Noreudesmane sesquiterpenoids from the leaves of Nicotiana tabacum.
Six new 14-noreudesmane sesquiterpenoids, nicotabacosides A-F (1-6), along with five known sesquiterpenoids (7-11), were isolated from the leaves of Nicotiana tabacum. The structures of compounds 1-6 were elucidated as isorishitin 3-O-β-D-glucopyranoside (1), rishitin 3-O-β-D-glucopyranoside (2), rishitin 2-O-β-D-glucopyranoside (3), 1, 6-dehydro-rishitin 3-O-β-D-glucopyranoside (4), 2-hydroxyl-ligudentatol 3-O-β-D-glucopyranoside (5) and oxyglutinosone 3-O-β-D-glucopyranoside (6) based on extensive spectroscopic analyses (HRESIMS, UV, IR, 1D and 2D NMR). Their absolute configurations were determined by X-ray single-crystal diffraction and comparison of their electronic circular dichroism (ECD) spectra.
14-Noreudesmane sesquiterpenes from leaves of Nicotiana tabacum and their antiviral activity
Abstract Three new 14-noreudesmane sesquiterpenes ( 1 ⿿ 3 ) as well as four known ones ( 4 ⿿ 7 ) were isolated from the leaves of Nicotiana tabacum . Their structures were determined mainly by spectroscopic methods, including extensive 1D- and 2D NMR techniques. Compounds 1⿿7 were evaluated for their anti-tobacco mosaic virus (anti-TMV) activities. The results showed that compound 1 exhibited moderate anti-TMV activity with inhibition rate of 46.7%, which were higher than that of positive control (ningnanmycin).
Biosynthetic studies of stress metabolites from potatoes: incorporation of sodium acetate-13C2 into 10 sesquiterpenes
The results of incorporation studies of doubly-labelled sodium acetate-13C2 into the stress metabolites produced by fungal invasion of potato tubers are presented. The 13C-labelling patterns for 10 sesquiterpenes have been determined by 13C nmr. Two of these products have not been described previously and their structural elucidation is discussed. The biosynthetic interrelationships of these compounds are considered in detail.