Morphology and development of secretory structures in Hypericum perforatum and H. richeri

Secretory organs are a specialised anatomical feature of plants, these tissues function in the production and/or storage of specific chemical substances, which often have pharmacological properties. The genus Hypericum is characterised by the presence of specialised secretory structures such as black nodules, translucent glands and secretory canals. The presence of these structures is not homogeneous for all the species or between the various floral and vegetative parts of the plants. In this study, we have compared the distributions, morphology and development of secretory structures in the leaves of H. perforatum and H. richeri. Whilst, black nodules occurred in both species, translucent glands followed different development stages depending on the leaf age.     

Inter-population variability of secondary metabolites in Hypericum spp. (Hypericaceae) of the Northern Apennines, Italy

Hypericum spp. flowers were collected from different sites of Northern Apennines in Italy and were analysed by HPTLC technique to determine their contents in flavonoids (rutin, hyperosid, quercitrin, isoquercitrin and quercetin) and hypericins (pseudohypericin and hypericin). The H. perforatum and H. richeri composition was evaluated in order to investigate the influence of ecological conditions on secondary metabolites production. The species studied showed some differences in the amounts of investigated metabolites and high variability was observed in populations gathered in different places. No significant effects of environmental factors on active compound production were observed, except for the rutin content which is in positive correlation with the altitude of the growing site. Interesting informations are also given about the morphology of secretory structures found in Hypericum richeri.     

Chemical Composition and Antimicrobial Activity of the Essential Oils from Several Hypericum Taxa (Guttiferae) Growing in Central Italy (Appennino Umbro‐Marchigiano)

The chemical composition of the essential oils of nine taxa from seven sections of Hypericum L. (Guttiferae; H. perforatum subsp. perforatum, H. perforatum subsp. veronense, H. calycinum, H. montanum, H. richeri subsp. richeri, H. hyssopifolium, H. hirsutum, H. hircinum subsp. majus, and H. tetrapterum) occurring in central Italy (Appennino Umbro‐Marchigiano) was analyzed by GC/FID and GC/MS. A total of 186 compounds were identified in the different species and subspecies, accounting for 86.9–92.8% of the total oils. The major fraction of the oil was always represented by sesquiterpene hydrocarbons (30.3–77.2%), while quantitative differences occurred between the other classes of volatiles depending on the taxa considered. Chemical composition of the nine Hypericum entities with respect to the taxonomical classification was discussed. Essential oils obtained from six taxa, i.e., H. perforatum subsp. perforatum, H. perforatum subsp. veronense, H. calycinum, H. richeri subsp. richeri, H. hirsutum and H. tetrapterum, were also tested for their antimicrobial properties against five different microbial strains by the broth‐microdilution method, and they were found to have significant activity (expressed as MIC) on B. subtilis, moderate activity on C. albicans and S. aureus, and weak activity on E. coli and E. faecalis, the most active being those from H. hirsutum, H. richeri subsp. richeri, and H. tetrapterum.     

Energy content,storage substances,and construction and maintenance costs of Mediterranean deciduous leaves

Summary At monthly intervals water content, crude fibre, total and protein nitrogen, sugars, starch, total lipids, ash content and calorific total energy were measured throughout the lifespan of the leaves of the deciduous mediterranean shrubs Pistacia terebinthus L. and Cotinus coggygria Scop. From these data the construction costs and maintenance costs, as well as the construction costs of non-storage compounds and energy expenditure values were calculated. The latter values were also calculated for the evergreen stemmed shrub Ephedra distachya for reasons of comparison with an evergreen mediterranean species. The water status in the deciduous leaves is stable for a long time during the drought period until the beginning of senescence in August/September. In Cotinus an early and considerable increase of storage compounds is found, whilst in Pistacia terebinthus the accumulation is more uniform until August. The N-content is rather low compared with other deciduous leaves, the calorific energy is in the lower range of the values reported for similar species. The construction costs of the leaves of both deciduous species are significantly lower than those calculated by Williams et al. (1987) for two drought deciduous chaparral species but are in agreement with the data reported by other authors on deciduous leaves. Contrary to the findings of Williams et al. they are lower than those of evergreen species; this is also true when the construction cost of the non-storage compounds alone is considered. The values found for Ephedra are similar to the maintenance costs do not show a significant variation in the deciduous leaves. They are higher than those known for evergreen leaves but somewhat lower than the values calculated for deciduous chaparral leaves.     

Higher amount of steviol detected in the leaves of a non-toxic endangered medicinal herb, <Emphasis Type="Italic">Aconitum heterophyllum</Emphasis>

Aconitum heterophyllum is the only non-toxic species of Aconitum genus having immense therapeutic potential. To date, only roots of this plant species are used for the preparation of various herbal formulations while leaves are discarded due to lack of information on the presence of any therapeutically active compounds. To the best of our knowledge, this is the first report on the detection and quantification of diterpene steviol in the leaves of A. heterophyllum. Interestingly, the level of steviol is equivalent to Stevia rebaudiana leaves which is the richest source reported so far. Thus, A. heterophyllum leaves will not only provide a novel source for extraction of steviol but also benefit the harvesters to get additional economic returns on leaf biomass for this high-value non-toxic plant species.     

Tree leaf chemical characters: selective pressures by folivorous primates and invertebrates

Plants have evolved a variety of chemical means to deter herbivory. Several studies have documented that secondary compounds are strong deterrents to certain herbivores, while others have demonstrated that some herbivores ingest large quantities of these compounds without exhibiting deleterious effects. This inconsistent response suggests that plants have evolved compounds to deter specific herbivores. Based on a study in Kibale National Park, Uganda, we explored how two major groups of herbivores, invertebrates and colobus monkeys, respond to chemical characteristics of leaves: protein, attractive from a nutritional perspective, and alkaloids, saponins and cyanogenic glycosides, which are all plant defences, detering herbivory. The intensity that colobus monkeys fed on leaves of different tree species was determined by observations (1300 h), and invertebrate herbivory was indexed by collecting leaves from 20 species and digitizing tracings to quantifying invertebrate damage. Invertebrate damage to leaves varied among species (1.5–22.5%), but showed no relationship with saponin or protein content, or the presence or absence of alkaloids. Colobine foraging effort did not relate to the saponin and protein of leaf species, nor to the presence or absence of alkaloids. Prunus africana, the only species to test positive for cyanogenic glycosides, was fed on by colobus monkeys for 8.1% of their foraging time, but, as it occurred at low densities, it was the most preferred species. These results can be interpreted in different ways. First, it is possible that inactive compounds are retained because they increase the probability of producing new active compounds. Secondly, the indices used to evaluate compound effects may be inappropriate. For example, monkeys may only be able to tolerate a toxin to a specific threshold in a single feeding session, but our index of foraging effort was averaged over the year. Thirdly, it may be that these compounds play an active role with organisms not considered (e.g. prevent fungal attack). Finally, these compounds may serve some unknown function and selection may operate for that purpose.     

The herbaceous lycophyte Haskinsia Grierson and Banks from the Devonian of western Venezuela, with observations on leaf morphology and fertile specimens

The Devonian herbaceous lycophyte genus Haskinsia Grierson and Banks is characterized by narrow dichotomizing stems and helically arranged petiolate leaves with a broad, approximately deltoid, lamina. New specimens are reported from four horizons in the Lower Member of the Campo Chico Formation, Sierra de Perijá, western Venezuela. H. sagittaka Edwards and Benedetto has sagittate leaves, and fertile specimens are reported for the first time; the ellipsoidal/obovoid adaxially-flattened sporangium is attached to unmodified leaves towards the top of the petiole in the adaxial position. H. sp. has sagittate leaves which are larger than any yet attributed to the genus but is represented by only three specimens. H. hastata sp. nov. has hastate leaves; the sporangia are more globose but positioned similarly to those of H. sagittata. The occurrence of the sporangia on unmodified microphylls indicates that Haskinsia is a member of Protolepidodendrales. The status of Haskinsiaceae is discussed. The Venezuelan specimens are compared with other records of Haskimi and Haskinsia -like plants from North America, Kazakhstan, North China, North Africa and Antarctica.     

Leaf structure of the cerrado (Brazilian savanna) woody plants

With the aim of recognizing the commonest leaf pattern found in the woody flora of the cerrado (the Brazilian savanna) we analyzed the leaf anatomy of 30 representative species. The leaves are mostly dorsiventral and hypostomatic and covered by trichomes and a thick layer of wax and cuticle; the vascular bundles are surrounded by a sheath of fibers. The mesophyll has a developed palisade tissue, dispersed sclerified cells and idioblasts bearing crystals and phenolic compounds. We compared the results with those reported for other species (60 species) from the same biome and for the families that the studied species belong. The present study suggests that the xeromorphism observed for the cerrado leaves is related to the evolutionary history of this biome, since its first floristic elements must have faced deficient water conditions as well as the consequent soil acidity and toxicity. Therefore we may infer that the leaf anatomical pattern here observed was already present in the first elements of the cerrado and was selected to guarantee the survival of those species in the new environment. Furthermore, the xeromorphic features present in those leaves continue nowadays to help the plants protecting themselves from the different biotic and abiotic factors they are subjected to.     

Caucasicosides E-M, furostanol glycosides from Helleborus caucasicus

Nine furostanol glycosides, namely caucasicosides E-M, were isolated from the MeOH extract of the leaves of Helleborus caucasicus, along with 11 known compounds including nine furostanol glycosides, a bufadienolide and an ecdysteroid. Their structures were established by the extensive use of 1D and 2D NMR experiments along with ESIMSⁿ analyses. The steroidal composition of leaves of H. caucasicus shows as particular feature the occurrence of steroidal compounds belonging to the 5β series, unusual for Helleborus species, and in particular, caucasicosides F-H are based on a 5β-polyhydroxylated steroidal aglycon never reported before.     

Diversity of phenolic compounds and plant traits in coexisting Patagonian desert shrub species of Argentina

Desert shrubs often accumulate different types of phenolic compounds but what determines the amount and diversity of these compounds is an issue scarcely explored. The aim of this study was to assess differences in the amount and diversity of phenolic compounds in leaves among coexisting shrub species differing in rooting depth and leaf turnover. We hypothesized that the diversity and amount of phenolic compounds in leaves of desert shrubs are related to access to soil water through rooting depth, and to leaf turnover. The study was carried out in the Patagonian Monte of Argentina. We collected green leaves of six species representing the dominant shrub morphotypes (tall evergreen, tall deciduous, and medium evergreen shrubs) and assessed lignin concentration and groups of soluble phenols obtained by sequential extraction with ethyl ether, ethyl acetate, and amyl alcohol. We also assessed nitrogen concentration in leaves and leaf mass per unit area (LMA) as traits related to leaf lifespan. The diversity of phenolic compounds was higher in green leaves of tall shrubs with deep rooting depth than in those of medium evergreen shrubs with shallow rooting depth. Diversity of phenolic compounds in green leaves was negatively related to lignin concentration. Evergreen shrubs had higher amount of phenolic compounds in green leaves than deciduous ones and the total amount of phenolic compounds in green leaves was positively related to LMA. We concluded that access to soil water sources and leaf turnover were related to the amount and diversity of phenolic compounds in green leaves of desert shrub species and these results are consistent with those predicted by the resource availability theory for plants from resource-rich and resource-poor habitats.     

Seasonal Changes in the Cytokinin Content of the Leaves of Salix babylonica

The young and old leaves of Salix babylonica contain at least four cell division-inducing compounds which coeluted with zeatin, zeatin riboside and their glucosylated derivatives. During the course of the growing season quantitative changes in the cytokinin content of the leaves were observed. The cytokinin glucosides increased as the leaves aged. The compounds which co-chromatographed with zeatin and zeatin riboside initially increased until early autumn and then decreased as the leaves senesced. It appears as though the cytokinins transported from the roots are metabolized in the leaves and are converted to their glucosides. Although it has been reported in the literature that Salix root exudate contains very small amounts of cytokinin in late summer and autumn, these compounds increase in the leaves for most of the growing season, suggesting that the leaves may not only obtain cytokinins from the roots but may well be an active site of cytokinin synthesis. It is, however, possible that cytokinins are also transported to the leaves via the phloem, thus accounting for their accumulation in these organs.     

Secretory structures and cytochemical investigation of the leaf of Phlomis fruticosa, a seasonally dimorphic subshrub. Secreting activity of the leaf-originating calluses

Various species of the genus Phlomis have been reported to produce metabolites demonstrating significant pharmacological efficiency. In mature summer leaves of Phlomis fruticosa several secretory cells and structures were detected. A spectrum of compounds was localized histochemically within them. Calluses produced from leaf-cell cultures were histochemically investigated as well. Callus cells, although of low-differentiation, are synthetically active and produce various compounds. Many of them could be of pharmaceutical interest.     

Morphogenetic and diurnal variation of hypericin in some Hypericum species from Turkey during the course of ontogenesis

The genus Hypericum has received considerable interest from scientists, as it is a source of a variety of biologically active compounds including the hypericins. The present study was conducted to determine ontogenetic, morphogenetic and diurnal variation of the total hypericins content in some species of Hypericum growing in Turkey namely, Hypericum aviculariifolium subsp. depilatum var. depilatum (endemic), Hypericum perforatum and Hypericum pruinatum. The Hypericum plants were harvested from wild populations at vegetative, floral budding, full flowering, fresh fruiting and mature fruiting stages four times a day. Plants were dissected into stem, leaf and reproductive tissues, which were dried separately, and subsequently assayed for total hypericin content. The density of dark glands on leaves at full flowering plants was determined for each species. Floral parts had the highest hypericin content in all species tested. But diurnal fluctuation in the hypericin content of whole plant during the course of ontogenesis varied among the species. It reached the highest level at floral budding and tended to increase at night in H. aviculariifolium subsp. depilatum var. depilatum and H. pruinatum, whereas in H. perforatum hypericin content was the highest at full flowering and no diurnal fluctuation was observed. In general, hypericin content of leaves and whole plant was higher in H. aviculariifolium subsp. depilatum var. depilatum whose leaves had more numerous dark glands than those of the two other species.     

Development of a synthetic plant volatile-based attracticide for female noctuid moths. II. Bioassays of synthetic plant volatiles as attractants for the adults of the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

This paper reports olfactometer studies to determine the attractiveness of synthetic equivalents of plant volatiles to Helicoverpa armigera (Hübner) moths. Synthetic volatiles identified from host plants and other volatiles reported in literature as attractants to various noctuid species were tested in a two-choice olfactometer. Of 34 single chemicals tested, only seven were significantly attractive, and six were significantly repellent. However, when presented as blends of two or more volatiles, 21 of 31 blends tested were significantly attractive, and only one was significantly repellent. The most attractive blends were those containing four to six components, including aromatic volatiles primarily found in flowers, especially 2-phenylethanol and phenylacetaldehyde and volatiles found primarily in leaves, including green leaf volatiles and terpenoids. Some general principles in blending volatiles for developing attracticides for H. armigera are presented, including the need for blend complexity, the combination of volatiles from leaves and flowers, and early consideration of pragmatic factors such as price and toxicological profile.     

Chemical composition of <Emphasis Type="Italic">Catha edulis</Emphasis> (khat): a review

Khat (Catha edulis) belongs to Celastraceae family which contains 60–70 genera and 850–900 species. It is an indigenous plant to Ethiopia and Yemen as the countries of origin. It is also found in many other east and southern African countries. Khat leaves are chewed by the local people for their stimulant action. The main active ingredient compounds those are responsible for this action is cathinone and a mild stimulant cathine. In addition to these khat contains several phytochemicals such as alkaloids (phenylalkylamines and cathedulins), flavonoids, steroid and triterpenoids, monoterpenes and volatile aromatic compounds, and other miscellaneous compounds like vitamins and amino acids. Hence, this paper presents a comprehensive and unified review of literatures which concerned on the phytochemical composition of khat plant. And it also provides the isolated compounds with their chemical structures.     

Hydrogen peroxide acts as a second messenger for the induction of defense genes in tomato plants in response to wounding, systemin, and methyl jasmonate

The systemic accumulation of both hydrogen peroxide (H(2)O(2)) and proteinase inhibitor proteins in tomato leaves in response to wounding was inhibited by the NADPH oxidase inhibitors diphenylene iodonium (DPI), imidazole, and pyridine. The expression of several defense genes in response to wounding, systemin, oligosaccharides, and methyl jasmonate also was inhibited by DPI. These genes, including those of four proteinase inhibitors and polyphenol oxidase, are expressed within 4 to 12 hr after wounding. However, DPI did not inhibit the wound-inducible expression of genes encoding prosystemin, lipoxygenase, and allene oxide synthase, which are associated with the octadecanoid signaling pathway and are expressed 0.5 to 2 hr after wounding. Accordingly, treatment of plants with the H(2)O(2)-generating enzyme glucose oxidase plus glucose resulted in the induction of only the later-expressed defensive genes and not the early-expressed signaling-related genes. H(2)O(2) was cytochemically detected in the cell walls of vascular parenchyma cells and spongy mesophyll cells within 4 hr after wounding of wild-type tomato leaves, but not earlier. The cumulative results suggest that active oxygen species are generated near cell walls of vascular bundle cells by oligogalacturonide fragments produced by wound-inducible polygalacturonase and that the resulting H(2)O(2) acts as a second messenger for the activation of defense genes in mesophyll cells. These data provide a rationale for the sequential, coordinated, and functional roles of systemin, jasmonic acid, oligogalacturonides, and H(2)O(2) signals for systemic signaling in tomato plants in response to wounding.     

Analysis of the volatile components of five Turkish Rhododendron species by headspace solid-phase microextraction and GC-MS (HS-SPME-GC-MS)

Volatile constituents of various solvent extracts (n-hexane, CH2Cl2, H2O) of 15 different organs (leaves, flowers, fruits) of five Rhododendron species (Ericaceae) growing in Turkey were trapped with headspace solid-phase microextraction (HS-SPME) technique and analyzed by GC-MS. A total of 200 compounds were detected and identified from organic extracts, while the water extracts contained only traces of few volatiles. The CH2Cl2 extract of the R. luteum flowers was found to exhibit the most diverse composition: 34 compounds were identified, with benzyl alcohol (16.6%), limonene (14.6%) and p-cymene (8.4%) being the major compounds. The CH2Cl2-solubles of R. x sochadzeae leaves contained only phenyl ethyl alcohol. This study indicated appreciable intra-specific variations in volatile compositions within the genus. Different anatomical parts also showed altered volatile profiles. This is the first application of HS-SPME-GC-MS on the volatiles of Rhododendron species.     

Antioxidant metabolites from Limonium brasiliense (Boiss.) Kuntze

A free radical scavenging activity guided fractionation of the polar extract from roots of Limonium brasiliense (Plumbaginaceae) led to the isolation of five active compounds including: myricetin 3-O-alpha-rhamnopyranoside (1), (-)-epigallocatechin 3-O-gallate (2), (-)-epigallocatechin (3), (+)-gallocatechin (4) and gallic acid (5). These and other chemical constituents are reported for the first time for this species. The characterization of these compounds was achieved by spectroscopic methods (1H NMR, 13C NMR and UV).     

Identification of anti-inflammatory constituents in Hypericum perforatum and Hypericum gentianoides extracts using RAW 264.7 mouse macrophages

Hypericum perforatum (St. John’s wort) is an herb widely used as supplement for mild to moderate depression. Our prior studies established synergistic anti-inflammatory activity associated with 4 bioactive compounds in a fraction of a H. perforatum ethanol extract. Whether these 4 compounds also contributed to the ethanol extract activity was addressed in the research reported here. Despite the popularity of H. perforatum, other Hypericum species with different phytochemical profiles could have their anti-inflammatory potentials attributed to these or other compounds. In the current study, ethanol extracts of different Hypericum species were compared for their inhibitory effect on LPS-induced prostaglandin E2 (PGE2) and nitric oxide (NO) production in RAW 264.7 mouse macrophages. Among these extracts, those made from H. perforatum and H. gentianoides demonstrated stronger overall efficacy. LC–MS analysis established the 4 compounds were present in the H. perforatum extract and pseudohypericin in all active fractions. The 4 compounds accounted for a significant part of the extract’s inhibitory activity on PGE2, NO, tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) in RAW 264.7 as well as peritoneal macrophages. Pseudohypericin was the most important contributor of the anti-inflammatory potential among the 4 compounds. The lipophilic fractions of H. gentianoides extract, which did not contain the previously identified active constituents, decreased PGE2 and NO potently. These fractions were rich in acylphloroglucinols, including uliginosin A that accounted for a proportion of the anti-inflammatory activity observed with the active fractions. Overall, the current study established that a different group of major anti-inflammatory constituents were present in H. gentianoides, while showing that the previously identified 4 compound combination was important for H. perforatum’s anti-inflammatory potential.     

Expression in antennae and reproductive organs suggests a dual role of an odorant-binding protein in two sibling Helicoverpa species

Odorant-binding proteins (OBPs) mediate both perception and release of semiochemicals in insects. These proteins are the ideal targets for understanding the olfactory code of insects as well as for interfering with their communication system in order to control pest species. The two sibling Lepidopteran species Helicoverpa armigera and H. assulta are two major agricultural pests. As part of our aim to characterize the OBP repertoire of these two species, here we focus our attention on a member of this family, OBP10, particularly interesting for its expression pattern. The protein is specifically expressed in the antennae of both sexes, being absent from other sensory organs. However, it is highly abundant in seminal fluid, is transferred to females during mating and is eventually found on the surface of fertilised eggs. Among the several different volatile compounds present in reproductive organs, OBP10 binds 1-dodecene, a compound reported as an insect repellent. These results have been verified in both H. armigera and H. assulta with no apparent differences between the two species. The recombinant OBP10 binds, besides 1-dodecene, some linear alcohols and several aromatic compounds. The structural similarity of OBP10 with OBP1 of the mosquito Culex quinquefasciatus, a protein reported to bind an oviposition pheromone, and its affinity with 1-dodecene suggest that OBP10 could be a carrier for oviposition deterrents, favouring spreading of the eggs in these species where cannibalism is active among larvae.