Identification and quantitative analysis of the phytoecdysteroids in Silene species (Caryophyllaceae) by high-performance liquid chromatography - Novel ecdysteroids from S-pseudotites

Many species in the genus Silene (Caryophyllaceae) have previously been sho wn to contain ecdysteroids and this genus is recognised as a good source of novel ecdysteroid analogues. We have used ecdysteroid-specific radioimmuno assays and the microplate-based Drosophila melanogaster B-II cell bioassay for ecdysteroid agonist and antagonist activities to identify further phyto ecdysteroid-containing species in this genus. The main ecdysteroid componen ts from 10 Silene species (S. antirrhina, S. chlorifolia, S. cretica, S. di sticha, S. echinata, S. italica, S. portensis, S. pseudotites, S. radicosa, S. regia) were isolated and identified, mainly by normal-phase and reverse d-phase high-performance liquid chromatography. The amount of each ecdyster oid was determined by comparing chromatogram peak areas with those for refe rence 20-hydroxyecdysone (20E) on reversed-phase HPLC. 20E is the most abun dant ecdysteroid in each of the Silene extracts. Polypodine B, 2-deoxy-20-h ydroxyecdysone and ecdysone are also common ecdysteroids in these Silene sp ecies, but the proportions of these ecdysteroids vary between the Silene sp ecies. HPLC proved to be a quick and effective way to screen Silene species , determine ecdysteroid profiles and, hence, identify extracts containing n ovel analogues. An extract of the aerial parts of S. pseudotites was found to contain several new ecdysteroids. These have been isolated and identifie d spectroscopically (by NMR and mass spectrometry) as 2-deoxyecdysone 22 be ta -D-glucoside, 2-deoxy-20,26-dihydroxyecdysone and 2-deoxypolypodine B 3 beta -D-glucoside. Additionally, (5 alpha -H)-2-deoxyintegristerone A (5 al pha-H-2 91%, 5 alpha-H-1 9%) was isolated as an artefact. This study contri butes to the understanding of ecdysteroid distribution in Silene species an d provides further information on the chemotaxonomic significance of ecdyst eroids in Silene species. (C) 2001 Elsevier Science B.V. All rights reserve d.