Strategic design, theoretical insights, synthesis, and unveiling antioxidant potential in a novel ascorbic acid analog

CONTEXT

In this study, we investigated the antioxidant potential of a novel ascorbic acid analog, DsD, assessing its interactions with the methylperoxyl (CH3OO·) radical in aqueous and lipid environments. Our focus was on understanding the acid-base equilibrium and how pH affects DsD's primary reaction mechanisms. Our findings indicate a marked preference for hydrogen atom transfer in lipid media, contrasting with sequential proton loss electron transfer (SPLET) in aqueous solutions. Remarkably, DsD's radical scavenging activity significantly outperforms ascorbic acid, being 4.05 and 9469.70 times more potent in polar and lipid contexts, respectively. This suggests DsD's superior efficacy as an antioxidant, potentially offering enhanced protection in biological systems. Additionally, we have demonstrated DsD's synthetic feasibility through a straightforward condensation reaction between ascorbic acid and 1,2-diaminoethane, followed by comprehensive physicochemical and spectroscopic characterization.

METHODS

All computational analyses in this study were conducted using the Gaussian 09 software suite, employing the M05-2X functional and the 6-31 + G(d) basis set. Enthalpy calculations were executed under standard conditions (298.15 K and 1 atm), incorporating appropriate thermodynamic corrections. Rate constants were evaluated using transition state theory (TST), and the overall assessment of radical scavenging activity was guided by the Quantum Mechanics-based Test for Overall Radical Scavenging Activity (QMORSA) protocol.

Repair of trabecular fatigue fractures. Cadaver studies of the upper femur

The healing process and the distribution of trabecular fatigue fractures were studied on upper femora obtained at autopsy. Macroscopically, two main types of trabecular fatigue fractures were found on the basis of callus formation that in histologic sections were composed of woven and lamellar bone. A third type characterized by its vestigial callus was found only in histologic sections. Fatigue fractures were more numerous in regions of the femoral head submitted mainly to compressive rather than tensile stress. Trabeculae submitted to compressive stress had a majority of the type of fatigue fractures with an exuberant thorny callus composed of woven bone (most of them located subjacent to the subchondral bone plate), whereas trabeculae submitted mainly to tension or to minimal stress, as in Ward's triangle, had a majority of fatigue fractures with a small, smooth-surfaced callus composed of lamellar bone.