Eucalyptus Sideroxylon Bark Anti-inflammatory Potential, Its UPLC-PDA-ESI-qTOF-MS Profiling, and Isolation of a New Phloroglucinol

Abstract

Eucalyptus barks contain complex biomass of constituents with considerable chemical and structural diversity. Reports about Eucalyptus sideroxylon Cunn. ex Woolls bark composition and biological activities are limited. Non-targeted metabolomic analysis via ultra-performance liquid chromatography-quadrupole-time-of-flight-photodiode array-mass spectrometry (UPLC-qTOF-PDA-MS) enabled first-time detection of 41 secondary metabolites of which 31 were identified including; 6 flavonoids, 4 ellagic acid derivatives, 8 triterpenes, 10 fatty acids and 3 miscellaneous. The isolation and structure elucidation of methyl morolate, β-sitosterol, syringaldeyhde and 7'-deoxyguajavadial A were reported. The bark methylene chloride: methanol (8:2) extract demonstrated significant (P < 0.01) in vitro anti-inflammatory activity through membrane stabilization, protein denaturation inhibition, anti-lipoxygenase, and proteinase inhibition assays. The strongest anti-inflammatory activity was via membrane stabilization (34.4%) as compared to diclofenac sodium (26%) at the same concentration (125 μg/mL). Our study represents the sole complete map for E. sideroxylon bark components and represents it as new anti-inflammatory drug.