Wax composition of the Kazanlik and Damask roses

The Kazanlik and Damask roses ditter qualitatively and quantitatively in the composition of the flower waxes. These chemotaxonomic data suggest that these two oil-bearing roses are different from each other.     

Epicuticular waxes of Sorghum and some compositional changes with plant age

Epicuticular wax from mature plants of Sorghum bicolor SD-102 was compared with that from panicles and seedlings of the same variety at the fourth-fifth leaf stage of growth. The composition of wax from SD-102 panicles was quite different from that of mature leaf blades and sheaths. Free fatty alcohols were the dominant class of wax from SD-102 seedlings and C₃₂ was the major homologue of alcohols and aldehydes. For comparison purposes, the epicuticular waxes from whole plants of two other S. bicolor varieties, Alliance A and Martin A, grown up to the tasseling stage, have been analysed. The major wax components were free fatty acids. The typical chain lengths of aldehydes, free alcohols and free fatty acids were C₂₈ and C_30.p-Hydroxybenzaldehyde was not a wax component of the studied varieties of sorghum.     

Long chain conjugated alkadienes; a new component of plant waxes

It is shown by TLC, IR- and UV-spectra that a new component of plant waxes, conjugated alkadienes, are contained in wax, obtained from Bulgarian rose flower (Rosa damascena Mill.). GLC of the hydrogenated dienes indicates that they are represented in the wax as a mixture of members in the C₁₁–C₃₃ range, in which C₁₉, C₂₉, C₂₇ and C₂₁ are prevalent. It is suggested that there exists a biogenetic relationship between paraffins, olefins and dienes, since hydrocarbons with the same number of carbon atoms are prevalent in these homologous series in the wax studied.     

Structures and molecular dynamics of plant waxes

Waxes from the leaves of Fagus sylvatica L. (European beech tree) and Hordeum vulgare L. (barley) have been investigated using NMR, DSC, X-ray diffraction and gas chromatographic methods. The wax from Fagus sylvatica, consisting mainly of n-alkanals, n-alkanes and 1-alkanols, has chain-lengths ranging from 20 to 52 carbon atoms with an average chain-length of 30.5 carbon atoms. The X-ray results show that the wax is to a large extent ( 70%) amorphous. The wax from the leaves of Hordeum vulgare L., consisting mainly of n-alkanols, has chain-lengths ranging from 20 to 50 carbon atoms with an average chain-length of 27.4 carbon atoms. The wax is 52% crystalline. It seems that the structure of this wax differs from those of other plant waxes that have been investigated in that the longer chains bridge the amorphous zone between two adjacent layers of crystalline material, thus linking the two layers. This linking affects the melting point of the wax noticeably. The activation energies for the different molecular motions in these waxes have been extracted from the NMR spin-lattice relaxation time measurement. Correspondence to: E. C. Reynhardt     

The effects of stress on plant cuticular waxes

Plants are subject to a wide range of abiotic stresses, and their cuticular wax layer provides a protective barrier, which consists predominantly of long-chain hydrocarbon compounds, including alkanes, primary alcohols, aldehydes, secondary alcohols, ketones, esters and other derived compounds. This article discusses current knowledge relating to the effects of stress on cuticular waxes and the ways in which the wax provides protection against the deleterious effects of light, temperature, osmotic stress, physical damage, altitude and pollution. Topics covered here include biosynthesis, morphology, composition and function of cuticular waxes in relation to the effects of stress, and some recent findings concerning the effects of stress on regulation of wax biosynthesis are described.     

Crystallinity of plant epicuticular waxes: electron and X-ray diffraction studies

The crystal structure of the epicuticular waxes of 35 plant species has been examined by electron diffraction and X-ray powder diffraction. The waxes include the most common morphological wax types such as platelets, tubules, films and rodlets. Most of them were prepared with a special mechanical isolation method, which preserves the original crystal structure. Solvent-extracted recrystallized plant waxes were compared with mechanically isolated samples. The waxes were found to occur in three different crystal structures. Most of the waxes exhibited an orthorhombic structure which is the most common for aliphatic compounds. Tubules containing mainly secondary alcohols showed diffraction reflections of a triclinic phase; broad reflection peaks indicated a significant disorder. Ketones, in particular beta-diketone tubules, displayed the reflections of a hexagonal structure. Mixtures of different phases could be identified. For most of the waxes, the 'long spacing' diffraction reflections indicated a layer structure with the characteristics of the major component. Others showed no 'long spacing' reflections indicating a strong disorder of the molecular layers.     

Trialkyltrioxanes in flower wax of some decorative roses

The polymeric form in which long-chain aliphatic aldehydes are present in rose flower waxes has been established as the 2,4,6-trialkyl 1,3,5-trioxane.     

Epicuticular wax of Juniperus scopulorum

Epicuticular wax from Juniperus scopulorum contains hydrocarbons (16%), esters (11%), free acids (1%), nonacosan-10-ol (27%), nonacosane-diols (7%) and estolides (16%). The major hydrocarbon is tritriacontane; the principal esters are C₃₄–C₄₆, mainly octyl and decyl esters of C₂₈-C₃₆ acids; and the diols consist of nonacosane-4,10-diol (57%),5,10-diol (28%), 7,10-diol (11%) and 10,13-diol (4%). Hydrolysis of the estolides gave a mixture of acids, ω-hydroxy acids, , ω-diols, alcohols and hydroxy acids. The hydroxy acids are a new class of C₂₈–C₃₆ acids with the OH attached to either the eighteenth or twentieth carbon from the terminal methyl end; the major component is 13-hydroxydotriacontanoic acid. Syntheses of this acid and of nonacosane-4,10-dione and nonacosane-4,10-diol are described.     

Composition of neutral components in flower wax of some decorative roses

A homologous series of long-chain secondary alcohols in which each member is a mixture of three isomers with a hydroxyl group at 4, 5 and 6 positions has been identified for the first time in a plant wax. The isomer, having an OH-group at C₅ is the prevalent one. Data are also presented on the presence of unsaturated primary alcohols and ester-bound secondary alcohols in the waxes isolated from decorative roses.     

Triterpenoids in epicuticular waxes of Dudleya species

The pentacyclic triterpenoids, β-amyrin acetate and taraxerone, are major components in the epicuticular wax of the genus Dudleya.     

Epicuticular waxes of hexaploid and octaploid triticales

Leaf and stem wax of triticales contain alkanes, esters, aldehydes, free alcohols, free acids, β-diketones and hydroxy gb-diketones. The wax compositions of the triticales investigated are closer to that of wheat than to that of rye.     

Biotransformation of a guaiane 6,12-diol to the corresponding guaianolide in hypocotyl cuttings of Phaseolus aureus

The hypocotyl cuttings of Phaseolus aureus brought about the biotransformation of a guaiane 6,12-diol to the corresponding lactone during the formation of adventitious roots.     

Composition of leaf surface waxes of Triticum species: Variation with age and tissue

The composition of cuticular wax from plants of spring wheat (varieties Selkirk and Manitou) and of durum wheat (variety Stewart 63) at various stages of growth, and of wax from different parts of the plants varies considerably. Wax was analysed, without preliminary separation, by GLC using Dexsil 300 as liquid phase. Alcohols are major components of wax from leaf blades and β-diketones are major components of wax from leaf sheaths, especially the flag leaf sheath. Glaucousness of the leaf sheath is due to the high β-diketone content. In the first 50 days after germination, before sheaths and flag leaf are completely developed, the major component is octacosanol (> 50%). At 66 days, when sheath development is complete, β-diketone content is greatest. Hydrocarbon composition differs for wax from leaf blade and leaf sheath and also for different leaf blades and between adaxial and abaxial sides of the flag leaf. From 66 to 100 days ester content of wax increases, especially in Selkirk wheat, apparently due to formation of wax containing high proportions of esters of trans-α,β-unsaturated C₂₂ and C₂₄ acids. The content of these acids in the free fatty acids and of diesters based on these acids also increases during this period.     

D:b-friedoolean-5-ene-3β,29-diol,an angular methyl oxygenated d: b-friedooleanene from elaeodendron balae

A new dioxygenated D: B-friedooleanene from Elaeodendron balae root bark was shown to be D:B–friedoolean-5-ene-3β,29-diol by relating it to 29-oxygenated D:A-friedooleanane. This is the first report of angular methyl oxygenation in the D: B-friedooleananes.     

Epicuticular waxes of Andropogon hallii and A. Scoparius

Leaf waxes of Andropogon hallii and A. scoparius contain hydrocarbons (2%, 2%), esters (4%, 2%), free acids (3%, 4%), free alcohols (1%, 0.2%, major component dotriacontanol) β-diketones (67%, 80%) and hydroxy β-diketones (16%, 5%). β-Diketones of A. hallii consist mainly of tritriacontane-12,14-dione and hentriacontane-12,14-dione (86:8) and of A. scoparius of tritriacontane-12,14-dione and hentriacontane-10,12-dione (67:29). Hydroxy β-diketones of A. hallii are composed mainly of 5-hydroxytritriacontane-12,14-dione and 5-hydroxy-hentriacontane-12,14-dione (90:8); wax of A. scoparius contains only 5-hydroxytritriacontane-12,14-dione. The hydroxyl group of the major hydroxy β-diketone has the R-configuration opposite to that of all previously described hydroxy β-diketones.     

Epicuticular waxes of Secale cereale and Triticale hexaploide leaves

Wax on leaves of rye and of hexaploid Triticale (60–70-day-old plants) contains hydrocarbons (6–8%), esters (10%), free alcohols (14-8%), free acids (3%), hentriacontane-14,16-dione (39–45%), 25 (S)-hydroxyhentriacontane-14,16-dione (13–11%) and unidentified (14–15%). Diesters (1–3%) are also present in rye wax. Compositions of hydrocarbons (C₂₇-C₃₃) and esters (C₂₈,C₅₈) are similar for both waxes. Free and combined alcohols of rye wax are mainly hexacosanol but alcohols of Triticale wax are mainly octacosanol. The composition of Triticale wax is close to that of its wheat parent Triticum durum (cv. Stewart 63). Esters of wax from ripe rye contain 58% of trans 2,3-unsaturated esters. *NRCC No. 14033.     

Ferroelectricity in the arterial wall: A new physical component of atherosclerosis

The appearance of two electric potentials in the aorta is explained by the blood pulse and the remote steps of atherosclerosis are elucidated from the physical point of view. When the first C-C-2W is deposited in the intimamedia, the primary cause of their retention is the stress-induced polarization of the membrane. C-C-2W possesses a permanent dipole moment which may be reversed by the field produced by the radial expansion/contraction of the arteries.The initial C-C-2W increases the polarization of the aorta walls, favoring accumulation of more oriented material on top of the first. C-C-2W is also ferroelectric and constitutes a polar continuum with the membranes. By the time fatty streaks appear, the entire aorta wall is ferroelectric and energy has been stored in the walls under the form of residual polarization. This storage gradually destroys the wall, leading to aneurism. The biological significance of the new theory is summarized in Table 2.     

5,8-Disubstituted indolizidines: A new class of noncompetitive blockers for nicotinic receptor-channels

A series of 8-methyl-5-substituted indolizidines inhibit binding of the noncompetitive blocking agent [³H]perhydrohistrionicotoxin to muscle-type nicotinic acetylcholine receptor-channels in membranes fromTorpedo electroplax. The K_i values range from 0.16 to 1.12 M, making these alkaloids among the most potent ligands for this site. Unlike most noncompetitive blockers, the potencies of the 8-methyl-5-substituted indolizidines arereduced in the presence of carbamylcholine. Indolizidine 205A (8-methyl-5-(4-pentynyl)indolizidine) is unique in enhancing binding of [³H]perhydrohistrionicotoxin by 1.5-fold. The enhancement is at a maximum at 0.01 to 0.1 M, followed by progressive inhibition with an IC₅₀ of about 20 M. In the presence of carbamylcholine, which itself enhances binding of [³H]perhydrohistrionicotoxin, indolizidine 205A causes only an inhibition of binding with an IC₅₀ of about 10 M. Indolizidines with a hydroxy substituent on the 8-methyl group have very low activity. None of the indolizidines affect binding of [¹²⁵I]-bungarotoxin to acetylcholine recognition sites. In pheochromocytoma PC12 cells, indolizidine 205A has no agonist activity, but only inhibits carbamylcholine-elicited²²Na⁺ influx. The profile of potencies for the 8-methyl-5-substituted indolizidines is similar in electroplax membranes and PC12 cells. Indolizidines 205A and 209B (8-methyl-5-pentylindolizidine) have no apparent effect on desensitization of receptors in PC12 cells. The 5,8-disubstituted indolizidines appear to represent an atypical and potent class of noncompetitive blockers for muscle-type and ganglionic nicotinic receptor-channels.