Designed antitumor agent with a highly promising pharmacological profile
Modern methods of "high-throughput screening" make it possible to search for new pharmaceuticals in giant-though sometimes quite randomly compiled-substance libraries. In contrast, an interdisciplinary team at the Sloan-Kettering Institute for Cancer Research in New York is depending on quality rather than quantity. Starting with a pharmaceutically active natural substance, researchers working with chemist Samuel J. Danishefsky and pharmacologist Ting-Chao Chou "rework" the molecule very precisely, in order to give it, step by step, an improved pharmacological profile. The newly designed molecules are then built out of the simplest possible components in a "total synthesis". That this method of "chemical editing" can be highly successful is demonstrated by the team's latest development: an epothilone with unusually promising antitumor activity. Derived from microorganisms, epothilones work similarly to the yew-derived taxoids (such as Taxol®), which are used as cytostatics. Both types of drugs stabilize the microtubuli of the cells, locking them into one phase of the cell-division process, which leads to the death of the cell.
The basic structural framework of epothilones consists of a fifteen-membered carbon chain that is closed into a ring by an (oxygen-containing) lactone bond. The oxygen atom forms a bridge between carbon atoms twelve and thirteen. This bridge seems to be responsible for a large part of the non-tumor-specific cytotoxicity, a potential source of side effects in medicines. Danishefsky and his chemistry colleagues removed the bridge and replaced it with a double bond between the two carbon atoms. However, this disruption caused some of the agent's effectiveness against tumor cells to be lost. The researchers were able to partially compensate for this loss by introducing an additional double bond between carbon atoms nine and ten. This had a positive side effect; the double bond significantly stabilizes the compound with regard to decomposition in the plasma. However, the researchers were still not completely satisfied. They replaced the three hydrogen atoms of a methyl group (CH3) with three fluorine atoms. This third modification to the molecule doesn't just stabilize it even further; it apparently allows the agent to more easily enter into the tumor cells. These edited epothilones cause human tumors that have been transplanted into mice, to permanently disappear. Of course, the path from xenograft mice to human clinical applications is fraught with uncertainty but these results are quite exciting said Drs. Chou and Danishefsky. The second generation compounds are being developed in a collaborative effort embracing Memorial Sloan-Kettering Cancer Center, Kosan Biosciences and Hoffman LaRoche.
Other news from the department science
Get the chemical industry in your inbox
From now on, don't miss a thing: Our newsletter for the chemical industry, analytics, lab technology and process engineering brings you up to date every Tuesday and Thursday. The latest industry news, product highlights and innovations - compact and easy to understand in your inbox. Researched by us so you don't have to.
Most read news
More news from our other portals
Possible trigger of Crohn’s disease discovered
Dysfunctional mitochondria disrupt the gut microbiome
Cost-effective modular system for optical imaging from the 3D printer
Like building with Lego bricks
See the theme worlds for related content
Topic world Synthesis
Chemical synthesis is at the heart of modern chemistry and enables the targeted production of molecules with specific properties. By combining starting materials in defined reaction conditions, chemists can create a wide range of compounds, from simple molecules to complex active ingredients.
Topic world Synthesis
Chemical synthesis is at the heart of modern chemistry and enables the targeted production of molecules with specific properties. By combining starting materials in defined reaction conditions, chemists can create a wide range of compounds, from simple molecules to complex active ingredients.
