New Monoterpene Acid and Gallic Acid Glucose Esters with Anti-Inflammatory Activity from Blue Gum () Leaves.

Blue gum () is a widely used botanical in the cosmeceutical and food industries. Although blue gum leaves are known for abundant essential oils, their nonvolatile phytochemical constituents and bioactivities remain unclear. Herein, a phytochemical investigation of blue gum leaves led to the identification of eight new monoterpene acid and gallic acid glucose esters ( and ; glubosides A-H, respectively) and 12 known analogues ( and ). Their structures were determined based on extensive spectroscopic data analysis, chemical degradation, and chiral separation. Oleuropeic acid conjugated glucose esters (, , , , and ) are reported as epimeric mixtures. Compounds , , , , and (at 30 μM) inhibited nitrite release in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Compounds and (at 3-30 μM) also down-regulated proinflammatory biomarkers, including cytokines (TNF-α, IL-6, and IL-1β), protein expression (iNOS and COX-2), and transcription factor nuclear translocation (NF-κB) in LPS-stimulated RAW264.7 cells. This work highlights the anti-inflammatory potential of phytochemicals from blue gum leaves, which supports their further development as cosmeceutical and/or nutraceutical products.