Meroapplanins A–E: Five Meroterpenoids with a 2,3,4,5-Tetrahydropyridine Motif from Ganoderma applanatum

A General Entry to Ganoderma Meroterpenoids: Synthesis of Applanatumol E, H, and I, Lingzhilactone B, Meroapplanin B, and Lingzhiol

Ganoderma meroterpenoids are fungal derived hybrid natural product class containing a 1,2,4-trisubstituted benzene ring and a polycyclic terpenoid part. The representatives applanatumol E, H and I, lingzhilactone B, and meroapplanin B share the same bicyclic lactone moiety connected to the arene. Employing photo-Fries rearrangements as the key step enabled a general entry to these natural products. For the synthesis of the tetracyclic framework of lingzhiol, we made use of a powerful photoredox oxidative decarboxylation/Friedel-Crafts sequence.

Insights into Ganoderma fungi meroterpenoids opening a new era of racemic natural products in mushrooms

Ganoderma meroterpenoids (GMs) containing 688 structures to date were discovered to have multiple remarkable biological activities. 65.6% of meroterpenoids featuring stereogenic centers from Ganoderma species are racemates. Further, GMs from different Ganoderma species seem to have their own characteristics. In this review, a comprehensive summarization of GMs since 2000 is presented, including GM structures, structure corrections, biological activities, physicochemical properties, total synthesis, and proposed biosynthetic pathways. Additionally, we especially discuss the racemic nature, species-related structural distribution, and structure-activity relationship of GMs, which will provide a likely in-house database and shed light on future studies on GMs.

The Artist's Conk Medicinal Mushroom Ganoderma applanatum (Agaricomycetes): Mycological, Mycochemical, and Pharmacological Properties: A Review

As a commonly used Chinese herbal medicine, Ganoderma applanatum (Pers.) Pat., also known as flat-ling Ganoderma (Chinese name bianlingzhi), old mother fungus (laomujun), and old ox liver (laoniugan), has high medicinal value. It is used as an anti-cancer drug in China and Japan. Besides, it can treat rheumatic tuberculosis and has the effect of relieving pain, clearing away heat, eliminating accumulation, stopping bleeding and eliminating phlegm. The purpose of this review is to analyze the research progress systematically and comprehensively in mycology, mycochemistry and pharmacological activities of G. applanatum, and discuss the prospect of prospective research and implementation of this medicinal material. A comprehensive literature search was performed on G. applanatum using scientific databases including Web of Science, PubMed, Google Scholar, CNKI, Elsevier. Collected data from different sources was comprehensively summarized for mycology, mycochemistry and pharmacology of G. applanatum. A total of 324 compounds were recorded, the main components of which were triterpenoids, meroterpenoids, steroids, and polysaccharides. G. applanatum and its active ingredients have a variety of pharmacological effects, including anti-tumor, liver protection, hypoglycemic, anti-fat, anti-oxidation, antibacterial and other activities. Although G. applanatum is widely used in traditional medicine and has diverse chemical constituents, more studies should be carried out in animals and humans to evaluate the cellular and molecular mechanisms involved in its biological activity.

Structural diversity, hypothetical biosynthesis, chemical synthesis, and biological activity of Ganoderma meroterpenoids

Covering: 2018 to 2022Meroterpenoids found in fungal species of the genus Ganoderma and known as Ganoderma meroterpenoids (GMs) are substances composed of a 1,2,4-trisubstituted benzene and a polyunsaturated side chain. These substances have attracted the attention of chemists and pharmacologists due to their diverse structures and significant bioactivity. In this review, we present the structures and possible biosynthesis of representative GMs newly found from 2018 to 2022, as well as chemical synthesis and biological activity of some interesting GMs. We propose for the first time a plausible biosynthetic pathway for GMs, which will certainly motivate further research on the biosynthetic pathway in Ganoderma species, as well as on chemical synthesis of GMs as important bioactive compounds for the purpose of drug development.

NMR Assignments of Six Asymmetrical N-Nitrosamine Isomers Determined in an Active Pharmaceutical Ingredient by DFT Calculations

N-nitrosamines, which are well-known pro-mutagens, are found in drugs, pickled food and tobacco. Therefore, controlling their concentrations is very important. When an HPLC, GC or NMR analysis is conducted to investigate certain asymmetrical N-nitrosamines, two sets of signals attributed to the asymmetric N-nitrosamine isomers are usually observed. However, few reports on the NMR assignment of asymmetrical N-nitrosamine isomers have been published. In this study, we investigated the NMR assignments of the Z/E isomers of six asymmetrical N-nitrosamines by means of density functional theory (DFT) calculations. The configuration of the major isomer of asymmetrical N-nitrosamine 3 was the Z-configuration. The configuration of the major isomers of asymmetrical N-nitrosamines 4–7 was the E-configuration. Then, we determined the Z/E ratios of these asymmetrical N-nitrosamines by means of variable temperature (VT) and room temperature (RT) ¹H-NMR experiments. The ratios of the Z/E isomer 3 quickly increased beyond 100% in the VT ¹H NMR experiments. The ratios of Z/E isomers 4–7 were increased in the range of 10–60% in the VT ¹H NMR experiments. The results of this study indicate that identifying the isomers of asymmetrical N-nitrosamine is necessary to control the quality of N-nitrosamines for active pharmaceutical ingredients (APIs).

A critical review on the use of DP4+ in the structural elucidation of natural products: the good, the bad and the ugly. A practical guide

Covering: 2015 up to the end of 2020Even in the golden age of NMR, the number of natural products being incorrectly assigned is becoming larger every day. The use of quantum NMR calculations coupled with sophisticated data analysis provides ideal complementary tools to facilitate the elucidation process in challenging cases. Among the current computational methodologies to perform this task, the DP4+ probability is a popular and widely used method. This updated version of Goodman's DP4 synergistically combines NMR calculations at higher levels of theory with the Bayesian analysis of both scaled and unscaled data. Since its publication in late 2015, the use of DP4+ to solve controversial natural products has substantially grown, with several predictions being confirmed by total synthesis. To date, the structures of more than 200 natural products were determined with the aid of DP4+. However, all that glitters is not gold. Besides its intrinsic limitations, on many occasions it has been improperly used with potentially important consequences on the quality of the assignment. Herein we present a critical revision on how the scientific community has been using DP4+, exploring the strengths of the method and how to obtain optimal results from it. We also analyze the weaknesses of DP4+, and the paths to by-pass them to maximize the confidence in the structural elucidation.

Applanmerotic acids A and B, two meroterpenoid dimers with an unprecedented polycyclic skeleton from Ganoderma applanatum that inhibit formyl peptide receptor 2

Applanmerotic acids A and B (1 and 2) with a polycyclic skeleton isolated from Ganoderma applantum showed anti-inflammatory activity via inhibiting the activation of FPR2.

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 baphicacanthcusine A from Baphicacanthus cusia.