Elicitation of 7-methyljuglone in Drosera capensis

Abstract

Drosera capensis L. (Droseraceae) is an important source of pharmacologically active 1,4-naphthoquinones including 7-methyljuglone which has been shown to have significant antimicrobial and antifungal as well as antituberculosis activity. In this study, we report on the production of 7-methyljuglone in D. c apensis under in vivo conditions by salicylic acid and jasmonic acid elicitation and by applying different strengths of media as well as different levels of total inorganic nitrogen (N) and ratios of nitrate (NO 3 −) to ammonium (NH 4 +) to a plant tissue culture medium. The amount of 7-methyljuglone produced was highest at 60 mM total nitrogen and at a 50:50 nitrate to ammonium ratio, which is ten-times higher when compared to the normal basal Murashige and Skoog growth medium. Elicitation of 7-methyljuglone in greenhouse grown plants using salicylic acid and jasmonic acid showed that the amount of 7-methyljuglone was the highest in the shoots of plants elicited with 50 µM of salicylic acid and jasmonic acid after 48 h and 3 h respectively. In roots, the highest amount of 7-methyljuglone was found in plants treated with 50 µM of salicylic acid and 100 µM of jasmonic acid after 1.5 h. The 7-methyljuglone concentration is generally higher in the roots than in shoots.