Lars Porskjær Christensen

Ginsenosides chemistry, biosynthesis, analysis, and potential health effects.

Ginsenosides are a special group of triterpenoid saponins that can be classified into two groups by the skeleton of their aglycones, namely dammarane- and oleanane-type. Ginsenosides are found nearly exclusively in Panax species (ginseng) and up to now more than 150 naturally occurring ginsenosides have been isolated from roots, leaves/stems, fruits, and/or flower heads of ginseng. Ginsenosides have been the target of a lot of research as they are believed to be the main active principles behind the claims of ginsengs efficacy. The potential health effects of ginsenosides that are discussed in this chapter include anticarcinogenic, immunomodulatory, anti-inflammatory, antiallergic, antiatherosclerotic, antihypertensive, and antidiabetic effects as well as antistress activity and effects on the central nervous system. Ginsensoides can be metabolized in the stomach (acid hydrolysis) and in the gastrointestinal tract (bacterial hydrolysis) or transformed to other ginsenosides by drying and steaming of ginseng to more bioavailable and bioactive ginsenosides. The metabolization and transformation of intact ginsenosides, which seems to play an important role for their potential health effects, are discussed. Qualitative and quantitative analytical techniques for the analysis of ginsenosides are important in relation to quality control of ginseng products and plant material and for the determination of the effects of processing of plant material as well as for the determination of the metabolism and bioavailability of ginsenosides. Analytical techniques for the analysis of ginsenosides that are described in this chapter are thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC) combined with various detectors, gas chromatography (GC), colorimetry, enzyme immunoassays (EIA), capillary electrophoresis (CE), nuclear magnetic resonance (NMR) spectroscopy, and spectrophotometric methods.

Acetylenes and related compounds in anthemideae

Abstract In this review acetylenes and related compounds, such as alkamides, sulphur compounds, isocoumarins and lactones, which have been isolated from the tribe Anthemideae (Asteraceae) are listed. Some of these compounds are widely distributed in Asteraceae, especially in the tribes Astereae, Cynareae and Heliantheae and others are characteristic natural products of this tribe. On the basis of their distribution in Anthemideae, the chemotaxonomy of this tribe is discussed. Furthermore, the biosynthesis of some of the isolated compounds is evaluated.

Acetylenes and related compounds in heliantheae

Abstract In this review acetylenes and related compounds, such as thiophenes, alkamides, unsaturated alkyl ketones and hydrocarbons, which have been isolated from the tribe Heliantheae (Asteraceae) are listed. Some of these compounds are widely distributed in Asteraceae, especially in the tribes Anthemideae, Cynareae, Helenieae and Inuleae. On the basis of their distribution in Heliantheae, the chemotaxonomy of this tribe is discussed. Furthermore the biosyntheses of some of the isolated compounds are evaluated.

Acetylenes and related compounds in astereae

Abstract In this review an attempt has been made to list all acetylenes and related compounds such as polyenes, unsaturated hydrocarbons and thiophenes, which have been isolated from the tribe Cynareae (Asteraceae). Some of these compounds are widely distributed in Asteraceae and others are characteristic natural products of this tribe. On the basis of their distribution in Cynareae, the chemotaxonomy of this tribe is discussed. Furthermore the biosynthesis and biological activities of some of the isolated compounds are evaluated.

Fruits and Vegetables of Moderate Climate

The flavour of fruits and vegetables is a very important aspect of quality. This review has focused on the most important aroma compounds in fruits and vegetables of moderate climate and demonstrated that a wide variety of volatile compounds are formed naturally in the products or after processing that influence the aroma and flavour of fresh and processed fruits and vegetables.

Tuliposides from Tulipa sylvestris and T. turkestanica

Abstract The investigation of leaves⧸stems and flowers of Tulipa turkestanica afforded, in addition to 6-tuliposide A, 1-tuliposide A, tuliposide D and the lactonized aglycones tulipalin A and (−)-tulipalin B, two new tuliposides. The structure of the new tuliposides were determined by spectral methods to be 1- (4-hydroxy-2-methylenebutanoate)-6- (( S )-3,4-dihydroxy-2-methylenebutanoate)- β - d -glucopyranose (tuliposide F) and 6- (( S )-3,4-dihydroxy-2-methylenebutanoate)- d -glucopyranose (6-tuliposide B), the latter being a new acyl derivative of the known 1-tuliposide B. The investigation of Tulipasylvestris gave 6-tuliposide A and B, tuliposide D and tulipalin A and B. The possible biosynthesis of the isolated compounds is briefly discussed.

Compositae dermatitis from airborne parthenolide

Backgroundu2002 Compositae dermatitis confined to exposed skin has often been considered on clinical grounds to be airborne. Although anecdotal clinical and plant chemical reports suggest true airborne allergy, no proof has been procured. Feverfew (Tanacetum parthenium) is a European Compositae plant suspected of causing airborne contact allergy, and its most important allergen is the sesquiterpene lactone (SQL) parthenolide (PHL).

Flavones and other constituents from Centaurea species

Abstract Roots, green parts and flower heads of Centaurea nervosa and C. phrygia were examined separately. Eight flavones, nine polyacetylenes and four tetraenic aldehydes of known structures, together with aplotaxene and the lignan (−)-aretigenin were isolated and characterized. The flavones apigenin, kaempferol 3-methyl ether, kaempferol 3,6-dimethyl ether, centaureidin, jaceidin and hispidulin were found in appreciable amounts in both plants.

Acetylenes and other constituents from Centaurea species

Abstract Roots, green parts and flower heads of Centaurea dealbata and C. montana were examined separately. Thirty-five acetylenes, three monothiophenes and four tetraenic aldehydes of known structures together with aplotaxene, the flavones apigenin, apigenin 3-methyl ether and the lignan (−)-arctigenin were isolated and characterized.

The Polyacetylenes Falcarinol and Falcarindiol Affect Stress Responses in Myotube Cultures in a Biphasic Manner

The effects of the bioactive polyacetylenes, falcarinol and falcarindiol, present in carrots, celery, celeriac and other umbelliferous vegetables, on the stress responses in primary myotube cultures, were studied. Biphasic responses on cellular stress responses in myotube cultures were investigated by exposing them to various concentrations of falcarinol and falcarindiol for 24 h before testing effects of 100 μM H2O2 on the intracellular formation of reactive oxygen species (ROS), transcription of the antioxidative enzyme cytosolic glutathione peroxidase (cGPx), and the heat shock proteins (HSP) HSP70 and HO1. At low concentrations (1.6 to 25 μM) polyacetylenes caused a slightly accelerated intracellular ROS formation, increased cGPx transcription and decreased HSP70 and HO1 transcription. The increased cGPx transcription may be interpreted as an adaptive response to the increased ROS formation and may have caused a reduced demand for the protective functions of the HSPs. ROS formation, however, was substantially decreased after pre-incubation with both polyacetylenes at 50 and 100 μM, the cGPx transcription was reduced and the HSP70 and HO1 transcription increased, indicating a need for the protective and repairing functions of the HSPs. In conclusion, pre-incubation with low concentrations of both polyacetylenes prior to H2O2 exposure induced a cytoprotective effect whereas higher concentrations had adverse effects.