Table 2.

Classification of plant secondary metabolites.

Groups	Chemical structures	Examples
Phenolics with one aromatic ring	C6	Phenol, hydroquinone, pyrogallol acid
	C6-C1	Gallic acid, salicylic acid, methyl syringate, vanillic acid
	C6-C2	Acetophenones, apocynin
	C6-C3	Hydroxycinnamic acid, ferulic acid, sinapic acid, coumaric acid, eugenol, zosteric acid
Phenolics with two aromatic rings	C6-C1-C6 Xanthones	Mangostin
	C6-C2-C6 Stylbenes	Reservatrol, chlorophorin
	C6-C3-C6 Flavonoids	Quercetin, glyceollin, sakuranetin
Quinones	Naphthoquinones Antraquinones Benzoquinones	Alizarin, emodin
Flavonoid polymers and non flavonoid polymers		Tannins
Terpenoids	C5 Hemiterpene	Isoprene, prenol, isovaleric acid
	C10 Monoterpene	Limonene, cineol, pinene, thymol, camphor, turpentin, carvacrol, citral, γ-terpinene, myrcene
	C15 Sesquiterpene	Abscisic acid, humulanes, culmorin, gossypol, zealexin
	C20 Diterpene	Gibberellin, taxol, oryzalexins, phytocassanes, momilactone, kauralexin
	C30 Triterpene	Brassinosteroids, squalen, lanosterol, avenacin
	C40 Tetraterpene	Carotenoids, lycopen
	C > 40 Polyterpenes	Rubber, glisoprenin
	Mixed origin (meroterpenes)	Cytokines, vitamine E
Nitrogen-containing	Alkaloides	Tomatin, solanin, nicotine
	Glucosinolates	Sinigrin, glucobrassicin
	Non protein amino acids	L-canavanine
	Amines	Phenylethylamine, tyramine, morphin
	Cyanogenic glycosides	Amygdalin, sambunigrin, linamarin