Pinoresinol is a lignan found in Styrax sp. and in Forsythia suspensa. It is also found in the caterpillar of the cabbage butterfly, Pieris rapae where it serves as a defence against ants. In food, it is found in sesame seed, in Brassica vegetables and in olive oil. A first dirigent protein was discovered in Forsythia intermedia. This protein has been found to direct the stereoselective biosynthesis of (+)-pinoresinol from coniferyl alcohol monomers. Recently, a second, enantiocomplementary dirigent protein was identified in Arabidopsis thaliana, which directs enantioselective synthesis of (-)-pinoresinol. Pinoresinol inhibits the enzyme α-glucosidase in vitro and may therefore act as a hypoglycemic agent. A study involving extra virgin olive oil showed that pinoresinol possess in vitro chemoprevention properties. Increased apoptosis and cellular arrest at the G2/M stage in p53-proficient cells occurred.
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