Norbergenin derivatives from the stem bark of Diospyros sanza-minika (Ebenaceae) and their radical scavenging activity

Three new norbergenin derivatives, 11-O-p-hydroxybenzoylnorbergenin (3), 4-O-(3′-methylgalloyl)norbergenin (4) and 4-O-syringoylnorbergenin (5) were isolated from the stem bark of Diospyros sanza-minika, along with three known compounds: norbergenin, 4-O-galloylnorbergenin and quercitol. Some of the above compounds showed radical scavenging properties in a DPPH solution assay.