Native Mass Spectrometric Insights into the Formation and Stability of DNA Triplexes.

Deoxyribonucleic acid is a genetic biomacromolecule that contains the inherited information required to build and maintain a living organism. While the canonical duplex DNA structure is rigorously characterized, the structure and function of higher order DNA structures such as DNA triplexes are comparatively poorly understood. Previous literature has shown that these triplexes can form under physiological conditions, and native mass spectrometry offers a useful platform to study their formation and stability. However, experimental conditions including buffer salt concentration, pH, and instrumentation parameters such as ion mode can confound analysis by impacting the amount of triplex observed by mass spectrometry. Using model 30mer Y-type triplex sequences, we demonstrate the influence a range of experimental variables have on the detection of DNA triplex structures, informing suitable conditions for the study. When carefully considered conditions are used, mass spectrometry offers a powerful complementary tool for the analysis of higher order DNA assemblies.

Ecklonia radiata extract containing eckol protects neuronal cells against Aß1-42 evoked toxicity and reduces aggregate density.

Brown seaweed (Phaeophyceae) polyphenolics such as phlorotannins are ascribed various biological activities, including neuroprotection. Of these seaweeds, Ecklonia radiata (E. radiata) is found abundantly along South Australian coastal regions; however it has not been explored for various biological activities relative to any component phlorotannins previously ascribed neuroprotective capacity. In the present study, we evaluated neuroprotective activity against the neurotoxic amyloid ß protein (Aß1-42) of an ethanol extract of E. radiata compared with various additional solvent-solubilised fractions in a neuronal PC-12 cell line. The ethyl acetate fraction comprising 62% phlorotannins demonstrated the most efficacious neuroprotective activity, inhibiting neurotoxicity at all Aß1-42 concentrations. In addition, this fraction demonstrated a significant reduction in Aß aggregate density, but did not alter overall aggregate morphology. Centrifugal partitioning chromatography was used to isolate the major component, eckol, in high yield and liquid chromatography-mass spectrometry was used to characterize the major components of the ethyl acetate fraction. Our results demonstrate that the prevalence of eckol-type phlorotannins are associated with neuroprotective bioactivity of E. radiata, suggestive of potential nutraceutical and biopharmaceutical uses of this brown seaweed phlorotannin in dementia.