AOB-w is a water-soluble antioxidant extracted from bamboo leaves, containing four flavone C-glucosides (orientin, isoorientin, vitexin, and isovitexin) as functional components. Flavone C-glucoside esters were firstly synthesized by three lipases (CALB, RM IM, and TL IM) in an organic solvent system or a solvent-free system. Results indicated that C12 fatty acid ester exhibited the optimal antioxidant capacity; CALB was the most efficient lipase in both systems; and higher conversion yields were achieved in a solvent-free system. Highest conversion was obtained with 1% water content for CALB and 2% water content for RM IM and TL IM. All lipases displayed absolute 6 00 -regioselectivities with monoester. It is required to consider both hydrophobicity and antioxidant capacity in order to prepare high-efficiency oil-soluble antioxidants. Regression equations were built up to illuminate the relationship between conversion yield of flavone C-glucoside and antioxidant capacity of its corresponding ester. The highest antioxidant capacity could be achieved when conversion yield was nearly 60% for flavone C-glucosides. Based on reaction parameters of flavone C-glucosides, high-efficiency eAOB-o was prepared, which could be expected as an excellent oil-soluble antioxidant in lipids.Practical applications: Water-soluble antioxidant of bamboo leaves (AOB-w) is a natural food antioxidant extracted from bamboo leaves, with four flavone C-glucosides (orientin, isoorientin, vitexin, and isovitexin) as functional components. This study aimed to provide a practical procedure to prepare high-efficiency lipid antioxidant by enzymatic acylation. Based on the optimal parameters from the synthesis of flavone C-glucoside esters, a high-efficiency oil-soluble antioxidant of bamboo leaves (eAOB-o) was prepared. eAOB-o exhibited higher antioxidant capacity than cAOB-o, which has been approved as a food antioxidant in China. Abbreviations: AOB-w, water-soluble antioxidant of bamboo leaves; BLFs, bamboo leaves flavonoids; CALB, Candida antarctica lipase B; cAOB-o, oil-soluble antioxidant of bamboo leaves synthesized by chemical acylation; eAOB-o, oil-soluble antioxidant of bamboo leaves synthesized by enzyme; ESI À , electrospray negative ionization; LDL, lowdensity lipoprotein; MS, mass spectrum; RM IM, Rhizomucor miehei lipase; TLC, thin-layer chromatography; TL IM, Thermomyces lanuginosus lipase 1636Eur.