Structures of angrendiol, ferolin, and chimganidin
SummaryOn the basis of the results of a study of the products of chemical transformations and spectra, the structure of angrendiol has been established as 4,8-dihydroxygermacra-1(10), 5(6)-diene. It has been shown that ferolin and chimganidin are monoesters of angrendiol with parahydroxybenzoic and vanillic acids, respectively, at the secondary hydroxy group.
Terpenoids—L : Transformation products of costunolide
Abstract Costunolide, containing a ten-membered carbocyclic ring system with the unique distribution of double bonds, undergoes many interesting transformations. The diol prepared by lithium aluminium hydride reduction of costunolide when subjected to metal amine reduction gives a hydrocarbon, C15H26, a secondary alcohol, C15H26O, and a primary alcohol, C15H26O, and a primary alcohol, C15H26O to which structures, VIII, X and XII have been assigned on the basis of spectral data and their conversions to elemene-type products on pyrolysis and to mono-ethenoid bicyclic products on acid catalysed cyclization. The secondary alcohol X has been converted to d -junenol which constitutes a new synthesis of the alcohol from costunolide. Pyrolysis and acid catalysed cyclization of 12-methoxydihydrocostunolide have also been described.
The peculiar thermo-structural behavior of the anionic lipid DMPG.
Aqueous dispersions of the anionic phospholipid dimyristoyl phosphatidylglycerol (DMPG), around 100 mM ionic strength, are known to exhibit a thermal behavior similar to that of the largely studied lipid dimyristoyl phosphatidylcholine (DMPC), which undergoes a gel to liquid crystalline phase transition at 23 degrees C, well characterized by differential scanning calorimetry (DSC), and other methods. However, at low ionic strength, DMPG has been shown to present a large gel-fluid transition region, ranging from 18 to 35 degrees C. This intermediate phase is optically transparent and characterized by a continuous change in membrane packing. Structural properties of the DMPG gel-fluid transition region will be discussed, based on results obtained by several techniques: electron spin resonance (ESR) of spin labels at the membrane surface and intercalated at different depths in the bilayer; light scattering; DSC; small angle X-ray scattering (SAXS); and fluorescence spectroscopy of probes in the bilayer.