Leaf Terpenoids Research Articles

Supercritical CO2 Extraction of Terpenoids from Indocalamus latifolius Leaves: Optimization, Purification, and Antioxidant Activity.

This study aimed to investigate the efficacy of supercritical CO2 (SC-CO2) extraction in enhancing the extraction rate, purity, and antioxidant activity of Indocalamus latifolius (Keng) McClure (Poaceae) leaf terpenoids (ILLTs). Crude extracts obtained from leaves were subjected to qualitative and quantitative analyses, revealing neophytadiene, phytol, β-sitosterol, β-amyrone, squalene, and friedelin as the primary terpenoid constituents, identified through gas chromatography-mass spectrometry (GC-MS). Compared with steam distillation extraction (SD), simultaneous distillation extraction (SDE), ultra-high pressure-assisted n-hexane extraction (UHPE-Hex), ultra-high pressure-assisted ethanol extraction (UHPE-EtOH), ultrasound-assisted n-hexane extraction (UE-Hex), and ultrasound-assisted ethanol extraction (UE-EtOH), SC-CO2 exhibited a superior ILLT extraction rate, purity, and antioxidant activity. Scanning electron microscopy (SEM) observations of the residues further revealed more severe damage to both the residues and their cell walls after SC-CO2 extraction. Under optimal parameters (4.5 h, 26 MPa, 39 °C, and 20% ethyl alcohol), the ILLT extraction rate with SC-CO2 reached 1.44 ± 0.12 mg/g, which was significantly higher than the rates obtained by the other six methods. The subsequent separation and purification using WelFlash C18-l, BUCHI-C18, and Sephadex LH-20 led to an increase in the purity of the six terpenoid components from 12.91% to 93.34%. Furthermore, the ILLTs demonstrated cytotoxicity against HepG2 cells with an IC50 value of 148.93 ± 9.93 μg/mL. Additionally, with increasing concentrations, the ILLTs exhibited an enhanced cellular antioxidant status, as evidenced by reductions in both reactive oxygen species (ROS) and malondialdehyde (MDA) levels.

Intraspecific chemodiversity provides plant individual- and neighbourhood-mediated associational resistance towards aphids.

Some plant species express an extraordinarily high intraspecific diversity in phytochemicals (= chemodiversity). As discussed for biodiversity, higher chemodiversity may provide better protection against environmental stress, including herbivory. However, little is known about whether the resistance of a plant individual towards herbivores is mostly governed by its own chemodiversity or by associational resistance provided by conspecific neighbours. To investigate the role of chemodiversity in plant-aphid interactions, we used the Asteraceae Tanacetum vulgare, whose individuals differ pronouncedly in the composition of leaf terpenoids, forming distinct chemotypes. Plants were set up in a field consisting of plots containing five individuals of either the same or different chemotypes. Presence of winged aphids, indicating attraction, and abundance of winged and unwinged aphids, indicating fitness, were counted weekly on each plant. During the peak abundance of aphids, leaf samples were taken from all plants for re-analyses of the terpenoid composition and quantification of terpenoid chemodiversity, calculated on an individual plant (Shannon index, Hsind, also considered as α-chemodiversity) and plot level (Hsplot, = β-chemodiversity). Aphid attraction was neither influenced by chemotype nor plot-type. The real-time odour environment may be very complex in this setting, impeding clear preferences. In contrast, the abundance was affected by both chemotype and plot-type. On average, more Uroleucon tanaceti aphids were found on plants of two of the chemotypes growing in homogenous compared to heterogenous plots, supporting the associational resistance hypothesis. For Macrosiphoniella tanacetaria aphids, the probability of presence differed between plot-types on one chemotype. Terpenoid chemodiversity expressed as a gradient revealed negative Hsplot effects on U. tanaceti, but a positive correlation of Hsind with M. tanacetaria abundance. Aphids of M. fuscoviride were not affected by any level of chemodiversity. In conclusion, this study shows that not only the chemotype and chemodiversity of individual plants but also that of conspecific neighbours can influence certain plant-herbivore interactions. These effects are highly specific with regard to the plant chemotype and differ between aphid species and their morphs (winged vs. unwinged). Furthermore, our results highlight the importance of analysing chemodiversity at different levels.

GENETIC VARIATION AND EVOLUTION OF SECONDARY COMPOUNDS IN NATIVE AND INTRODUCED POPULATIONS OF THE INVASIVE PLANTMELALEUCA QUINQUENERVIA

We examined multivariate evolution of 20 leaf terpenoids in the invasive plant Melaleuca quinquenervia in a common garden experiment. Although most compounds, including 1,8-Cineole and Viridiflorol, were reduced in home compared with invaded range genotypes, consistent with an evolutionary decrease in defense, one compound (E-Nerolidol) was greater in invaded than home range genotypes. Nerolidol was negatively genetically correlated with Cineole and Viridiflorol, and the increase in this compound in the new range may have been driven by this negative correlation. There was positive selection on all three focal compounds, and a loss of genetic variation in introduced range genotypes. Selection skewers analysis predicted an increase in Cineole and Viridiflorol and a decrease or no change in Nerolidol, in direct contrast to the observed changes in the new range. This discrepancy could be due to differences in patterns of selection, genetic correlations, or the herbivore communities in the home versus introduced ranges. Although evolutionary changes in most compounds were consistent with the evolution of increased competitive ability hypothesis, changes in other compounds as well as selection patterns were not, indicating that it is important to understand selection and the nature of genetic correlations to predict evolutionary change in invasive species.

Cryptic speciation between Juniperus deltoides and Juniperus oxycedrus (Cupressaceae) in the Mediterranean

Analyses of individuals classically treated as Juniperus oxycedrus L. var. oxycedrus from Morocco, Portugal, Spain, France, Italy, Greece and Turkey, using DNA sequencing of nrDNA (ITS 1, 5.8S, ITS 2) plus RAPDs, leaf terpenoids and morphology revealed that two cryptic, genetically distinct but morphologically almost identical species are present. These species, J. oxycedrus L. var. oxycedrus and Juniperus deltoides R.P. Adams, are about as different from each other as Juniperus navicularis and Juniperus macrocarpa are from J. oxycedrus var. oxycedrus. Examination of herbarium specimens revealed that the two species are largely allopatric with J. deltoides occurring from Italy eastward through Turkey into the Caucasus Mts. and Iran. J. oxycedrus var. oxycedrus appears to be largely concentrated west of Italy (France, Spain, Portugal, Morocco). Cryptic speciation is discussed.

PODOPHYLLOTOXIN CONTENT IN LEAVES OF EASTERN RED CEDAR (JUNIPERUS VIRGINIANA)

PODOPHYLLOTOXIN CONTENT IN LEAVES OF EASTERN RED CEDAR (JUNIPERUS VIRGINIANA)

Plant genetics affects arthropod community richness and composition: evidence from a synthetic eucalypt hybrid population.

To examine how genetic variation in a plant population affects arthropod community richness and composition, we quantified the arthropod communities on a synthetic population of Eucalyptus amygdalina, E. risdonii, and their F1 and advanced-generation hybrids. Five major patterns emerged. First, the pure species and hybrid populations supported significantly different communities. Second, species richness was significantly greatest on hybrids (F1 > F2 > E. amygdalina > E. risdonii). These results are similar to those from a wild population of the same species and represent the first case in which both synthetic and wild population studies confirm a genetic component to community structure. Hybrids also acted as centers of biodiversity by accumulating both the common and specialist taxa of both parental species (100% in the wild and 80% in the synthetic population). Third, species richness was significantly greater on F1s than the single F2 family, suggesting that the increased insect abundance on hybrids may not be caused by the breakup of coadapted gene complexes. Fourth, specialist arthropod taxa were most likely to show a dominance response to F1 hybrids, whereas generalist taxa exhibited a susceptible response. Fifth, in an analysis of 31 leaf terpenoids that are thought to play a role in plant defense, hybrids were generally intermediate to the parental chemotypes. Within the single F2 family, we found significant associations between the communities of individual trees and five individual oil components, including oil yield, demonstrating that there is a genetic effect on plant defensive chemistry that, in turn, may affect community structure. These studies argue that hybridization has important community-level consequences and that the genetic variation present in hybrid zones can be used to explore the genetic-based mechanisms that structure communities.

Chemical differentiation between leaves of seedlings and spatially close adult trees from the tropical rain‐forest species Nectandra ambigens (Lauraceae): an alternative test of the Janzen–Connell model

1. We tested the hypothesis of Langenheim and Stubblebine that differences in chemical composition between maternal trees and the seedlings under them arise from differential mortality; only seedlings different from the mother survive. Such mortality could explain at least some of the cases where seedlings accumulate under adult conspecifics, contrary to the extreme form of the Janzen–Connell hypothesis. 2. We investigated Nectandra ambigens (Lauraceae), an upper‐canopy tree at Los Tuxtlas tropical rain forest, Mexico, whose seedlings survive under the canopy of conspecific trees. We analysed chromatographic profiles of leaf terpenoids of 15 groups, each formed by an adult tree and its surrounding seedlings. 3. We predicted that seedlings chemically similar to the adult would be absent under the tree canopy and that they would be present outside that canopy. We also predicted that younger seedlings would be more similar to the adult than the older ones. 4. Chemical similarity analyses showed that most seedlings were significantly different from their closest adult and thus supported the Langenheim and Stubblebine hypothesis. However, we did not find chemical differentiation among seedlings regarding their age or their position inside or outside the tree canopy.

Geographic variation and systematics of monospermous Juniperus (cupressaceae) from the Chihuahua Desert based on rapds and terpenes

Random amplified polymorphic DNAs (RAPDs) and the steam volatile leaf terpenoids of Juniperus erythrocarpa, J. monosperma var. monosperma, J. m. var. gracilis and J. pinchotii were analyzed by principal coordinate analyses and contour mapping. Juniperus monosperma var. gracilis was elevated to specific rank as J. angosturana R. P. Adams nom. nov.; J. erythrocarpa var. erythrocarpa was treated as a segregate of J. pinchotii; and J. erythrocarpa var. coahuilensis was accepted as a distinct species, J. coahuilensis (M. Martinez) Gaussen ex. R. P. Adams. Geographic and chemical analyses of J. coahuilensis suggests that hybridization and introgression with J. angosturana has been factor in the variation of this taxon. RAPDs and terpene data supported the recognition of Arizona-New Mexico populations of J. coahuilensis as a new variety, J. c. var. arizonica R. P. Adams, var. nov. In addition, several terpenoids previously reported as unknown are now identified.

Geographic variation in the volatile terpenoids of Juniperus monosperma and J. osteosperma

The steam volatile leaf terpenoids of Juniperus monosperma and J. osteosperma were analyzed by principal coordinate analyses. Juniperus monosperma was found to have the least amount of populational variability of any juniper in North America analyzed to date. The major trend found was a east-west cline. Analyses of J. osteosperma populations revealed typical infra-specific variation with a major north-south trend. Some limited hybridization might be possible between the taxa south of Shiprock, New Mexico. In addition, several terpenoids previously tentatively identified or unidentified are now identified.

Systematic relationships in Juniperus based on random amplified polymorphic DNAs (RAPDs).

SummaryAdams, R. P. & Demeke, T.: Systematic relationships in Juniperus based on random amplified polymorphic DNAs (RAPDs). – Taxon 42: 553–571. 1993. – ISSN 0040‐0262.44 taxa of Juniperus were analysed using RAPDs, similarity measures and principal coordinate analyses (PCO). The three sections of Juniperus (sect. Caryocedrus, sect. Juniperus, sect. Sabina) were found to be distinguished by RAPDs. The genus appears to be naturally divided into three major sections with two series (serrate and smooth leaf margins) in J. sect. Sabina. Additional examinations of specific and infraspecific taxa confirms earlier taxonomic work based on leaf terpenoids. Computer software (PCO3D from R.P.A.) for PCO is introduced for the analysis of RAPDs. RAPDs were found to be of taxonomic use ranging from sectional to varietal levels.

Variations in leaf terpenoids with ploidy level in citrus cultivars and hybrids

The leaves of six diploid and six tetraploid citrus taxa contain monoterpenes, sesquiterpenes, phytol, β-amyrin and three phytosterols. The total amounts of lower terpenoids and phytosterols per gram fresh weight of leaf decreased with increasing ploidy level. The same trend was apparent when the amounts of the individual terpenoid components were analysed, although the phytosterol composition showed less variation than in the case of the lower terpenoids.

EVIDENCE FOR ABSORPOTION OF EUCALYPT ESSENTIAL OILS BY PAROPSZS ATOMARZA OLIVIER (COLEOPTERA. CHRYSOMELIDAE)

AbstractA terpenoid budget was constructed for Paropsis atomariu (Olivier) feeding on Eucalyptus blakelyi Maiden leaves to determine if larvae absorbed leaf terpenoids. Groups of larvae were fed leaves which contained a range of terpenoid concentrations (1–7.9%). The amounts of terpenoids consumed and excreted by each group were determined. Calculation of the ‘expected’ concentration of terpenoids in the excreta was calculated based on the digestive efficiency of each larval group and the assumption that terpenoids passed unaffected through the digestive system.Comparisons of the amounts of terpenoids excreted with amounts expected if no absorption occurred showed that larvae absorbed a major proportion of ingested terpenoids. Larvae absorbed, or otherwise converted to other compounds, 86% of ingested cineole, a component which commonly makes up more than 75% of the total terpenoids in E. blakelyi. Analyses of larval tissue showed that leaf terpenoids were not present and therefore not sequestered. It is suggested that larvae metabolise leaf terpenoids.

GEOGRAPHIC VARIATION IN JUNIPERUS SILICICOLA AND J. VIRGINIANA OF THE SOUTHEASTERN UNITED STATES: MULTIVARIATE ANALYSES OF MORPHOLOGY AND TERPENOIDS

SummaryNatural populations of Juniperus silicicola were sampled from throughout the recorded range along the coast of North America. Additional populations of J. virginiana from inland sites were sampled. Morphological characters which have traditionally been used to separate the two taxa were measured along with analyses of the volatile leaf terpenoids. These data were analyzed by canonical variate analysis and contour mapping of the canonical variates. The amount of variation among inland populations of J. virginiana was comparable to the divergence of J. silicicola. The volatile leaf oils differed only quantitatively for a few components. Characters used in keys (female cone size, leaf tip shape) were not significantly different between the taxa. The populations in Texas, previously treated as J. silicicola, were found to be J. virginiana in both their morphology and chemistry. Some inter‐gradation was found between the Macon, Georgia and Brunswick, Georgia populations. The coastal, foredune juniper of the southeastern United States (J. silicicola), being circumscribed within the range of variation encountered within J. virginiana, is treated as a varietas (J. virginiana var. silicicola (Small) Silba).

Genetic Relationships Among Chemical Constituents in Seeds, Flower Buds, Terminals, and Mature Leaves of Cotton1

This experiment was conducted to determine the genetic association among chemical constituents considered to be associated with pest resistance of cotton (Gossypium hitsuture L.). Three replications of 39 cotton genotypes were grown in field plots at Stoneville, Miss. in 1977. Flower buds, terminals, and mature leaves of the genotypes were assayed for terpenoid aldehydes (including gossypol) and condensed tannis; seed were assayed for terpenoid aldehydes (including gossypol), oil, and protein. Cabbage looper [Trichoplusia ni (Hubner)] damage and lint percentages for all genotypes were determined.Seed and flower bud terpenoid contents were highly variable among genotypes. Although less variability was found for the remaining characteristics, all except leaf terpenoid content were significantly variable. Flower bud and terminal condensed tannins were significantly correlated (r = 0.67); each was moderately correlated with leaf condensed tannin (r = 0.41 and 0.45, respectively). Condensed tannin content of the plant parts was weakly correlated with terpenoid content.Lint percentages appeared to be independent of all chemical constituents measured. Seed oil was negatively correlated with flower bul (r _ ‐‐0.39) terpenoid content. Cabbage looper damage correlations of ‐‐0.46, ‐‐0.60, and ‐‐0.31 for flowerbud, terminals, and leaf terpenoids, respectively, were obtained. No relationship was found between looper damage and tannin content.