A simple one-step ultrasonic-assisted extraction and derivatization method coupling to high-performance liquid chromatographyfor the determination of ε-aminocaproic acid and amino acids in cosmetics.

Nowadays, the safety of cosmetics is a widespread concern. Amines are common cosmetic additives. Some of them such as amino acids are beneficial. Another kind of amines, however, ε-aminocaproic acid (EACA) is prohibited to add into cosmetics for its adverse reactions. In this study, a simple, rapid, sensitive and eco-friendly one-step ultrasonic-assisted extraction and derivatization (UAE-D) method was developed for determination of EACA and amino acids in cosmetics by coupling with high-performance liquid chromatography (HPLC). By using this sample preparation method, extraction and derivatization of EACA and amino acids were finished in one step in ultrasound field. During this procedure, 4-fluoro-7-nitrobenzofurazan (NBD-F)was applied as derivatization reagent. The extraction conditions including the amount of NBD-F, extraction and derivatization temperature, the ultrasonic vibration time and pH value of the aqueous phase were evaluated. Meanwhile, the extraction mechanism was investigated. Under optimized conditions, the method detection limits were 0.086-0.15 µg/L, and method quantitation limits were 0.29-0.47 µg/L with RSDs less than 3.7% (n = 3). The recoveries of EACA and amino acids obtained from cosmetic samples were in range from 76.9% to 122.3%. Amino acids were found in all selected samples and quantified in range from 1.9 ±â€¯0.9 to 677.2 ±â€¯17.9 µg/kg. And EACA was found and quantified with the contents of 1284.3 ±â€¯22.1 µg/kg in a toner sample. This UAE-D-HPLC method shortened and simplified the sample pretreatment as well as enhanced the sensitivity of analytical method. In our record, only 10 min was needed for the total sample preparation process. And the method detection limits were two orders of magnitude less than literature reports. Furthermore, we reduced the consumption of solvent and minimized the usage of organic solvents, which made our method moving towards green analytical chemistry. In brief, our UAE-D-HPLC method is a simple, rapid, sensitive and eco-friendly analytical method for the determination of EACA and amino acids in cosmetics.

Conditions for the formation of dilysyl-dipyrrolones A and B, and novel yellow dipyrrolone derivatives formed from xylose and amino acids in the presence of lysine.

Foods derived from plants contain pentose in addition to hexose. It is well known that pentose contributes more to browning by the Maillard reaction than hexose does. We have recently found novel yellow compounds formed from xylose and lysine under weakly acidic conditions, named dilysyldipyrrolones (dilysyl-DPLs) A and B. We indicate in this study that dilysyl-DPLs were specifically formed under weakly acidic conditions from pentose, but not hexose. Moreover, we found novel DPL derivatives which were formed from xylose and such amino acids as alanine, arginine, aspartic acid, glutamic acid, isoleucine, leucine, phenylalanine, serine, and valine in the presence of lysine.

Biotinylated derivative of a human brain lectin: synthesis and use in affinoblotting for endogenous ligand studies.

Coupling of biotin to an endogenous lectin yields a probe which can be used for selective nonradioactive detection of complementary endogenous ligands. To exemplify practical applications of this type of compounds, we have synthesized and characterized a biotinylated derivative of a beta-galactoside-specific human brain lectin. Proteins which bind this lectin can be located on nitrocellulose sheets after electrophoretic transfer from gradient polyacrylamide gels, by sequential incubation with biotinylated probes and streptavidin-peroxidase, with visualization by an insoluble reaction product (affinoblotting). Biotinylated galactoside-binding plant lectins were used in the same way to visualize human brain glycoproteins, and their binding specificity was compared with that of human brain lectin. The results obtained by means of these different probes showed the usefulness of the endogenous lectin derivative to actually identify its endogenous partners. Thus this approach may find extended applications in the study of biological activities of vertebrate lectins in homologous systems, i.e., with lectins and ligands coming from the same tissue origin.