Tomikazu Sasaki

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Name: Sasaki, Tomikazu
Organization: University of Washington , USA
Department: Department of Chemistry
Title: Professor(PhD)

TOPICS

Co-reporter:Yitong J. Zhang;Xi Zhan;Liguo Wang;Rodney J.Y. Ho
Journal of Pharmaceutical Sciences 2015 Volume 104( Issue 5) pp:1815-1824
Publication Date(Web):
DOI:10.1002/jps.24407

Artemisinin (ART), a well-known antimalaria drug, also exhibits anticancer activities. We previously reported a group of novel dimeric artemisinin piperazine conjugates (ADPs) possessing pH-dependent aqueous solubility and a proof-of-concept lipid nanoparticle formulation based on natural egg phosphatidylcholine (EPC). EPC may induce allergic reactions in individuals sensitive to egg products. Therefore, the goal of this report is to develop ADP-synthetic lipid particles suitable for in vivo evaluation. We found that ADP binds to 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) with greater than 90% efficiency and forms drug–lipid particles (d ∼ 80 nm). Cryo-electron microscopy of the ADP drug–lipid particles revealed unilamellar vesicle-like structures. Detailed characterization studies show insertion of the ADP lead compound, ADP109, into the DPPC membrane and the presence of an aqueous core. Over 50% of the ADP109 was released in 48 hours at pH4 compared with less than 20% at neutral. ADP109–lipid particles exhibited high potency against human breast cancer, but was tolerated well by nontumorigenic cells. In MDA-MB-231 mouse xenograft model, lipid-bound ADP109 particles were more effective than paclitaxel in controlling tumor growth. Cellular uptake studies showed endocytosis of the nanoparticles and release of core-trapped marker throughout the cytosol at 37°C. These results demonstrate, for the first time, the in vivo feasibility of lipid-bound ART dimer for cancer chemotherapy. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:1815–1824, 2015

Co-reporter:Shusheng Wang, Tomikazu Sasaki
Bioorganic & Medicinal Chemistry Letters 2013 Volume 23(Issue 15) pp:4424-4427
Publication Date(Web):1 August 2013
DOI:10.1016/j.bmcl.2013.05.057
The Ugi four-component reaction was used to prepare a series of artemisinin monomers and dimers. We found that the endoperoxide group in artemisinin remains intact during the reaction. The new artemisinin dimers showed potent anti-cancer activity against two human breast cancer cell lines, MDA-MB-231 and BT-474. One of the Ugi artemisinin dimers showed an IC50 value of 12 nM when tested on BT474 cells, more than 600 times more potent than artesunate. Furthermore, the same Ugi artemisinin dimer showed a low toxicity when tested on MCF10A, a nontumorigenic cell line, resulting in a selectivity index of more than 8000.
Co-reporter:Teruaki Hasegawa and Tomikazu Sasaki  
Chemical Communications 2003 (Issue 8) pp:978-979
Publication Date(Web):24 Mar 2003
DOI:10.1039/B212364A
Glyco-helix is designed as a novel model system to investigate cis carbohydrate–carbohydrate interactions. Adhesive Lac–Lac interactions stabilize α-helix of Lac-peptide in the presence of fluorinated alcohols, but no such an interaction was observed in GlcNAc-peptide.
Co-reporter:Yitong J. Zhang, Xi Zhan, Liguo Wang, Rodney J.Y. Ho, Tomikazu Sasaki
Journal of Pharmaceutical Sciences (May 2015) Volume 104(Issue 5) pp:1815-1824
Publication Date(Web):1 May 2015
DOI:10.1002/jps.24407
Artemisinin (ART), a well-known antimalaria drug, also exhibits anticancer activities. We previously reported a group of novel dimeric artemisinin piperazine conjugates (ADPs) possessing pH-dependent aqueous solubility and a proof-of-concept lipid nanoparticle formulation based on natural egg phosphatidylcholine (EPC). EPC may induce allergic reactions in individuals sensitive to egg products. Therefore, the goal of this report is to develop ADP-synthetic lipid particles suitable for in vivo evaluation. We found that ADP binds to 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) with greater than 90% efficiency and forms drug-lipid particles (d ~ 80 nm). Cryo-electron microscopy of the ADP drug-lipid particles revealed unilamellar vesicle-like structures. Detailed characterization studies show insertion of the ADP lead compound, ADP109, into the DPPC membrane and the presence of an aqueous core. Over 50% of the ADP109 was released in 48 hours at pH4 compared with less than 20% at neutral. ADP109-lipid particles exhibited high potency against human breast cancer, but was tolerated well by nontumorigenic cells. In MDA-MB-231 mouse xenograft model, lipid-bound ADP109 particles were more effective than paclitaxel in controlling tumor growth. Cellular uptake studies showed endocytosis of the nanoparticles and release of core-trapped marker throughout the cytosol at 37°C. These results demonstrate, for the first time, the in vivo feasibility of lipid-bound ART dimer for cancer chemotherapy. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:1815–1824, 2015