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

Abstract

Blue gum (Eucalyptus globulus) 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 (1−4 and 14−17; glubosides A−H, respectively) and 12 known analogues (5−13 and 18−20). Their structures were determined based on extensive spectroscopic data analysis, chemical degradation, and chiral separation. Oleuropeic acid conjugated glucose esters (1−13, 15, 16, 18, and 20) are reported as epimeric mixtures. Compounds 7, 12, 14, 19, and 20 (at 30 μM) inhibited nitrite release in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Compounds 7 and 14 (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.

Pharmaceutical Potential of Remedial Plants and Helminths for Treating Inflammatory Bowel Disease

“…The compound 1,8-cineole demonstrated the downregulation of inflammatory responses in dextran sulfate sodium (DSS)-induced colitis in mice and decreased proinflammatory chemokine production in TNF-stimulated HT-29 cells, proving to be a potent compound in treating human IBD [53]. Monoterpene acid and gallic acid glucose esters and phenolic compounds have also been reported in Eucalyptus species, which have shown a substantial reduction in the production of pro-inflammatory cytokines, including TNF, IL-1β, and IL-6 in LPS-stimulated peripheral blood mononuclear cells (PBMCs) and LPS-stimulated murine macrophage (RAW264.7) cells, indicating significant anti-inflammatory effects [54,55]. Studies have also reported the presence of phenolic compounds (including flavonoids, phenylpropanoids, and polyphenols) [56][57][58] and triterpenoids (including lupine, ursane, and oleanane derivatives) in Melaleuca species [59][60][61][62].…”