Total Synthesis of Two Diastereomers of Megastigmane Glycoside Lauroside B

C13-Norisoprenoid megastigmanes: Biosynthesis, classification, natural sources, biological activities, and structure-activity relationship - A comprehensive review

C13-Norisoprenoid megastigmanes are a currently expanding class of secondary metabolites originating from the oxidative degradation of carotenoids such as lutein and neoxanthin. These metabolites have been isolated either in free, glycosidically bound forms or as acylated derivatives from a wide diversity of the plant kingdom. The classification of megastigmanes depends on the diversity of the oxygenation positions and the biogenetic origin. These compounds play a crucial role in imparting wine with its characteristic variant flavors, and they are potentially important flavoring agents for the food and pharmaceutical industries. Striking examples for the class are the unusually potent fragrances β-ionone, β-damascenone, and megastigmatrienone. The literature highlighted several compounds that need further development and optimization for drug discovery programs of hepatoprotective, anti-inflammatory, antioxidant, cytotoxic, anti-melanogenic, and cholesterol and triglycerides metabolism-promoting drugs. This comprehensive review focuses on classification, biosynthesis, distribution in natural sources, and chemical structures, the studied biological activities, as well as the structure-activity relationship of the new natural C13-norisoprenoid megastigmanes. A total of 800 C13-norisoprenoid megastigmanes were covered from the first reported isolation of megastigmanes up to December 2024 and 355 references are cited.

ANALYSIS OF CARBOHYDRATES AND GLYCOCONJUGATES BY MATRIX-ASSISTED LASER DESORPTION/IONIZATION MASS SPECTROMETRY: AN UPDATE FOR 2015-2016

This review is the ninth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2016. Also included are papers that describe methods appropriate to analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation and arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals. Much of this material is presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions and applications to chemical synthesis. The reported work shows increasing use of combined new techniques such as ion mobility and the enormous impact that MALDI imaging is having. MALDI, although invented over 30 years ago is still an ideal technique for carbohydrate analysis and advancements in the technique and range of applications show no sign of deminishing. © 2020 Wiley Periodicals, Inc.