Classification of Natural Products based on molecular skeleton

Classification of Naturally Occurring Compounds According to Number of carbon atoms in the molecule.

# of Carbon Atoms	Carbon Skeleton	Possible Groupings
5	C5	Isoprenoids
6	C6	Simple phenols
7	C6 – C1	Phenolic acids
8	C6 – C2	Acetophenones; phenylacetic acid
9	C6 – C3	Cinnamic acid derivatives; phenyl propenes; coumarins, isocoumarins, chromenes
10	C6 – C4 C5 – C5	Naphthoquinones Monoterpenes
13	C6 – C1 – C6	xanthones
14	C6 – C2 – C6	Stilbenes, anthraquinones
15	C6 – C3 – C6 C5 – C5 – C5	Flavonoids, isoflavonoids, neoflavonoids Sesquiterpenoids
18	(C6 – C3) 2	Lignans
20	(C5 – C5) 2	Diterpenes
24	C6 – C3 – C6 – C3 – C6	Complex flavonoids
30	(C6 – C3 – C6) 2 (C5 – C5) 3	Biflavonoids Triterpenoids
40	(C5 – C5) 4	Carotenoids
n	(C6 – C3) n (C6 – C1) n (C6 – C3 – C6) n	Lignins Tannins (hydrolysable) Tannins (condensed)
Depends on N-containing heterocyclic ring	alkaloids	Sometimes as glycosides