Proposed structures of: a) a DGDG di-estolide (DGDG 72:8) identified in this study by HPLC-MS and MS/MS. Exact mass (C87H148O19), 1497.0615 Da; m/z of [M+NH4]+ (C87H152O19N), 1515.0953. b) a DGDG tri-estolide (DGDG 90:10) identified in this study by HPLC-MS and MS/MS. Exact mass (C105H178O21), 1775.2861 Da; m/z of [M+NH4]+ (C105H182O21N), 1793.3199. In these figures the estolide is shown esterified to the sn-2 position of glycerol, as suggested by Hamberg [10], but our data do not preclude the possibility that some or all of the estolides may be esterified at sn-1.