Alkaloids defined

Nonalcoholic and strong drinks (tea, wine) contain a number of aromatic substances with amino and hydroxyl groups (first of all, there are polyphenolic compounds and alkaloids) which defined sort and quality of drinks. 

The influence of factor series to electrode characteristics has been established. Dependency of the potential of ISE from concentration of defined substance is linear in interval of concentration l lO - l lO mol/1 at the pH 2,0-6,5. Slopping of the graduated graph form 55-56 mV/pC for single-chai ge cation. Potentiometric factors of the selectivity K,, ISE for alkaloids of Papaver Somnifemm has been determined. 

Alkaloids of the Laurales. Well-defined alkaloids have been... 

D. consolida, L. From this species Keller isolated three alkaloids of which one (Base A ) was well defined. Markwood obtained three crystalline alkaloids of which delcosine was probably Keller s base A, and Cionga and Iliescu have added to Markwood s observations, but failed to obtain his third base. This work has recently been critically revised by Marion and Edwards, ( > who have isolated from the seeds six alkaloids of which two, delcosine and delsoline, were already known another, consolidine, may be Markwood s third base, and the remaining three are new records for this species, viz. delsonine, lycoctonine and anthranoyllycoctonine. They have also altered the empirical formulas of the alkaloids delcosine and delsoline. 

The chemistry of some speeies of the genus is in a eoiifused state Owing to the uneertain botanieal origin of the materials used. The following is a list of the species examined and their alkaloidal components so far known more detailed deseriptions of the better defined alkaloids are given later —... 

Achillea spp. A. millefolium L. contains achilleine, amorphous hydrolysed to achUletine, CnHj,04N, also amorphous, ammonia and a reducing sugar. A. moschata contains achilleine and moschatine, CjiHjjOjN, an ill-defined gluco-alkaloid.2 ((1) Zanon, Annalen, 1846, 58, 21. (2) von Planta, ibid., 1870,... 

The combination of positive and negative charges within the same molecule causes a more complicated situation, which obviously has not been well-defined to date. A quite large number of pyrrolizidine alkaloids are related to Otonecine (8) (Scheme 3). Spectroscopic investigations show that these alkaloids exist in the nonionized form in CDCI3, and in the zwitterionic form in D2O (00JNP857, 71TL3421). The dipolar structure is the result of an intramolecular interaction between a nucleophilic and an electrophilic center. 

In contrast to the alkaloids mentioned so far, heterocyclic mesomeric betaines are defined as neutral conjugated molecules which can be represented only by dipolar structures in which both the negative and the positive charges are delocalized within the rr-electron system (38JCS824, 85T2239). The first heterocyclic mesomeric betaine was prepared unknowingly by Emil Fischer (1882LA316). The real structure remained unknown... 

Demethylvasconine (85) (9-methoxy-5-methyl-phenanthridin-8-olate) presented in Scheme 31 was found in Crinum kirkii (95P1291) (Amaryllidaceae). Although published as cation, no information about the anion of this alkaloid is given. Its relationship to other alkaloids of this class, however, makes a betainic structure more than likely and this is confirmed by a comparison of the NMR data of 85 with the cationic and betainic alkaloids presented in Table III. This betaine is isoconjugate with the 2-methylphenanthrene anion and thus defined the alkaloid as a member of class 1 (odd alternant hydrocarbon anions). Whereas substitution of the isoconjugate phenanthridinium moiety at the 1-position with an anionic fragment results in zwitterions (cf. Section III.D), the phenanthridinium-2-olate is a mesomeric betaine. 

In order to develop compounds that can selectively target duplex RNA, Sinha et al. [ 194] studied the interaction of berberine with two different conformations of poly(rC) poly(rG) structures. Poly(rC) poly(rG) has been shown [15,215] to exist in two conformations depending on the pH of the solution, the A-form at physiological pH and the protonated form at pH 4.3. These two conformations have been characterized to have clearly defined but distinctly different circular dichroic and absorption spectral characteristics. Both the A-form and the protonated form of the RNA induced moderate hypochromic change and bathochromic shifts in the absorption maxima peaks at 344 nm and 420 nm of the alkaloid with three isosbestic points centered around 357,382 and 448 nm. Binding of berberine to both forms enhanced the fluorescence intensity, which was higher with the protonated form than with the A-from, suggesting clear differences in the nature of orientation... 

The most recent report of Myer and Kock47 afforded a more robust assessment of the value of 1,1-ADEQUATE data as a part of the input data set for the COCON CASE program. The output of the structure generation for the brominated phakellins (18a, b) and brominated isophakellin (19a, b) alkaloids is summarized in Table 3. Structures generated without specified hybridization are noted on the first line for each compound that can be compared with the number of structures generated when pre-defined hybridization was employed on the second line for each... 

This chapter is an historical perspective with selected examples from our own laboratory, first at the University of Munich, and now at the Leibniz Institute of Plant Biochemistry in Halle, that reflect the changes in how we define and exploit sequence-based approaches to alkaloid biosynthesis gene identification. ... 

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