Scrodentoids F–I, four C19-norditerpenoids from Scrophularia dentata

A Comprehensive Review of the Classification, Sources, Phytochemistry, and Pharmacology of Norditerpenes

Norditerpenes are considered to be a common and widely studied class of bioactive compounds in plants, exhibiting a wide array of complex and diverse structural types and originating from various sources. Based on the number of carbons, norditerpenes can be categorized into C19, C18, C17, and C16 compounds. Up to now, 557 norditerpenes and their derivatives have been found in studies published between 2010 and 2023, distributed in 51 families and 132 species, with the largest number in Lamiaceae, Euphorbiaceae, and Cephalotaxaceae. These norditerpenes display versatile biological activities, including anti-tumor, anti-inflammatory, antimicrobial, and antioxidant properties, as well as inhibitory effects against HIV and α-glucosidase, and can be considered as an important source of treatment for a variety of diseases that had a high commercial value. This review provides a comprehensive summary of the plant sources, chemical structures, and biological activities of norditerpenes derived from natural sources, serving as a valuable reference for further research development and application in this field.

Natural Products Targeting Liver X Receptors or Farnesoid X Receptor

Nuclear receptors (NRs) are a superfamily of transcription factors induced by ligands and also function as integrators of hormonal and nutritional signals. Among NRs, the liver X receptors (LXRs) and farnesoid X receptor (FXR) have been of significance as targets for the treatment of metabolic syndrome-related diseases. In recent years, natural products targeting LXRs and FXR have received remarkable interests as a valuable source of novel ligands encompassing diverse chemical structures and bioactive properties. This review aims to survey natural products, originating from terrestrial plants and microorganisms, marine organisms, and marine-derived microorganisms, which could influence LXRs and FXR. In the recent two decades (2000-2020), 261 natural products were discovered from natural resources such as LXRs/FXR modulators, 109 agonists and 38 antagonists targeting LXRs, and 72 agonists and 55 antagonists targeting FXR. The docking evaluation of desired natural products targeted LXRs/FXR is finally discussed. This comprehensive overview will provide a reference for future study of novel LXRs and FXR agonists and antagonists to target human diseases, and attract an increasing number of professional scholars majoring in pharmacy and biology with more in-depth discussion.

Pushing the limits of concertedness. A waltz of wandering carbocations

Among the array of complex terpene-forming carbocation cyclization/rearrangement reactions, the so-called "triple shift" reactions are among the most unexpected. Such reactions involve the asynchronous combination of three 1,n-shifts into a concerted process, e.g., a 1,2-alkyl shift followed by a 1,3-hydride shift followed by a second 1,2-alkyl shift. This type of reaction so far has been proposed to occur during the biosynthesis of diterpenes and the sidechains of sterols. Here we describe efforts to push the limits of concertedness in this type of carbocation reaction by designing, and characterizing with quantum chemical computations, systems that could couple additional 1,n-shift events to a triple shift leading, in principle to quadruple, pentuple, etc. shifts. While our designs did not lead to clear-cut examples of quadruple, etc. shifts, they did lead to reactions with surprisingly flat energy surfaces where more than five chemical events connect reactants and plausible products. Ab initio molecular dynamics simulations demonstrate that the formal minima on these surfaces interchange on short timescales, both with each other and with additional unexpected structures, allowing us a glimpse into a very complex manifold that allows ready access to great structural diversity.

Hot off the press

A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as hitorin A from Chloranthus japonicus.

Diterpenoids of terrestrial origin

This review covers the isolation and chemistry of diterpenoids from terrestrial as opposed to marine sources and includes labdanes, clerodanes, abietanes, pimaranes, kauranes, cembranes and their cyclization products. The literature from January to December, 2016 is reviewed.