title: Very-long-chain 3-hydroxy fatty acids, 3-hydroxy fatty acid methyl esters and 2-alkanols from cuticular waxes of Aloe arborescens leaves.
abstract: The present work aimed at a comprehensive chemical characterization of the cuticular wax mixtures covering leaves of the monocot species Aloe arborescens. The wax mixtures were found to contain typical aliphatic compound classes in characteristic chain length distributions, including alkanes (predominantly C31), primary alcohols (predominantly C28), aldehydes (predominantly C32), fatty acid methyl esters (predominantly C28) and fatty acids (bimodal distribution around C32 and C28). Alkyl esters ranging from C42 to C52 were identified, and found to mainly contain C28 alcohol linked to C16-C20 acids. Three other homologous series were identified as 3-hydroxy fatty acids (predominantly C28), their methyl esters (predominantly C28), and 2-alkanols (predominantly C31). Based on structural similarities and homolog distributions, the biosynthetic pathways leading to these novel wax constituents can be hypothesized. Further detailed analyses showed that the A. arborescens leaf was covered with 15 μg/cm(2) wax on its adaxial side and 36 μg/cm(2) on the abaxial side, with 3:2 and 1:1 ratios between epicuticular and intracuticular wax layers on each side, respectively. Terpenoids were found mainly in the intracuticular waxes, whereas very-long-chain alkanes and fatty acids accumulated to relatively high concentrations in the epicuticular wax, hence near the true surface of the leaf.
authors.affiliation: Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada.
authors.forename: Radu C
authors.initials: RC
authors.lastname: Racovita
authors.affiliation: Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada.
authors.forename: Chen
authors.initials: C
authors.lastname: Peng
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Awakawa
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Ikuro
authors.initials: I
authors.lastname: Abe
authors.affiliation: Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada; Department of Botany, The University of British Columbia, 6270 University Boulevard, Vancouver, BC V6T 1Z4, Canada. Electronic address: reinhard.jetter@botany.ubc.ca.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Jetter
mesh_terms: D000438:Alcohols / Q000737:chemistry / Q000302:isolation & purification*; D000504:Aloe / Q000737:chemistry*; D004952:Esters; D005227:Fatty Acids / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D015394:Molecular Structure; D018515:Plant Leaves / Q000737:chemistry; D014315:Triterpenes / Q000737:chemistry; D014885:Waxes / Q000737:chemistry*
chemical_list: D000438:Alcohols; D004952:Esters; D005227:Fatty Acids; D014315:Triterpenes; D014885:Waxes
keywords: Aloe arborescens; Candelabra aloe; Chain length profiling; Cuticular wax; Fatty acid methyl esters; Hydroxy fatty acids; Secondary alcohols; Wax ester isomers; Xanthorrhoeaceae