Abietane Diterpenes from and Their Anti-Neuroinflammatory Activity.

Seven new abietane diterpenoids, comprising medusanthol A-G (-, , -) and two previously identified analogs ( and ), were isolated from the hexane extract of the aerial parts of The structures of the compounds were elucidated by HRESIMS, 1D/2D NMR spectroscopic data, IR spectroscopy, NMR calculations with DP4+ probability analysis, and ECD calculations. The anti-neuroinflammatory potential of compounds - was evaluated by determining their ability to inhibit the production of nitric oxide (NO) and the proinflammatory cytokine TNF-α in BV2 microglia stimulated with LPS and IFN-γ. Compounds - and exhibited decreased NO levels at a concentration of 12.

An Integrated ANN-PRA/DP4+ Tandem Computational Approach Contributing to the Ordering of the Heliannuol Family.

Heliannuols are a unique class of sesquiterpenes isolated mostly from , commonly known as sunflower. The interesting allelopathic properties, combined with their unprecedented carbon skeletons, have drawn wide attention to phytochemistry and synthetic groups. So far, 14 heliannuols (heliannuols A-N) have been described in the literature, although some of them have not yet been validated by total synthesis.

Structure Revision of the Sesquiterpene Nordine Based on NMR Spectroscopic Analysis and X-ray Crystallography.

Nordine was reported to be an unusual humulene-type macrocyclic sesquiterpenoid that contains an ether-bridged bicyclic ring between C-10 and C-6 with a hydroxy group at position 2. Here, we report the structure revision of nordine based on incongruities found for carbon chemical shifts in the originally proposed structure, in addition to formation of a diacetylated derivative. As expected, a single-crystal X-ray diffraction analysis unambiguously confirmed our proposal that the nordine () structure contains an ether-bridged bicyclic ring between C-10 and C-7 and hydroxy groups at C-2 and C-6.

Revisiting the structure of Heliannuol L: A computational approach.

Recently, structural elucidation of natural products has undergone a revolution. The combined use of different modern spectroscopic methods has allowed obtaining a complete structural assignment of natural products using small amounts of sample. However, despite the extraordinary ongoing advances in spectroscopy, the mischaracterization of natural products has been and remains a recurrent problem, especially when the substance presents several stereogenic centers.