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Yusuke Wataya

Publications and source records attributed to Yusuke Wataya.

At least 37 records · Page 2Linked to original sources
PubMed2003

In vitro antimalarial activity of metalloporphyrins against Plasmodium falciparum.

The in vitro antimalarial activity against Plasmodium falciparum and heme polymerization were evaluated for ten metalloporphyrins: gallium protoporphyrin IX (GaPPIX), sodium salt of gallium protoporphyrin IX, silver protoporphyrin IX, palladium protoporphyrin IX, cobalt protoporphyrin IX, manganese protoporphyrin IX, tin protoporphyrin IX (SnPPIX), chromium protoporphyrin IX, gallium deuteroporphyrin IX (GaDPIX) and gallium hematoporphyrin IX. Metalloporphyrins inhibited parasite growth with 50% inhibitory concentrations (IC(50)) ranging from 15.5 microM to 190 microM. In trophozoite lysate-mediated heme polymerization assays, SnPPIX, GaPPIX and GaDPIX exerted potent inhibitory activity similar to that of artemisinin and chloroquine.

Animals↗
PubMed2003

New semisynthetic quassinoids with in vivo antimalarial activity.

On the basis of a comparative analysis for stability in mouse serum between 15-O-acetylbruceolide and bruceolide 15-methyl carbonate, several 3,15-dialkyl carbonates of bruceolide were synthesized and their in vitro antimalarial activity was assessed. Methyl, ethyl, and isopropyl carbonates with pronounced in vitro activity were further evaluated for in vivo antimalarial potency. Both the methyl and ethyl carbonates significantly increased the life span of mice as compared with 3,15-di-O-accetylbruceolide and chloroquine.

Animals↗
PubMed2003

Acute disseminated encephalomyelitis following Plasmodium vivax malaria.

A 24-year-old Japanese man showed neurological disturbances 2 weeks after complete recovery from Plasmodium vivax infection. Magnetic resonance (MR) images of the brain showed multiple high-intensity spotty lesions in the left cerebral cortex and subcortex. Cerebrospinal fluid examination, including polymerase chain reaction analysis for viruses, revealed no sign of active infection. Repeated blood smears were negative for malaria. We diagnosed acute disseminated encephalomyelitis (ADEM) following Plasmodium vivax malaria from the clinical course and MR images. ADEM should be regarded as one of the neurological complications after malarial infection.

Adult↗
PubMed2003

In vitro antiplasmodial activity of antimalarial medicinal plants used in Vietnamese traditional medicine.

Among 42 extracts, prepared from 14 medicinal plants used in Vietnamese traditional medicine to treat malaria, 24 were found to have antiplasmodial activity by inhibiting the growth of the chloroquine-resistant Plasmodium falciparum strain FCR-3 with EC(50) values less than 10 microg/ml. Each medicinal plant possessed at least one active extract. The methanol extract of Coscinium fenestratum had the strongest antiplasmodial activity with EC(50) value of 0.5 microg/ml. Activity-guided fractionation led to identification of berberine as the major active constituent.

Animals↗
PubMed2003

Antimalarial activity of herbal extracts used in traditional medicine in Korea.

Aqueous extracts of 6 traditional Korean medicines used to treat malaria were tested in vitro for their antimalarial activity against Plasmodium falciparum. The EC50 values for the herbal extracts were in the range 1.4-8.1 microg/ml. Significant antimalarial activity was observed with Coptis japonica (EC50=1.4 microg/ml), but it demonstrated no selective toxicity (selectivity=1). In contrast, Kalopanax pictus showed antimalarial activity (EC50=4.6 microg/ml) and higher selective toxicity (>4). This indicated that K. pictus may be potent for a new antimalarial agent.

Animals↗
PubMed2002

Antimalarial activity of yingzhaosu A analogues.

Iodonium ion mediated cyclization of unsaturated hydroperoxides 1 afforded the expected yingzhaosu A analogues 2. In some cases, however, the corresponding cyclic ethers 5 were formed competitively with the cyclic peroxides 2, the ratios of these two products being a marked function of the structure of the starting materials. Some of the cyclic peroxides 2 showed significant antimalarial activities in vitro and in vivo.

Animals↗
PubMed2002

Potent antimalarial febrifugine analogues against the plasmodium malaria parasite.

Although febrifugine (1) and isofebrifugine (2), alkaloids isolated from roots of the Dichroa febrifuga plant, show powerful antimalarial activity against Plasmodium falciparum, strong side effects such as the emetic effect have precluded their clinical use against malaria. However, their antimalarial potency makes them attractive substances as leads for developing new types of chemotherapeutic antimalarial drugs. Thus, we have evaluated the in vitro antimalarial activity of the analogues of febrifugine (1) and isofebrifugine (2). The activities of the analogues derived from Df-1 (3) and Df-2 (4), condensation products of 1 and 2 with acetone, respectively, were also obtained. The 3' '-keto derivative (7, EC(50) = 2.0 x 10(-8) M) of 1 was found to exhibit potential antimalarial activity with high selectivity against P. falciparum in vitro. The in vitro activities of the reduction product (8, EC(50) = 2.0 x 10(-8) M) of 1 at C-2' and its cyclic derivatives 9 and 10 (EC(50) = 3.7 x 10(-9) and 8.6 x 10(-9) M, respectively) were found to be strongly active and selective. Additionally, the Dess-Martin oxidation product of 3 was found to be strongly active with high selectivity against P. falciparum. A structure-activity relationship study (SAR) demonstrates that the essential role played by the 4-quinazolinone ring in the appearance of activity and the presence of a 1' '-amino group and C-2', C-3' ' O-functionalities are crucial in the activity of 1. For 7, 8, and 9, prepared as racemic forms, an in vivo study has also been conducted.

Animals↗
PubMed2002

Rhodacyanine dyes as antimalarials. 1. Preliminary evaluation of their activity and toxicity.

The rhodacyanine dye MKT-077 (1), a potent antitumor agent, was found to possess strong in vitro activity against Plasmodium falciparum and a low cytotoxicity. Several new rhodacyanine dyes related to 1, containing a variety of linked heterocyclic moieties, were synthesized, and their antimalarial potencies were evaluated. The synthetic rhodacyanines were found to have EC(50) values against P. falciparum in vitro in the range of 4-300 nM. Several compounds in this series have remarkable selective toxicity profiles (>100).

Animals↗
PubMed2002

New neplanocin analogues. 12. Alternative synthesis and antimalarial effect of (6'R)-6'-C-methylneplanocin A, a potent AdoHcy hydrolase inhibitor.

An improved method for the synthesis of (6'R)-6'-C-methylneplanocin A (RMNPA, 2), a potent S-adenosyl-L-homocysteine (AdoHcy) hydrolase inhibitor, was developed via a chelation-controlled stereoselective addition of MeTiCl(3) to the neplanocin A 6'-aldehyde derivative 6. Compound 2 effectively inhibited the growth of malaria parasites both in vitro and in vivo. The antimalarial EC(50) value of 2 against Plasmodium berghei in mice was 1.0 mg/kg/day, which was superior to that of chloroquine (EC(50) = 1.8 mg/kg/day).

Adenosine↗
PubMed2002

Genomic analysis of mefloquine-resistant Plasmodium falciparum.

We studied sequence polymorphism, expression level of pfmdr1 gene and drug sensitivity in mefloquine sensitive-strain as well as mefloquine-resistant clone/24 to understand underlying drug resistance mechanism. Mefloquine-resistant clone/24 exhibited decreased susceptibility to mefloquine, quinine, halofantrine and artemisinin and increased susceptibility to chloroquine. We analyzed sequence of pfmdr1 gene and found mutation in pfmdr1 on clone/24. Moreover, overexpression of mRNA level of pfmdr1 has been observed in mefloquine-resistant clone/24. Our results explain gene mutation and expression level of pfmdr1 may be associated in mefloquine resistance mechanism.

Animals↗
PubMed2002

Analysis of single nucleotide polymorphisms in uridine/cytidine kinase gene encoding metabolic enzyme of 3'-ethynylcytidine.

We investigated single nucleotide polymorphisms (SNPs) in uck2 gene encoding metabolic enzyme of 3'-ethynylcytidine (ECyd) which were associated with drug response of ECyd, and the newly synthesized antitumor ribonucleoside analog. We analized that on exon-intron junction and exon region to affect the qualitative alteration of gene product directly in ECyd sensitive and resistant human cancer cell lines. As the results, cSNP and sSNP were detected in exon 4. In the promoter region, 3 SNPs were detected. Our data seem to be able to give an important knowledge, when ECyd is applied clinically.

Cytidine↗
PubMed2002

Mechanisms of cell death induced by 5-fluoro-2'-deoxyuridine (FUdR)--necrosis or apoptosis after treated with FUdR.

5-Fluoro-2'-deoxyuridine (FUdR) inhibits thymidylate synthase (TS). The inhibition of TS causes an imbalance of intracellular deoxyribonucleoside triphosphate (dNTP) pools which subsequently induced cell death. We investigated the molecular mechanisms of cell death after treated with FUdR in F28-7 strain (which induced necrosis) and F28-7-A strain (mutant of F28-7 strain which induced apoptosis). After treated with FUdR, we observed different size of DNA fragmentations. F28-7 strain induced DNA cleavaged into 100-200 kbp fragments and F28-7-A strain induced DNA cleavaged into oligonucleosomal sized fragments. In F28-7 strain, FUdR induced the increased mRNA level of c-jun, c-fos and c-myc genes, caspase-3 like protease activity and the changes of mitochondrial membrane potential which were greater and earlier than those of F28-7-A strain. On the other hand, F28-7-A strain induced release of cytochrome c from mitochondrial, but not F28-7 strain. Furthermore, caspase-5 inhibitor was strongly inhibited the cell death of F28-7 strain. We suggest that it is concerned with intensity of intracellular signals in the cell death of F28-7 strain and F28-7-A strain.

Apoptosis↗
PubMed2002

Anticancer mechanisms of 1-(3-C-ethynyl-beta-D-ribo-pentofuranosyl) cytosine (ECyd, TAS-106).

We investigated the molecular mechanisms of cell death induced by 1-(3-C-ethynyl-beta-D-ribo-pentofuranosyl)cytosine (ECyd, TAS-106), a potent inhibitor of RNA synthesis, using mouse mammary tumor FM3A cells and human fibrosarcoma HT1080 cells. ECyd induced the characteristics of apoptosis on these cells, such as morphological changes, DNA fragmentations and caspase-3-like protease activation. General caspases inhibitor, Z-Asp-CH2-DCB inhibited cell death. Interestingly, we also found that ECyd induced rRNA fragmentation. The cleavage pattern of rRNA resembled in that mediated by RNase L. On the other hands, it was suggested that caspase-1, 3, 8 and 9 concerned with ECyd-induced apoptosis through mitochondria. ECyd-induced rRNA fragmentation was inhibited by general caspases inhibitor (Z-Asp-CH2-DCB) and caspase-5 inhibitor (Z-WEHD-fmk). So it is clear that caspase-5 (ICErel III/TY), member of ICE (Interleukin-1 beta-converting enzyme) protease, activated pathway concerned with ECyd-induced rRNA fragmentation. These results indicate that antitumor mechanisms of ECyd are involved in caspase-dependent activation of RNase L. rRNA fragmentation may occur one of the death events, as a result of inhibition of RNA synthesis and play an important role in the antitumor activity of ECyd.

Animals↗
PubMed1999

Catalytic Asymmetric Synthesis of Antimalarial Alkaloids Febrifugine and Isofebrifugine and Their Biological Activity.

Antimalarial alkaloids febrifugine (1) and isofebrifugine (2) were efficiently synthesized from simple achiral starting materials on the basis of the catalytic asymmetric synthesis. The first key reaction was performed using the tin(II)-mediated catalytic asymmetric aldol protocol to afford chiral aldehyde 3 in high yield with high diastereo- and enantioselectivities. The second key step, a Mannich-type reaction, did not give satisfactory results according to the conventional methods. We then developed a novel aqueous Mannich-type three-component reaction of an aldehyde, an amine, and a vinyl ether using a Lewis acid-surfactant combined catalyst (LASC), and the key intermediates 16 and 17 were obtained in high yields. The final coupling reactions of bromoacetone 14 with 4-hydroxyquinazoline were carried out using basic conditions, and successive deprotection gave 1 and 2, respectively, without any isomerization. These unambiguous total asymmetric syntheses revealed that the absolute configurations of febrifugine and isofebrifugine were not (2'S,3'R) and (2'R,3'R) as reported previously but (2'R,3'S) and (2'S,3'S), respectively (1' and 2'). Finally, antimalarial activities of the synthesized febrifugine and isofebrifugine, and their antipodes, were examined. It was revealed that the activities and selectivities of natural febrifugine and isofebrifugine were much higher than those of the antipodes.

Journal Article↗