New acylphloroglucinols from a crude acetone extract of Eucalyptus camaldulensis Dehnh. leaf

Acylphloroglucinols are well-known Eucalyptus secondary metabolites which exhibit a variety of structures and bioactivities. The investigation of a crude acetone extract of Eucalyptus camaldulensis leaves led to the isolation of two new acylphloroglucinols, eucalypcamals O and P (1 and 2) together with seven phloroglucinols (3-9), and a benzene derivative (10). Their chemical structures were elucidated by 1D and 2D nuclear magnetic resonance (NMR) spectroscopy and mass spectroscopy. The absolute configurations of compounds 1 and 2 were established by comparison of experimental and calculated electronic circular dichroism (ECD) data. In the putative biosynthetic pathway, eucalypcamals O and P should be derived from hetero-Diels-Alder reaction between grandinol and trans-isoeugenol.

Automated summary

Acylphloroglucinols are secondary metabolites of Eucalyptus trees with various structures and bioactivities. Two new acylphloroglucinols, eucalypcamals O and P, were discovered in a crude acetone extract of Eucalyptus camaldulensis leaves, along with other compounds. Their chemical structures were determined using NMR spectroscopy and mass spectroscopy, and their absolute configurations were confirmed through experimental and calculated ECD data.