Proanthocyanidins are found in a wide range of foods, such as fruits, tree nuts, cereals, legumes, wine, and chocolate. They affect nutritional value, appearance, taste, and texture of these foods and can promote the better health by preventing cardiovascular diseases, cancers, urinary tract infections, and other aging-related metabolic complications. However, their health benefits in vivo may be limited as they are recognized as xenobiotics by human body. The bioavailability of proanthocyanidin proanthocyanidins is largely influenced by their degree of polymerization. Monomers could be rapidly absorbed from the upper portion of small intestine and reach a peak concentration in the plasma within 2 h after intake of proanthocyanidin-rich foods. The quantity consumed affects their metabolic fate of monomers. The absorption rate of proanthocyanidin dimers is only 5-10% of that of monomeric proanthocyanidins. Their metabolism might be of minor importance. (-)-epicatechin. Trimers and tetramers had lower absorption rates than dimers. Absorbed intact dimers, trimers, and tetramers undergo limited phase II metabolism in the intestine and liver in rats compared with (-)-epicatechin. Proanthocyanidins with a high degree of polymerization (>4over 4 (DP>4) are not absorbable because of their large molecular size which limits their absorption through and gut barrier. Therefore, the Depolymerization of proanthocyanidins in the gastrointestinal tract was negligible. The majority of proanthocyanidins reachreaches the colon intact. Proanthocyanidinscan beand is degraded into Phenylvalerolactonesphenylvalerolactones and several phenolic acids by human colon microbiota. The These microbial metabolites of proanthocyanidins are smaller molecules and are generally better absorbed in the gut. However, the biologicalmay contribute to the health promoting properties of the microbial metabolites are believed to be less active than their parental compounds. This review will summarize the literatures on proanthocyanidins within vivo. Future research of proanthocyanidin bioavailability will likely focus on the absorption andidentification of new microbial metabolism ofmetabolites and investigation of how proanthocyanidins influence human health by affecting the composition of human gut microbiota.
Interest in the tribological performance of ionic liquids (ILs) has increased significantly since they were first introduced as lubricants in 2001. The primaryMain advantages of ILs over conventional lubricants lie in their better ability to form a tribofilm, higher thermal stability, less harm to environmental friendliness, and better adaptabilitytion to various applications. Remarkable reduction of friction and wear reduction is has been observed afterwith the addition of ILs in oil- or water- based media, suggesting that ILs are promising candidate materials It indicates that ILs are premising as neat lubricants as well as lubricant additives. Even though massive Despite the relatively common utilization applications of ILs as lubricating media their wider use is limited by have shortcomings such as being their high cost and corrosive properties. Yet ILs are among the-mest premising candidates as next generatien lubricants. This review paper provides a brief introduction to relevant IL structures and properties, focusing on recent applications of the materials of ILs with fecus on their recent applications in engineering tribology. Due to the considerable efforts of many previous researchers, ILs have been widely accepted as effective, environmentally friendly lubricants/or lubricant additives. In recent years, chemists have synthesized a variety of new various new ILss while engineersing have systematically scientists evaluated their lubrication performance and generated novel types of lubricants with desired properties for specific applications. The collaborative work of the researchers worldwide have successfully promoted the development and utilization of ionic lubricants in a wide array of industrial fields. In this paperarticle, the advances made in IL investigating lubricating performance and of ILs and inexploration ofing their potential applications as lubricating media are will be reviewed and discussed at length.
