Cyclic diarylheptanoids from Myrica javanica: isolation, transformation, and bioactivity evaluation

Three cyclic diarylheptanoids, myricanol (1), myricanone (2), and porson (3), were isolated from Myrica javanica (Myricaceae). As a major component, myricanol (1) was obtained from dry powdered bark and twigs (up to 1.6%). Transformation of myricanol (1) afforded 5-prenylmyricanol (4) and 5-benzylmyricanol (5) in 84.5% and 65% yields, respectively. The bioactivities of the isolated cyclic diarylheptanoids and their derivatives were investigated to determine their cytotoxicity and DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging activities. The cytotoxicity assay against murine leukaemia P-388 cells demonstrated that compounds 4 and 5 showed an almost two-fold increase in the activity of their parent molecule (1), with an IC50 value of 12 µM. Furthermore, the free radical scavenging assay showed that myricanol (1) had the highest radical scavenging activity, revealing the importance of the free phenolic group (IC50 39.3 µM).

Recent Advances in the Synthesis of Diarylheptanoids

In the quest for synthesizing biologically important natural products, medicinal chemists embark on an endless journey. This review focuses on the reports published towards the syntheses of diarylheptanoids, classifying them into linear, tetrahydropyran, diarylether, and biphenyl categories. The synthesis methods for each class from 2013 to 2023 are discussed, providing a comprehensive overview of the advancements in the field. Representative natural product examples are highlighted for each category. The review emphasizes the importance of diarylheptanoids in the realms of chemistry and medicine, showcasing their potential as valuable compounds for medicinal and synthetic chemists.

Access to 12-Membered Cyclic ortho,meta-Diarylheptanoids: Total Synthesis of Actinidione via Isomyricanone

We describe herein the first access to 12-membered cyclic[7,0]ortho,meta-diarylheptanoids. The key features of the synthesis include both a Suzuki-Miyaura coupling and a ring closing metathesis. Actinidione, a promising natural product, along with a bioactive tetracyclic derivative were obtained in 14 steps for the first time from cheap commercially available substrates with an overall yield of 18-21%. Our modus operandi complies with the principles of the synthesis ideality by using notably strategic reactions.

Palladium-catalyzed aerobic oxyarylthiolation of alkynone O-methyloximes with arylhydrazines and elemental sulfur

A novel and practical palladium-catalyzed aerobic oxyarylthiolation of alkynone O-methyloximes for the assembly of 4-sulfenylisoxazole derivatives using S8 and arylhydrazines as the S-aryl sources is accomplished. In the presence of 0.1 mol% of IPr-Pd-allyl-Cl as the catalyst and O2 (1 atm) as the sole oxidant, both alkynone O-methyloximes and arylhydrazines are suitable substrates, delivering diverse 4-sulfenyl isoxazoles in moderate to good yields with good functional group tolerance. Notably, the phenyl diazonium salt and sodium phenyl sulfinate are also suitable arylation reagents, providing an alternative synthetic strategy to access structurally diverse 4-sulfenyl isoxazoles.

New synthesized polyoxygenated diarylheptanoids suppress lipopolysaccharide-induced neuroinflammation

In neurodegenerative diseases, such as Alzheimer's disease, Huntington's disease, Parkinson's disease and multiple sclerosis, neuroinflammation induced by the microglial activation plays a crucial role. In effort to develop effective anti-neuroinflammatory compounds, different new linear polyoxygenated diarylheptanoids were synthesized. In LPS-triggered BV-2 microglial cells their ability to reduce the concentration of IL-6 and TNF-α pro-inflammatory cytokines was evaluated. Moreover, their effect on NF-κB and ATP citrate lyase (ACLY), a recently emerged target of metabolic reprogramming in inflammation, was assessed. Finally, we turned our attention to inflammatory mediators derived from the cleavage of citrate catalyzed by ACLY: prostaglandin E₂, nitric oxide and reactive oxygen species. All compounds showed null or minimal cytotoxicity; most of them had a great anti-neuroinflammatory activity. Diarylheptanoids 6b and 6c, bearing a halide atom and benzyl ether protective groups, exhibited the best effect since they blocked the secretion of all inflammatory mediators analyzed and reduced NF-κB and ACLY protein levels.

Palladium-Catalyzed Cascade Annulation/Allylation of Alkynyl Oxime Ethers with Allyl Halides: Rapid Access to Fully Substituted Isoxazoles

A novel and efficient approach for the synthesis of functionalized isoxazoles via palladium-catalyzed cascade annulation/allylation of alkynyl oxime ethers with allyl halides has been established. The present protocol exhibits mild reaction conditions, good functional group compatibility, and convenient operation. Moreover, scalability was performed and further decoration of the isoxazole product was achieved.