Induction of naphthoquinone and flavonoid production in Dionaea muscipula and Drosera capensis

The secondary metabolites (naphthoquinones: plumbagin and ramantaceone, flavonoids: myricetinand quercetin) from Droseraceae plants: Dionaea muscipula and Drosera capensis 'Broadleaf' are used as anticancer drugs and antispasmodic agents. The aim of the study was to check the ability of the biotic elicitors to induce the production of secondary metabolites in in vitro grown D. muscipula and D. capensis 'Broadleaf'. The optimal conditions for micropropagation of both species were described as: 0.75% agar solidified ½ MS medium with 25mg/l ascorbic acid and 2% sucrose, pH 5.6. Autoclaved overnight suspension of Agrobacterium rhizogenes and a crude elicitor from Verticillium dahliae Kleb. were added to ½ MS medium as elicitors, to the final concentration of 2.5% and 0.2–0.4mg%, respectively. A 4–6-week-old plantlets were planted on these media and after 30 days of growth they were collected and the extraction of naphthoquinones and flavonoids was performed. The extraction was carried out in an ultrasonic bath Sonic-5. Quantitative and qualitative determination of naphthoqinones and flavonoids in chloroform and methanol extracts was performed by using NP – HPLC/UV-DAD. Dihydroksypropyl stationary phases, hexane and tetrahydrofuran mixture as eluent and gradient elution were used. HPLC analysis of chloroform extracts indicated 3 times higher accumulation of plumbagin in D. muscipula plants elicited with A. rhizogenes than in the control ones. In D. capensis elicited with A. rhizogenes about 100% increase of ramantaceone was determined. Also increase of myricetin and quercetin content was observed after biotic elicitation. Chloroform and methanol extracts obtained from A. rhizogenes elicited D. muscipula and D. capensis plants show antimicrobial activity. Methanol extracts of D. muscipula exhibit the strongest antimicrobial activity against a broad spectrum of tested human pathogenic bacteria: Enterococcus faecalis, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa; MBC from 25 to 75mg fw/mL.

Acknowledgements: State Committee for Scientific Research, Grant No KBN 0430/P04/2004/26.