Shyi-Tai Jan

Structure-based design of a novel synthetic spiroketal pyran as a pharmacophore for the marine natural product spongistatin 1

SPIKET-P, a novel synthetic spiroketal pyran, was rationally designed as a pharmocophore for the tubulin depolymerizing marine natural product Spongistatin 1. SPIKET-P was prepared from the commercially available benzyl (R)-(-)-glycidyl ether using a versatile 11-step synthetic scheme in a stereocontrolled fashion. At nanomolar concentrations, SPIKET-P caused tubulin depolymerization in cell-free turbidity assays and exhibited potent cytotoxic activity against cancer cells as evidenced by destruction of microtubule organization, and prevention of mitotic spindle formation in human breast cancer cells.

Targeting SYK kinase-dependent anti-apoptotic resistance pathway in B-lineage acute lymphoblastic leukaemia (ALL) cells with a potent SYK inhibitory pentapeptide mimic.

The present study found that the pentapeptide mimic C‐61, targeting the substrate binding P‐site of SYK tyrosine kinase acted as a potent inducer of apoptosis in chemotherapy‐resistant SYK‐expressing primary leukemic B‐cell precursors taken directly from relapsed B‐precursor leukaemia (BPL) patients (but not SYK‐deficient infant pro‐B leukaemia cells), exhibited favourable pharmacokinetics in mice and non‐human primates, and eradicated in vivo clonogenic leukaemia cells in severe combined immunodeficient mouse xenograft models of chemotherapy‐resistant human BPL at dose levels non‐toxic to mice and non‐human primates. These in vitro and in vivo findings provide proof of principle for effective treatment of chemotherapy‐resistant BPL by targeting SYK‐dependent anti‐apoptotic blast cell survival machinery with a SYK P‐Site inhibitor. Further development of C‐61 may provide the foundation for therapeutic innovation against chemotherapy‐resistant BPL.

Stereocontrolled synthesis of a novel pharmacophore of the tubulin-depolymerizing marine natural product spongistatin

Abstract We report here the synthesis and X-ray structure of a novel spiroketal pyran, SPIKET-P1, as a pharmocophore for the tubulin-depolymerizing marine natural product spongistatin 1. Following its retro-synthetic analysis, SPIKET-P1 was prepared using a versatile 11-step synthetic scheme in a stereocontrolled fashion.

AZT-5′-(p-Bromophenyl Methoxyalaninyl Phosphate) as a Potent and Non-Toxic Anti-Human Immunodeficiency Virus Agent

The potency and selectivity index of the AZT-phenyl phosphate derivatives in thymidine kinase (TK)-deficient T cells were substantially enhanced by introducing a single para-bromo substituent in the phenyl moiety. AZT-5′-(p-bromophenyl methoxyalaninyl phosphate) was 43-fold more potent than AZT-5′-(phenyl methoxyalaninyl phosphate) and was fivefold more potent than AZT in inhibiting human immunodeficiency virus (HIV) replication in TK-deficient CEM cells.

Synthesis of dual function (5R,6R)- and (5S,6S)-5-bromo-6-methoxy-5,6-dihydro-AZT-5'-(para-bromophenyl methoxyalaninyl phosphate) as novel spermicidal and anti-HIV agents.

We synthesized a novel compound, 5-bromo-6-methoxy-5,6-dihydro-AZT-5′-(p-bromophenyl methoxyalaninyl phosphate), which had an EC50 value of 5 µM in sperm motility assays. This is >1 log10 better than that of the detergent spermicide nonoxynol-9 (EC50 81 µM). The compound also displayed a potent anti-human immunodeficiency virus (HIV) activity with an IC50 value of 0.005 µM in HIV replication assays, which was virtually identical to that of AZT (IC50 0.006 µM) and >2 log10 more potent than that of nonoxynol-9 (IC50 2.2 µM). The promising results reported herein recommend the further development of the dual function 5-halo-6-alkoxyl-5,6-dihydro-AZT derivatives as a new class of vaginal contraceptives capable of preventing the sexual transmission of HIV while providing fertility control for women who are at high risk of acquiring HIV by heterosexual transmission. These dual function 5-halo-6-alkoxyl-5,6-dihydro-AZT derivatives may also have utility in curbing domestic and wildlife animal retroviral transmissions.

Stereoselective synthesis of a versatile intermediate for the total synthesis of mono- and bis-THF containing annonaceous acetogenins

Abstract Stereoselective synthesis of epoxy tetrahydrofuran (THF) 1 , a versatile synthetic precursor for mono-THF and bis-THF containing annonaceous acetogenins, is reported. Compound 1 was synthesized from tridecanal in 11 steps with an overall yield of 24%. The requisite configurations of the stereogenic centers in 1 were established by Sharpless asymmetric epoxidation and Sharpless asymmetric dihydroxylation. Formation of the THF-ring unit was accomplished by acid catalyzed epoxide ring opening and 5- exo cyclization reaction.