Parvifloranines A and B, Two 11-Carbon Alkaloids from Geijera parviflora

Two novel alkaloids (parvifloranines A and B), possessing an unusual 11-carbon skeleton linked with amino acids, were isolated from Geijera parviflora, an endemic Australian Rutaceae. Their structures were elucidated by extensive spectroscopic measurements including 2D NMR analyses. Parvifloranine A was found to be a mixture of two enantiomers, (S)-1 and (R)-1, in a ratio of 1:4, based on their separation using a chiral column. Parvifloranine B is also believed to be a mixture of enantiomers. Proposed biosynthetic pathways are discussed. Parvifloranine A inhibited the synthesis of nitric oxide in LPS-stimulated RAW 264.7 macrophages with an IC₅₀ value of 23.4 μM.