Preliminary studies of monoterpenoid variability in Satureja douglasii

Monoterpenoid composition of samples from 10 populations of Satureja douglasii in a 250-ha area were analyzed in Spring 1974. Two distinct compositional types were found: Type A contained large amounts of limonene and carvone but very small quantites of piperitenone, piperitone, pulegone and isomenthone (3-oxy compounds), whereas Type B was essentially the reverse. This variation is attributed to a genotypic difference. The amounts of 3-oxy compounds varied greatly among the Type B populations. Increasing shade conditions were correlated with increased amounts of the more reduced compounds isomenthone and piperitone. Clonal lines were established from two Type B populations whose habitats represented extremes of sun and shade conditions. The two clonal lines, which had very different compositions in the field, produced similar oils under controlled conditions. Growth under different temperature regimes had little effect on composition. Developmental changes in composition implied the precursor-product relationships piperitenone→piperitone and pulegone→isomenthone. The data suggest that S douglasii monoterpenoid compositional patterns are significantly influenced by genetic and environmental factors (probably light intensity) as well as developmental processes.     

Geographic patterns of monoterpenoid composition in Satureja douglasii

Monoterpenoid composition of mature leaves from populations distributed throughout the range of Satureja douglasii was determined by GLC. Five compositional types (I–V) were characterised, based on the high relative proportions of either carvone, pulegone, isomenthone, menthone or bicyclic compounds (camphenecamphor). These compositional types occured in restricted but overlapping portions of the species range. All samples contained camphene and camphor, amounts of which varied clinally along latitudinal gradient. Transplants were grown under greenhouse conditions. Although some populations exhibited significant environmental modification in amounts of principal constituents, the patterns of geographic variation were retained. Compositional types I–IV are based on compounds having -menthane structures and relationships among them are consistent with single gene actions within a common biosynthetic pathway. Using the dominant components of the collection site vegetation as an indication of habitat conditions, correlation of the genetically-determined compositional variation with environmental conditions was attempted. The distribution of the compositional types was partially isolated in this manner. Environmental factors which might be controlling the genetically-determined variation are discussed.     

Effect of light and temperature on monoterpenoid yield and composition in Satureja douglasii

Light intensity and day temperature were identified as principal modifying factors of monoterpenoid composition and yield in individuals of Satureja douglasii. The individuals represent compositional type and clinial patterns of infraspecific compositional variation. The lack of compositional interconversion confirms the tight genetic control of biosynthesis which results in these infraspecific patterns. There was marked influence by light intensity on monoterpenoid yield per leaf dry weight and by day temperature on yield per leaf. Low light intensity reduced leaf dry weight but had little effect on the amount of monoterpenoids per leaf whereas low day temperature increased both leaf weight and yield per leaf, compared to high light and day temperature effects. Day temperature modification of yield per leaf was related to modification of composition.     

The effect of moisture stress on monoterpenoid yield and composition in Satureja douglasii

The effect of moisture stress on monoterpenoid yield and composition of Satureja douglasii was studied under controlled conditions and in the field. Large differences in monoterpenoid yield observed among field populations were closely correlated with moisture stress. In greenhouse transplants grown under uniformly moist conditions these differences were significantly reduced. In all plants studied yield per leaf dry weight decreased with development. A growth chamber study using clones grown under different soil moisture regimes showed that high moisture stress reduced leaf weight and monoterpenoid yield per leaf, but had little effect on yield per leaf dry weight. Effects on monoterpenoid composition were less striking with high moisture stress causing a small decrease in the percentage of monoterpenoids with a p-menthane carbon skeleton and perhaps accelerating the rate of developmental conversions.     

Hydroquinone derivatives and monoterpenoids from the Neotropical liverwort Plagiochila rutilans

The structure of a prenylbenzene derivative isolated previously from a Cuban specimen of the liverwort Plagiochila rutilans is revised to 2-methoxy-6-prenylhydroquinone. The hydroquinone was observed as a prominent component of the NMR and GC-MS fingerprints of five recent specimens of the liverwort from Bolivia, Brazil and Costa Rica. The corresponding quinone was observed as a minor component. Two new methylated derivatives of the hydroquinone were observed as prominent components in one specimen from Bolivia; these were isolated, characterized, and their structures elucidated as 2-methoxy-1-O-methyl-6-prenylhydroquinone and 2-methoxy-4-O-methyl-6-prenylhydroquinone using 1H NMR spectroscopy. The liverwort has a strong peppermint-like odour that is caused by the presence of several menthane monoterpenoids, including notably pulegone, menthone, isomenthone. terpinolene and limonene. One of the Costa Rican specimens contained considerable amounts of the new lactone 3,7-dimethyl-2,6-octadien-1,6-olide as the principal monoterpenoid in place of pulegone. Two Costa Rican specimens distinguished morphologically as Plagiochila standleyi (a taxon closely related to P. rutilans and reduced elsewhere to a variety of that species) are characterized by large amounts of 3-hydroxy-4'-methoxybibenzyl. P. standleyi was also reported to have a peppermint-like odour in the field. Menthane monoterpenoids were again responsible but in this case the major components were limonene, beta-phellandrene, alpha-terpinene and the endoperoxide ascaridole.     

Variation of monoterpenoids inartemisia feddei andArtemisia scoparia

The composition and concentration of monoterpenoids in the leaves and stems ofArtemisia feddei andArtemisia scoparia were determined, and seasonal variation in the monoterpenoids ofArtemisia species were investigated. The two species possessed different compositions and concentrations of monoterpenoids. The total amount of monoterpenoid inA. scoparia was always higher than that of A.feddei, and the monoterpenoid yields of leaves were higher than stem yields in both species as compounds formed. The major constituents of A.scoparia were 25 while A.feddei consisted of 26 compounds. Sixteen common monoterpenoid compounds were found in both plants. Large differences in the relative amounts of the monoterpenoids were found between species and seasons. Extremely large differences in the relative amounts of naphtalene, sabinene, β-pinene, cyclohexene, and octatrine were found in the leaf monoterpenoids of the two species. The largest differences in relative amounts of stem monoterpenoids were in s abinene and β-pinene levels.     

Structural diversity and biosynthesis of plant derived p-menthane monoterpenes

Phytochemistry Reviews - p-Menthanes are among the most valuable groups of monoterpenoids produced by plants. Products such as menthol, carvone, pulegone, and limonene are well-known fragrance...     

Chemogenetic evidence supporting multiple allele control of the biosynthesis of (−)-menthone and (+)-isomenthone stereoisomers in Mentha species

The essential oils of certain Mentha species and chemotypes have proportions of (?)-menthone and (+)-isomenthone which differ but show a high degree of heritability in clonal propagation. Oil from an F₂ individual (69–296), selected from numerous 4n M. longifolia (4n = 48) × M. crispa (2n = 48) hybrids for high isomenthone content, had 41.3% isomenthone; the associated but seldom observed alcohols, 1.6% isomenthol, 10.3% neoiso-menthol; and 13% of their esters; in contrast to 8% menthone with 0.1% menthol, 5.0% neo-menthol, and 1.7% esters. Self-pollination of strain 69–296 gave a 3:1 ratio of high isomenthone: high menthone. Crosses with a true breeding high menthone plant having 80% menthone and 3.2% isomenthone gave a 1:1 ratio of the parental phenotypes by GLC analyses and herbage odor. This and data from high isomenthone and high menthone crosses with tester strains lead us to postulate the involvement of a single locus having multiple alleles with true breeding menthone having the genotype P^s P^s, true breeding isomenthone P^r P^r, 69–296 P^r P^s, and high pulegone pp. The P^r allele is not completely dominant over the P^s allele in 69–296 as about 18% of the total ketone derived from pulegone is menthone. Both are dominant over the recessive allele p that largely prevents menthone development. The quantitative amounts of the two isomers are believed to be controlled by the six combinations of the three alleles in a diploid species with graded effects obtained in the more complex genotypes possible in double diploid and octoploid species. 69–296 has (?)-piperitone even though (+)-piperitone is believed to be the common isomer in Mentha.     

Shade-avoidance responses in two common coastal redwood forest species,Sequoia sempervirens (Taxodiaceae) and Satureja douglasii (Lamiaceae), occurring in various light quality environments

Shade-avoidance responses were examined for two species common to the coastal redwood forest, Sequoia sempervirens and Satureja douglasii. Sequoia seedlings demonstrated a shade-avoidance response when given end-of-day far-red light by increased hypocotyl, epicotyl, and first-node extension, and greater total number of needles and reduced anthocyanin concentration. Thus, Sequoia seedlings respond as sun-adapted plants. Satureja has several leaf monoterpene chemotypes that occur in different light environments including the redwood forest, and the types responded differently to the light treatments. The pulegone type responded to end-of-day far-red light as a sun-adapted plant with significant extension growth, increased leaf area and chlorophyll, and reduced anthocyanin. The isomenthone type responded as a shade-tolerant plant and did not exhibit extension growth nor a change in other parameters with end-of-day far-red light. However, the carvone and bicyclic types had variable responses depending on the parameter studied, which indicated genetic variation for these traits.     

Decoupling subgenomes within hybrid lavandin provide new insights into speciation and monoterpenoid diversification of Lavandula

Polyploidization and transposon elements contribute to shape plant genome diversity and secondary metabolic variation in some edible crops. However, the specific contribution of these variations to the chemo-diversity of Lamiaceae, particularly in economic shrubs, is still poorly documented. The rich essential oils (EOs) of Lavandula plants are distinguished by monoterpenoids among the main EO-producing species, L. angustifolia (LA), L. × intermedia (LX) and L. latifolia (LL). Herein, the first allele-aware chromosome-level genome was assembled using a lavandin cultivar ‘Super’ and its hybrid origin was verified by two complete subgenomes (LX-LA and LX-LL). Genome-wide phylogenetics confirmed that LL, like LA, underwent two lineage-specific WGDs after the γ triplication event, and their speciation occurred after the last WGD. Chloroplast phylogenetic analysis indicated LA was the maternal source of ‘Super’, which produced premium EO (higher linalyl/lavandulyl acetate and lower 1,8-cineole and camphor) close to LA. Gene expression, especially the monoterpenoid biosynthetic genes, showed bias to LX-LA alleles. Asymmetric transposon insertions in two decoupling ‘Super’ subgenomes were responsible for speciation and monoterpenoid divergence of the progenitors. Both hybrid and parental evolutionary analysis revealed that LTR (long terminal repeat) retrotransposon associated with AAT gene loss cause no linalyl/lavandulyl acetate production in LL, and multi-BDH copies retained by tandem duplication and DNA transposon resulted in higher camphor accumulation of LL. Advances in allelic variations of monoterpenoids have the potential to revolutionize future lavandin breeding and EO production.     

An enone reductase from Nicotiana tabacum: cDNA cloning, expression in Escherichia coli, and reduction of enones with the recombinant proteins

In the course of the purification of enone reductase participating to the reduction of pulegone, two reductases (NtRed-1 and NtRed-2) were isolated from cultured cells of Nicotiana tabacum. The partial amino acid sequences of the reductases revealed that NtRed-1 was allyl-alcohol dehydrogenase (Accession No. BAA89423) and NtRed-2 was malate dehydrogenase (Accession No. CAC12826). cDNA cloning and expression of these reductases in Escherichia coli were performed. Reduction with recombinant proteins was examined with cyclic α,β-unsaturated ketones, such as pulegone, carvone and verbenone, as substrates. It was found that the recombinant NtRed-1 catalyses the hydrogenation of the exocyclic C-C double bond of pulegone.     

Changes in monoterpene composition of Mentha aquatica produced by gene substitution from a high limonene strain of M. Citrata

The dominant gene Lm that causes 60–90% limonene/cineole was substituted into M. aquatica by four convergent backcrosses. The natural strain of M. aquatica has 7·7% cineole, 4·9% limonene, traces of terpinolene and pulegone, 0·1% menthone, 0.2% menthol, and 66·4% menthofuran. The two modified hybrid strains with dominant gene Lm have 53·8 and 78·7% limonene/cineole and a total of only 1·0-3·8% 3-oxygenated compounds in contrast to a total of 66·7% found in the natural strain. The postulate is made that the Lm gene largely prevents either the conversion of a-terpineol → terpinolene or of limonene → isopiperitenone and that in these strains the recessive cc genotype largely but not completely prevents the conversion of limonene → carvone resulting in limonene accumulation. Mentha species almost invariably have either 2-oxygenated or 3-oxygenated compounds, not both. Close coupling phase linkage of the genes Lm and C explains why the self-pollinated progeny of M. spicata or M. crispa C-Lm/c-lm have a ratio of 3 carvone/dihydrocarvone: 1 pulegone/menthone rather than a ratio of 9 carvone : 3 limonene : 3 carvone and menthone: 1 menthone which would be expected if the genes Lm and C were independently inherited     

Essential Oils of Micromeria dalmatica Benth., a Balkan Endemic Species of Section Pseudomelissa

The essential oils of 13 Greek populations of Micromeria dalmatica, a Balkan endemic species and member of the section Pseudomelissa, were examined for the first time. Among the studied populations, two main oil types could be distinguished. Type I was found to be rich in β‐pinene, limonene, and germacrene D (accounting for 55.6–70.2% of the total oil), and Type II was characterized by the preponderance of p‐menthane compounds (accounting for 64.2–89.9% of the oil). The latter oil type could be further divided into two subtypes, one comprising oils with predominance of piperitenone and piperitenone oxide and another composed of oils containing high proportions of pulegone, menthone, and isomenthone. The abundance of p‐menthane compounds is a common feature of the oils of all members of the section Pseudomelissa studied to date. However, the existence of oils of Type I has not been previously reported for M. dalmatica, neither for other members of the section Pseudomelissa.     

Biocidal Compounds from Mentha sp. Essential Oils and Their Structure–Activity Relationships

Essential oils from Greek Mentha species showed different chemical compositions for two populations of M. pulegium, characterized by piperitone and pulegone. Mentha spicata essential oil was characterized by endocyclic piperitenone epoxide, piperitone epoxide, and carvone. The bioactivities of these essential oils and their components have been tested against insect pests (Leptinotarsa decemlineata, Spodoptera littoralis and Myzus persicae), root‐knot nematodes (Meloydogine javanica) and plants (Lactuca sativa, Lolium perenne, Solanum lycopersicum). The structure–activity relationships of these compounds have been studied including semi‐synthetic endocyclic trans‐carvone epoxide, exocyclic carvone epoxide, a new exocyclic piperitenone epoxide and trans‐pulegone epoxide. Leptinotarsa decemlineata feeding was affected by piperitenone and piperitone epoxide. Spodoptera littoralis was affected by piperitone epoxide and pulegone. The strongest nematicidal agent was piperitenone epoxide, followed by piperitone epoxide, piperitenone and carvone. Germination of S. lycopersicum and L. perenne was significantly affected by piperitenone epoxide. This compound and carvone epoxide inhibited L. perenne root and leaf growth. Piperitenone epoxide also inhibited the root growth of S. lycopersicum. The presence of a C(1) epoxide resulted in strong antifeedant, nematicidal and phytotoxic compounds regardless of the C(4) substituent. New natural crop protectants could be developed through appropriate structural modifications in the p‐menthane skeleton.     

Plant protection in sustainable systems of agriculture

Abstract

A comprehensive evaluation of 13 plant essential oils namely: caraway, chenopodium, cinnamon, clove, eucalyptus, garlic, geranium, lemon, matrecary, peppermint, rose, rosemary and thyme and 14 of their monoterpenoidal constituents: borneol, camphor, carvacrol, carveol, carvone (R and S), chlorothymol, cineol, cinnamaldehyde, citronellol, eugenol, geraneol, menthol, and thymol was investigated for their antibacterial activity against the two phytopathogenic bacteria, Agrobacterium tumefaciens and Erwinia carotovora var carotovora. Trials for improving the antibacterial activity by either structure modification or mixing with the three synergists: piperonyl butoxide, Triton X-100 and Tween 20 were achieved. New N-methyl carbamate derivatives based on monoterpenoids were introduced. Cinnamon, clove, chenopodium, caraway, rosemary and thyme oils proved to possess good antibacterial activity. Thymol, chlorothymol, and carvacrol were potent against the tested bacteria and quite close to the effect of the standard. Conversion of menthol into its carbamate derivative gave good enhancement in the bactericidal activity at all concentrations compared to menthol itself. Also, the carbamate derivatives of β-citronellol and borneol improved the bactericidal activity against E. carotovora, but decreased it against A. tumefaciens. Synergistic antibacterial activity of the tested monoterpenoids was observed when combined with each of the three synergists particularly with Triton X-100.     

裂叶荆芥花穗腺鳞代谢规律研究

为揭示荆芥穗腺鳞在不同开花序列中数量性状及内含物的代谢规律,本实验通过对荆芥穗不同开花序列的萼片进行腺鳞密度及半径的测算,以腺鳞指数拟合评价其数量性状的动态变化;同时对不同开花序列腺鳞内含物中6种单萜类成分(β-月桂烯、d-柠檬烯、dl-薄荷酮、薄荷呋喃、胡薄荷酮、β-石竹烯)进行气相色谱检测与定量研究。结果显示:腺鳞的主要发生阶段为开花前期,并于开花期基本完成;荆芥穗开花后,腺鳞因受到外界因素的影响数量逐渐减少;以D10轮为界,腺鳞中对薄荷烷型单萜类成分的代谢过程存在明显的物候迭代规律,并致使胡薄荷酮在腺鳞内含物中蓄积。说明荆芥穗腺鳞于开花期基本完成其数量性状增长及内含物的合成,但薄荷酮、薄荷呋喃、β-石竹烯等化合物在开花后期仍处于旺盛代谢状态,并且其含量变化可直接造成荆芥穗药效性质的改变,因此D10轮可作为荆芥穗的采收节点。     

Variation of Satureja douglasii monoterpenoids in relation to light intensity and herbivory

Genotypic variation of monoterpenoid yield and composition in Satureja douglasii was shown by growth of clonal transplants under uniform conditions. Differentiation of monoterpenoid yield was correlated with light intensity and degree of herbivory along transects. High-yielding genotypes occurred under low light, high herbivory conditions, whereas low-yielding genotypes occurred in high light, low herbivory conditions. Differentiation of monoterpenoid composition was more weakly correlated with herbivory and light intensity than was yield. There was also some evidence for seasonal variations of yield.     

Distribution of gastropods in floodplain compartments and feeding preferences for river corridor plant species: Is there an effect of gastropod herbivory on the distribution of river corridor plants?

Herbivory through gastropods has among others been proposed as a potential factor responsible for the river corridor distribution of plant species, which is a well known but poorly understood ecological pattern. Since floodplains are characterised by seasonally changing abiotic conditions, viz. floods during winter and spring and severe summer drought that are unsuitable for gastropods they may present safe habitats for highly palatable plant species.In the present study we compared species composition of gastropods and vegetation of twelve grassland sites situated within three floodplain compartments along the Upper Rhine. Additionally, we studied the palatability of 7 days and 25 days old seedlings of five typical floodplain plant species and five mesic grassland species to the slug Deroceras reticulatum in laboratory experiments.Our results showed that both vegetation and gastropod community composition but not gastropod diversity and abundance differed between floodplain compartments. Owing to omnivory of most gastropods the similarity structure of sites based on plants and gastropods was not significantly correlated. In general, slug herbivory significantly reduced survival and biomass of 7 days old seedlings, but responses were species-specific. In contrast, with the exception of Arabis nemorensis, Viola pumila and Taraxacum sect. Ruderalia biomass of 25 days old seedlings was not significantly affected by slug herbivory. Although the response of floodplain plant species as a group to slug herbivory did not differ from common grassland species, our results suggest that gastropods may potentially influence the distribution pattern of the highly palatable river corridor species Arabis nemorensis and Viola pumila. However, further research is needed to estimate the damage to river corridor plants through gastropod herbivory and its effect on competitive relationships under natural conditions.     

Investigation of monoterpenoids rich essential oils of two Ocimum basilicum L. varieties at different agro-climatic conditions in India

India is an emerging basil essential oil producer in South-east Asia. Two high essential oil yielding hybrids, namely one inter specific hybrid between of O. basilicum and O. kilimandscharicum Gürke (HYBL-1) and another intraspecific hybrid of O. basilicum × O. basilicum (OBL-1) of basil were analyzed using GC, enantiomeric GC, NMR, enantio-GC–MS and GC–MS methods. Inter specific hybrid HYBL-1 contained high essential oil-rich in linalool (68.5%), camphor (8%), and 1,8-cineole (4.6%) as characteristic constituents among monoterpenoids, whereas β-caryophyllene (1.9%), germacrene D (1.0%), and epi-α-cadinol (1.9%) were the sesquiterpenoids at the Lucknow (North Indian conditions) and linalool (71.8%), camphor (9.4%) and 1,8-cineole (4.3%) at Hyderabad (South Indian conditions) locations. Intraspecific hybrid (OBL-1) possessed linalool (66.1%), 1,8-cineole (5.4%) and geraniol (8.6%) with sesquiterpenoids in low proportions. Inter specific hybrid HYBL-1 showed superiority over OBL-1 in the multi-location trials conducted at Lucknow and Hyderabad. Average mean performance of inter specific hybrid over locations was: herb yield 44.80 t/ha, oil content 0.63%, oil yield 188.50 kg/ha, linalool content 67.65%, camphor content 8.90% v/s OBL-1 herb yield 21.32 t/ha, oil content 0.53%, oil yield 97.50 kg/ha, linalool content 65.55%, camphor content 0.00%, respectively. The essential oil of these two hybrids subjected to enantiomer differentiation revealed a high enantiomeric excess for (3R) -(?)-linalool, whereas (1R)- (+)-camphor was recorded exclusively in inter specific hybrid. The extensive NMR experiments were performed to confirm constituents in these hybrids and found that NMR spectroscopy could also be an ideal tool for the differentiation of essential oils from commercial samples declared as natural.     

Monoterpenoids and their glycosides from the leaf of thyme

From the polar portion of the methanol extract of thyme (leaf of Thymus vulgaris; Labiatae), which has been used as an important stomachic, carminative, a component of prepared cough tea, and a spice, seven monoterpenoid glycosides were isolated together with two known monoterpenoids and three known monoterpenoid glucosides. Structures of the seven monoterpenoid glycosides were determined by spectral analysis.