A comparative study of the IR spectra of alkaloids containing piperidine and quinolizidine rings in the 2500–2830 cm−1 region
Summary1. A comparative method of studying the conformational states of alkaloids of the piperidine and quinolizidine series by comparing the intensities of the IR bands in the 2500–2830 cm−1 region in the solid and liquid states has been proposed.2. It has been shown that the process of inversion and other labile conformational transformations affect the number, frequency, and intensity of the vibrational transitions in the “Bohlmann region.”
Correlation between the stereochemistry of quinolizidine alkaloids and their infrared spectra from 2840-2600 CM-1.
Abstract The IR spectra from 2840-2600 cm −1 of a number of sparteine type quinolizidine alkaloids and their selectively α-deuterated derivatives have been examined. It was shown that a single absorption band or band complex arises from the stretching vibrations of one or more axially oriented C α H bonds. The intensity and general complexity of this absorption is roughly proportional to the number of these trans -diaxial α hydrogens and their steric environment. The characteristic absorption in the 2840-2600 cm −1 region has been correlated with different conformations of quinolizidine ring fusions. Steric factors influencing this absorption in sparteine type alkaloids are discussed. An attempt has been made to rationalize the nature of the specific interaction of C α H(a) bonds with the lone electron pair on nitrogen in the compounds investigated.
Use of a specific antiserum for renin detection in human kidney.
The use of anti-human renin antibodies made possible the intrarenal localization of renin in human kidney by immunofluorescence. In normal kidney, only some juxtaglomerular apparatus (JGA) were fluorescent. In these JGA, granular or diffuse fluorescence was only seen in afferent arterioles and was not present in all cells. In the ischemic areas of partially infarcted kidney, fluorescence was seen in all JGA and in interlobular arteries. In these arteries the most eccentric cells were often the most positive. In the nonischemic areas of the same kidneys, fluorescence was not seen in JGA, but was observed in proximal tubular cells, suggesting the reabsorption of filtered renin at this site.