What molecule am I?
Halichondrin B is a polyether macrolide1 that, along with eight other similar macrolides, was isolated from the marine sponge Halichondria okadai by Yoshimasa Hirata at Meijo University (Nagoya, Japan) and Daisuke Uemura* at Shizuoka University (Japan). In their 1986 report, the authors described halichondrin B as exhibiting a “remarkable in vivo antitumor activity”.
The same year in Japanese patent application 61191687, Tsukitani Yasumasa and co-inventors at Fujisawa Pharmaceutical Co. (Osaka, Japan; now part of Astellas Pharma) covered the extraction of halichondrin B from the sponge and its physiochemical properties and antitumor activities against leukemia and melanoma in mice.
In subsequent years, much research was performed on the anticancer properties of halichondrin B, which was prioritized by the US National Cancer Institute. In 1992, Yoshito Kishi and co-workers at Harvard University (Cambridge, MA) reported the total synthesis of the molecule, a prodigious feat considering that it has 32 chiral centers. Kishi’s group also fully synthesized a derivative, homohalichondrin B2.
The Kishi synthesis enabled chemists to create simpler, yet similarly effective, molecules that would become cancer drugs. This research led to the development of eribulin3, a macrolide with only 40 carbon atoms, compared with halichondrin B’s 60. The synthesis of eribulin was reported in 2001 by Melvin J. Yu and co-workers at Eisai Research Institute (Andover, MA); it was improved in 2009 by Kishi and colleagues at Harvard.
The US Food and Drug Administration approved the use of eribulin for treating advanced or metastatic breast cancer and unresectable liposarcoma in 2010. The European Medicines Agency approved it in 2011.
For more information, see ScienceDirect topics pages about halichondrin B in agriculture and biological sciences and in neuroscience. Hazard information for halichondrin B is not available.
1. A macrolide is an eight-membered or larger lactone ring that typically contains ketone, hydroxyl, and/or ether groups.
2. CAS Reg. No. 101383-39-5.
3. CAS Reg. No. 253128-41-5.
Molecules in the News
Poly(lactic acid)1 (PLA) is the generic term for all polymers of lactic acid, whether the monomers are the natural, more abundant L-enantiomer2, the less common D-enantiomer3, or both. PLA is manufactured commercially via the direct polymerization of the monomer or polymerization of the cyclic lactic acid diester, lactide4.
PLA has garnered considerable attention in recent years for making biodegradable plastics that can be used in food containers, films, disposable garments, and drug capsules. This February, in anticipation of last week’s Mardi Gras celebrations, a Louisiana State University (LSU) blog reported that researchers at the institution are developing Mardi Gras beads made from PLA and another group of biodegradable polymers called polyhydroxyalkanoates5 (PHAs). After Mardi Gras celebrations in New Orleans and elsewhere, traditional petroleum-based beads find their way into the environment, releasing hazardous decomposition products and clogging sewers. Naohiro Kato and his students at LSU developed a method for 3-D printing PLA/PHA beads that they intend to have ready for mass production for Mardi Gras 2026.
1. CAS Reg. No. 26100-51-6.
2. CAS Reg. No. 79-33-4.
3. CAS Reg. No. 10326-41-7.
4. CAS Reg. No. 96-96-5; mixture of all isomers.
5. e.g., poly(4-hydroxybutyrate), CAS Reg. No. 114959-05-6.
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Halichondrin B
fast facts
| CAS Reg. No. | 103614-76-2 |
| SciFindern name | See entry |
| Empirical formula | C60H86O19 |
| Molar mass | 1111.32 g/mol |
| Appearance | White crystals |
| Melting point | 164–166 ºC |
| Water solubility | Slight |
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