Three New Clerodane Diterpenoids and Their NLRP3 Inflammasome Activation Inhibitory Activity from Callicarpa arborea Roxb

Three new compounds callicarpenoids A-C (1-3), were isolated from the stems of Callicarpa arborea Roxb together with fifteen known compounds (4-18). The structures of these compounds were elucidated using advanced spectroscopic techniques, including 1D and 2D NMR, UV, IR, HR-ESI-MS, ECD, ORD, and quantum chemical calculations. Compound 3, a rare rearranged diterpenoid with a fused 5/6-ring system demonstrated strong potential as an inhibitor of the NLRP3 inflammasome activation with an IC50 value of 3.153 μM. It effectively reduced GSDMD-NT production, inhibited caspase-1 activation, and suppressed IL-1β secretion, thereby mitigating NLRP3 inflammasome-induced pyroptosis in J774A.1 cells. These findings suggest that compound 3 warrants further research and development as a promising NLRP3 inflammasome inhibitor.

Cytotoxic Dehydroabietylamine Derived Compounds

BACKGROUND AND METHODS

Chemotherapy remains one of the most important methods for the treatment of cancer. More recently in this context, some products derived from natural products have raised scientific interest which especially include many terpenes. Thereby, diterpenoids represent a special class, and within this class of important secondary natural products, especially compounds derived from Dehydroabietylamine (DA), are of particular interest.

RESULTS

This review not only gives a summary of the most important findings on the cytotoxic behavior of DAderived compounds but also shows some drawbacks of these compounds, such low bioavailability and/or poor solubility of several derivatives of DA. It focusses on the chemical aspects and summarizes the DA related biological effects without deep discussion of underlying biochemical pathways.

CONCLUSION

Dehydroabietylamine-derived cytotoxic compounds hold a high potential to be developed into efficient antitumor active drugs.

Total synthesis of the natural product EBC-329

The first total synthesis of an anti-leukemic diterpene natural product EBC-329 (1) has been accomplished starting from readily available 6,6-dimethyl-3-oxabicyclo[3.1.0]hexane-2,4-dione (7). An efficient and general approach has been reported for the synthesis of EBC-329 in 13 steps with an overall yield of 10%.

Synthesis and Biological Evaluation of Strictosamide Derivatives with Improved Antiviral and Antiproliferative Activities

A series of novel derivatives of strictosamide were synthesized and biologically evaluated. Most of the new compounds exhibited improved activities than the parent compound strictosamide. Among them, compounds Ib and If possessed antiviral activities against influenza A virus (A/Jinan/15/90) with IC50 values of 4.12 and 12.35 μg/mL, respectively. Compound Ie possessed antiviral activity against respiratory syncytial virus (RSV) with an IC50 value of 9.58 μg/mL. Both compounds IIc and IId had moderate antiproliferative effects against five human cancer cell lines. The preliminary structure-activity relationships were also concluded. This study provides a promising new template with potential antiviral activity.

Biological activity of natural sesquiterpenoids containing a gem-dimethylcyclopropane unit

The biological activity of sesquiterpenes containing the gem-dimethylcyclopropane unit is described.

Antifeedant and Antiviral Diterpenoids from the Fresh Roots of Euphorbia jolkinii

The perennial herbaceous plant Euphorbia jolkinii (Euphorbiaceae) is a noxious weed widely distributed in the grasslands of northwestern Yunnan and has greatly threatened the local biodiversity. Phytochemical investigation on the fresh roots of E. jolkinii afforded six new diterpenoids 1, 2, 4-6, and 8, together with fifteen known diterpenoids. Their structures were elucidated on the basis of 1D and 2D NMR and other spectroscopic methods. Casbane, lathyrane, abietane, and ent-kaurane diterpenoids were reported from this plant for the first time. Selected compounds were evaluated for their antifeedant and anti-RSV (respiratory syncytial virus) activities. Compound 2 and ingenol (3) exhibited moderate antifeedant activity against a generalist insect herbivore, Spodoptera exigua, with EC50 values of 17.88 and 17.71 μg/cm(2) respectively. Compound 19 showed significant anti-RSV activity, with 50 % inhibition (IC50) value of 10.0 μM and selective index of 8.0. Compounds 1 and 2 were less active against RSV virus, both with IC50 value of 25 μM, and with selective indices of 1.0 and 3.2 respectively. These findings provided new evidence for the biological functions and utilization of the diversified diterpenoid metabolites in the roots of this rich but harmful plant.

Evolution of an oxidative dearomatization enabled total synthesis of vinigrol

The evolution of the synthetic strategy resulting in a total synthesis of vinigrol is presented. Oxidative dearomatization/intramolecular Diels-Alder cycloaddition has served as the successful cornerstone for all of the approaches. Extensive radical cyclization efforts to form the tetracyclic core resulted in interesting and surprising reaction outcomes, none of which could be advanced to vinigrol. These cyclization obstacles were successfully overcome by using Heck instead of radical cyclizations. The total synthesis features a trifluoroethyl ether protecting group being used for the first time in organic synthesis. The logic of its selection and the group's importance beyond protecting the C8a hydroxyl group is presented along with a discussion of strategies for its removal. Because of the compact tetracyclic cage the route is built around many unusual reaction observations and solutions have emerged. For example, a first of its kind Grob fragmentation reaction featuring a trifluoroethyl leaving group has been uncovered, interesting interrupted selenium dioxide allylic oxidations have been observed as well as intriguing catalyst and counterion dependent directed hydrogenations.

Heterocyclic terpenes: linear furano- and pyrroloterpenoids

This review of furano- and pyrroloterpenoids covers the literature, 180 articles in all, published from January 2006 to December 2013.