Solution Chemistry of Dihydroxyacetone and Synthesis of Monomeric Dihydroxyacetone

Precision-cut liver slices as an ex vivo model to assess impaired hepatic glucose production

Fasting hypoglycemia is a severe and incompletely understood symptom of various inborn errors of metabolism (IEM). Precision-cut liver slices (PCLS) represent a promising model for studying glucose production ex vivo. This study quantified the net glucose production of human and murine PCLS in the presence of different gluconeogenic precursors. Dihydroxyacetone-supplemented slices from the fed mice yielded the highest rate, further stimulated by forskolin and dibutyryl-cAMP. Moreover, using 13C isotope tracing, we assessed the contribution of glycogenolysis and gluconeogenesis to net glucose production over time. Pharmacological inhibition of the glucose 6-phosphate transporter SLC37A4 markedly reduced net glucose production and increased lactate secretion and glycogen storage, while glucose production was completely abolished in PCLS from glycogen storage disease type Ia and Ib patients. In conclusion, this study identifies PCLS as an effective ex vivo model to study hepatic glucose production and opens opportunities for its future application in IEM research and beyond.

A tipping point in dihydroxyacetone exposure: mitochondrial stress and metabolic reprogramming alter survival in rat cardiomyocytes H9c2 cells

Exogenous exposures to the triose sugar dihydroxyacetone (DHA) occur from sunless tanning products and electronic cigarette aerosol. Once inhaled or absorbed, DHA enters cells, is converted to dihydroxyacetone phosphate (DHAP), and incorporated into several metabolic pathways. Cytotoxic effects of DHA vary across the cell types depending on the metabolic needs of the cells, and differences in the generation of reactive oxygen species (ROS), cell cycle arrest, and mitochondrial dysfunction have been reported. We have shown that cytotoxic doses of DHA induced metabolic imbalances in glycolysis and oxidative phosphorylation in liver and kidney cell models. Here, we examine the dose-dependent effects of DHA on the rat cardiomyocyte cell line, H9c2. Cells begin to experience cytotoxic effects at low millimolar doses, but an increase in cell survival was observed at 2 mM DHA. We confirmed that 2 mM DHA increased cell survival compared to the low cytotoxic 1 mM dose and investigated the metabolic differences between these two low DHA doses. Exposure to 1 mM DHA showed changes in the cell's fuel utilization, mitochondrial reactive oxygen species (ROS), and transient changes in the glycolysis and mitochondrial energetics, which normalized 24 h after exposure. The 2 mM dose induced robust changes in mitochondrial flux through acetyl CoA and elevated expression of fatty acid synthase. Distinct from the 1 mM dose, the 2 mM exposure increased mitochondrial ROS and NAD(P)H levels, and sustained changes in LDHA/LDHB and acetyl CoA-associated enzymes were observed. Although the cells were exposed to low cytotoxic (1 mM) and non-cytotoxic (2 mM) acute doses of DHA, significant changes in mitochondrial metabolic pathways occurred. Further, the proliferation increase at the acute 2 mM DHA dose suggests a metabolic adaption occurred with sustained consequences in survival and proliferation. With increased exogenous exposure to DHA through e-cigarette aerosol, this work suggests cell metabolic changes induced by acute or potentially chronic exposures could impact cell function and survival.

Dihydroxyacetone: A User Guide for a Challenging Bio-Based Synthon

1,3-dihydroxyacetone (DHA) is an underrated bio-based synthon, with a broad range of reactivities. It is produced for the revalorization of glycerol, a major side-product of the growing biodiesel industry. The overwhelming majority of DHA produced worldwide is intended for application as a self-tanning agent in cosmetic formulations. This review provides an overview of the discovery, physical and chemical properties of DHA, and of its industrial production routes from glycerol. Microbial fermentation is the only industrial-scaled route but advances in electrooxidation and aerobic oxidation are also reported. This review focuses on the plurality of reactivities of DHA to help chemists interested in bio-based building blocks see the potential of DHA for this application. The handling of DHA is delicate as it can undergo dimerization as well as isomerization reactions in aqueous solutions at room temperature. DHA can also be involved in further side-reactions, yielding original side-products, as well as compounds of interest. If this peculiar reactivity was harnessed, DHA could help address current sustainability challenges encountered in the synthesis of speciality polymers, ranging from biocompatible polymers to innovative polymers with cutting-edge properties and improved biodegradability.