<unk> s are a class of<unk> s containing a structural moiety of<unk> ; many<unk> s also include isoprene groups and are thus called terpene<unk> s. Containing more than 4100 known different compounds, it is one of the largest classes of<unk> s. Many of them possess significant physiological activity and some of them are used in medicine. The amino acid tryptophan is the biochemical precursor of<unk> s.
Indole alkaloid
Polycyclic aromatic hydrocarbon
Terpene
Haloalkane
Nitrobenzene
Oxoacid
Flavonoid
Organophosphate