Brassicaceae esters

Cinnamic esters are also found as sugar esters, or as esters of a variety of other organic acids. For example, sinapoyl esters represent a class of UV-absorbing compounds in the family of the Brassicaceae. Examples include sinapoyl malate (1.19) present in leaves, and sinapoyl choline (1.20) present in roots (Ruegger and Chappie, 2001). 

Sinapoyl esters are phenolic compounds found in members of the Brassicaceae, which includes the model plant Arabidopsis thaliana. The two major sinapoyl esters are sinapoyl malate (3.92) and sinapoyl choline (3.93), which accumulate in leaves and seeds, respectively. Sinapoylmalate plays a role in the protection against UV-radiation (Landry et al., 1995), whereas sinapoyl choline may be used as a storage form of choline in seeds (Shirley and Chappie, 2003). The precursor of these two esters is sinapate (3.35). 

Structure occurrence The T. a. occur principally in plants of the Solanaceae, Convolvulaceae, Eryth-roxylaceae, Proteaceae, and Rhizophoraceae families as well as in isolated species of the Euphorbiaceae and Brassicaceae. The most important of the ca. 140 known T. a. are either esters of 3a-tropanol (tropine) or, less commonly, of 3/S-tropanol (pseudotropine). Prominent examples are the T. a. of the Solanaceae hyoscya-mine [racemate ( )-hyoscyamine= atropine], scopolamine, and the T. a. of the Erythroxylaceae (Coca... 

The distribution of sinapine (2) (3,5-dimethoxy-4-hy-droxycinnamoylcholine) and aromatic choline esters in many genera of the Brassicaceae have been surveyed (Bouchereau et al., 1991). These compounds were analyzed by high-performance liquid chromatography (HPLC). 

Unusual pyronotropane tropane alkaloids have been fotmd in the family Proteaceae. Tropine and pseudotropine esters of benzoic acid have been isolated from the family Euphorbiaceae. Novel dithiolane esters, along with tropine esters of acetic, propionic, n-butyric, isobutyric, isovaleric, and benzoic acids have been fotmd in the Rhizophoraceae. Calystegines, as well as a 3-hydroxybenzoate ester, have been fotmd in Brassicaceae. The calystegines have been used as chemotaxonomic markers in the Convolvulaceae family [20]. Tropine esters with methoxy-substituted benzoic acids are also characteristic for the later family. 

Proteins from seeds of the mustard family (Brassicaceae), such as turnip, rapeseed or brown or black mustard, contain glucosinolates which can be enzymatically decomposed into pungent mustard oils (esters of isothiocyanic acid, R—N=C=S). The oils are usually isolated by steam distillation. The reactions of thiogly-cosidase and a few glucosinolates occurring in Brassicaceae are covered in section 17.1.2.6.5. 

The above-mentioned plants, as Brassicacea, contain mustard oil glucosides (glucosinolates, cf. 17.1.2.6.5) which, immediately after seed crushing, are hydrolyzed to esters of isothio-cyanic acid. The hydrolysis is dependent on seed moisture and is catalyzed by a thioglucosidase enzyme called myrosinase (EC 3.2.3.1). In the presence of the enzyme, some of the isocyanates are isomerized into thiocyanates (esters of normal thiocyanic acid or rhodanides) and, in part, are decomposed into nitrile compounds which do not contain sulfur. All these compounds are volatile and, when dissolved in oil, are hazardous to health and detrimental to oil flavor. Moreover, they interfere with hydrogenation of the oil by acting as Ni-catalyst poisons (cf. 14.4.2.2). Therefore, in the production of rapeseed oil, a dry conditioning step is used (without live steam) to... 

Arabidopsis thaliana, Brassicaceae), which is a plant used as a model organism in molecular biology and genetics. The major components of this wax are alkanes (38%), followed in quantity by ketones (30%), primary alcohols (12%), secondary alcohols (10%), aldehydes (6%), free fatty acids (3%) and their esters (1%). The main alkane is nonacosane (C29), the main ketone is ditetradecylketone (C29), myricyl alcohol (mehssyl alcohol, C29) and ceryl alcohol (C2g) are the main primary alcohols, the main secondary alcohols are C29, Cjj and C27 compounds, and the major fatty acids are meUisic acid (Cjq) and montanic acid (C2g). The epicuticular wax of wheat and related species contains alkanes (5-10%), esters (10-30%), aldehydes (<5%), alcohols (15-55%) and acids (<5%). 

A representative of shikimic acid depsides is 3-0-caffeoyl-L-shikimic acid, known as dactyhferic acid (8-87), which occurs in dates. This acid and other related depsides are substrates of oxi-doreductases in enzymatic browning reactions in dates. The seeds and shoots of plants of the genus Brassica of the cabbage family (Brassicaceae) contain various esters of cinnamic acids with malic... 

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