• Kazusamycin B, EvoPure� packaged and labeled in glass vial.

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SKU: K019

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Kazusamycin B is a metabolite and minor member of the Leptomycin complex isolated from some Streptomyces species. It is a hydroxylated analog of Leptomycin A, a nuclear export inhibitor. It is similar to Leptomycins A and B in physico-chemical and biological characteristics. It has anti-cancer properties.  This metabolite can inhibit nuclear export and translocation of Rev, a gene product in the HIV-1 genome, at nanomolar concentrations.

Kazusamycin B is soluble in ethanol and methanol but practically insoluble in water.  It is unstable in DMSO. 

We also offer:

  • Kazusamycin A (K018)
  • Leptomycin A (L020)
  • Leptomycin B (L004)

    CAS Number


    Molecular Formula


    Molecular Weight


    Mechanism of Action

    Members of the Leptomycin complex can induce abnormal condensation of nuclei and arrest cell cycle of yeast and mammalian cells in both G1 and G2 phases, but the mechanism of action is still unknown.

    Storage Conditions



    It has antifungal activity (S. pombe, R. javanicus). It is inactive against Gram-positive and Gram-negative bacteria.


    Cancer Applications

    Kazusamycin B has potent antitumor activity against L1210 cells, arresting the cell cycle at the G1 phase (Takamiya et al, 1988). It also has activity against experimental tumors including murine tumors S180, EL-4, and B16. It had in vitro against doxorubicin-resistant P388 cells (Yoshida et al, 1987). It had cytocidal activity against P388 leukemia cells in vitro (Funaishi et al, 1987).

    Eukaryotic Cell Culture Applications

    Kazusamycin A has strong cytotoxic activity against HeLa cells in vitro, and 3.3 ng/ml conc. prevented cell growth (Umezawa et al, 1984).

    Microbiology Applications

    Kazusamycin A and B, along with Leptomycins A and B were isolated from Streptomyces sp. strain A87-18203.  These compounds were identified via a screening assay for low MW inhibitors of Rev nuclear transport.  They were all found to inhibit the translocation of the regulatory protein Rev at nanomolar concentrations.  Rev is need for viral replication of HIV-1  (Wolff et al, 1997).





    Colourless Film


    Streptomyces spp.



    Funaishi K et al (1987)  Kazusamycin B, a novel antitumor antibitioc. J. Antibiot. (Tokyo) 40(6):778-785

    Komiyama K et al (1985)  Antitumor activity of a new antibiotic, Kazusamycin.  J. Antibiot. 38:224

    Roberts BJ et al (1986)  In vivo and in vitro anticancer activity of the structurally novel and highly potent antibiotic CI-940 and its hydroxy analog (PD 114,721).  Cancer. Chemother. Pharmacol. 16:95

    Sawamura M (1992)  Growth inhibitory effect of a new anticancer antibiotics, Kazusamycin A, on human transitional cancer cell lines in vitro. Nihon Hinyokika Gakkai Zasshi. 83(5):627-635  PMID 1495200

    Takamiya K(1988)  The effect of Kazusamycin B on the cell cycle and morphology of cultured L1210 cells. J. Antibiot. (Tokyo) 41(12):1854-1861  PMID 3209477

    Umezawa I et al (1984)  A new antitumor antibiotic, Kazusamycin. J. Antibiot. (Tokyo) 37(7):706-711  PMID 6432763

    Wolff B et al. (1997)  Leptomycin B is an inhibitor of nuclear export: Inhibition of nucleo-cytoplasmic translocation of the human immunodeficiency virus type 1 (HIV-1) Rev protein and Rev-dependent mRNA. Chem. Biol. 4:139  PMID 9190288

    Yoshida et al (1987)  Antitumor effect of Kazusamycin B on experimental tumors. J. Antibiot. (Tokyo) 40(11):1596-1604  PMID 3693127

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