Rapid and effective recovery of oleanolic and maslinic acid from olive products using centrifugal partition extraction

Oleanolic acid (OA) and maslinic acids (MA) represent the main triterpens of Olea europaea and are characterized as high-value natural compounds with important biological activities. Due to the increased scientific interest of these compounds, large amounts of pure metabolites are urgently needed. In the present study, a separation method based on Centrifugal Partition Extractor (CPE) was developed, resulting in rapid and effective isolation of oleanolic and maslinic acid in pure form. The preliminary study of our group revealed that the unpolar extract of olive leaves (OLUE) contains an important amount of OA while total phenolic fraction (TPF) obtained from the liquid-liquid extraction of EVOO is a good source of MA. Both OLUE and TPF extracts have been initially fractionated by dual-mode CPE using the biphasic system n-hexane-ethylacetate-ethanol-water 3:2:3:2 (v/v/v/v). The analysis was run in ascending mode and lasted 40 min for both extracts resulting in the fast recovery of the enriched fractions. The second step of the process included the treatment of the enriched fractions using pH-zone refining CPE method. The biphasic system consisted of n-hexane-ethylacetate-ethanol-water 8:2:5:5 (v/v/v/v) while TFA and TEA were added in the stationary and mobile phase respectively. Following this two-step procedure, 640 mg of OA and 550mg of MA were recovered with greater than 95% purity, as determined by HPTLC and ¹H-NMR analysis. This methodology can be efficiently used for the large-scale purification of oleanolic and maslinic acid from olive products as well as for the isolation of acidic terpenoids from natural sources.

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