Search results for "RPE"

The Synthesis of Bioactive Sesquiterpenes from Santonin

2000

Abstract This article reviews the literature published in the last decade dealing with the transformation of α-santonin into bioactive or potentially bioactive sesquiterpenes. A number of syntheses starting from 8α-hydroxysantonin (artemisin) have also been included. Special emphasis has been placed on synthesized products that show biological activity. Major advances in this field include the application of new reagents and methodologies for the structural modification of the santonin skeleton and functionality, and its transformation into other sesquiterpenes, especially sesquiterpene lactones. The review has been organised into five parts: 1. Introduction: An overview of the structure an…

Triterpene saponins from Schefflera abyssinica

2006

1987

X-ray measurements of stretched crosslinked liquid-crystalline side group polymers show that two types of orientation of the mesogenic groups relative to the polymer chains (parallel or perpendicular) are possible, depending on the structure of the polymer chain. For two liquid-crystalline polymethacrylates with long spacer groups (6 methylene units) the mesogenic groups orient preferably perpendicularly to the polymer chains (axis of strain). For three liquid-crystalline polyacrylates with long or short spacer groups (6 or 2 methylene units), the mesogenic groups orient preferably parallel to the polymer chains (axis of strain). The reason for this difference is not yet clear. These result…

Biologically and Pharmacologically Active Saponins from Plants: Recent Advances

2000

Saponins as triterpene or steroid glycosides were well known in ancient times for their detergent, haemolytic and fish toxic activities, properties which are correlated with the amphiphilic character of the molecules and their ability to complex cholesterol.

Neo-clerodane diterpenoids from Teucrium kotschyanum

1989

Abstract From the aerial parts of Teucrium kotschyanum three new neo-clerodane diterpenoids have been isolated. Their structures, (12R)-15,16-epoxy-19-nor-10α-neo-cleroda-4,13(16),14-triene-18,6β; 20,12-diolide (12-epiteucvidin), (12R)-15,16-epoxy-19-nor-neo-cleroda-4,13(16),14-triene-18,6β; 20,12-diolide (12-epiteufiin) and (12S,18R)-15,16-epoxy-6β-hydroxy-neo-cleroda-13(16),14-dien-20,12-olide-l8,19-hemiacetal (teukotschyn), have been established by chemical and spectroscopic means. In addition, ursolic acid, the flavones cirsimaritin and cirsiliol, and six previously known neo-clerodane diterpenoids (teucvidin, teuflin, teuscorodin, teucrin H2, teuscorodonin and montanin D) were also fou…

Riesenzellbildung und virusspezifische antigene bei herpesvirus hominis: Informationsflu� von der eltern-DNS

1969

Es wird uber den Einflus von Cytosin-Arabinosid, Hydroxy-Urea und von Mitomycin C auf die Entstehung membranstandiger oder extrahierbarer Antigene, auf die Riesenzellbildung sowie auf die Herpesvirus-bedingte Hemmung der Zell-RNS-Synthese berichtet. Durch die Verabreichung der drei Substanzen wird die Reduplikation der DNS des eingedrungenen Virus vollig blockiert. Trotzdem lassen sich die Phanomene der Riesenzellbildung, der Virus-Antigen-Synthese und der Synthesehemmung der Zell-RNS in vollem Umfange nachweisen.

Electrosynthesis of Stable Betulin‐Derived Nitrile Oxides and their Application in Synthesis of Cytostatic Lupane‐Type Triterpenoid‐Isoxazole Conjuga…

2021

Synthetic studies toward natural furanosesquiterpenoids from santonin. Synthesis of (+)-1,2-dihydrotubipofuran

1994

Abstract Santonin (1) was converted into (+)-1,2-dihydrotubipofuran (13) via a synthetic pathway involving a very easy preparation of 7,11-ene-8,12-olide and 8,12-furan moieties and A-ring elaboration on the eudesmane framework.

Bonandiol: A new, irregular, monocyclic diterpene from (L.) Halacsy (umbelliferae)

1984

A new, irregular, monocyclic diterpene, bonandiol (1), has been isolated from Bonannia graeca. The structure of bonandiol has been deduced from spectral data and chemical evidence.

Sesquiterpene lactones, flavonoids and coumarins from Centaurea collina

1989

Abstract The isolation and characterization of two coumarins, five flavonoids and four sesquiterpene lactones from the aerial parts of Centaurea collina are reported. The 13 C NMR data are included.