UHPLC-QTOF-MS as a valuable tool for the identification of novel faradiol fatty acid diesters of Calendula officinalis flowers

Abstract

Calendula officinalis L. (marigold) flower extracts are recommended for the treatment of minor inflammation of the skin and wounds [1]. Triterpenes from the 20-taraxastene type, especially faradiol seem to be crucial for the anti-inflammatory potential [2, 3]. Besides monols triterpene diols and triols are present in the form of their C3 lauric, myristic and palmitic acid monoesters. Here we report on the isolation of a mixture of novel faradiol fatty acid diesters (20-taraxastene 3β,16β-diester). 1D and 2D NMR analysis revealed the triterpene skeleton and the esterification position. However, only after UHPLC-QTOF-MS analysis the fatty acids could be identified and assigned to the respective triterpene. This method allowed identification of intact [M+H+]+ molecular ion peaks of faradioldimyristate (863.7354 m/z), faradioldipalmitate (919.8302 m/z) and faradiolmyristate, palmitate (891.7633 m/z). Moreover, this technique is also suitable for the separation and identification of the arnitriol A 3- and the lupane-3β,16β,20-triol 3-fatty acid monoesters which is here reported for Calendula officinalis L. flowers for the first time.