A Novel Normethylfriedelane-Type Isoprenoid from Syzygium guineense Stem Bark

Isolated from the n-hexane soluble fraction of the chloroform extract of Syzygium guineense stem bark were two friedelane-type isoprenoids, friedelan-3-one (1) and a novel derivative 12-hydroxy-27-normethylfriedelan-3-one (2). Mass, NMR (1- and 2-D), and FTIR spectroscopic techniques were used for structural elucidation. GC-MS analysis of the lipoidal column eluate afforded the known isoprenoids γ-sitosterol (3) and olean-12-en-3-one (4) and the two fatty acids n-hexadecanoic acid (5) and octadecanoic acid (6). This is the first report on the phytochemistry and isolation of the novel 12-hydroxy-27-normethylfriedelan-3-one (2) from the stem bark of this plant. The pharmacological and nutritional profiles of these isoprenoids and fatty acids are highlighted.