Using Resonance Raman microspectrometry we identify polyenes as shell pigments in 13 gastropod, 1 cephalopod and 4 bivalve taxa. The pigments are either isolated polyenes or polyenes bound to other molecules. Polyenes are present in coloured parts of the shell of all investigated taxa. Pigments differ between taxa and there is no trivial relationship between colour, pigment and taxon. The same ...

Recent studies demonstrate that the actual interactions of polyenes with membrane sterols are the basis for their antimycotic toxicity and not, as previously assumed, their potential to form pores. Therefore, sterols must play a vital role in membranes and this function is seriously disturbed once polyenes bind to and/or sequester them. Essential membrane proteins obviously require sterols for ...

Amphotericin B and N-D-ornithyl amphotericin B methyl ester were compared for therapeutic efficacies against experimentally induced cryptococcal meningitis and Candida albicans endocarditis with pyelonephritis in rabbits. Antifungal activity of the two polyenes in vitro was similar for the yeasts used in these experiments. N-D-ornithyl amphotericin B methyl ester gave a slightly higher concentr...

Skipped polyenes (that is, 1,4-dienes and higher homologues) are stereodefined components of a vast array of biologically important natural products, including polyunsaturated fatty acids. Although widespread in nature, these architectures are generally considered to represent significant barriers to efficient chemical synthesis. Partial reduction of skipped poly-ynes provides a pathway to a su...

The room temperature absorption and emission spectra of the 4-cis and all-trans isomers of 2,4,6,8,10,12,14-hexadecaheptaene are almost identical, exhibiting the characteristic dual emissions S1-->S0 (21Ag- --> 11Ag-) and S2-->S0 (11Bu+ --> 11Ag-) noted in previous studies of intermediate length polyenes and carotenoids. The ratio of the S1-->S0 and S2-->S0 emission yields for the cis isomer in...

Since the low energy absorption spectrum of a linear polyene is dominated by the strongly allowed 1 Ag→1 Bu transition ~S0 to S2!, it can be reconstructed for any chain length if the 0–0 band excitation energy, the band profile, and intensity are known. From this premise, this paper uses information developed in high resolution experiments on well-defined linear polyenes to extract the distribu...

The en masse cyclization of polyolefins into polycyclic terpenoids by cyclase enzymes (e.g. squalene to hopene), is a biosynthetic reaction of particular fascination to chemists. Noteworthy recent additions to synthetic mimics of the cyclase enzymes are asymmetric methods that include Brønsted–Lewis acids (BLA), masked equivalents of Br and I, organocatalysts, and electrophilic metal catalysts....