Glossary – phytochemistry (under construction)

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C3 – a photosynthetic pathway in which carbon is fixed as the 3C compound 3-phosphoglycerate

C4 – a photosynthetic pathway in which carbon is fixed as the 4C compound phosphoenolpyruvate, and this converted into 4C acids, from these the fixed carbon entering the plant metabolic cycles via the Calvin cycle as the 3C compound 3-phosphoglycerate, often associated with a distinct tissue structure that allows the initial carbon fixation to occur spatially separate from the Calvin cycle (Kranz anatomy)

Caffeic acid – a hydroxycinnamic acid; a phenol formed from cinnamic acid containing both phenolic and acrylic functional groups; more frequently present as an ester, as in chlorogenic acid

Caffeine – a pseudo-alkaloid

Caffeoylphenylethanoid glycosides – caffeic acid esters of phenylethanoid glycosides

Callose – a polymer of glucose, a β-1,3-glucan, found especially in the area of the sieve plate in sieve elements, also in the pollen tube, etc.

CAM – photosynthetic pathway in which stomata are closed during the day and open during the night, carbon being fixed in the dark as 4C compound (e.g. malic acid) by phosphoenolpyruvate, these later being broken down releasing CO₂ and carbon entering the plant metabolic cycles as the 3C compound 3-phosphoglycerate

Campnospermonol – a ketonic phenol, present in Campnospermum

L-(+)-(S)-Canavanine – a non-protein α-amino acid present in some Faboideae (mainly in the seeds); L-(+)-(S)-canavanine differs from L-arginin by having an oxa group (oxygen atom) instead of a methylene group

Cannabinoids – a class of compounds, e.g. phytocannabinoids (tetrahydrocannabinol, cannabidiol, cannabinol, cannabigerol, tetrahydrocannabivarin, cannabichromene, etc.); cannabinoids activate cannabinoid receptors

Cantleyoside – an iridoid

Carboxylated iridoids – normal iridoids; a class of route II iridoids (normal route II) derived from epi-iridodial and epi-iridotrial via glucosylation and oxidation of C₁₁ to the carboxyl level; examples are strictoloside and ipolamiide

Cardanol – a phenol obtained from anacardic acid

Cardenolides – subclass of triterpenoids (nortriterpenoids), specifically steroids, basically C₃₀ compounds made up of 6 isoprene units, a C₂₃ unit with a five-membered lactone ring attached at C₁₇, including cardiac glycosides (heart poisons and toxins) that are taken up by monarch and danaid butterflies, also some aphids

Cardiac glycosides – a kind of cardenolide

Cardiospermin – a cyanogenic glucoside

Carotenoids – subclass of fat-soluble terpenes that consist of two diterpene phytol-like units (C₄₀ compounds, 8 isoprene units), the most familiar tetraterpenoids forming one of the two main groups of plant pigments and occurring as yellow, orange or red carotenes and xanthophylls

Castanospermine – a polyhydroxy alkaloid

Casuariin – a C-glucosidic ellagitannin

Casuarinine – a polyhydroxy alkaloid

Catalpol – a route II iridoid

Catechins – flavan-3-ols, a class of flavonoids

Catechol – a phenolic compound, i.a. the probable precursor of phytomelan

C-glucosyl- or C-glycosyl- – of e.g. flavonoids in which linkage of a carbon-carbon bond involves the anomeric carbon of the sugar and position 6, 8, or both, of a flavone (vertical bond on left-hand side between the benzene ring and the sugar), difficult to hydrolyse

Chalcones – intermediates in the production of all flavonoids, but rarely accumulated, isomeric with flavanones, the A ring being derived from acetate and with a phloroglucinol oxidation pattern, the B ring from a phenylpropanoid precursor, and with an allyl bridge (-CH:CH.O) separating the two rings, yellow and most often found in flowers; chalcones are anthochlors; examples of chalcones are marein, coreopsin (butein 4’-glucoside), stillopsin, lanceolin, naringin (naringenin 7-glucoside), and polyhydroxychalcones

Chelidonic acid – an organic acid derived from a condensation of C3 and C4 units related to phosphoenolpyruvic acid and erythrose-4-phosphate

Chinic acid – cyclohexanecarboxylic acid, present in Cinchona bark and other angiosperms

Chlorogenic acid – type of phenylpropanoid involving cinnamic acid derivatives; a depside of caffeic acid linked to quinic acid

Chromoalkaloids – see Betalains

Chromones – 1-benzopyran-4-ones; ketone derivatives of benzopyran consisting of a benzene ring fused to a pyrone ring with a methyl group at the C2 position and oxygenated at the C5 and C7 positions

Chrysophanol – an anthraquinone

Cinnamic acid – a simple phenol derived from L-phenylalanine, involved in formation of phenylpropanoids, present in various aromatic resins; common hydroxycinnamic acids are caffeic acid, ferulic acid, p-coumaric acid, sinapic acid; depsides include chlorogenic acid and rosmarinic acid

Citric acid – a carboxylic acid; citrate is an important constituent in the citric acid cycle

Citronellol – dihydrogeraniol, an acyclic monoterpenoid present in two enantiomers

Citrulline – an α-amino acid

Colchicine – N-[(7S)-1,2,3,10-tetramethoxy-9-oxo-5,6,7,9-tetrahydrobenzo[a]heptalen-7-yl]acetamide; an alkaloid present in Colchicaceae; colchicine is a frequently used drug, also inhibiting chromosome segregation during meiosis and hence used for inducing polyploidy in plant cell

Coniferin – a glucoside of coniferyl alcohol; an intermediate in cell wall lignifications in conifers

Coniine – a pyridine alkaloid

Cornosides – ursolic acid esters; compounds that occur in taxa where there are no iridoids, even though these might be expected; frequent in many asterids

Coumaric acid – a hydroxycinnamic acid, a hydroxyl derivative of cinnamic acid, present in three isomers: o-coumaric acid, m-coumaric acid and p-coumaric acid, differing by the position of the hydroxyl substitution of the phenyl group; p-coumaric acid, sinapyl alcohol and coniferyl alcohols are the major components of lignocellulose

p-Coumaric acid – a hydroxycinnamic acid derived from L-phenylalanine, involved in formation of phenylpropanoids, readily convertible into salicylic acid

Coumarins – 1-benzopyran-2-ones, ketone derivatives of benzopyran; lactones of phenylpropanoic acids with a H-benzopyranone nucleus, occurring as glycosides, sometimes located in secretory ducts called vittae, produce the characteristic new-mown hay smell of many grasses; c. 800 different kinds of coumarins are known

Coumestans – class of flavonoids derived from isoflavones, which have a coumarin structure

Croceins – a group of red or orange acid azo dyes (carotenoids)

Cucurbitacins – triterpenoid steroids, bitter-tasting, sometimes coloured

Cuphiin – a macrocyclic hydrolyzable tannin (ellagitannin) present in, e.g., Cuphea

Curcumins – dimers of hydroxycinnamic acid, i.e. with hydroxyl (and other) groups attached to the phenolic ring of cinnamic acid, orange-yellow

Cutin – polymer of fatty acids and hydroxyl fatty acids, occurring in the cuticle

Cyanidin – a type of anthocyanidin present in red fruits etc.; colour changing with pH

Cyanine – (fluorescent) dye of the polymethine group; examples are hemicyanines, streptocyanines (open chain cyanines) and closed chain cyanines

Cyanogenic compounds – c. 60 different kinds of cyanogenic compounds are known; they are derivatives of α-hydroxynitriles (cyanohydrins) and may be cyanogenic lipids or cyanogenic glucosides; they liberate a carbonyl compound and HCN, when their fatty acid or glucose moiety is removed

Cycasin – cycad toxin with glucose molecule

Cyclitol – a cyclic sugar alcohol or polyol based on inositol isomers where hexitol are linked through the C1-C6 carbons to form a ring, a cyclic polyol

Cyclopentenoids – cyanogenic glycosides producing HCN, often found as cyclopentenyl fatty acids, e.g. hydnocarpic acid

Cyclopropenes – a class of compound derived from the very reactive cycloalkane C₃H₆, found in the plant as fatty acids

Cyclotides – small, disulphide-rich proteins characterized by a circular backbone formed by a peptide bond linking their N and C termini and a knitted arrangement of three interlocked disulphide bonds

Cystisine – a quinolizidine alkaloid