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

Chromenes and benzofurans of the asteraceae, their chemistry and biological significance

South African Helichrysum species: a review of the traditional uses, biological activity and phytochemistry.

Twenty-one acylphloroglucinol derivatives and further constituents from south african Helichrysum species

In the present study, the titanium dioxide nanoparticles (TiO2NPs) were synthesized by using Ageratina alttissima (L.) King & H.E. Robines. (White Snakeroot) medicinal plant aqueous leaf extracts by microwave irradiation method. The green synthesized TiO2NPs showed the best photocatalyst due to its long thermodynamic stability and strong oxidizing power. The synthesized titanium dioxide nanoparticles were characterized by using UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), and Energy dispersive X-Ray analysis (EDX). FTIR was performed to identify the possible functional biomolecules capped on the surface of TiO2NPs during interaction. In XRD result, the dominant peak of TiO2 2 value is matched with the crystallographic rutile structure which indicates the polycrystalline nature. FESEM analysis revealed the spherical shape and size of the synthesized TiO2NPs. In this study, the degradation process of textile dyes was carried by photocatalytic activity using synthesized TiO2NPs. The photocatalytic activity of the synthesized TiO2NPs showed enhanced percentage of decoloring of textile dyes such as methylene blue (86.79 %), alizarin red (76.32 %), crystal violet (77.59 %), and methyl orange (69.06 %). The findings of this study clearly indicated that the synthesized TiO2 nanoparticles A. alttissima be used as an alternative and eco-friendly compound to remove and degrade the pollutants released from textile and dyeing industries.

http://ukaazpublications.com/attached/publications/Venkatachalam%20(69-75).pdf

Green engineering of titanium dioxide nanoparticles using Ageratina altissima (L.) King & H.E. Robines. medicinal plant aqueous leaf extracts for enhanced photocatalytic activity

Wolfgang Dorner

Papers

Neue sesquiterpenlactone und andere inhaltsstoffe aus vertretern der Eupatorium-gruppe☆

Neue diterpene und sesquiterpene aus südafrikanischen Helichrysum-arten☆