Determination of macrocyclic ellagitannin oenothein B in plant materials by HPLC-DAD-MS: method development and validation.

Oenothein B (OeB) is a dimeric macrocyclic ellagitannin occurring mainly in the genus Oenothera. In the literature no validated HPLC method for quantification of this compound has been reported. To develop and validate an efficient HPLC method for quantification of OeB in plant materials. Extraction conditions of OeB from plant material were optimised. Then the first validated HPLC method for quantification was developed. We have shown that ultrasonic-assisted extraction at 40 °C in 15 min using water are the most optimal conditions for OeB extraction. We have quantified OeB in several plant materials belonging to Oenotheraceae family. The lowest amount of OeB was present in Circaea lutetiana herb (27.64 ± 0.26 mg/g) and the highest was quantified in Epilobium hirsutum aerial parts (72.91 ± 1.38 mg/g). The first HPLC method for quantification of OeB in plant materials was developed and validated. We also for the first time optimised the extraction conditions for OeB.