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

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.     

Aliphatic and aromatic amines during development of Nicotiana tabacum

Putrescine, spermidine, spermine, tyramine and phenethylamine have been analysed in the apical parts, leaves, stems, flowers and roots of the tobacco p     

Phenolic and terpenoid heartwood constituents of Libocedrus yateensis

The heartwood of Libocedrus yateensis has been found to contain cumic acid and several related hydroxyacids so far not reported from any conifer, a sesquiterpene (?)-cryptomerione and (E, E)-1,4-bis-(p-hydroxyphenyl)-buta-1,3-diene, both known from Taxodiaceae. Further constituents were ‘conioids’; hinokiresinol and a related ketone, probably dehydroagatharesinol, a lignan, ‘yatein’, and a novel diphenylbutane derivative, yateresinol. Structural relations between conioids, lignans and diphenylbutanes are discussed.     

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

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.     

Ferulic acid: a substrate for two isoperoxidases from Nicotiana tabacum tissue cultures

An anodic isoperoxidase (A₂) from tobacco tissue culture W-38 and a cathodic isoperoxidase (C₄) from tobacco tissue suspension culture WR-132 have been separated and characterized. Both isoperoxidases catalysed oxidation of ferulic acid in the presence of H₂O₂. When the reaction mixture was subjected to TLC, ferulic acid was found to have been converted to an unknown compound which, after treatment with ammonia, fluoresces green in UV light. Both the isoperoxidases A₂ and C₄ appear to follow simple Michaelis-Menten kinetics with respect to guaiacol as the substrate. The Kms for guaiacol are 4 and 4·5 mM for isoperoxidases C₄ and A₂, respectively. The pH optimum for both enzymes is about 6·0. The effect of various phenolic and related compounds on the activity of each isoperoxidase is reported and discussed.     

Partial purification and characterization of two Nicotiana tabacum leaf ribonucleases

Two enzymes with similar properties that degrade RNA but not DNA have been partially purified from tobacco leaves. They differ in sub-cellular localization and in ability to hydrolyse ribonucleoside 2′,3′-cyclic phosphates.     

Constituants volatils de Lycopersicon esculentum

The volatile components of the tomato have been studied by combined GC-MS with and without previous separation by preparative GC. 5-Methylfurfuryl ketone, furfuryl alcohol, p-anisaldehyde, p-vinylphenol and geraniol were identified and 2-methyl-2-pentanol, 2-heptanol, 4-heptanol, trans-3-hexene-1-ol and trans-2-hexene-1-ol, sec-butyl butyrate, lactone of 5,6-dihydroxyhexanoic acid and isopropyl anisole were tentatively identified.     

Saccharopine from tobacco leaves

5-Acetoamino-2-hydroxyvaleric acid, (5-AHV) was metabolized to δ-acetylornithine in tobacco leaves. On the other hand, δ-acetylornithine fed to tobacco leaves was metabolized into at least 5 components, one major component being 5-AHV. These results show that tobacco plant has a reversible metabolic pathway between 5-AHV and δ-acetylornithine.     

A nor-sesquiterpene glycoside,rishitin-β-sophoroside,from tobacco

A new nor-sesquiterpene glycoside, isolated from flue-cured tobacco, was identified as rishitin-β-sophoroside. The absolute configuration of the aglycone, rishitin, was identical with that obtained from potato tuber tissue infected by pathogens.     

An N-acylamino acid acylase from Nicotiana tabacum leaves

An N-acylamino acid acylase was partially purified from tobacco (Nicotiana tabacum) leaves and some of its properties are described. It hydrolyses N-acetylarginine, N-acetylmethionine, N-acetylcysteine and to a lesser extent N-formylmethionine. It does not appreciably hydrolyse N-formyl peptides and is therefore unlikely to be involved in protein synthesis.     

Ribonucleases in Nicotiana tabacum leaf extracts treated with phenol

When tobacco leaf extracts are treated with phenol, ca 20% of the ribonuclease (RNase) activity survives and can be measured when the phenol is removed. After purification, the resistant RNase is inactivated by phenol; this suggests that tobacco leaves contain material that protects the RNase. Phenol-resistant RNase may be one of the TMV-RNA inactivating systems present in phenol extracts of tobacco leaves.     

Plant growth inhibition by naphthoic acid esters

A series of alkyl esters of 1 - and 2-naphthoic acids and 1 - and 2-naphthaleneacetic acids were synthesized and tested for growth regulating activity     

Caffeic acid-O-methyltransferase in a suspension of cell aggregates of tobacco

Aggregates of tobacco cells in suspension in 2,4-D (10^?6 M) and kinetin (10^?5 M) cultures were fractionated by size, then their O-methyltransferase (OMT) activities were assayed. Only the kinetin culture showed high OMT activity, which was higher in the larger than the smaller aggregates at all stages of cell growth. The contents of phenolic acids were also greater in the larger cell aggregates in the kinetin culture. However, when the kinetin cultured cells were transferred to a medium containing 10^?6 M of 2,4-D, the relationships between the cell size of the aggregates and OMT, lignin and the phenolic acids disappeared. The importance of kinetin and cell association for OMT and the subsequent lignification of the cells is discussed.     

Isolation and characterization of two isoperoxidases from tobacco tissue cultures

Two isoperoxidases (A_f and C_n) from the medium of tobacco tissue suspension culture WR-132 grown in darkness have been purified to apparent homogeneity and partially characterized. C_n and A_f have MWs of ca 30 000 and 54 000, respectively. A_f has ca 5.1% carbohydrate, but none could be detected in C_n. Both isoperoxidases appear to follow simple Michaelis-Menten kinetics with respect to guaiacol as the substrate. The K_ms for guaiacol are 4 and 13.3 mM for Af and C_n, respectively, while both isoperoxidases have a pH optimum at 6.5. C_n, is dissimilar to other isoperoxidases from tobacco tissue cultures, but A_f is very similar to isoperoxidase A₃ from W-38 tobacco tissue culture.