Kouhei Matsui

Pyridoacridine alkaloids inducing neuronal differentiation in a neuroblastoma cell line, from marine sponge Biemna fortis.

A new and three known pyridoacridine alkaloids were isolated from the Indonesian marine sponge Biemna fortis as neuronal differentiation inducers against a murine neuroblastoma cell line, Neuro 2A. The chemical structure of the new compound, labuanine A (1), was determined by spectroscopic study and chemical conversion. These pyridoacridine alkaloids induced multipolar neuritogenesis in more than 50% of cells at 0.03-3 micro M concentration. Compound 3, which showed the strongest neuritogenic activity among them, also induced increase of acetylcholinesterase, a neuronal marker in Neuro 2A and arrested cell cycle at the G2/M phase.

Structure–activity relationship of neuritogenic spongean acetylene alcohols, lembehynes

Abstract Two new long-chain acetylene alcohols named lembehynes B ( 2 ) and C ( 3 ) were isolated from an Indonesian marine sponge of Haliclona sp. Lembehynes B ( 2 ) and C ( 3 ), which have different types of long carbon-chain parts compared with that of lembehyne A ( 1 ), also exhibited neuritogenic activity against a neuroblastoma cell line, Neuro 2A. For structure–activity relationship study of lembehynes, analogue-I ( 4 ), analogue-II ( 5 ) and analogue-III ( 6 ), which have different types of long carbon-chain parts, were synthesized from suitable fatty acids. As a result of neurite outgrowth assay for these related compounds, it was revealed that the carbon-chain length is important for neuritogenic activity, while the unsaturated bonds in the long-chain part are not. On the other hand, analogue-IV ( 7 ) with 3 S configuration showed much weaker activity than analogue-III ( 6 ) with 3 R configuration and the same type of long carbon-chain part. This indicates the importance of the stereochemistry of the hydroxyl group at C-3 in lembehynes for neuritogenic activity.

Smenospongine, a spongean sesquiterpene aminoquinone, induces erythroid differentiation in K562 cells.

The differentiation of K562 chronic myelogenous leukemia (CML) cells by smenospongine, which is a sesquiterpene aminoquinone isolated from a marine sponge, was examined. Smenospongine increased hemoglobin production in K562 cells at concentrations of 3–15 μM. In addition, flow cytometric analysis of smenospongine-treated K562 cells with FITC-labeled glycophorin A antibody showed an increase of glycophorin A expression, a marker for erythroid differentiation. Cell-cycle analysis showed G1 arrest in K562 cells after treatment with smenospongine for 24 h. The effect on expression of CIP/KIP family cyclin-dependent kinase inhibitors was investigated by Western blotting analysis and the result showed increased expression of p21, which is known to play an important role in differentiation. Furthermore, smenospongine was also found to inhibit the phosphorylation of Crkl, a substrate of Bcr–Abl tyrosine kinase, which is known as a causative protein of CML. In conclusion, our investigation indicated that smenospongine induced the differentiation of K562 cells into erythroblasts along with cell-cycle arrest at G1 phase and the mechanism might be attributed to the increased expression of p21.

Brianthein A, a novel briarane-type diterpene reversing multidrug resistance in human carcinoma cell line, from the gorgonian Briareum excavatum

Abstract A novel briarane-type diterpene named brianthein A (1), which has been isolated from the gorgonian Briareum excavatum, reversed multidrug resistance (MDR) in human carcinoma cell lines, KB-C2, overexpressing P-glycoprotein (P-gp). The absolute stereostructure of 1 was elucidated by the detailed 2D-NMR analysis of 1 and the application of the modified Moshers method to the partially deacetylated derivative of 1. Furthermore, novel analogous compounds, briantheins B (8) and C (9), were also isolated from the same gorgonian. From the structure-activity relationship study, each of the 2, 3 and 14-acetoxyl groups and 11,12-olefin in 1 were found to be crucial for the MDR reversing activity.

In situ photoaffinity labeling of the target protein for lembehyne A, a neuronal differentiation inducer

A C36 linear acetylene alcohol, lembehyne A (LB‐A), induces neuronal differentiation against neuroblastoma cells morphologically and also functionally. The differentiation and cytostatic effect induced by LB‐A was specific to neuroblastoma, Neuro 2A cells. To identify the target protein for LB‐A, a radioactive photoaffinity probe, [125I]18‐(2′‐azido‐5′‐iodo‐benzoyloxy)‐LB‐18 ([125I]azido‐LB‐18), was synthesized. As a result of in situ labeling experiments against Neuro 2A cells, a protein of M r 30 kDa was photolabeled specifically. This labeling was inhibited in the presence of LB‐A or the active analogs of LB‐A, whereas the inactive analogs showed no inhibitory effect on this labeling. These results suggest that this protein of M r 30 kDa is the target protein for LB‐A and may play an important role for the neuronal differentiation in neuroblastoma, Neuro 2A cells.