In October 1997 the chemical class system was simplified. For more information, see *CLASS in Chapter 7 of Volume 2.
Percentage of Database
1 Carbohydrates 1.5%
2 Nucleosides & nucleotides 0.7%
3 Amino-acids, peptides & complexes 2.9%
4 Porphyrins, corrins & complexes 1.1%
5 Antibiotics 0.6%
6 Steroids 1.2%
7 Terpenes 1.6%
8 Alkaloids 1.0%
9 Miscellaneous natural products 0.9%
10 Supramolecular entities 3.0%
11 High polymers 0.1%