Description

Leptomycin B CAS NO 21609-90-5 is a potent and specific secondary metabolite antibiotic and antitumor agent, originally isolated from *Streptomyces* species. Its primary value lies in its function as a highly specific and irreversible inhibitor of nuclear export, particularly of proteins containing a leucine-rich nuclear export signal (NES), by covalently binding to CRM1/exportin 1. This makes it an indispensable research tool for studying nucleocytoplasmic transport, cell cycle regulation, and signal transduction pathways. It is critically needed by researchers in molecular biology, oncology, and biochemistry for fundamental research and drug discovery applications.

Application

• Biomedical Research: As a definitive CRM1 inhibitor for studying nuclear export mechanisms, protein localization, and cell cycle control.
• Oncology & Cancer Biology: Investigation of apoptosis induction, tumor suppressor protein function (e.g., p53), and the role of nucleocytoplasmic transport in cancer progression.
• Virology Research: Study of viral replication cycles that depend on CRM1-mediated export of viral RNA and proteins.
• Signal Transduction Studies: Tool for dissecting pathways affected by the mislocalization of transcription factors and signaling molecules.
• Drug Discovery & Validation: A reference compound for screening and developing next-generation, clinically relevant CRM1 inhibitors (SINE compounds).
• Cell Biology & Biochemistry: Used in experiments to trap specific proteins in the nucleus to elucidate their function.

Basic Information

Product Name	Leptomycin B
CAS No.	21609-90-5
Molecular Formula	C₃₃H₄₄O₈
Molecular Weight	556.70 g/mol
Synonyms	LMB; (3E,5E,7S,9S)-7,9-Epoxy-3,5,7,9-tetramethyl-11-[2R-(2R*,3R*,4S*)]-4-hydroxy-3-methyl-5-oxo-2-tetrahydrofuranyl]-2,10-dodecadien-6,12-olide; Antibiotic CI 940; Antibiotic X 5108; NSC 672121; CRM1 Inhibitor Leptomycin B
EINECS	Contact for details

Quality Control

Our Leptomycin B is produced and handled under strict quality protocols to ensure batch-to-batch consistency and reliability for critical research applications. Each lot undergoes comprehensive analytical testing, including identity confirmation, purity assessment, and impurity profiling. A detailed Certificate of Analysis (COA) is provided with every shipment, documenting key parameters such as assay purity and solvent content. We adhere to high-purity research-grade standards to support reproducible scientific results.

Storage

Preserve in a tightly closed container, protected from light. For long-term stability, store at -20°C or below. Allow the vial to equilibrate to room temperature in a desiccator before opening to prevent condensation. Solutions in DMSO or ethanol should be aliquoted and stored at -80°C to minimize freeze-thaw cycles and activity loss.

Specification

Item	Specification
Appearance	White to off-white solid
Identification (HPLC/MS)	Conforms
Purity (HPLC)	≥95%
Water Content (KF)	≤1.0%
Solvent Residue (GC)	Meets ICH guidelines
Biological Activity (CRM1 Inhibition)	Confirmed

Note: Specifications can be tailored. Please contact us for the detailed technical data sheet of a specific grade.