[Applications and perspectives of ketone body D-ß-hydroxybutyrate in the medical fields].

Human body can obtain energy from either carbohydrate or fat digestion. Although glucose metabolism derived from carbohydrate-based diets has long been utilized for energy supply, it has been recently discovered that shifting from glucose to fatty acid metabolism may become a novel way for improving human health especially when carbohydrate is deprived. In recent years, intermittent fasting and ketogenic diets have received a lot of attention in respect to favoring fatty acid metabolism. In all cases, fatty acid metabolism produces D-ß-hydroxybutyrate (D3HB), which is a natural ketone body, as well as, a monomer of microbial poly-D-ß-hydroxybutyrate (PHB). D3HB can be utilized by different cells of the body as an alternative energy fuel or an intracellular signaling molecule with multiple downstream signaling pathways. Usually, the serum level of D3HB is increased during ketogenic diets, however, requires a very long period of adaptation (over 3-months) and exhibits unwanted adverse effects. Hence, exogenous ketone supplements using D3HB have become a more effective approach to induce and maintain nutritional ketosis for subsequent functional effects. This review describes how D3HB is produced and metabolized within the body, the functional roles played by D3HB, and a detailed summary of the different applications of exogenous ketones that have been explored to date in both nutritional and therapeutical context.

On the nutritional and therapeutic effects of ketone body D-ß-hydroxybutyrate.

D-ß-hydroxybutyrate (D-3HB), a monomer of microbial polyhydroxybutyrate (PHB), is also a natural ketone body produced during carbohydrate deprivation to provide energy to the body cells, heart, and brain. In recent years, increasing evidence demonstrates that D-3HB can induce pleiotropic effects on the human body which are highly beneficial for improving physical and metabolic health. Conventional ketogenic diet (KD) or exogenous ketone salts (KS) and esters (KE) have been used to increase serum D-3HB level. However, strict adaptation to the KD was often associated with poor patient compliance, while the ingestion of KS caused gastrointestinal distresses due to excessive consumption of minerals. As for ingestion of KE, subsequent degradation is required before releasing D-3HB for absorption, making these methods somewhat inferior. This review provides novel insights into a biologically synthesized D-3HB (D-3-hydroxybutyric acid) which can induce a faster increase in plasma D-3HB compared to the use of KD, KS, or KE. It also emphasizes on the most recent applications of D-3HB in different fields, including its use in improving exercise performance and in treating metabolic or age-related diseases. Ketones may become a fourth micro-nutrient that is necessary to the human body along with carbohydrates, proteins, and fats. Indeed, D-3HB being a small molecule with multiple signaling pathways within the body exhibits paramount importance in mitigating metabolic and age-related diseases. Nevertheless, specific dose-response relationships and safety margins of using D-3HB remain to be elucidated with more research. KEY POINTS: • D-3HB induces pleiotropic effects on physical and metabolic health. • Exogenous ketone supplements are more effective than ketogenic diet. • d-3HB as a ketone supplement has long-term healthy impact.

[Application perspectives of polyhydroxyalkanoates].

Polyhydroxyalkanoates are polyesters of hydroxyalkanoates synthesized by many bacteria and haloarchaea as carbon and energy storage materials. There are more than 150 types of polyhydroxyalkanoate monomers reported, resulting in a variety of Polyhydroxyalkanoates with diverse properties. The material variability, nonlinear optical properties, piezoelectric properties, gas barrier properties, thermoplasticity, biodegradability, and biocompatibility allow polyhydroxyalkanoates to be used for plastic packaging, chiral chemicals generation, medicine, agriculture and bio-energy fields. This review introduces the current applications and future development of polyhydroxyalkanoates.