University of Bath, UK
Mai Ahmed completed her Master’s degree in Pharmaceutical Sciences at the age of 28 years from Assiut University, Egypt and worked there as an assistant lecturer. In 2011, she got a fully funded scholarship (for which we thank the Egyptian Government) and now she is a fi nal year student in the Dept. of Pharmacy and Pharmacology, University of Bath, UK.
Aconitum napellus is a highly poisonous plant; all of its parts are rich in toxic C19-norditerpenoid alkaloids e.g. aconitine and mesaconitine. General extraction procedures for aconitine and diester diterpenoid alkaloids require maceration in alcohols. Mass spectra of A. napellus seed extracts show various alkaloidal contents. HPLCcombined with mass spectrometry was used to study the stability of aconitine in methanol, followed by separation and identifi cation of the main artefact whose formation could follow a synchronous fragmentation. Th e HRMS data from A. napellus seed extracts, from methanol and acetone, showed the same alkaloidal profi le with an extra peak in the methanolic extract at m/z MH+ = 618.3271, MH+ of O-methyl-14-O-benzoylaconinerequires 618.3278. Its semi-synthesis was carried out by refl uxing aconitine in methanol (6 h at 65oC). Th e suggested mechanism for the formation of thisartefact is via a Grob-type fragmentation, cleavage of the C-7-C-17 bond with the nitrogen lone pair and C-7- C17orientatedanti-parallel to the C-8-acetate bond, and then adding methanol back. Th eNMR data of the HPLC purifi ed artefact (10 mg) were compared with those of aconitine. Assigning the new O-methyl at C-8 followed from the chemical shift data, δH 3.14, 3.28, 3.28, 3.31 and 3.74 (each 3H, s) and δC 49.9, 55.0, 58.5, 59.1 and 62.4 (respectively), while in aconitine, four methoxy singlets appear at δH 3.16, 3.26, 3.29 and 3.75, with associated carbon signals at δC 58.1, 56.1, 59.3 and 61.3. Quaternary C-8 resonates at δC 82.4 in 8-O-methyl-14-O-benzoylaconine and atδC 92.2 in (8-acetoxy) aconitine.