Fluorescent products and polyunsaturated fatty acids of human testes

Abstract

Lipid soluble fluorescent pigments from human testis were fractionated by silicic acid column chromatography and silica gel thin layer chromatography. Fluorescence analyses revealed a family of at least 3 compounds with similar fluorescence properties, including excitation and emission maxima, reversible fluorescence quenching by alkaline pH, and fluorescence quenching by heavy metal chelation. These fluorescence characteristics strongly indicated the presence of the conjugated Schiff base fluorophore-N=C-C=C-N-. The chromatographic separations employed enabled a more definitive fluorescence characterization of the lipid soluble pigments known to accumulate late in tissues with age and as a result of lipid peroxidation. Total lipids and fatty acid composition of the total lipids were determined. Polyenoic acids constituted about 40% of the total fatty acids. Histological examination of the tissues revealed some degeneration and edema, but significant spermatogenesis and normal complement of Leydig cells.

Independent Synthesis, Solution Behavior, and Studies on the Mechanism of Formation of a Primary Amine-Derived Fluorophore Representing Cross-linking of Proteins by (E)-4-Hydroxy-2-nonenal

“…Compounds 1 are fairly stable in acidic, neutral, and slightly basic conditions, but there is a gradual decrease in fluorescence intensity between pH 9.0 and 9.5 and an abrupt decrease between pH 9.5 and 10.0 (Figure ). This pH dependence resembled that of fluorescent pigments seen in aging as well as in the ceroid of atherosclerotic plaques. ,− The fluorescence intensity of 1 was totally quenched at pH ≥ 12. Rapid neutralization/acidification of base-exposed samples of 1 restored the ex/em 360/430 nm signature, though the extent to which this could be observed decreased both with increasing pH and the duration of base exposure prior to neutralization.…”

“…Interestingly, the 1:1 adducts 9a and 10 that are generated alongside 1 in the reaction of amines with 3,4-dioxononanal (Scheme 3) have the same core structure as other adducts formed between amines and proposed lipoxidation products 36,37 and generate fluorescence at a wavelength (ex/em 350/428 nm) (Figure B) similar to that of 1 . However, the fluorescence of these 1:1 adducts was stable at pH 10 but quenched in an acidic medium (pH ≤ 3.5) (Figure ), a trend opposite to that seen for 1 and age-related lipofuscin. ,− It is noteworthy that the fluorescence of 9a is also solvent-dependent. In contrast to the exclusive presence of the fluorescent form 9a in protic solvents such as methanol or water, the molecule exists in a nonfluorescent form in aprotic solvents, shown by 1 H NMR in CDCl 3 to be ring-opened tautomer 9b (Scheme ).…”

Isolation and analysis of age‐related fluorescent substances in rat testes

“…One might expect the fluorescent substances to contain a phosphate moiety inasmuch as in vivo lipid oxidation is generally believed to involve the polyunsaturated fatty acids of phospholipids. However, should these fluorescent substances undergo partial hydrolysis by lysosomal lipases, which is highly plausible, fluorescent residues that contain no phosphorous, as detected here, might be produced as suggested by Trombly et al (19). Moreover, the large number and complexity of fluorescent substances detected in mammalian tissue might well be explained on the basis of partial degradation of these substances by lysosomal enzymes.…”

“…No phosphorus was detected in the ARFS as observed in the main fraction of fluorescent substances isolated from testes by Trombly et al (19). Moreover, the excitation-emission maxima 355 and 490 nm of the ARFS was similar to this fraction which was isolated by silicic acid column chromatography.…”

Measurement of and Protection from in Vivo Lipid Peroxidation

“…Lipid-soluble fluorescent pigments from human testis were fractionated by silicic acid column chromatography and silica gel thin layer chromatog raphy [29]. Fluorescence analyses revealed a family of at least three compounds with similar fluorescence properties, including excitation and emission maxima, reversible fluorescence quenching by alkaline pH, and fluorescence quenching by heavy-metal chelation.…”