https://pubs.rsc.org/en/content/articlepdf/2019/NP/C8NP00092A

Marine natural products.

The year 2017 marks the twentieth anniversary of terpenoid cyclase structural biology: a trio of terpenoid cyclase structures reported together in 1997 were the first to set the foundation for understanding the enzymes largely responsible for the exquisite chemodiversity of more than 80000 terpenoid natural products. Terpenoid cyclases catalyze the most complex chemical reactions in biology, in that more than half of the substrate carbon atoms undergo changes in bonding and hybridization during a single enzyme-catalyzed cyclization reaction. The past two decades have witnessed structural, functional, and computational studies illuminating the modes of substrate activation that initiate the cyclization cascade, the management and manipulation of high-energy carbocation intermediates that propagate the cyclization cascade, and the chemical strategies that terminate the cyclization cascade. The role of the terpenoid cyclase as a template for catalysis is paramount to its function, and protein engineering can...

Structural and Chemical Biology of Terpenoid Cyclases.

Over the course of the past half century, the structural elucidation of unknown natural products has undergone a tremendous revolution Before World War II, a chemist would have relied almost exclusively on the art of chemical synthesis, primarily in the form of degradation and derivatization reactions, to develop and test structural hypotheses in a process that often took years to complete when grams of material were available Today, a battery of advanced spectroscopic methods, such as multidimensional NMR spectroscopy and high-resolution mass spectrometry, not to mention X-ray crystallography, exist for the expeditious assignment of structures to highly complex molecules isolated from nature in milligram or sub-milligram quantities In fact, it could be argued that the characterization of natural products has become a routine task, one which no longer even requires a reaction flask! This Review makes the case that imaginative detective work and chemical synthesis still have important roles to play in the process of solving nature's most intriguing molecular puzzles

https://onlinelibrary.wiley.com/doi/pdf/10.1002/anie.200590046

Chasing molecules that were never there: misassigned natural products and the role of chemical synthesis in modern structure elucidation.

Medicinal plants are a rich source of bioactive phytochemicals or bionutrients. Studies carried out during the past 2â€“3 decades have shown that these phytochemicals have an important role in preventing chronic diseases like cancer, diabetes and coronary heart disease. The major classes of phytochemicals with disease-preventing functions are dietary fibre, antioxidants, anticancer, detoxifying agents, immunity-potentiating agents and neuropharmacological agents. Each class of these functional agents consists of a wide range of chemicals with differing potency. Some of these phytochemicals have more than one function. There is, however, much scope for further systematic research in screening Indian medicinal plants for these phytochemicals and assessing their potential in protecting against different types of diseases.

https://www.phytojournal.com/archives/2013/vol1issue6/PartA/26.pdf

Phytochemistry of Medicinal Plants

Phloroglucinol compounds of natural origin

Terpen-derivate aus Senecio-arten

Die zum Tribus Heliantheae gehorende Helianthella uniflora enthalt neben Spuren des weitverbreiteten Pentain-ens1 zahlreiche Acetophenon-Derivate(2–12), die alle einen Isopentenyl-Rest als Seitenkette oder als Teil von Ringsystemen besitzen. Die Strukturen ergeben sich aus den spektralen Daten. Ihre biogenetischen Beziehungen werden diskutiert.



New Isopentenyl-acetophenone Derivatives from Helianthella uniflora



Helianthella uniflora belonging to the tribe Heliantheae contains besides traces of the widespread pentayne-ene 1 several acetophenone derivatives all bearing an isopentenyl residue as sidechain or as part of ring systems. The structures are elucidated by their spectral data and the biogenetical relationships are discussed.

Neue Isopentenyl‐acetophenon‐Derivate aus Helianthella uniflora

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

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

Die Untersuchung von zwei Arten der Gattung Flourensia zeigt, das hier neben bereits bekannten, fur die Tribus charakteristischen Acetylenverbindungen vor allem 4-Hydroxyacetophenon-Derivate vorkommen. 14 Verbindungen (2–4, 8, 11, 13, 14, 18–23 und 25) sind bisher noch nicht isoliert worden. Ihre Konstitutionen werden durch spektroskopische Methoden geklart.



On Constituents of the Genus Flourensia



The investigation of two species of the genus Flourensia yields, besides the already known characteristic acetylenic compounds of the tribe, mainly 4-hydroxyacetophenone derivatives. 14 compounds (2–4, 8, 11, 13, 14, 18–23, and 25) have not been isolated before. Their structures have been elucidated by spectroscopic methods.

Michael Grenz

Papers

Terpen-derivate aus Senecio-arten

Neue Isopentenyl‐acetophenon‐Derivate aus Helianthella uniflora

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

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

Über Inhaltsstoffe der Gattung Flourensia