Inger Wahlberg

Effects of flue-curing and ageing on the volatile, neutral and acidic constituents of Virginia tobacco☆

Abstract Several volatile compounds are generated and the concentrations of many others increase on flue-curing and ageing of Virginia tobacco. Oxidative degradation of isoprenoids, Maillard reactions and phenylalanine metabolism are the major processes accounting for the formation of the majority of these compounds. A number of alcohols, aldehydes and ketones, which are apparently products of fatty acid degradation, are lost during the post-harvest handling.

3-epi-betulinic acid, a new triterpenoid from Picramnia pentandra

Abstract Extraction of the bark of Picramnia pentandra Sw. gave as the main component a new triterpenoid, whose structure was established as 3-epi-betulinic acid.

Potential nitrite scavengers as inhibitors of the formation of N-nitrosamines in solution and tobacco matrix systems

The ability of 20 compounds, all but one tobacco constituents, to inhibit the formation of tobacco-specific N-nitrosamines (TSNA) was investigated in buffer and detergent solution and in tobacco midrib and lamina systems. In solution at pH 5.5, ascorbic acid and the phenolic acids caffeic and ferulic acid were the most potent inhibitors of the reaction between nornicotine and nitrite, with nearly complete inhibition at molar ratios test compound/nitrite > 1:1. Also, cysteine > dihydrocaffeic acid > protocatechuic acid approximately catechin acted as strong inhibitors with >90% inhibition at a ratio of 3:1. Lower inhibitions were observed with chlorogenic acid > p-coumaric acid > sclareol > serine. Rutin showed an inhibition of 34% at a ratio of 0.1:1. Sclareol, alanine, proline, and serine did not significantly affect the N-nitrosonornicotine (NNN) formation. alpha-Tocopherol and glutathione enhanced NNN formation at pH 5.5 but were inhibitors at pH 3. Cinnamic acid, vanillic acid, eugenol, and esculin enhanced NNN formation. Increased NNN formation was also observed for dihydrocaffeic acid, chlorogenic acid, protocatechuic acid, and catechin at a less-than-equimolar ratio of test compound to nitrite. The tobacco matrix experiments were performed with air-cured, ground tobacco midrib and lamina. Caffeic acid, ferulic acid, dihydrocaffeic acid and catechin were potent inhibitors of the formation of TSNA in the midrib as well as in the lamina. Also protocatechuic acid, glutathione, ascorbic acid, p-coumaric acid, chlorogenic acid and cysteine were inhibitors, while alpha-tocopherol and rutin inhibited the reaction in the midrib but not in the lamina. Cinnamic acid, vanillic acid, eugenol, alanine, proline and serine showed small effects only. The molar ratio of secondary alkaloid(s)/nitrite in the test systems were 0.1:1 (solution), approximately 0.25:1 (midrib), and approximately 1:1 (lamina) and is most likely the major contributor to the observed order of inhibition potency (solution > midrib > lamina) of the test compounds. The vicinal phenolic hydroxyl groups of polyphenols and the simultaneous presence of a phenol group and an olefinic bond in hydroxycinnamic acids were the most characteristic structural elements of the potent inhibitors.

Three new 5,10-epoxygermacranolides from Liatris chapmanii and Liatris gracilis☆

Abstract Examination of Liatris chapmanii (T + G) Kuntze led to the isolation of two new germacranolides, chapliatrin ( 1 a) and isochapliatrin ( 1 b). Liatris gracilis Pursh gave chapliatrin and acetylchapliatrin 1 c). The stereochemistry assigned to C-3, C-4 and C-10 is tentative. All three compounds possess the hitherto-unreported 5,10-oxygen linkage. L. gracilis also gave the benzofuran euparin ( 2 ) and the flavones hispidulin (dinatin, 3 a and 3′,6-dimethoxy-4′,5,7-trihydroxyflavone ( 3 b). L. chapimanii also gave 5-hydroxy-3′,4′,6,7-tetramethoxyflavone ( 3 c).

Effects of flue-curing and ageing on the volatile basic constituents of Virginia tobacco☆

Abstract Flue-curing and ageing of Virginia tobacco reduce the amounts of nicotine and several of its transformation products. In contrast, the concentrations of certain structurally simple pyridines and a few compounds, which are presumably products of sugar—amino acid interactions, are found to increase. Generation of several pyridines and a few other bases during the leaf processing is also observed.

A new dihydrobenzofuran from Liatris provincialis

Abstract A chloroform extract of Liatris provincialis Godfrey gave as a minor component a new dihydrobenzofuran, whose structure was established as I.

Eight new cembranoids from tobacco - structural elucidation and conformational studies ☆

Abstract Eight new cembranoids have been isolated from an extract of flowers of Greek tobacco. They have been identified as (1S,2E,4S,R,7E,10R,11E)-2,7,11-cembratriene-4,6,10-triol (1), the corresponding (10S)-, (4R*)- and (4R*,10S*)-diastereomers (2–4), (1S*,2E,4R*,6R*,7E,10S*,11Z)-2,7,11-cembratriene-4,6,10-triol (5), (1S,2E,4S,6R,7E,11E)-4,6-dihydroxy-2,7,11-cembratrien-10-one (6), the corresponding (4R*)-epimer (7) and (1S*,2E,4S*,7E,10S,11E)-4,10-dihydroxy-2,7,11-cembratrien-6-one (8) with the aid of chemical and spectral methods, 2D-NMR techniques being particularly helpful. The crystal structure of the diacetate 11 has been determined and is described. The solution conformations of triols 1 and 3 have been studied by using NMR methods in conjunction with molecular mechanics calculations (MM3). The biogenesis of the new compounds is discussed.

7,8-epoxy-4-basmen-6-one, a tobacco diterpenoid having a novel skeleton, having a novel skeleton

Abstract A dieterpenoid, probably cembrane-derived and having an novel skeleton, has been isolated from Greek tobacco. Its structure has been determined by spectroscopic methods and X-ray analysis.

Conformational analysis of a 7,8-epoxycembranoid

Abstract An analysis of the solution conformation of (1S,2E,4S,6R,7R,8R,11E)-7,8-epoxy-2,11-cembradiene-4,6-diol (1), a tobacco diterpenoid, has been performed by using NMR methods, molecular mechanics calculations and molecular dynamics simulations, and the solid state structure has been determined by X-ray analysis. The results obtained indicate that the solid state structure is essentially retained in solution.

Long-range proton–carbon chemical shift correlation by 1D and 2D n.m.r. spectroscopy: structure of a sucrose ester

The structure of an octa-acylated derivative of a disaccharide isolated from oriental tobacco has been confirmed with the aid of long-range proton–carbon-13 shift correlation by 2D n.m.r. spectroscopy using a 10 mg sample.