Pharmacologically Active C-19 Diterpenoid Alkaloids from the Aerial parts of Aconitum laeve Royle

Two new lycoctonine type C19-diterpenoid alkaloids, swatinine-A (1), and swatinine-B (2), along with four known C19-diterpenoid alkaloids, foresticine (3), neoline (4), delvestine (5), and chasmanine (6), were isolated from the aerial parts of the Aconitum laeve Royle. The structures of compounds 1 and 2 were deduced on the basis of spectroscopic techniques (EI-MS, HREI-MS, 1H NMR, 13C NMR, HMQC, and HMBC). Biological activities like inhibition of the multifunctional copper-containing enzyme tyrosinase, anti-oxidant and anti-inflammatory have also been carried out for all the compounds and reported herein. The structure-activity relationships for the inhibition of the enzyme tyrosinase by the compounds have been discussed.