Diterpene Alkaloids from Aconitum anthora and A. moldavicum

Aconitum , Delphinium and Consolida species are known to produce various hydroxy-, alkoxy- and ester-substituted diterpene alkaloids. Many alkaloids exhibit high toxicity and a broad spectrum of pharmacological activities, including antinociceptive, anti-inflammatory, local anaesthetic and tyrosinase inhibitory activities [1,2]. In recent years it was demonstrated that some diterpene and norditerpene alkaloids exhibit antifeedant, insect repellent activity and cytotoxic effects against different human tumour cell lines with strong molecular selectivity [3]. As a part of our current studies on diterpene alkaloids of Ranunculaceae species Aconitum anthora L. and A. moldavicum L. were investigated. Seven alkaloids were isolated from the alkaloid-containing fractions of the methanolic extracts by means of multistep chromatographic purification, using CC, VLC, PLC, CPC and gelchromatography. The structures were determined with the aid of HR-ESIMS, 1 H-NMR, JMOD, 1 H, 1 H-COSY, NOESY, HSQC and HMBC experiments. Isothalatisidine, 8,14-dimethoxyisothalatisidine and hetisinon were isolated from A. anthora . Two new compounds were identified from A. moldavicum besides ajacine and delcosine. With except of isothalatisidine [4] all alkaloids are reported for the first time from the investigated plant species. The accumulation of the diterpene alkaloids in the different organs of A. anthora was also examined using a newly developed TLC-densitometric method. It was found, that in the flowering period the accumulation of the alkaloids is highest in the generative organs. Taking into consideration the published antifungal, insecticide and antifeedant effects of diterpene alkaloids [3] it can be assumed that these compounds protect the reproductive organs of the plant against fungal infections and insect attacks. References: [1] Ameri, A. (1998) Prog. Neurobiol. 56: 211–223. [2] Shaheen, F. et al. (2005) Phytochemistry 66: 935–40. [3] González-Coloma, A. et al. (2004) J. Chem. Ecol. 30: 1393–1408. [4] Meriçli, A.H. et al. (2000) Pharmazie 55: 696–698.