Caffeoylquinic acid derivatives (CQAs) from <i>Daphne gemmata</i> and their antimicrobial activities

One new caffeoylquinic acid derivative, daphnequinic acid (<b>1</b>), along with six known analogues (<b>2</b>-<b>7</b>), were isolated from <i>Daphne gemmata</i>. The new caffeoylquinic acid was elucidated through interpretation of comprehensive NMR spectral data, in combination with a quantum chemical calculations ECD analysis. Compounds <b>1</b>-<b>7</b> were evaluated for their antimicrobial activities against <i>E. coli</i>, <i>S. aureus</i>, <i>S. enterica</i>, and <i>P. aeruginosa</i>. The antibacterial activity assay demonstrated that compounds <b>3</b>, <b>6</b>, and <b>7</b> exhibited moderate antibacterial activity against <i>S. aureus</i>, with minimum inhibitory concentration (IC₅₀) values of (41.97 ± 0.16) <i>μ</i>M, (23.35 ± 0.32) <i>μ</i>M, and (18.91 ± 1.55) <i>μ</i>M, respectively.