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

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.