 , 25 , 27 , and 28 increased cellular accumulation of vincristine in multidrug-resistant tumor cells as potent as verapamil, while taxol ( 36 ) and taxol-type compounds did not show such an activity. In addition, the non-taxol-type compounds enhancing vincristine accumulation inhibited competitively binding of azidopine to P-glycoprotein. These results suggest that some non-taxol-type taxoids may be useful for overcoming multidrug resistance in tumor cells.

Convolutamides A ∼ F, novel γ-lactam alkaloids from the marine bryozoan Amathia convoluta

Abstract Convolutamides A ∼ F, new alkaloids containing an N-acyl-γ-lactam moiety with a dibromophenol group, have been isolated from the Floridian bryozoan Amathia convoluta and the structures elucidated on the basis of spectroscopic data.

Antimitotic activity of moroidin, a bicyclic peptide from the seeds of Celosia argentea.

A unique bicyclic peptide, moroidin (1), from the seeds of Celosia argentea (Amaranthaceae) strongly inhibited the polymerization of tubulin. The stereostructure of moroidin (1) was reinvestigated by spectroscopic data, chemical degradation, and molecular dynamics simulation.

Nakijiquinones A and B, new antifungal sesquiterpenoid quinones with an amino acid residue from an Okinawan marine sponge

Abstract Two new sesquiterpenoid quinones with an amino acid residue, nakijiquinones A (1) and B (2), have been isolated from an Okinawan marine sponge

Modulation of multidrug resistance by taxuspine C and other taxoids from Japanese yew

Taxuspine C (1), a new taxoid from the Japanese yew Taxus cuspidata, increasing the cellular accumulation of vincristine (VCR) in multidrug-resistant tumor cells as potent as verapamil enhanced the chemotherapeutic effect of VCR in P388/VCR-bearing mice. When taxuspine C (1) was given i.p. daily at 200 mg/kg with 0.2 mg/kg VCR for 5 days, a treated/control (T/C) value of 138% was obtained. The other new taxoids, taxezopidines G (8) and H (9), from the yew also increased the VCR accumulation as potent as verapamil. These results suggest that some taxoids may be useful for overcoming multidrug resistance in tumor cells.