Showing papers by "Yusuke Hirasawa published in 2015"
TL;DR: The Bis-A-induced autophagosome formation was suggested to be caused by its interference with the AKT-mTOR signaling pathway, and down-regulation of these kinases suggests that the increase in LC3 lipidation may be due to mTOR deactivation.
Abstract: We have previously reported that bisleuconothine A (Bis-A), a novel bisindole alkaloid isolated from Leuconotis griffithii, showed cytostatic activity in several cell lines. In this report, the mechanism of Bis-A-induced cytostatic activity was investigated in detail using A549 cells. Bis-A did not cause apoptosis, as indicated by analysis of annexin V and propidium iodide staining. Expression of all tested apoptosis-related proteins was also unaffected by Bis-A treatment. Bis-A was found to increase LC3 lipidation in MCF7 cells as well as A549 cells, suggesting that Bis-A cytostatic activity may be due to induction of autophagy. Subsequent investigation via Western blotting and immunofluorescence staining indicated that Bis-A induced formation but prevented degradation of autophagosomes. Mechanistic studies showed that Bis-A down-regulated phosphorylation of protein kinase B (AKT) and its downstream kinase, PRAS40, which is an mTOR repressor. Moreover, phosphorylation of p70S6K, an mTOR-dependent kinase,...
18 citations
TL;DR: Two new aromadendrane sesquiterpenoids, dysosesquiflorins A and B, were isolated from Dysoxylum densiflorum bark, and their structures were elucidated on the basis of NMR spectroscopic data.
Abstract: Two new aromadendrane sesquiterpenoids, dysosesquiflorins A and B (1 and 2), were isolated from Dysoxylum densiflorum bark, and their structures were elucidated on the basis of NMR spectroscopic data. These dysosesquiflorins showed in vitro cytotoxic activity against several cancer cell lines.
15 citations
TL;DR: In this paper, the vobasine-iboga type bisindole alkaloid, voacalgine F (I) was isolated and structure elucidation was performed.
Abstract: isolation and structure elucidation of the new vobasine-iboga type bisindole alkaloid, voacalgine F (I)
5 citations
TL;DR: In this paper, a degradation product of mollugin was found to be the main active substance of degradation, showing a potent inhibitory activity on NO-production including nuclear factor kappa B signals.
Abstract: Mollugin, a naphthoquinone derivative, was reported to possess various biological activities such as anti-inflammatory and anti-tumor activity. Mollugin isolated from Rubia tinctorum roots inhibited lipopolysaccharide-induced nitric oxide (NO) production in RAW264.7 macrophages. However, mollugin synthesized for further investigation of its anti-inflammatory mechanism showed weak activity in addition to unstable assay results. From the result of analysis on a degradation product of mollugin, oxomollugin was found to be the main active substance of mollugin degradation, showing a potent inhibitory activity on NO-production including nuclear factor kappa B signals.
4 citations
TL;DR: A new benzylisoquinoline alkaloid, lincangenine-4- β -D-glucopyranoside, has been isolated from the roots of Leontice altaica, together with 5 known alkaloids.
Abstract: A new benzylisoquinoline alkaloid, lincangenine-4-β-D-glucopyranoside (1), has been isolated from the roots of Leontice altaica, together with 5 known alkaloids. Its structure was elucidated on the basis of 1D and 2D NMR data, and chemical means.
2 citations
TL;DR: In this article, the vobasine-iboga type bisindole alkaloid, voacalgine F (I) was isolated and structure elucidation was performed.
Abstract: isolation and structure elucidation of the new vobasine-iboga type bisindole alkaloid, voacalgine F (I)