Three new phenanthrene derivatives from <i>Pinalia densa</i> and their cytotoxic activity against human prostate cancer cells

Phytochemical analysis on the entire plant of <i>Pinalia densa</i> disclosed the existence of three new phenanthrene derivatives, named pinadensins A-C (<b>1-3</b>), in addition to ten known compounds (<b>4-13</b>). Structural elucidation of all new compounds was accomplished by several interpreting spectroscopic data such as CD, MS and NMR. Pinadensin A (<b>1</b>) and 9,9'-<i>O</i>-di-(<i>E</i>)-feruloyl-(-)-secoisolariciresinol (<b>12</b>) induced cytotoxic effects in human prostate cancer cell lines (PC-3 and DU145) as well as human normal keratinocyte HaCaT cells in relation to the dose; with an IC₅₀ value of 30.97 ± 9.0 μM, liparisphenanthrene B (<b>11</b>) demonstrated significant cytotoxic action on PC-3, while having a less cytotoxic impact on HaCaT cells.