Biological activities of sesquiterpene lactones

The Asteraceae is characterized by structurally diverse sesquiterpene lactones and furanosesquiterpenes. In this review the tribal, subtribal and generic distribution of sesquiterpene lactones is examined and the compounds’ utility as taxonomic characters discussed. Sesquiterpene lactones fulfill the major requirements for good analytic and synthetic characters. Studies of infraspecific sesquiterpene lactone variation indicate that different elements within complex taxa are often defined by distinct chemistries, termed chemotypes. Chemotypes have been identified within many of the thoroughly investigated taxa:Ambrosia camphorata, A. chamissonis, A. confertiflora, theA. cumanensis-A. psilostachya-A. artemisiifolia complex,A. dumosa, Artemisia tridentata, Gaillardia pulchella andMelampodium leucanthum. Such an analytic usage is mostly restricted to the infraspecific level. Synthetic usage at the interspecific level and above profits from the application of a biogenetically based methodology for sorting out the complex molecules’ carbon-skeletal and substitutional features into unit characters. Cladistics or Hennigian phylogenetic systematics provides a useful framework for such an analysis. Preliminary surveys indicate that sesquiterpene lactones are especially good characters for differentiating subtribes within several major tribes: the Vernonieae, Heliantheae and Mutisieae. As yet, too few data are available for other tribes to discern such patterns. Species surveys inVernonia, Ambrosia, Iva, Parthenium,Tetragonotheca andArtemisia demonstrate that sesquiterpene lactones are useful in discerning infrageneric groups. The biogenetic cladistic analysis of the interspecific sesquiterpene lactone variation inIva shows the efficacy of this analytical methodology. At present, such biogenetically based approaches are impeded by limited biosynthetic evidence and the erratic distribution of sesquiterpene lactones within the family. Instances of apparent displacement of sesquiterpene lactones by other terpenoids (i.e. sesquiterpene furans, alcohols and acids, diterpenes, diterpene acids, etc.) at various taxonomic levels suggest that ultimately sesquiterpene lactones must be interpreted as taxonomic characters in the context of the family’s total terpene chemistry. All taxa from which sesquiterpene lactones have been reported are listed together with the compound names, major structural features and the literature cited. A less-complete listing is provided for taxa producing furanosesquiterpenes. Structures for all reported compounds are included. Two appendices listing alphabetically taxa and compounds and relevant text page numbers permit cross-indexing of plants and compounds.

Sesquiterpene lactones as taxonomic characters in the asteraceae

http://nfudee.nfu.edu.tw/ezfiles/43/1043/img/341/A19%3DSynthesisandluminescentpropertiesofLn3%2B(Eu3%2B,Sm3%2B,Dy3%2B)-doped.pdf

Synthesis and luminescent properties of Ln3+ (Eu3+, Sm3+, Dy3+)-doped lanthanum aluminum germanate LaAlGe2O7 phosphors

Sulfur is the fifteenth most abundant element in the continental crust of the Earth (260 ppm), and the sixth most abundant element in seawater (885 ppm). Sulfur (atomic number 16) has the ground-state electronic structure [Ne]3 s 2 3p 4 , and is the first of the group VIB elements in the periodic table (S, Se, Te, Po). In minerals, sulfur can occur in the formal valence states S2−, S, S4+, and S6+, corresponding to the sulfide minerals, native sulfur , the sulfite minerals, and the sulfate minerals. In the sulfide minerals, S2− functions as a simple anion (e.g. CuFeS2, chalcopyrite) and as a compound S2 anion (e.g. FeS2, pyrite). In the sulfosalts, S2− functions as a component of a complex anion (e.g. AsS3 in tennantite, Cu12As4S13). In the sulfite minerals, S4+ has four valence electrons available for chemical bonding, and occurs in triangular pyramidal coordination with O. In the sulfate minerals, S6+ has six valence electrons available for bonding, and occurs in tetrahedral coordination with O. In addition, there are the thiosulfate minerals, in which S is in the hexavalent state, but is coordinated by three O2− anions and one S2− anion. Chemists frequently write the thiosulfate group as S2O3; however, we write it as SO3S to emphasize that one of the S atoms is an anion and is involved in a tetrahedral group. Although the focus of this chapter is the sulfate minerals, we will deal also with the sulfite and thiosulfate minerals, as they occur in the same types of geochemical environments.

We adopt a pragmatic approach to matters involving chemical bonding. We use bond-valence theory …

The Crystal Chemistry of Sulfate Minerals

2,6-dimethoxy-1,4-benzoquinone, a new contact allergen in commercial woods

REAlGe2O7, neue Verbindungen der Aluminium-Germanate Seltener Erden

A first allergenic sesquiterpene lactone from Chrysanthemum indicum L.: arteglasin-A.

Received September 22 and November 25, 1980 I. Riding, R., Watts, N.R.: Int. Assoc. Sedimentologists 1st Europ. Mtg., Bochum 1980, Abstr. 206 (1980) 2. Riding, R., in : European Fossil Reef Models. Soc. Econ. Paleont. Min. Spec. Publ. (in press) 3. Ginsburg, R.N., Schroeder, J.H.: Sedimentology 20, 575 (1973) 4. Adey, W.H.: Atoll Res. Bull. 187, 1 (1975) 5. Adey, W.H., Burke, R.: Geol. Soc. Am. Bull. 87, 95 (1976) 6. Setchell, W.: Am. Phil. Soc. 65(2), 136 (1926) 7. Emery, K.O., Tracey, J.I., Jr., Ladd, H.S.: U.S. Geol. Surv. Profess. Pap. 260-A 1 (1954) 8. Maxwell, N.: Atlas of the Great Barrier Reef. Amsterdam: Elsevier 1968 9. Laufeld, S.: Sver. geol. Unders C705, 1 (1974)

Erste Seltene Erden-Aluminium-Germanate vom Typ REAlGeO 5

Das Achsenverhgl tuis a:b = |/3: t zeigt die enge Verwandt schaf t zu hexagonalen Ver t re tern dieses Typs wie Nephel in und Tridymit . Einkristal le liegen nur als Bruchst i icke yon gr6Beren Kris ta l len vor, ansons ten werden ausschlieBlich Drillinge mi t Zwill ingsebenen nach (I t0) und (t30) beobachte t , die in R6n tgenbeugungsau fnahmen zu ether ErhShung der Lane -Symmet r i e auf 6in m m fiihren. Als Modellsubstanz fiir eine Koord ina t enbes t immung wurde die S t ruk tur yon NH4LiSO 4 [1~ zugrunde gelegt, die dem Typ (b) nach [2] entspr icht . Das Ergebnis der Verfeinerung nach e inem Rl -Wer t von 2,6 % zeigt die Tabelle (alle Koord ina tenwer te s ind n i t t04 mult ipliziert) :

O. H. Jarchow

Papers

2,6-dimethoxy-1,4-benzoquinone, a new contact allergen in commercial woods

REAlGe2O7, neue Verbindungen der Aluminium-Germanate Seltener Erden

A first allergenic sesquiterpene lactone from Chrysanthemum indicum L.: arteglasin-A.

Erste Seltene Erden-Aluminium-Germanate vom Typ REAlGeO 5

Die Kristallstruktur von RbSiAlO4