Table 2 Structure-based classification of antitumor compounds

Phenolic compounds

Plant, fruit, spices, vegetable, and grains

synthesized from shikimate pathways, containing one or more hydroxylated aromatic rings

Flavonoids

Stilbenes

Phenolic acids

Terpenopids

essential oils, resins, or oleoresins

linear arrangements of isoprene, and their carbon skeletons consist of two or more carbon units

Mono-terpenoids

Di-terpenoids

Tetra-terpenpids

Nitrogen-containing alkaloids and sulfur-containing compounds

Alaloids

All Plants

derived from amino acids, and have a nitrogen-atom-containing heterocyclic ring

14 sub-groups based on ring structure:

pyrrolidine,

pyrrolizidine,

piperidine,

tropone,

quinoline,

isoquinoline,

acridine,

quinolizidine,

benzopyrrole,

indolizidine,

imidazole,

purine,

quinolizidine, and

oxazole

Organosulfur Compounds (OCS)

Allium genus, Brassica genus, sulfur-containing organic compounds

sulfur-containing organic compounds

cycloalliin,

thiosulfonates,

cysteine alkyl disulfides,

glucosinolates,

goitrin, and

epithionitrile