Aki Ishiyama

Learn More
Ethyl acetate (EtOAc) extract from the stem bark of Erythrina fusca showed a antimalarial activity against the multi-drug-resistant strain (K1) of Plasmodium falciparum, and six flavonoids, lupinifolin (1), citflavanone (2), erythrisenegalone (3), lonchocarpol A (4), liquiritigenin (5), and 8-prenyldaidzein (6), were isolated from the extract. Diprenylated(More)
In our investigation of in vitro antimalarial screening of medicinal herbal extracts, the n-BuOH extract from the root of Wikstroemia indica showed a potent inhibitory effect. Fractionation of the active extract led to the isolation of two biflavonoids, sikokianin B ( 1) and sikokianin C ( 2) with IC (50) values 0.54 microg/mL and 0.56 microg/mL,(More)
To discover antimalarial substances from plants cultivated in Thailand 80%-EtOH extracts from selected plants were screened for in vitro antimalarial activity against the drug resistant K1 strain of Plasmodium falciparum. In total, 86 Thai medicinal plant samples representing 48 species from 35 genera in 16 families were screened and two species (Polyalthia(More)
More than 400 compounds isolated from soil microorganisms, and catalogued in the antibiotic library of the Kitasato Institute for Life Sciences, were screened against African trypanosomes. Ten compounds were found to have selective and potent antitrypanosomal activity in vitro: aureothin, cellocidin, destomycin A, echinomycin, hedamycin, irumamycin, LL-Z(More)
Two new nucleotide antibiotics, named sinefungin VA and dehydrosinefungin V, were separated by cation exchange column chromatography and purified by HPLC from the culture broth of Streptomyces sp. K05-0178, together with the known antibiotics, sinefungin, dehydrosinefungin and KSA-9342. The structures of the two novel sinefungin analogs were elucidated by(More)
Merobatzelladines A (1) and B (2) have been isolated from a marine sponge Monanchora sp. as antibacterial constituents. Their structures including relative stereochemistry were determined by interpretation of spectral data. The absolute stereochemistry of merobatzelladine B (2) was elucidated after introduction of the fourth ring system preinstalled with a(More)
Five pregnane glycosides were isolated from Caralluma tuberculata (1-5), in addition to a known one (russelioside E, 6). The structures of the isolated compounds were elucidated by the analysis of NMR data and FAB-MS experiments. All the isolated compounds were tested for their antimalarial and antitrypanosomal activities as well as their cytotoxicity(More)
Borrelidin, a structurally unique 18-membered macrolide, was found to express antimalarial activity against drug-resistant Plasmodium falciparum malaria parasites, with IC50 value of 0.93 ng/mL. However, it also displays strong cytotoxicity against human diploid embryonic MRC-5 cells. To investigate the issue of the cytotoxicity of borrelidin,(More)