Phloroglucinol–meroterpenoids from the leaves of Eucalyptus camaldulensis Dehnh

Fourteen undescribed phloroglucinol-meroterpenoids, namely eucalypcamals A–N, were isolated from a CH2Cl2 extract of the leaves of Eucalyptus camaldulensis Dehnh. In addition, from the same extract, twelve known phloroglucinols, three known flavonoids, and four known phenolic compounds were also isolated. The structures of the undescribed compounds were analyzed by 1D and 2D nuclear magnetic resonance (NMR) spectroscopy, and high resolution electrospray ionization mass spectrometry (HRESIMS). The assignments of the absolute configurations were performed by comparing the experimental electronic circular dichroism (ECD) data with the calculated values. Eucalyprobusal E was found to be cytotoxic against HCT116, Jurkat, and MDA-MB-231 cell lines with IC50 values of 17.6, 9.44, and 17.9 μM, respectively. Eucalrobusone F exhibited antibacterial activity against methicillin-resistant S. aureus (MRSA) and S. aureus with minimum inhibitory concentration/minimum bactericidal concentration (MIC/MBC) values of 4/4 μg/mL while euglobal Ia1 showed antifungal activity with MIC/MFC values of 16/16 μg/mL. Fourteen undescribed phloroglucinol-meroterpenoids from a CH2Cl2 extract of the leaves of Eucalyptus camaldulensis were isolated and spectroscopically characterized. Their cytotoxic and antimicrobial activities were evaluated. [Display omitted] •Fourteen undescribed phloroglucinol-meroterpenoids were isolated.•Their structures were elucidated on the basis of spectroscopic evidence.•Their cytotoxic and antimicrobial activities were evaluated.•Eucalrobusone F exhibited strong antibacterial activity against MRSA and S. aureus.