Glossary – phytochemistry (under construction)

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S-lignin – referring to a kind of lignin in which there is a major percentage of syringyl units (sinapyl being the alcohol) and which is found mostly in angiosperms other than monocots

Salacinol – a polyol consisting of a 1-deoxy-4-thioarabinofuranosyl sulfonium cation and a 1’-deoxyerythrosyl-3’-sulfate anion

Salicylic acid – orthohydroxybenzoic acid, obtained from the bark of the white willow and wintergreen leaves, its salts are the salicylates

Saponins – water-soluble and sometimes toxic glycosides based on steroid or terpenoid alcohols; saponins become a foam when in solution and then shaken; they are derived from the 30-carbon oxidosqualene (containing six isoprene units) to which glycosyl residues are attached

Sarracenin – an iridoid monoterpene

Scoparone – 6,7-dimethoxycoumarin

Scopoletin – 7-hydroxy-6-methoxycoumarin

Secoiridoids – a class of route I iridoids derived from deoxyloganic acid via oxidation to carboxyl at C₁₁; examples are deutzioside, patrinoside, and secologanin

Senecionine – a pyrrolizidine alkaloid

Sesamin – a lignin

Sesquiterpene alkaloids – alkaloids derived from sesquiterpene precursors; examples of sesquiterpene alkaloids are, i.a., dendrobine in Dendrobium (Orchidaceae), nupharidine in Nymphaeaceae, and evonine, hippocrateine, maytine, maytoline in Celastraceae

Sesquiterpene lactones – lactones, subclass of C₁₅ terpenoids (sesquiterpenoids, sesquiterpenes), bitter-tasting and toxic, derived via the mevalonate pathway from three C₅ isopentenyl pyrophosphate units

Shikimic acid – an aromatic carboxylic acid that is a precursor in the biosynthesis of alkaloids and flavonoids

Simaroubolide – quassinoids, e.g. simarolide, present in Simaroubaceae

Simmondsin – jojoba oil, a dicyclic dimethylpolyol; an active substance in Simmondsia seeds

Simple pyrrolidine and piperidine derivatives, tropane alkaloids

Sinapic acid – sinapinic acid; a phenylpropanoid, a monosaccharide ester of a hydroxycinnamic acid

Sinapine – a methyl glucosinolate

Sinigrine – a methyl glucosinolate

β-Sitosterol – a phytosterol with structure similar to cholesterol

Sorbitol – a straight-chained hexitol formed by reduction of the carbonyl group of glucose

Stachyose – an oligosaccharides made up of four sugar units, two galactose, one glucose, and one fructose, serially linked

Stachyurin – a C-glucosidic ellagitannin

Starch – a more or less coiled-chain polysaccharide made up of α-glucose units, with amylase and amylopectin, and staining black with an iodine/potassium iodide solution

Steroidal alkaloids – pregnane alkaloids, cholesterol alkaloids (i.a. pregnenolone, holaphyllamine); particularly frequent in Apocynaceae (e.g. conessine), Solanaceae (solanidine alkaloids, e.g. etioline, solanidine and verazine; spirosolanes, e.g. solasodine and tomatidine; juribidine) and Melanthiaceae (Veratrum alkaloids, e.g. cyclopamine, cyclopsine and jervine)

Steroidal saponins – steroidal amines, bufadienolides, cardenolides, spiroketal saponins

Steroids – a large class of organic compounds characterized by a nucleus of 17 carbon atoms in the form of four fused-rings (three containing six carbon atoms and one containing five), derived from triterpenes, and with varying substituents and degrees of unsaturation, including sterols, cardiac-active glycones, bufadienolides, cardenolides, and some sapogenins and alkaloids

Sterols – terpenoids, solid, unsaturated steroid alcohols with an -OH group at the C₃ position; sterols occur both free and as esters or glycosides, and are classified according to the organism in which they are found as mycosterols (in fungi), phytosterols (in plants), etc.

Stigmasterol – a phytosterol; related to β-sitosterol, campesterol, ergosterol, brassicasterol, δ-7-stigmasterol and δ-7-avenasterol

Stilbenes –a diarylethene, a hydrocarbon consisting of a trans-ethene ((E)-stilbene) or a cis-ethene ((Z)-stilbene) double-bond substituted with a phenyl group on both carbon atoms of the double-bond

Strictinin – a C-glucosidic ellagitannin

Stypandrol – a toxic binaphthalenetetrol, a dimer of dianellidin

Stypandrone – 6-acetyl-5-hydroxy-7-methyl-1,4-naphthoquinone; a toxic naphthalene-14-quinone

Suberin – cell wall component made up of polyphenolic elements with appreciable hydroxycinnamic acids and their derivatives and also a glycerol-bridged polyester network, occurring in e.g. endodermis and cork

Sugar alcohol – see Polyol

Surianol – a triterpenoid diol, present in Suriana (Surianaceae)

Swainsonine – a toxic indolizine alkaloid (a polyhydroxy alkaloid)

(+)-Syringaresinol – a furofuran lignan

Syringetin – an O-methylated flavonol

Syringin – lilacin; glucoside of sinapyl alcohol