Daphnicyclidin M, a new alkaloid from Daphniphyllum paxianum Rosanth

A new daphniphyllum alkaloid daphnicyclidin M (1), containing one rare cyclopentadienyl anion, was isolated from the stems and leaves of Daphniphyllum paxianum Rosanth along with five known alkaloids, long-istylumphylline A (2), caldaphnidine A (3), caldaphnidine E (4), daphnilongeranin A (5), and 2-hydroxyyunnandaphnine D (6). The structures were elucidated on the basis of spectroscopic data, and the absolute configuration of 1 was assigned by single-crystal X-ray diffraction crystallography. The isolated compounds were found to have no antibacterial activity against Bacillus subtilis, Escherichia coll., Bacillus cereus, Staphylococcus aureus and Erwinia carotovora.