Botond Borcsa

Diterpene Alkaloids from Aconitum anthora and Assessment of the hERG-Inhibiting Ability of Aconitum Alkaloids

A new norditerpene alkaloid, 10-hydroxy-8- O-methyltalatizamine (1), was isolated from the whole plant of ACONITUM ANTHORA L. besides the known isotalatizidine (2) and hetisinone (3). The structures were determined by means of HR-ESI-MS, 1D and 2D NMR spectroscopy, including ¹H-¹H COSY, NOESY, HSQC and HMBC experiments, resulting in complete ¹H and ¹³C chemical shift assignments for 1- 3, and revision of some earlier ¹³C-NMR data. The effects of the isolated compounds, together with twenty-one other ACONITUM alkaloids with different skeletal types and substitution patterns, on hERG channels were studied by the whole-cell patch clamp technique, using the QPatch-16 automated patch clamp system. At 10 µM, aconitine, 14-benzoylaconine 8- O-palmitate, songoramine, gigactonine and neolinine demonstrated significant hERG K+ channel inhibition; all other compounds exerted only low (6-21%) inhibitory activity.

Diterpene alkaloids from the roots of Aconitum moldavicum and assessment of Nav 1.2 sodium channel activity of aconitum alkaloids.

A new aconitane alkaloid, 1-O-demethylswatinine (1), was isolated from the root of Aconitum moldavicum together with the known compounds cammaconine (2), columbianine (3), swatinine (4), gigactonine (5), delcosine (6), lycoctonine (7), and ajacine (8). The structures were established by means of HRESIMS, 1D and 2D NMR spectroscopy, including 1H-1H COSY, NOESY, HSQC, and HMBC experiments, resulting in complete 1H-NMR chemical shift assignments for 1-4. The effects of the isolated compounds 4-8, together with eighteen other Aconitum diterpene and norditerpene alkaloids with different skeletal types and substitution patterns, were studied on Nav 1.2 channels by the whole-cell patch clamp technique, using the QPatch-16 automated patch clamp system. Pyroaconitine, ajacine, septentriodine, and delectinine demonstrated significant Nav 1.2 channel inhibition (57-42 %) at 10 µM concentration; several other compounds (acovulparine, acotoxicine, hetisinone, 14-benzoylaconine-8-O-palmitate, aconitine, and lycoctonine) exerted moderate inhibitory activity (30-22 %), while the rest of the tested alkaloids were considered to be inactive. On the basis of these results and by exhaustive comparison of data of previously published computerized QSAR studies on diterpene alkaloids, certain conclusions on the structure-activity relationships of Aconitum alkaloids concerning Nav 1.2 channel inhibitory activity are proposed.

Comparison of a specific HPLC determination of toxic aconite alkaloids in processed Radix aconiti with a titration method of total alkaloids

Context: In traditional Chinese medicine, Aconitum (Ranunculaceae) roots are only applied after processing. Nevertheless, several cases of poisoning by improperly processed aconite roots have been reported. Objective: The aim of this study was to develop a reliable analytical method to assess the amount of toxic aconite alkaloids in commercial aconite roots, and to compare this method with the commonly used total alkaloid content determination by titration. Materials and methods: The content of mesaconitine, aconitine, and hypaconitine in 16 commercial samples of processed aconite roots was determined by an HPLC method and the total alkaloid content by indirect titration. Five samples were selected for in vivo toxicological investigation. Results: In most of the commercial samples, toxic alkaloids were not detectable, or only traces were found. In four samples, we could detect >0.04% toxic aconite alkaloids, the highest with a content of 0.16%. The results of HPLC analysis were compared with the results obtained by titration, and no correlation was found between the two methods. The in vivo results reassured the validity of the HPLC determination. Discussion and conclusion: Samples with mesaconitine, aconitine, and hypaconitine content below the HPLC detection limit still contained up to 0.2% alkaloids determined by titration. Since titration of alkaloids gives no information selectively on the aconitine-type alkaloid content and toxicity of aconite roots this method is not appropriate for safety assessment. The HPLC method developed by us provides a quick and reliable assessment of toxicity and should be considered as a purity test in pharmacopoeia monographs.