Euphosantianane A–D: Antiproliferative Premyrsinane Diterpenoids from the Endemic Egyptian Plant Euphorbia Sanctae-Catharinae

Abstract

<i>Euphorbia</i> species are rich in diterpenes. A solvent extraction of <i>Euphorbia sanctae-catharinae</i>, a species indigenous to the Southern Sinai of Egypt, afforded several premyrsinane diterpenoids (<b>1</b>⁻<b>4</b>) as well as previously reported metabolites (<b>5</b>⁻<b>13</b>) that included three flavonoids. Isolated compounds were chemically characterized by spectroscopic analysis. Identified compounds were bioassayed for anti-proliferative activity in vitro against colon (Caco-2) and lung (A549) tumor cell lines. Compound <b>9</b> exhibited robust anti-proliferative activity against A549 cells (IC₅₀ = 3.3 µM). Absolute configurations for <b>8</b> versus <b>9</b> were determined by experimental and TDDFT-calculated electronic circular dichorism (ECD) spectra.