Agmatine derivatives

The biosynthesis of synoxazolidinones A (1) and B (2) was postulated by Tadesse and coworkers and it is depicted in Scheme 1. It was assumed that brominated tyrosine derived metabolite 4 [11, 12] and an arginine /agmatine derivative 5 [13] react with each other and form a dipeptide 6, which further cyclize to form oxazolidinone ring. The biosynthesis of synoxazolidinone C (3) has not been studied and it was assumed that synoxazolidinone C (3) might be derived Irom synoxazolidinone A (1) [9]. 

The ubiquitous plant compound chlorogenic acid (isolated from green coffee beans) is formed by transesterification with the glycoside cinnamoyl-glucose.187 Coumaroyl-CoA is converted into monomeric and dimeric amides with agmatine, which provides barley plants with resistance to mildew.188 Similar compounds with various polyamines and derived from p-coumaric, caffeic, ferulic, or sinapic acid appear to... 

Hernandez-Jover et al. (72) derived an improved analytical method from the HPLC procedure setup they developed in 1995 (73) for the determination of BAs in fish. The method consists of the extensive extraction with HC104, ion-pair (with sodium octanesulfonate) RP-HPLC separation, postcolumn derivatization with PA/ME, and spectrofluorimetric detection. Determination limits were up to 1.5 mg/kg. In particular, His, Tyr, Phe, Ser (serotonine), Cre (creatinine), Try, Oct (octopamine), Dop (dopamine), Cad, Put, Agm (agmatine), Spm, and Spd were studied in pork and beef meat, fresh, cooked, or ripened. Tyramine, His, Put, Cad, and Try levels were... 

Several agmatine (16) (Scheme 2) derivatives have been isolated from barley seedlings. All are conjugates of coumaric acid and possess antifungal activity. 

Putrescine, cadaverine, spermidine, spermine, agmatine, and homoagmatine have been isolated. The latter two are guanidoamine derivatives. 

Figure 22 Biosynthesis of polyamines through the arginine decarboxylase pathway. Putrescine derived from L-arginine through the action of three successive enzymes arginine decarboxylase (ADC), agmatine iminohydrolase (AIH), and N-carbamoylputrescine amidohydrolase (NCPAH).

Aeruginosins, a main class of cyanobacteria peptides characterized by a derivative of hydroxyphenyl lactic acid (Hpla) at the N-terminus, 2-carboxy-6-hydroxyoctahydroindole (Choi) and the arginine derivative agmatine at the C-terminus. The aeruginosins 98-A and B from the blue-green alga Microcystis aeru -nosa act as trypsin inhibitors [M. Murakami et al.. Tetrahedron Lett. 1995, 36, 2785]. 

Most pyrrolizidine alkaloids are esters of basic alcohols known as necine bases. The most frequently studied pyrrolizidine alkaloids are formed from the polyamines, putrescine and spermidine, and possess one of three common necine bases retronecine, heliotridine, and otonecine. Putrescine is utilized exclusively as a substrate in secondary metabolism, whereas spermidine is a universal cell-growth factor involved in many physiological processes in eukaryotes. Spermidine biosynthesis begins with the decarboxylation of SAM by SAM decarboxylase 165). The aminopropyl group is then transferred from decarboxylated SAM to putrescine by spermidine synthase to form spermidine (Scheme 5). Putrescine can be produced from ornithine by ODC. However, putrescine is derived from the arginine-agmatine pathway in pyrrolizidine alkaloid-producing plants due to the absence of ODC activity 166). 

In addition to more or less complete amino acid separations, suitable chromatographic systems for the rapid determination of selected amino acids [4-amino-butyric acid (GABA) [336], histidine and 3-methylhisti-dine [367] or a group of selected amino acids, such as those involved in the urea cycle (arginine, citrulline, ornithine, agmatine) [368], have been reported. Precolumn derivative formation with OPA/R-SH reagents is also suited to the automated establishment of peptide maps [369]. A number of authors have published methods for the sensitive determination of aminoglycoside antibiotics [365,370—373]. The method has also found application for the determination of histamine and its methylation products [374—376], catecholamines and serotonin [377—379] and polyamines [380]. 

Pyrrolidine alkaloids are derived via the intermediacy of putrescine (1). Putrescine is derived by decarboxylation of arginine or ornithine the enzyme ornithine decarboxylase (E.C. 4.11.1.17) has been detected in tobacco roots (Leete, 1980) (also see Chapter 30). Arginine decarboxylase (E.C. 4.1.1.19) first converts arginine to agmatine, and subsequently to car-bamoylputrescine, and then to putrescine see Fig. 28.7 of Chapter 28). In several studies, arginine, rather than ornithine, appears to be the major precursor (Leete, 1990). 

Kotzabasis et al. [298] used a C g column (A = 254run) and a 23-min 55/45 —y 84/16 methanol/water gradient to separate the benzoyl derivatives of putrescine, cadaverine, spermidine, spermine, and agmatine extracted fiom leaves. Levels as low as 0.2 nmol were easily detected. Peak shapes were dramatically dependent upon the sample solvent chosen. Samples dissolved in 100% methanol generated extremely tailed peaks, whereas samples dissolved in 80/20 methanol/ water generated peak doublets. Odd peak shapes are not uncommon when a sample solvent-mobile phase mismatch occurs. A sample solvent similar to the mobile phase composition almost invariably gives the best peak shape and the most reproducible results. Whenever possible, a sample solvent identical in composition to the mobile phase is generally recommended. 

Figure 9.20 The guanosine derivative designated HF-7 from venom of Hololena curta, a funnel-web spider, and the amide of oxalic acid with agmatine (decarboxylated arginine) from a hunting spider Plectreurys tristis...

Aplysillamides A and B are antibacterial and antifungal amides formed from an acid with 10 carbon atoms and the amine agmatine, which is formally derived by the decarboxylation of arginine and has already been encountered in certain metabolites of cyanobacteria (see Chapter 8) as well as in phloeodictins (see above). These two atypical derivatives of guanidine were isolated from the... 

Compound 199 and purealidin O (200) are two oxime-type bromotyrosine-derived metabolites containing an agmatine moiety, isolated from Psammaplysilla purea and Oceanapia sp., respectively (79,90). Alkaloids 201, 202, and 203 were iodinated tyrosine derivatives isolated from the ascidian Aplidium sp. (127). 

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