Compounds, compositions and methods of agelastatin alkaloids

A method comprising:

• administering to a subject in need thereof a therapeutically effective amount of a compound of formula I:
• or a pharmaceutically acceptable salt thereof,
• wherein:
• R1 is —H or —CH3;
• R2 is —OH or —OCH3;
• R3 is —H or —OH;
• and
• R4 is —H when R1 is H, or —Br when R1 is —CH3;
• and
• wherein said method treats blood cancer, inhibits growth of blood cancer cells, inhibits proliferation of blood cancer cells, promotes apoptosis of blood cancer cells, arrests cell cycle in blood cancer cells, or induces arrest in G2/M phase in blood cancer cells, or any combination thereof.