Rule-of-Three (Ro3)

Proposed by Robin Carr et al. from Astex Technologies [1], Rule-of-Three (Ro3) compliance is designed for fragment-based drug discovery [2, 3] and enforces the following properties:

  • Molecular weight ≤ 300;
  • Octanol/water partition coefficient, ClogP ≤ 3;

You see that chemistry is everywhere. You could try this out andunderstand the importance of chemistry in your day to day life.Chemistry studies matter and how it interactswithotherenergy and matter forms. Chemistry plays animportant role in every aspect of our lives and this is why schools have this subject in their curriculum.

Most students find chemistry to be boring andcomplicated. However,once you understandwhatchemistry is and what significance it hasin your life then the subject starts to getinteresting. Explosions andfireworks use chemistry. There is logic andmaths that you needto apply when you study chemistry and this definitely makesit challenging. In a nutshell,chemistry is interestingwhen you understand what it teachesyouabout and when you can relate the subject with how things function around you.

Take for example theprocess of cooking. Chemistry explains the waysin which thetexture of the food changes when you cook it. It also explains how the food rots and the ways to preserve food for long. Chemistry also explains how the body uses up the food that you eat and how the various raw materials and otheringredientsinteract to give the final form and taste to your favourite dish.

Chemistry also explains the cleaningmechanism. You clean yourhome, clothes and the dishes. Chemistry lets you decide which the best cleaner that you should use is. You usedisinfectants andbleaches as well asordinarysoap to clean. All this usechemistry to give you aspic andspan home.

Chemistry also plays a vital role in the medicines andthe drug manufacturing industry. Chemistry plays a crucial role in developing new treatments and drugs.

  • number of H-bond donors and acceptors less than, or equal to 3;
  • three or less flexible bonds;polar surface area ≤ 60 Ã…2.

[1] Congreve, M., Carr, R., Murray, C. and Jhoti, H. A ‘Rule of Three’ for fragment-based lead discovery? Drug Discov. Today 2003, 8, 876-877.
[2] Fattori D: Molecular recognition: The fragment approach in lead generation. Drug Discov. Today 2004, 9, 229-238.
[3] Hann MM, Oprea TI. Pursuing the leadlikeness concept in pharmaceutical research. Curr. Opin. Chem. Biol. 2004, 8, 255-263.


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