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The chemical composition of preen gland secretions of antbirds (Thamnophilidae and Formicaridae) and phylogenetically closely related Dendrocolaptidae, Tyrannidae and Pipridae were investigated to understand the role of environment in secretion components. The secretions of Thamnophilidae consisted of long chain acids, alcohols, esters, unsaturated hydrocarbons, and isoprenoids. Formicaridae secretions contained exclusively squalene and its derivatives. In Pipridae, secretions were made up of complex long chain esters. In Dendrocolaptidae, the secretions consisted of long chain esters of both saturated and monounsaturated acids combined with mono-alcohols and those of Tyrannidae consisted of long chain esters of saturated, mono- and tri-unsaturated acids with mono- and di-ols that were less complex. Higher molecular weight saturated and unsaturated components in tropical species suggest that the volatility of the secretion components is correlated to environmental temperatures experienced by the birds. Squalene is a precursor in steroid biosynthesis, but higher amounts in Formicaridae secretions suggest that it may have some additional functions.

Passeriformes is the largest order of birds and includes one third of the bird species of the world, living in very diverse habitats. We investigated the chemistry of preen gland secretions of some groups of passerines from temperate regions found in diverse microhabitats. Some of the common components were mixtures of homologous monoesters made up of long chain acids and alcohols. Individual species had characteristic distribution of esters and was unique to a given species, although there were some individual variations. We compared the composition of acids and alcohols that formed same molecular weight esters in different species and we found that the combination of acids and alcohols to arrive at same molecular compositions varied distinctly between species. To compare compositions of over all acids and alcohols that formed the esters, the representative samples of secretions from the individual species were transesterfied the produce methyl esters and alcohols. We found that there were distinct differences in number of acids and alcohols that produced the combination of homologous mixtures of esters. Also they differed both qualitatively and quantitatively. There were also seasonal differences in the secretion components. Thus though the intact mixtures of esters in individual species had some similarities, they were very complex mixtures and differed characteristically for individual species. Here we discuss possible causes for evolution of these variations. We suggest that the evolution in variation of preen gland secretion is probably due to selective pressures caused by ectosymbionts such as feather-mites and feather-chewing lice that live on feathers and probably feed on the secretions and surrounding environments

In order to compare ant and non-ant defended species of Melastomataceae, production of hydrogen cyanide gas was tested in the field for 51 species of 10 genera of the tribe Miconieae. Using both the picric acid and the Feigl–Anger tests all populations surveyed tested negative for the presence of cyanogenic glycosides. These results confirm that cyanogenesis is rare in the family, although not completely absent. Cyanogenic glycosides are not responsible for the protection against herbivory in non-ant defended species, but this does not rule out that there are quantitative of qualitative differences in other secondary metabolites.

Addition of phenylmethanethiols (benzylthiols), including (2-furyl)methanethiol, to butadiynes in potassium hydroxide/dimethyl sulfoxide affords the corresponding 2,5-diaryl-3-(phenylmethyl)thiophenes.

A gel permeation chromatographic (GPC) method was developed for measuring the content and M r s of cis -polyisoprene in tissue cultures of guayule ( Parthenium argentatum ). Rubber production and growth rates were investigated in several morphogenetically distinct cultures, including normal and crown gall callus, and root and shoot cultures. These results were compared with rubber production in leaves and stems of whole plants. Tissue cultures yielded 1 to 10% of the rubber found in mature guayule stem tissue. The M r distributions of rubber from cultures were bimodal in contrast with that of rubber from whole plant stems which is unimodal. In the intact plant only the rubber from leaf tissue is bimodal with most of it contained in a M r fraction with a peak of 22 300. In contrast, the rubber peak in stems of young guayule plants was 500 000. Rubber from shoot and root cultures had average M r s of 150000 and 201 000 respectively, and normal and tumour callus cultures had M r s of 415 000 and 291 000. The ability of tissue cultures to make comparatively high M r rubber relative to whole plants supports the use of guayule tissue cultures for studies of rubber biosynthesis.

Several environmental and chemical factors affected rubber accumulation in guayule (Parthenium argentatum) tissue cultures. Light increased rubber yields in callus and shoot cultures by 50 and 450% respectively. The Mr of rubber in light-grown callus increased by 60%. Daily periods of incubating callus at 4° increased rubber yield by 70% after five weeks. Increasing sucrose levels up to 7% in the medium stimulated rubber synthesis, but higher levels were inhibitory. Osmotic stress significantly inhibited both rubber production and growth. Rubber production in callus was highest when the content of NO3− in culture medium was 30 mol% of total N when compared to NH4+. Two previously reported stimulators of rubber production in whole plants, acetate and DCPTA, also enhanced the levels of rubber in callus cultures.

Leaf beetles of the speciesTrirhabda geminata are specialized herbivores that are able to feed on the chemically well-protected foliage of the desert sunflowerEncelia farinosa, which contains the insecticidal chromene derivative encecalin. Chemical analysis of the beetles and their fecal excretions indicated that encecalin is present only in the alimentary canal and is not absorbed across the gut membrane, as previously shown for other herbivorous insects (e.g., the Egyptian armyworm,Spodoptera littoralis) that are susceptible to this chromene derivative. Further differences betweenT. geminata and nonadapted insects were observed with regard to the metabolism of encecalin. Whereas the encecalin-resistent leaf beetles metabolize encecalin mainly to encecalol by reduction of the acetyl group, susceptible insects, such as larvae ofS. littoralis, metabolize encecalin mainly by exoxidation of the 3,4 double bond, which creates a powerful alkylating agent and is responsible for the toxicity of encecalin. Reductive rather than oxidative metabolism of encecalin therefore seems important for the resistance ofT. geminata against the chemical defense of their host plantE. farinosa.

Age-specific concentrations of farinosin, a sesquiterpene lactone, and encecalin and euparin, both chromenes, were measured in two semi-desert populations of Encelia farinosa in California over a three month period. All three natural products differed significantly in concentration. The average concentration of encecalin is 10 times that of euparin and eight times that of farinosin. Farinosin concentrations did not differ between the two populations, but both euparin and encecalin were in higher amounts in the UC Riverside population than in the Home Gardens population. Seasonal changes in natural products differed at the 0.05 level for all populations and compounds except euparin in the UC Riverside population. Percent nitrogen content of dried leaves was similar in both populations, but differed between collection dates. Water content did not vary significantly with leaf age on one collection date. The significance of these results is discussed in the light of herbivore history.

Six plant-derived simple beta-carboline alkaloids and eight other plant derivatives were tested for activity against the protozoan parasite, Trypanosoma cruzi, the organism responsible for Chagas' disease. The plant alkaloids in this study were screened using an in vitro test against epimastigotes. Four beta-carboline indoles, a complex indole and five other alkaloids significantly reduced population growth of T. cruzi (Costa Rica strain) epimastigote forms at a concentration of 50 micrograms/ml or less.

β-Carboline alkaloids are found worldwide in many plant families. Harman, harmine, and other simple β-carboline alkaloids were tested for activity against a generalist phytophagous insect, the beet army worm [Spodoptera exigua (Hubner)]. Chronic dietary exposure tests (neonate to pupa) reveal potent antifeedant and possible toxic effects. Acute dietary exposure tests on fifth-instar larvae also demonstrate antifeedant activity.

Chemical studies of Psilostrophe cooperi afforded in addition to psilotropin, four unreported helenanolides, two methylated flavonoids and a new pseudoguaianolide, cooperin, with an unusual enol-moiety. The structure of cooperin was established by spectroscopic methods and confirmed by X-ray analysis. In addition, all the sesquiterpene lactones were tested for mutagenic activity.

This review discusses the biochemical action and ecological significance of phototoxic phytochemicals. Mechanistic details of photosensitization as well as cellular and molecular targets of plant-derived phototoxins in model biological systems (microbial and in vitro) and in herbivorous insects are described. Findings from these studies suggest the potential importance of phototoxic plant metabolites in plant-insect interactions. Aspects of phototoxin distribution and significance in diverse ecosystems are considered, and areas for future research are suggested.

Hydrogenolysis and homologation of 1-pentene to butenes and hexenes take place simultaneously and at the same rate over a Ru/SiO/sub 2/ catalysts at 110/sup 0/C, suggesting that these two reactions are mechanistically related. /sup 13/C labeling experiments indicate that C-C cleavage occurs at the double bond of 1-pentene-1-/sup 13/C leading to unlabeled 1-butene and labeled hexenes. The product distribution in the hydrogenolysis of 1-pentene, 2-pentenes, 3-methyl-1-butene, 2-methyl-2-butene, and 2-methyl-1-butene is accounted for by a carbene-olefin mechanism, which can therefore be considered as a reasonable common path for the formation and cleavage of carbon-carbon bonds on metal surfaces.

Summary Thiarubrines are dithiacyclohexadiene polyacetylenes displaying considerable antimicrobial activity. A culture that accumulates these compounds was obtained by selection of red-colored areas from crown gall tumor cultures of Chaenactis douglasii . The tumors were induced by A. tumefaciens strain A277. The main acetylenic products found were two thiarubrines, A and B, and their corresponding thiophenes. Average yields of thiarubrines and thiophenes were 2.5 and 0.24 mg/g dry weight respectively, which are similar to the values seen in intact plants. The products accumulate in intercellular spaces arranged around a core of vascular tissue, forming red nodules of varying size. The structures crudely resemble the tissue organization of the roots of this plant, the only organ where these compounds accumulate. Formation of rootlets, however, does not take place at any stage during the growth of the tumors. Evidence is presented suggesting that the accumulation of these polyacetylenes by the tumor line is not a direct result of cellular transformation but a secondary effect of the existing degree of tissue differentiation.

The distribution and quantitative significance of biosynthetically related di- and ter-thiophenes from 27 species representing seven genera of the Pectidinae (Heliantheae) was investigated by reverse-phase HPLC. Adenophyllum, Chrysactinia and Nicolletia , three previously unstudied genera, were found to contain thiophenes for the first time. Four derivatives, 5-(4-hydroxy-1-butenyl)-2,2′-bithiophene ( 1 ), 5-(4-acetoxy-1-butenyl)-2,2′-bithiophene ( 2 ), 5-(3-buten-1-ynyl)-2,2′-bithiophene ( 3 ) and 2,2′:5′,2″-terthiophene ( 4 ) were common constituents in most species of Adenophyllum, Chrysactinia, Dyssodia, Hymenatherum, Nicolletia and Porophyllum . One additional compound, 5-methyl-2,2′:5′,2″-terthiophene ( 5 ), was also present in extracts of Adenophyllum, Dyssodia and Hymenatherum , but was not detected in any other genus. Acetylenic thiophenes were not found in any of the 18 species of Pectis examined.

Over 20 taxa of the genus Partenium (Compositae) representing four sections or five ecological groupings from throughout the Americas, were examined for sesquiterpene lactones, flavonoids and alkaloids. The tropical thorn-forest, arborescent members (sect. Parthenichaeta) were found to contain three different sesquiterpene lactone types and derivatives of the flavonols; quercetin, kaempferol and quercetagetin. The desert shrubs were remarkable for their high production of methylated quercetagetin flavonols and alkaloids, but lacked any appreciable amounts of sesquiterpene lactones. The temperate, submontane perennials (sect. Bolophytum), contained lactones and flavonols in extremely low concentrations. The herbaceous annuals (sect. Argyrochaeta) contained pseudoguaianolides only and together with quercetin, and kaempferol O- glycosides . The herbaceous perennials contained twice as many lactones and flavonoids as the annuals. It is suggested that the ecogeographical distribution of secondary products in Parthenium is probably a result of adaptive responses to various physical and biotic factors (herbivore pressure) in the environment.

Sesquiterpene lactones are characteristic constituents of the Compositae but also occur sporadically in other angiosperm families and even in some liverworts. These bitter substances often contain as a major structural feature an α,β-unsaturated-γ-lactone, which in recent studies has been shown to be associated with anti-tumor, cytotoxic, anti-microbial and phytotoxic activity. They are known to poison livestock, to act as insect feeding deterrents and to cause allergic contact dermatitis in humans. This review highlights the present state of knowledge on the biological activities and mechanism of action of some sesquiterpene lactones.

Natural products isolated from various species of Parthenium were fed (in artificial diets) to the herbivorous insects Heliothis zea and Spodoptera exigua to assess the ability of the compounds to inhibit larval growth. Sesquiterpene esters and triterpenes from guayule ( P.argentatum ) were relatively non-inhibitory over a range of concentrations reflecting those in the plant. A quercetagetin-based methylated flavonoid from guayule was equitoxic to quercetin, whereas a kaempferol-based methylated flavonoid was stimulatory to both insect species. Sesquiterpene lactones from Parthenium were consistently inhibitory to H. zea ; those oxygenated at C-14 and/or C-15 (parthenolides) were more inhibitory than their unsubstituted ambrosanolide analogues. At a dietary concentration of 3.0 mM/kg fr. wt, tetraneurin-A (a parthenolide) reduced larval growth of H. zea by 88 % relative to controls in a chronic feeding bioassay.

Chromenes (benzopyrans) and benzofurans are characteristic natural products of certain tribes of the Asteraceae. This review highlights recent findings

The principal phenolic constituents were isolated from the exudate of the glandular trichomes of TURRICULA PARRYI, a California shrub that causes severe contact dermatitis. The phenolic constituents consist of a complex mixture of methoxylated flavones and derivatives of both farnesylhydroquinone and 3-farnesyl- P-hydroxybenzoic acid in which the C-7 methyl of farnesyl is replaced by hydroxymethyl, formyl and carboxyl groups. Elicitors of allergic contact dermatitis were identified with guinea pigs sensitized to the crude exudate. The principal agents of dermatitis were the farnesyihydroquinone derivatives 3 and 6.

The components of the two major classes of natural products of the composite Encelia farinosa , sesquiterpene lactones and benzopyrans/benzofurans (chromenes), were resolved and quantified by high performance liquid chromatography. Geographic variation was examined over a range of mesic and xeric populations from California and Arizona (USA). The concentration of farinosin, a sesquiterpene lactone, varies significantly between individuals and seasonally within individuals. Ontogenetic comparisons revealed interpopulation variations within sesquiterpene lactones and chromenes. A geographic survey suggests the presence of two putative chemical races which vary in the amounts of sesquiterpene lactones and chromenes present. The adaptive significance of this quantitative variation is discussed.

The capacity of a reversed-phase high-performance liquid chromatographic system using Ultrasphere-ODS columns and a gradient of acetonitrile—water to separate sesquiterpene lactones has been studied. Retention times and capacity factors of 33 compounds of the pseudoguaianolide and xanthanolide skeletal types occurring in Parthenium (Asteraceae) are reported. Crude extracts of Parthenium schottii containing a mixture of sesquiterpene lactones have been analyzed and separated using the high-performance liquid chromatographic system.

Elytropappus rhinocerotis (Asteraceae) is a dominant, fire-adapted species of renosterveld shrub communities in the Cape region of South Africa. The leaves are covered by a thick lipophilic resin comprising up to 20% of their dry weight. Approximately 80% of the leaf resin is composed of phenolic and acidic products with the methoxylated flavones cirsimaritin, hispidulin, eupafolin and the flavonol quercetin the main components. Seven benzoic and cinnamic acid derivatives are also present in minor amounts. About 20% of the resin consisted of aliphatic constituents. Bioassays indicated allelopathic effects of the resin on the seed germination of Lactuca and Raphanus . The predominance of lipophilic flavonoids and phenolics suggests a dual role of repelling herbivores and reducing cuticular transpiration. Calorimetric measurements indicated no significant contribution of the non-volatile resin to the flammability of E. rhinocerotis .

Two populations of Encelia californica (Asteraceae) were analysed for chromenes and benzofurans on an organ specific basis using HPLC. Both classes of compounds were present in all parts of the plant studied including roots, stems, leaves, capitula and achenes. The distribution patterns were less complex in roots and achenes when compared to stems, leaves and capitula which yielded three chromenes and two benzofurans. In addition to the chromenes and benzofurans the capitula afforded a sesquiterpene lactone of the eudesmanolide type which was absent in the other parts of the plant.

The leaf alkanes of Parthenium argentatum (guayule), P. tomentosum var. stramonium, P. fruticosum var. trilobatum, and the first filial (F1) generations obtained from crosses with guayule were investigated by GC and mass spectrometry and shown to be useful in chemotaxonomic studies. The identified n-alkanes ranged from C19 to C40 with either n-C29 or n-C31 as the main component. The alkane chemistry of guayule with n-C31 being the main component predominated in most of the F1 hybrids. The presence of iso-branched alkanes (C27, C29, C31) in P. tomentosum and its hybrids could be detected by GC/MS. These preliminary investigations indicate that epicuticular wax alkanes can be useful in inheritance studies of guayule and its hybrids.

The principal contact allergens of the glandular trichomes of Phacelia campanularia and P. pedicellata were identified, and their potential to elicit allergic contact dermatitis was tested with guinea pigs. The active compounds from P. campanularia are novel derivatives of farnesylhydroquinone. The sensitizer of P. pedicellata , also a new compound, is 2,4-dihydroxy-6-geranylphenyl acetate.

Dicoria canescens from Baja California, Mexico afforded the known monoterpene glucoside, (−)- cis -chrysanthenol O -β- d -glucopyranoside, ivalbatin, a xanthanolide and two new sesquiterpene lactones, 4-dihydroivalbatin (dicorin) and 11β, 13-tetrahydrovalbatin (dihydrocorin).

The flavonoid and phenolic acid pattern of Adenostoma fasciculatum and A. sparsifolium, two dominant, endemic species of the Californian chaparral, was analysed qualitatively and quantitatively. Adenostoma sparsifolium was found to secrete large amounts of lipophilic, unusually substituted flavonoids onto the leaf surface; A. fasciculatum produces five hydrophilic flavonol 3-O-glycosides of kaempferol, quercetin and isorhamnetin. The phenolic acid pattern differed quantitatively but not qualitatively between the species. The amounts of phenolic acids that could be detected within the leaves, leaf litter and soil beneath the shrubs seem too small to explain allelopathic effects as the main reason for the dominance of the two species.

Various plants native to arid and semiarid habitats throughout the southwestern United States, Baja California, and northern Mexico were bioassayed for phototoxic natural products. Approximately 115 species representing 57 genera and eight plant families were assayed for phototoxic activity by standard antimicrobial techniques usingEscherichia coli andSaccharomyces cerevisiae. Phototoxic constituents were extracted from numerous members in the Asteraceae (Compositae) and occurred with highest frequency among species of the subtribe Pectidinae (tribe Heliantheae). Extracts ofPectis, the largest genus in the Pectidinae, had substantial light-activated biocidal action despite the paucity of acetylenic thiophenes, the phototoxins characteristic of most other genera in the subtribe. Leaf resin from the creosote bush [Larrea tridentata (Sesse & Mol. ex DC.) Coville; Zygophyllaceae], a dominant desert shrub, possessed potent antimicrobial activity in the absence of light; however, the toxicity of this extract was slightly enhanced in the presence of UVA irradiation. Phototoxic antimicrobials were not detected in extracts of selected species from the Asclepiadaceae, Chenopodiaceae, Hydrophyllaceae, Lamiaceae, Polygonaceae, or Solanaceae.

The discovery of a helenanolide sesquiterpene lactone in Hulsea supports placement of the genus in the tribe Heliantheae.

• Thirteen costus-sensitive patients were patch tested with 38 sesquiterpene lactones of five different classes over a two-year period. Cross-reacting agents fell into two chemical categories: (1) those that resembled the primary sensitizer, and (2) those belonging to different skeletal classes. An exocyclic methylene group conjugated to a γ-lactone was present in both chemicals that cross-reacted and those that did not. The difference between these two groups is that cross-reacting chemicals are not highly substituted, tending to be lipophilic, while those giving negative responses all are highly substituted at the C-8/C-6 position. This functional group may hinder binding of exocyclic methylene with skin protein or the actual antigenic site with an immune receptor cell. ( Arch Dermatol 116:59-60, 1980)

A new flavone 5,6-dimethoxy-3,7,4′-trihydroxyflavone was isolated from the external leaf resin of Adenostoma sparsifolium and identified by spect

A new diacetylene, 11,12-dehydrofaicarinol, was isolated from the ornamental ivy Hedera helix cv. Hahn's self-branching. Published 13 C NMR assignments of falcarinol and related compounds are corrected.

Geranylgeranylhydroquinone and 1-oxofarnesylhydroquinone were identified as contact allergens in trichomes of Phacelia minor and P. parryi .

The roots of Ambrosia chamissonis gave, in addition to known 1,2-dithia-3,5-cyclohexadienes, a new epoxide, a diol and their corresponding thiophenes.

Four flavonoids were identified from the external leaf extract of Adenostoma sparsifolium : the two new flavones 3, 7-dihydroxy-5, 6-dimethoxyflavone and 3, 5, 7-trihydroxy-8-methoxyflavone and the known compounds galangin and pinocembrin.