Title: Dihydrolipoyl dioleoylglycerol antioxidant capacity in phospholipid vesicles Authors
Submitted to: Chemistry and Physics of Lipids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 8, 2011
Publication Date: January 1, 2012
Repository URL: http://handle.nal.usda.gov/10113/53995
Citation: Laszlo, J.A., Evans, K.O., Compton, D.L., Appell, M.D. 2012. Dihydrolipoyl dioleoylglycerol antioxidant capacity in phospholipid vesicles. Chemistry and Physics of Lipids. 165:160-168. Interpretive Summary: A new vegetable oil derivative was found to have good antioxidant properties, which demonstrates that this material may have a positive influence on maintaining the health of cellular tissues. The newly developed lipoyl dioleoylglycerol molecule is a skin care product made from vegetable oil with the potential for delivering protective and energizing activities for improved facial skin health and appearance. In the present research we investigated how this molecule may perform on a molecular level. We observed that this molecule works well to stop the adverse chemical events that can lead to the destruction of vital structures in living cells. It readily incorporates into model cellular membranes and is able to prevent oxidative damage to these highly susceptible structures. These findings provide researchers with an enhanced understanding of how such molecules may promote dermal care.
Technical Abstract: Antioxidants have critical roles in maintaining cellular homeostasis and disease-state prevention. The multi-functional agent alpha-lipoic acid offers numerous beneficial effects to oxidatively stressed tissues. alpha-Lipoic acid was enzymatically incorporated into a triglyceride in conjunction with oleic acid, creating lipoyl dioleoylglycerol, and chemically reduced to form dihydrolipoyl dioleoylglycerol. The triglyceride forms of lipoic acid highly stabilized dioleoylphosphatidylcholine unilamellar liposomal vesicles, as judged by calcein–cobalt leakage rates. Stabilization resulted from increased packing density of phospholipid acyl chains. alpha-Lipoic acid did not influence vesicle stability. Scavenging activity against the 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) radical was monitored by oxidation of 4,4-difluoro-5-(4-phenyl-1,3-butadienyl)-4-bora-3a,4a-diaza-s-indacene-3-undecanoic acid (C11-Bodipy). Dihydrolipoyl dioleoylglycerol in vesicles demonstrated strong antioxidant capacity in comparison to the conventional Trolox standard. Fluorescence quenching measurements indicated the lipoyl moiety of dihydrolipoyl dioleoylglycerol is positioned near the vesicle aqueous/lipid boundary. Molecular modeling of lipoyl dioleoylglycerol and dihydrolipoyl dioleoylglycerol in a phospholipid layer confirmed the existence of an extended configuration for the molecules that accounts for the interfacial location of the lipoyl moiety, which may allow the antioxidant to readily react with adsorbing radical species.