关键词: 芦荟, HPLC-DAD-ESI-IT-TOF-MSⁿ, 蒽醌, 蒽酮, 色酮, 化学成分, 裂解途径

Abstract: To clarify the chemical constituents of the traditional Chinese medicine Aloe made from Aloe barbadensis, i.e., the concentrated dry matter of the juice of the leaves of A. barbadensis, a systematic qualitative analysis of them was conducted using the technique of HPLC-DAD-ESI-IT-TOF-MSⁿ in conjunction with the comparison of reference compounds and literature search. The gradient elution was performed with water(A)-acetonitrile(B)as mobile phase at a flow rate of 1.0 mL·min^-1. The liquid chromatography-mass spectrometry data were acquired under alternate negative ion and positive ion detection mode using an ESI ion source. The structure elucidation of the chemical constituents was mainly based on negative ion mass spectrometry data. The results were as follows:(1)For the first time, the fragmentation pathways of anthraquinones(aloe-emodin, physcion, and emodin-8-O-β-D-glucoside), anthrones(aloin A, aloinoside A), chromones(aloeresin D, 7-O-methylaloeresin A, altechromone A, aloesin, aloeresin G, and aloeresin C), and α-pyranones(aloenin A, aloenin B)in Aloe made from A. barbadensis were clarified. The fragmentation pathway of anthraquinones was dominated by loss of CO₂ and CO, and that of anthrones was dominated by cleavage of hexosides and loss of CO. The fragmentation pathways of chromones was dominated by cleavage of hexosides and hydrolysis of the ester group, and that of α-pyranones was dominated by cleavage of hexosides and loss of CO₂ and H₂O.(2)A total of 168 chemical constituents of Aloe made from A. barbadensis were detected, and 78 of them were identified on the basis of reference compound comparison, literature retrieval, and chemical database(such as SciFinder)searching. The 78 compounds included 3 anthraquinones, 29 anthrones, 35 chromones, 7 α-pyranones and 4 other constituents. Twenty-three of 78 compounds were discovered in the leaves of A. barbadensis for the first time. Fourteen of 23 were newly discovered compounds, including aloinoside D, isoeleutherin, and ethylidene-aloenin, possessed antibacterial, anti-inflammatory, or free radical scavenging activities. The results of this study further enrich the information on the chemical constituents of the traditional Chinese medicine Aloe made from A. barbadensis, and lay a foundation for the study of the therapeutic material basis and quality control methods of Aloe.

Key words: Aloe, HPLC-DAD-ESI-IT-TOF-MSⁿ, anthraquinone, anthrone, chromone, chemical constituents, fragmentation pathways