Abstract
Abstract Helichrysum kraussii is used to treat several diseases including tuberculosis. The biologically active compounds and their possible role as phytoalexins were investigated. Jasmonic acid was used as an elicitor to activate the resistance system of the plant, and to initiate the synthesis of defense compounds. To eliminate the risk of pathogen attack and activation of plants in the field, tissue cultures were initiated with the aim of producing cell suspension cultures. Different time intervals and concentrations of jasmonic acid were tested to determine the strongest activation. Two compounds were present in the activated cell cultures that were not present in the controls. After isolation the compounds were identified as the terpenoids α-amyrin and β-amyrin. These terpenoids were tested against the bacterium Bacillus cereus to determine their antibacterial activity. This is the first report of their presence in a Helichrysum species.
Highlights
Introduction and backgroundIntroduction1.1 General introduction and background It is estimated that there are about 250 000 species of higher plants on earth
more is learned of their adaptations every day
small molecular mass compounds produced in the plant after certain stress situations occurred in
Summary
Introduction and backgroundIntroduction1.1 General introduction and background It is estimated that there are about 250 000 species of higher plants on earth. Phytoalexins are small molecular mass compounds produced in the plant after certain stress situations occurred in its environment These stress situations could be a pathogen attack, insects feeding on the plant, UV light, etc. All these factors could be responsible for the activation of the resistance system, and could eventually lead to the production of phytoalexins as the resistance compounds of the plant (Dixon & Harrison, 1994). Jasmonic acid strongly elicits the production of rice phytoalexins, oryzalexins, momilactones, and sakuranetin, in leaves and cell suspension cultures of rice plants (Daniel & Purkayasta, 1995) The aim of this part of the study; was to relate the phytoalexin production observed in cell suspension cultures, to the plants in the field. Prenyl-butyrylphloroglucinol and kaurenoic acid were isolated from H kraussii, and showed antibacterial activity against five Gram positive and two Gram negative bacteria (Bremner & Meyer, 2000)
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