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

This invention provides compositions and methods useful for repelling target pests. The compositions comprise an amount of a monoterpenoid or sesquiterpenoid effective to repel a target pest from a target area, the monoterpenoid or sesquiterpenoid in combination with a carrier. In one embodiment, the monoterpenoid or sesquiterpenoid is from a biorational source, such as a plant volatile. In a particular embodiment, the plant volatile is a monoterpenoid, such as “nepetalactone” (or the individual nepetalactone isomers) derived from catnip ( Nepeta cataria ). In another embodiment, the plant volatile is any one or a combination of sesquiterpenoids derived from the fruit of the Osage orange tree ( Maclura pomifera ). Such compositions have repellency against arthropods, such as cockroaches, mosquitoes, mites, ticks, spiders, and so forth.

Biorational repellents obtained from terpenoids for use against arthropods

8 – Chirality Transfer via Sigmatropic Rearrangements

The different skeletal types of sesquiterpene lactones (SLs) are classified on the basis of their carbocyclic ring skeleton, in which the suffix “olide” is used to indicate the presence of a lactone group. The majority of SLs from higher plants contain α-methylene-γ-lactone functions (1) in which H-7 is, without exception, α-oriented.1–4 Certain liverworts, however, produce SLs of the enantiomeric series.5 In this review the biogenesis of only those common SLs will be considered in which one of the isopropyl methyls of the sesquiterpene ring is oxidized. The major skeletal types of SLs with the generally accepted numbering are outlined in Figure 1. The lactone rings are shown as 12,6-lactonized structures, although many SLs contain 12,8-lactones. The by far largest number of SLs has been isolated from the Asteraceae (Compositae),1–4 but they are also found in other angiosperm families including the Acanthaceae, Amaranthaceae, Apiaceae,6 Aristolochiaceae, Burseraceae, Bombacaceae, Coriariaceae, Illiciaceae, Magnoliaceae, Menispermaceae, Lamiaceae, Lauraceae, Polygonaceae and Winteraceae.

Sesquiterpene Lactones: Biogenesis and Biomimetic Transformations

Bioassay-guided fractionation of the root wood of Magnolia kachirachirai (Kanehira & Yamamoto) Dandy (Magnoliaceae) led to the isolation of three new compounds, kachiraterpenol (1), (E)-2,3-bis(4-hydroxy-3-methoxyphenyl)prop-2-enal (15), and kachiranol (19), together with 27 known compounds, of which 4,4'-dihydroxy-3,3'-dimethoxybenzophenone (16) was isolated for the first time from a natural source. Their structures were elucidated by spectroscopic analysis. Two of these isolates, costunolide (2) and dehydrosaussurea lactone (4), showed cytotoxic properties against MCF-7, NCI-H460, and SF-268 cancer cell lines in vitro.

Cytotoxic sesquiterpenes from Magnolia kachirachirai

Borontrifluoride catalyzed cyclization of costunolide. Synthesis of 4α-hydroxycyclocostunolide

Carbocyclization in natural products—II : Brominative cyclization of dihydrocostunolide

Reversible dimethylamine addition as a protecting reaction for α,β-unsaturated methylene groups of γ-lactones and its regeneration by basic elimination of quaternary ammonium salts: A convenient synthesis of dehydrosaussurea lactone☆☆☆

J.Edmund McCloskey

Papers

Borontrifluoride catalyzed cyclization of costunolide. Synthesis of 4α-hydroxycyclocostunolide

Carbocyclization in natural products—II : Brominative cyclization of dihydrocostunolide

Reversible dimethylamine addition as a protecting reaction for α,β-unsaturated methylene groups of γ-lactones and its regeneration by basic elimination of quaternary ammonium salts: A convenient synthesis of dehydrosaussurea lactone☆☆☆

Thermolysis of elemol. Silver (I) ion catalyzed conversion of elemol to eudesmols