Prabir K. Choudhury

Generation of Fluorescent Adducts of Malondialdehyde and Amino Acids: Toward an Understanding of Lipofuscin¶

Lipofuscin is a yellow‐brown, highly fluorescent pigment that undergoes an age‐related progressive accumulation in animal cells, mainly in postmitotic cells. It is a heterogeneous, high‐molecular weight material associated with proteins, lipids and nucleic acids. Lipofuscin is implicated in many aspects of human health, including aging, oxidative stress, macular degeneration, lipid peroxidation, atherosclerosis, dementia (Alzheimers Disease) and diseases associated with prions. Although the fluorescent properties of lipofuscin have long been recognized, neither histologists nor chemists have yet isolated the pigments themselves or characterized their optical properties. We have prepared lipofuscinlike species by reacting malondialdehyde (MDA) with cysteine (Cys). MDA: Cys adducts 3:2 and 2:2 are two of those that have been identified among the many that were present in the reaction. Whereas previous attempts to synthesize lipofuscinlike species resulted in compounds that were either nonfluorescent or emitted principally in the blue, the MDA: Cys adducts reported in this study are not only fluorescent but also emit over a broader range.

Identification of a Vibrational Frequency Corresponding to H‐atom Translocation in Hypericin¶

Using time‐resolved infrared spectroscopy, ab initio quantum mechanical calculations and synthetic organic chemistry a region in the infrared spectrum of triplet hypericin has been found between 1400 and 1500 cm−1 corresponding to the translocation of the hydrogen atom between the enol and the keto oxygens, O···H···O. This result is discussed in the context of the photophysics of hypericin and of eventual measurements to observe directly the excited‐state H‐atom transfer.

A synthesis of racemic deliquinone

Abstract A ten-step synthesis of deliquinone is described. A key step in the synthesis is a persulfate-mediated radical addition to a quinone.