Unraveling the functional components in medicinal <i>Aloe</i> species based on UPLC-MS/MS metabolomics

The typical <i>Aloe</i> plant is well known for its dual role as food and medicine, possessing an array of immune-modulating, antioxidant, antimicrobial, and antitumor properties. Species of <i>Aloe</i> are widely used in cosmetics, therapeutics, and health products. Here, using the LC-QTRAP ultra-high-performance liquid chromatography platform, a total of 813 metabolites were identified in <i>Aloe</i> plants. Principal component analysis and correlation analysis were conducted on 15 typical medicinal <i>Aloe</i> species. An, enrichment analysis of the metabolites found was performed using Kyoto Encyclopedia of Genes and Genomes, Human Metabolome Database, and LipidMaps databases. Based on the metabolomic data, 105 key metabolites were selected for a heatmap analysis, including 34 flavonoids, 16 quinones, 13 phenolic acids, 13 amino acids and derivatives, 6 organic acids, 5 lipids, 3 alkaloids, 2 lignans and coumarins, and 13 other metabolites. Dendrogram-based chemodiversity classification grouped these <i>Aloe</i> species into three major clusters: Group 1 whose sole member is <i>Aloe vera</i>; Group 2 consisting of <i>Aloe arborescens</i>, <i>Aloe kedongensis</i>, <i>Aloe secundiflora</i>, <i>Aloe greatheadii</i> var. <i>davyana</i>, <i>Aloe zebrina</i>, and <i>Aloe dewetii</i>; and Group 3 comprising <i>Aloe vera</i> var. <i>chinensis</i>, <i>Aloe marlothii</i>, <i>Aloe ferox</i>, <i>Aloe divaricata</i>, <i>Aloe rupestris</i>, <i>Aloe petricola</i>, <i>Aloe africana</i>, and <i>Aloe excelsa</i>. Further, the partial least squares discrimination analysis uncovered significant chemodiversity among the <i>Aloe</i> species. The enrichment analysis revealed that <i>Aloe</i> species metabolites were enriched mainly in pathways related to aminoacyl-tRNA biosynthesis, phenylalanine, tyrosine, and tryptophan biosynthesis, valine, leucine, and isoleucine biosynthesis, phenylalanine metabolism, the citrate cycle, glyoxylate and dicarboxylate metabolism, and valine, leucine, and isoleucine degradation. Altogether, these findings suggest significant potential for advancing key <i>Aloe</i> species to meet various human needs. Ultimately, this study enhances our understanding of the metabolic profiles of different <i>Aloe</i> species for their potential improved use in future applications.