Sesquiterpene lactones of Artemisia: TLC analysis and taxonomic significance

Samples of Artemisia arbuscula ssp. arbuscula, A. tridentata ssp. tridentata, ssp. wyomingensis, ssp. vaseyana and ssp. vaseyana f. spiciformis were collected from various locations in Montana and analyzed by TLC for their sesquiterpene lactone content. Artemisia tridentata ssp. tridentata and ssp. wyomingensis are distinct morphologically and chemically, whereas ssp. vaseyana has three distinct chemical groups not yet separated morphologically. Artemisia arbuscula ssp. arbuscula and A. tridentata ssp. vaseyana f. spiciformis are easily separated by morphology but have identical TLC patterns. It has been further shown that the sesquiterpene lactones produced for a particular species or subspecies are the same regardless of the time of the year collected, although the quantity varies from winter to summer.     

Arbusculin-D from Artemisia arbuscula ssp. Arbuscula

Abstract-Arbusculin-D (I), a new eudesmanolide, has been isolated from Artemisia arbuscula Nutt. ssp. arbuscula and is present also in A. arbuscula Nutt. ssp. thermopola Beetle. It represents a structural variant in the lactone grouping.     

Neue acetylenverbindungen aus Leucanthemum-arten und revision der struktur eines germacranolids

The investigation of three Leucanthemum species afforded, in addition to known compounds, two new C₁₇-acetylenes, a new isovalerate, two phenolic acetylenes, a C₁₂-isobutylamide and a new farnesol derivative. Chrysanthemum ferulaceum contains deacetyllaurenobiolide (spiciformin) which is identical with a lactone from Inula britannica previously assumed to be a cis, cis-germacranolide.     

Zwei neue germacranolide aus Artemisia argentea

The aerial parts of Artemisia argentea afforded, in addition to known compounds (arborescin, artemetin, sitosterol and lirioresinol-B-dimethyl ether), two new germacranolides, closely related to ketopelenolide, also isolated from an Artemisa species. The structures were elucidated by intensive ¹H NMR studies and by some chemical transformations.     

Ridentin-β: An eudesmanolide from Artemisia tripartita ssp. rupicola

Ridentin-B (I), a new eudesmanolide, has been isolated from Artemisia tripartite ssp. rupicola. It is biosynthetically closely allied with ridentin (IV), a germacronolide. The stereochemistry of ridentin is discussed.     

Volatile oil constituents of sagebrush

The volatile oil of Artemisia arbuscula arbuscula contained a new irregular monoterpene, 2,5-dimethyl-4-vinyl-1,5-hexadiene-3-ol (isolyratol), which was isolated and identified by spectral means. The optically pure furanoid (2S,5S)-trans-5-methyl-5-vinyltetrahydrofur-2-yl methyl ketone (arbusculone), was also characterized by transformation to known (2S,5S)-trans-linalyl oxide. The former component has never been isolated from natural sources prior to this study. The neutral pentane extract also contained several previously characterized non-head-to-tail monoterpenes including artemiseole, artemisia ketone, artemisyl acetate, methyl santolinate, and santolina triene, as well as the regular monoterpenes 1,8-cineole, camphor, p-cymene, camphene and the C₆ fragment, terelactone.     

Population genetics of the endangered Canarian endemic Atractylis arbuscula (Asteraceae): implications for taxonomy and conservation

We use the information provided by 36 RAPD loci and 15 morphological traits to describe and construe the population differentiation in A. arbuscula, a Canarian endemic Asteraceae threatened with extinction that exhibits a disjunct distribution in the islands of Gran Canaria (var. schizogynophylla) and Lanzarote (var. arbuscula). Our evaluation of morphological characters and the extent of RAPD differentiation found sets the stage for a taxonomic restructuring to hoist both var. arbuscula and var. schizogynophylla to subspecies category. Our genetic results suggest that fragmentation and generally low population sizes are jeopardising the survival of this species through a predominance of stochastic processes in microevolutionary dynamics, especially in Gran Canaria, where subpopulations exhibit the lowest levels of genetic variation and gene flow. If, as most Asteraceae, these plants have a sporophytic self-incompatibility system, the scarce reproductive turnover observed in the much smaller subpopulations from Gran Canaria (ssp. schizogynophylla) is possibly more influenced by a deficiency of S-alleles (that would be provoking the unavailability of compatible mating types, and a cascade of deleterious effects associated with the Allee effect) than by a reduced pollinator visitation frequency. Based on the depauperated values of genetic parameters for this subspecies, urgent mixed subpopulation reinforcements and reintroductions (with specimens belonging to the same subspecies) seem advisable on the grounds that they might allow the isolated habitat remnants to retrieve from inbreeding through the introduction of a new stock of S-alleles and the subsequent production of genotypes that may have a higher selective value.     

Three germacranolides and other constituents from Eremanthus species

The re-investigation of Eremanthus glomerulatus afforded three new germacranolides and a guaianolide, while from E. mollis two known furanoheliangolides and a new phenylpropanol derivative were isolated. The germacranolides most probably are precursors of the widespread glaucolides. The structures were elucidated by spectroscopic methods. The chemotaxonomic situation is discussed briefly.     

P-hydroxyacetophenone derivatives from Artemisia Campestris ssp. Glutinosa

The weakly acidic fraction from Artemisia campestris ssp. glutinosa contains five p-hydroxyacetophenone derivatives, which are structurally biogenetically related.     

Ludalbin,a new lactone from Artemisia ludoviciana

Artemisia ludoviciana Nutt. ssp. albula (Woot.) Keck, a member of the vulgaris complex, contains a sesquiterpene lactone, ludalbin, which is 8-α-acetoxydouglanine.     

New germacranolides and other sesquiterpene lactones from Dicoma species

Two subspecies of Dicoma anomala afforded, in addition to known compounds, an eudesmanolide, a guaianolide and four germacranolides, the latter being closely related 8, 12-lactones. D. schinzii gave three new germacranolides and D. zeyheri a pair of isomeric acetylenic compounds. The structures were elucidated by highfield ¹H NMR spectroscopy. The chemotaxonomic situation of this genus is discussed briefly.     

Novanin: A germacranolide from Artemisia nova

A new germacranolide, novanin (I), has been isolated from Artemisia nova and its structure determined. The compound is also present in small amount in A. tripartite Rydb. ssp. rupicola Beetle.     

New germacranolides from Isocarpha species

The investigation of two Isocarpha species has yielded eight new germacranolides most of them belonging to the heliangolides. In addition to known p-hydroxyacetophenone-derivatives, a new dihydroeuparine derivative was isolated. The chemotaxonomical aspects are discussed.     

Rupicolin-A and -B,rupin-A and -B,and cumambrin-B oxide from Artemisia tripartita ssp. Rupicola

Five new sesquiterpene Iactones have been isolated from Artemisia tripartita Rydb. ssp. rupicola Beetle. The compounds, all guaianolides, are structurally related in what appears to be a sequence in which epoxidation plays the principal role.     

Water- and temperature-dependence of DNA damage and repair in the fruticose lichen Cladonia arbuscula ssp. mitis exposed to UV-B radiation

The induction of cyclobutane pyrimidine dimers (CPDs) by ultraviolet‐B radiation (UV‐B, 280–315 nm) and repair mechanisms were studied in the lichen Cladonia arbuscula ssp. mitis exposed to different temperatures and water status conditions. In addition, the development and repair of CPDs were studied in relation to the different developmental stages of the lichen thallus podetial branches. Air‐dried lichen thalli exposed to UV‐B radiation combined with relatively high visible light (HL, 800 μmol m^?2 s^?1; 400–700 nm) for 7 days showed a progressive increase of CPDs with no substantial repair, although HL was present during and after irradiation with UV‐B. Fully hydrated lichen thalli, that had not been previously exposed to UV‐B radiation for 7 days, were given short‐term UV‐B radiation treatment at 25°C, and accumulated DNA lesions in the form of CPDs, with repair occurring when they were exposed to photoreactivating conditions (2 h of 300 μmol m^?2 s^?1, 400–700 nm). A different pattern was observed when fully hydrated thalli were exposed to short‐term UV‐B radiation at 2°C, in comparison with exposure at 25°C. High levels of CPDs were induced at 2°C under UV‐B irradiation, without significant repair under subsequent photoreactivating light. Likewise, when PAR (300 μmol m^?2 s^?1) and UV‐B radiation were given simultaneously, the CPD levels were not lowered. Throughout all experiments the youngest, less differentiated parts of the lichen thallus – namely ‘tips’, according to our arbitrary subdivision – were the parts showing the highest levels of CPD accumulation and the lowest levels of repair in comparison with the older thallus tissue (‘stems’). Thus the experiments showed that Cladonia arbuscula ssp. mitis is sensitive to UV‐B irradiation in the air‐dried state and is not able to completely repair the damage caused by the radiation. Furthermore, temperature plays a role in the DNA damage repairing capacity of this lichen, since even when fully hydrated, C. arbuscula ssp. mitis did not repair DNA damage at the low temperatures.     

Four new cis,cis-germacranolides from cytotoxic fractions of Melampodium cinereum

The aerial parts of Melampodium cinereum afforded an antineoplastic crude extract from which, besides the known dilactones cinerenin and melampodin B, four new cis-1(10)-cis-4,5- germacranolides, melcanthins DG, were isolated from cytotoxic fractions.     

模拟长期大风对木本猪毛菜表观特征的影响

风是一个重要的生态因子,对植物地上部分的生长和构型有重要影响。植物表观特征对植物获取光能、抵抗外界机械压力有着重要作用。木本猪毛菜(Salsola arbuscula Pall.)是新疆达坂城大风区植被的共建种,也是该区植被恢复潜在的先锋植物。为了研究木本猪毛菜在长期大风环境中形成的独特适应机制,以盆栽实验为手段,设置3个风速(小风:3 m/s,中风:7 m/s,大风:12 m/s),持续吹风105d,定量分析长期大风作用下木本猪毛菜地上部分的生长和空间构型的变化。结果表明:(1)风胁迫减小了木本猪毛菜的株高,增大了其顺风向的基径;大风减小了木本猪毛菜的叶片长度,中风和小风对其叶片长度没有影响;大风和中风增加了木本猪毛菜的叶片数,小风对叶片数没有影响。(2)木本猪毛菜植冠的空间构型在迎风面和背风面出现明显的不对称性;风胁迫减小了木本猪毛菜的主茎弯曲角度、叶倾角;大风和小风减小了木本猪毛菜的冠幅,中风没有影响;大风和中风减小了木本猪毛菜的枝倾角,小风没有影响;木本猪毛菜在大风和中风作用下出现了二级分枝,在小风作用下没有出现二级分枝。木本猪毛菜主要通过减小自身的扩大生长,增加空间构型的不对称性,减小枝与叶的受力面积等方式来降低风的阻力,以适应长期大风。     

New sesquiterpene lactones from Liriodendron tulipifera

Four new sesquiterpene lactones were obtained from L. tulipifera; two germacranolides, lipiferolide (4) and epitulipinolide diepoxide (5) from the leaves, an elemanolide, epitulipdienolide (7), and an eudesmanolide, γ-liriodenolide (6) from the root bark. Structural determination was by physical and chemical methods and by direct correlation to the known epitulipinolide (3). Lipiferolide and epitulipinolide diepoxide possess cytotoxic activity against KB cells.     

Baikal phytogeographic node as the newest center of endemism of Inner Asia

The Baikal center of phytodiversity is a consequence of complicate orographic dislocations that caused conjugated changes in the climate and geochemical processes in the lithosphere. The climatic changes led to adaptive florogenesis. Three phenomena of this kind have been recorded in the Baikal region. The most ancient (Early Tertiary) endemism is connected with the formation of forms of mountainous xerophytic elements of the Selenga Nountains (Vicia tscydenii Malyschev, Festuca dahurica (St.-Yves) V. Krecz. et Bobrov, Astragalus chorinensis Bunge). The latest endemics are found in the mountains of Northeastern Baikal region, their subspecies rank points to their young age and is more clearly exhibited in boreal genera Carex (C. pediformis ssp. kirilovii Turcz.), Festuca (F. ovina ssp. vylazaniae E. Alexeev, F. rubra ssp. baikalensis (Griseb.) Tzvelev), Draba (D. hirta ssp. bargusinensis Nikiforova), etc. An intermediate position in the temporal and florogenetic aspect is expressed in the endemism of the Sayan-Hangayn Range where speciation manifested itself both in the generic series of boreal genesis (Carex tatjanae Malyschev, Stellaria bungeana Fenzl s. str.), and in the ancient Mediterranean ones (Allium malyschevii N. Friesen, Oxytropis kuznetzovii Kryl. et Steinb., Artemisia pycnorhyza Ledeb.).