Separation and detection of apricot leaf triterpenes by high-performance thin-layer chromatography combined with direct bioautography and mass spectrometry

Prunus armeniaca leaf extract was screened for antibacterial compounds by high-performance thinlayer chromatography (HPTLC)-direct bioautography using a Gram-positive Bacillus subtilis bacterium. Six chromatographic zones exhibited characteristic bioactivity. Five of them also appeared after derivatization with vanillin-sulfuric acid reagent and could be characterized with HPTLC-electrospray ionization (ESI)-mass spectrometry (MS), suggesting the presence of triterpenoids and the fatty acids linolenic and palmitic acid. To confirm the identification of triterpenoids an HPTLC method using in situ prechromatographic derivatization with iodine was developed to separate the closely related triterpenoids. After development, the iodine could be eliminated from the chromatogram (verified by HPTLC-MS), making it suitable for the B. subtilis assay. Ursolic acid, oleanolic acid, betulinic acid, corosolic acid, and maslinic acid were discovered for the first time as antibacterial components of P. armeniaca leaves. Their presence was proved also by 2D-HPTLC combined with intermediate in situ derivatization by iodine. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

Automated summary

An antibacterial component screening of Prunus armeniaca leaf extract was conducted using HPTLC-direct bioautography and HPTLC-ESI-MS techniques. Triterpenoids and fatty acids were identified as the bioactive compounds. Ursolic acid, oleanolic acid, betulinic acid, corosolic acid, and maslinic acid were discovered for the first time as antibacterial components of P. armeniaca leaves, and their presence was confirmed by 2D-HPTLC and in situ derivatization with iodine.