Hypericum pedersenii: A Source of Novel Phloroglucinol With Cytotoxic Potential

A new dimeric acylphloroglucinol, pedersenol A (1), was isolated from the flowering aerials parts of Hypericum pedersenii, along with the known compound hyperbrasilol B. The structure of 1 was elucidated using one-dimensional, two-dimensional nuclear magnetic resonance, and mass spectrometry experiments, and by comparison with previously reported data for Hypericum dimeric acylphloroglucinols. Among several activities investigated for phloroglucinol derivatives, there are reports of cytotoxic effects. Thus, the hexane extract, the new phloroglucinol derivative, and some structurally related compounds isolated from several species of Hypericum native to south Brazil were assayed. Pedersenol A, hyperbrasilol B, and uliginosin B exhibited significant cytotoxic effects on HeLa, SiHa, Me-180, and K-562 cancer cell lines, with pedersenol A exhibiting great selective index for all tumor cell lines (selectivity index ≥10). This study demonstrates the value of natural product research in discovering selective and effective anticancer agents.