Reaction Mechanism About Isomerization of Resin Acids and Synthesis of Acrylopimaric Acid Based on DFT Calculation

Acrylopimaric acid is considered one of the possible substitutes for petroleum-based polymeric monomers, which is an important industrial product. Resin acids were isomerized to form levopimaric acid(4), which reacted with acrylic acid to synthesize isomers of acrylopimaric acid. Density functional theory calculation was used to investigate the reaction mechanisms with seven reaction paths in five different solutions. The values of ΔG were sorted from highest to lowest by levopimaric acid(4), neoabietic acid(3), palustric acid(2), and bietic acid(1). From the perspective of dynamics, the energy barrier in the isomerization of palustric acid(2) to levopimaric acid(4) was the lowest, whereas the highest energy barrier was the isomerization of neoabietic acid(3) to levopimaric acid(4) in the same solution. The addition reaction of levopimaric acid(4) and acrylic acid(5) to acrylopimaric acid c(8) was the optimal reaction path dynamically. However, ΔG of acrylopimaric acid c(8) was higher than that of acrylopimaric acid d(9). In general, the rates of isomerization reactions for rosin resin acids and addition reaction for acrylopimaric acid in water were higher than those in other solvents. HOMO-LUMO and ESP were analyzed for 8 kinds of molecules. For acylpyimaric acid, the non-planar six-memed ring and the C-C double bonds were easily attacked by nucleophile, while the non-planar six-memed ring and the carboxyl group are easily reacted with electrophiles. The highest electrostatic potential of the eight molecules is located at H of the carboxyl group, while the highest electrostatic potential is located at C-O double bond of the carboxyl group.

Ureido Derivatives of Neoabietic Acid

A series of ureido derivatives of neoabietic acid were synthesized by application of Curtius rearrangement reaction to neoabietic acid and amines. Structure characterization of these compounds was done by 1H-NMR, 13C-NMR and HRMS spectral analysis.

Chemical Composition of Natural Colophony from Pinus Brutia and Comparison with Synthetic Colophony

The compositions of colophony resins obtained from Pinus brutia Ten trees by three different methods (acid paste, carved hole and scraping) from Ayvacık, Gökova and Kemalpaşa in Turkey were analyzed by capillary GC-MS. The main components were the monoterpenes α-pinene, β-pinene, and Δ3-carene, and the diterpenic resin acids palustric, abietic, kaur-9(11)-16-en-18-oic and neoabietic acid. The synthetic colophony resins exhibited similar contents to those of the natural resins obtained from the Gökova and Kemalpaşa regions of Turkey. However, colophony resins from Ayvacık exhibited only half the diterpenic acid content as those of the Gökova and Kemalpaşa resins. Out of the three techniques, the carved hole method caused rather different percentages in the constituents of the essential oils.

Fate of Conifer Terpenes in a Polyphagous Folivore: Evidence for Metabolism by Gypsy Moth (Lepidoptera: Lymantriidae)

Conifers comprise a substantial portion of the host range of the gypsy moth, Lymantria dispar L. In this study, the effects and fates of the predominant conifer phytochemicals, monoterpenes and diterpene acids, were determined. Gypsy moth larvae were fed physiological levels of three monoterpenes (bornyl acetate, limonene, and myrcene) and two diterpene acids (isopimaric acid and neoabietic acid) for the duration of their second, third, and fourth stadia. Frass was collected daily, and larvae and exuviae were collected after the completion of the stadium. These samples were chemically analyzed for parent terpenes or their metabolites. Overall, gypsy moth larvae were highly tolerant of all terpenes administered, despite some treatment effects. Limonene, myrcene, isopimaric acid, and neoabietic acid were not recovered suggesting that, once ingested, these terpenes were converted into other products. Bornyl acetate was metabolized in part to borneol and also was recovered in small quantities from frass. Its metabolite borneol was mostly excreted, with a small amount remaining in body tissues. Additional experiments were performed, determining that monoterpenes were effectively ingested, and that monoterpenes were not lost substantially through volatilization from diet or larvae. There was no evidence that terpene metabolism was due to P450 enzymes or esterases, although these results are inconclusive. Gut bacteria do not appear to be primarily responsible for terpene metabolism.

Treating Scots pine seedlings with the herbicide atrazine does not affect shoot chemistry or feeding and oviposition by Lygusrugulipennis

Polyphagous Lygus (Heteroptera: Miridae) bugs, which have one of the widest documented host-plant ranges, have accepted nursery-grown conifer seedlings as host plants only recently. One explanation for this adaptation to the conifer nursery environment could be the increased attractiveness of conifer seedlings due to herbicide treatments. In three laboratory experiments, we tested whether atrazine treatments (2 or 4 kg•ha−1) affected shoot chemistry of pine seedlings and the feeding and oviposition behaviour of the European tarnished plant bug, Lygusrugulipennis Popp. Shoot growth of the pine seedlings was decreased by the atrazine treatment (2 kg•ha−1) in only one experiment. The number of feeding lesions caused by Lygus bugs and the number of eggs laid per seedling were not affected by herbicide treatments, nor was the proportion of seedlings damaged. Concentrations of total amino acids were not affected by the herbicide in any of the experiments. In one experiment, the level of lysine was increased in the atrazine treatment. Terpenes and resin acids were analysed only in one experiment, and total concentrations of these defence compounds were not affected by atrazine. Dominant monoterpenes were α-pinene and 3-carene, the latter varying strongly between individual seedlings. Abietic acid and neoabietic acid were the dominant abietane and pimarane resin acids. The results suggest that applications of atrazine are not likely to reduce the resistance of pine seedlings to Lygus bugs. Herbicides may have an indirect effect by reducing the availability of alternative host plants for bugs. Other potential causes for increased numbers of Lygus bugs on nursery-grown conifer seedlings are discussed.

Wound-induced changes of resin acid concentrations in living bark of Scots pine seedlings

One-year-old Pinussylvestris (L.) seedlings were wounded at the stem base by stripping off stem bark pieces of approximately 10 mm in length and covering about 50% of the stem circumference. The seedlings were thereafter planted out in the field or in a climate chamber. The field experiment was repeated on four different planting dates. Wounded and control seedlings were successively harvested for gas chromatographic determination of changes in resin acid concentrations of the bark surrounding the wounded area. Independent of planting date, wounded seedlings were found to have higher concentrations of total resin acids than corresponding controls. The most important quantitative changes in resin acids were observed for isopimaric, levopimaric + palustric, dehydroabietie, abietic, and neoabietic acid. In wounded seedlings the concentration of dehydroabietic acid showed the most significant increase, both in the field and in climate chamber experiments. This increase was rapid and appeared within 1 week in the field and within 3 days in the climate chamber. The other resin acids identified showed a somewhat similar variation pattern, but the differences were not as distinct as for dehydroabietic acid. These wound-induced rapid changes in resin acid concentrations could be important for resistance to pathogens.

CONVERSION OF NEOABIETIC ACID INTO MANOOL

not available