Alkaloids, measurement

In all Argentinean clones, the 6P-hydroxyhyoscyamine content predominates over hyoscyamine and scopolamine, while in Colombian clones the main alkaloid was hyoscyaniine. In addition, the Argentinean clones produced the highest 6P-hydroxyhyoscyamine concentration. In these cultures, scopolamine constituted about 4% of the three alkaloids measured and 6P-hydroxyhyoscyamine about 68%. 

Interpretation of the X-ray structure analysis data helps to explain the identical toxicity of PA of type la and Ib In all nine otonecine-type alkaloids measured to date, a necine conformation was found which is identical to those found in those having the C8-N bond (type la). 

Aledicine. A wide variety of alkaloids (qv) contain the quinoline ring system this fact accounts, in large measure, for the extensive synthetic research reported (107). In addition to the naturally occurring compounds, a large number of synthetic quinolines, eg, (22) and (23), have been prepared and studied for use in medicine. Table 3 presents selected examples. 

Ergotamine, like ergotoxine, is unstable, especially in aqueous solutions of its salts exposed to light the rate of deterioration for both alkaloids has been measured by Wokes and Elphick. ... 

Johnson has described a method for the estimation of physostigmine in the salicylate for the determination of minute amounts of the alkaloid Ellis, Plaehte and Straus have devised processes depending on (a) inhibition of serum choline-esterase by the alkaloid, or (b) measurement of the colour intensity produced by the conversion of physostigmine to rubreserine in an alkaline medium. i ... 

This review is an attempt to collect under one heading and to present in a systematic manner the large body of work which deals with the chemistry of the carboline ring systems. Some three hundred papers in this field have been published during the last decade, more than twice as many as appeared during the preceding fifty years. The renewed interest in the chemistry of the carbolines is due in no small measure to the discovery of serotonin and to the recent developments in the chemistry and pharmacology of the Rauwolfia and related alkaloids. 

After treatment with the reagent the detection limits for opium alkaloids are 50-500 ng per chromatogram zone, this is sometimes a somewhat lower sensitivity than that obtained by direct measurement of the UV absorption (cf. Table 1). However, the color reactions provided additional specificity. 

In Tobacco. At the time of harvesting, fresh tobacco leaves do not contain measurable amounts of nitrosamines (<5 ppb). However, these compounds are formed during curing, aging and fermentation. Their concentrations depend primarily on the content of proteins, alkaloids, agricultural chemicals and nitrate in the tobacco, as well as on the processing conditions which lead to the reduction of the nitrates. 

Spectrophotometric and spectrofluorimetric methods provide a wealth of information concerning structural determinations (identification, purity and precise measurement of concentration) and chemical changes in alkaloids. These techniques yield both quantitative and qualitative data on the effect of solvents, pH and other physiological conditions [141-143]. X-ray crystallography, H and NMR spectroscopy, infrared spectroscopy (IR) and circular dichroic spectroscopy were also used to study the physical properties... 

Table II presents H-NMR data of the hasubanan alkaloids obtained since 1976. During the period 1976-1986, the application of H-NMR spectroscopy was accelerated together with the improvement of measuring instruments. NOE, INDOR, and two-dimensional NMR experiments (7) have been undertaken to resolve the question of stereochemistry at the chiral centers.

Results of liquid phase NMR measurements (Table 4) show that only the real substrates influences the proton shift of H3 and H9 protons of CD. These data confirmed the liquid phase interaction between the diketones and the chiral modifier. No effect of dummy substrates (ethyl acetate, acetone, etc.) was observed. No direct connection was found between kinetic data (reaction rate and optical yield) and NMR proton shift. Liquid phase NMR measurements confirmed the interaction of both 2,3-butandione and 3,4-hexanedione with the alkaloid used. 

The majority of the alkaloids we are searching for will convert to salts in the first extraction phase. The second and third extraction phases take place over a longer period of time. This will ensure that we will be able to extract as many alkaloids as possible from our material. The third phase can be reduced to 1-2 days but will not produce the best yields. Remember, these measurements are all crude estimates. 

Since the configuration at C-16 is undetermined, both quaternary alkaloids diploceline and 16-epidiploceline, isolated from the root bark of Strychnos goss-weileri Exell (54), could be represented by formula 50. The absolute configurations of the C-3 and C-15 have been determined by CD measurements, and the cis junction of C/D rings is supported by H-NMR data [8 4.58 (C3—H), 8 3.58 (N—CH3) for diploceline]. 

It has been shown that CD measurement is a proper tool to determine the absolute configuration of the C-3 stereo center in corynantheine and yohimbine alkaloids (300). The chiroptical properties of stereoisomeric yohimbanes and 17-ketoyohimbanes also have been studied. Cotton effects due to aromatic and ketone absorptions have been considered in terms of the appropriate sector and... 

Results and data gathered on mass spectroscopy of various indole alkaloids have been summarized by Hesse (320). The derivation of the characteristic fragments of indolo[2,3-a]quinolizidines has been interpreted by Gribble and Nelson (321), who investigated C-3, C-5, C-6, C-20, and C-21 deuterated derivatives of octahydroindolo[2,3-a]quinolizine (1). Kametani et al. have observed and proved, with labeled compounds, a methyl transfer from the ester function of reserpine derivatives to the basic nitrogen atom during mass-spectroscopic measurement (322). 

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