Fungicidal activity of natural and synthetic sesquiterpene lactone analogs

Fungicidal activity of 36 natural and synthetic sesquiterpene lactones with guaianolide, trans, trans-germacranolide, cis, cis-germacranolide, melampo lide, and eudesmanolide carbon skeletons was evaluated against the phytopat hogenic fungi Colletotrichum acutatum, C. fragariae, C. gloeosporioides, Fu sarium oxysporum. Botrytis cinerea, and Phomopsis sp. Dose response data fo r the active compounds dehydrozaluzanin C. dehydrocostuslactone, 5 alpha-hy droxydehydrocostuslacone, costunolide, and zaluzanin C are presented. A new 96-well microbioassay procedure for fast and easy evaluation of antifungal activity was used to compare these compounds with commercial fungicide sta ndards. Some structure-activity conclusions are also presented. (C) 2000 Pu blished by Elsevier Science Ltd. All rights reserved.