Abstract
Phytochemical investigation of the stem bark of Syzygium cumini (L.) Skeels (Myrtaceae) yielded four new lignan derivatives characterised as (7α,8α,2′α)-3,4,5-trimethoxy-7,3′,1′,9′-diepoxylignan (cuminiresinol), (7α,7′α,8α,8′α)-3,4-dioxymethylene-3′,4′-dimethoxy-7,9′,7′,9-diepoxylignan-5′-ol (5′-hydroxy-methyl-piperitol), (7α,7′α,8α,8′α)-3′-methoxy-9-oxo-7,9′,7′,9-diepoxylignan-3,4,4′-triol or 3-demethyl-9-oxo-pinoresinol (syzygiresinol A), (7α,7′α,8α,8′α)-9-oxo-7,9′,7′,9-diepoxylignan-3,4,3′,4′,5′-pentaol or 3,3′-didemethyl-9-oxo-pinoresinol (syzygiresinol B) along with the known lignans di-demethyl-5-hydroxypinoresinol, dimethylpinoresinol, didemethoxypinoresinol, pinoresinol and 4′-methyl-5′-hydroxypinoresinol. The structures of these lignans were elucidated on the basis of structural data analysis and chemical reactions.