| Summary: | Diterpenes from the <i>Euphorbia</i> genus are known for their ability to regulate the protein kinase C (PKC) family, which mediates their ability to promote the proliferation of neural precursor cells (NPCs) or neuroblast differentiation into neurons. In this work, we describe the isolation from <i>E. resinifera</i> Berg latex of fifteen 12-deoxyphorbol esters (<b>1</b>–<b>15</b>). A triester of 12-deoxy-16-hydroxyphorbol (<b>4</b>) and a 12-deoxyphorbol 13,20-diester (<b>13</b>) are described here for the first time. Additionally, detailed structural elucidation is provided for compounds <b>3</b>, <b>5</b>, <b>6</b>, <b>14</b> and <b>15</b>. The absolute configuration for compounds <b>3</b>, <b>4</b>, <b>6</b>, <b>13</b>, <b>14</b> and <b>15</b> was established by the comparison of their theoretical and experimental electronic circular dichroism (ECD) spectra. Access to the above-described collection of 12-deoxyphorbol derivatives, with several substitution patterns and attached acyl moieties, allowed for the study of their fragmentation patterns in the collision-induced dissociation of multiple ions, without precursor ion isolation mass spectra experiments (HRMS<sup>E</sup>), which, in turn, revealed a correlation between specific substitution patterns and the fragmentation pathways in their HRMS<sup>E</sup> spectra. In turn, this allowed for a targeted UHPLC-HRMS<sup>E</sup> analysis and a biased non-targeted UHPLC-HRMS<sup>E</sup> analysis of 12-deoxyphorbols in <i>E. resinifera</i> latex which yielded the detection and identification of four additional 12-deoxyphorbols not previously isolated in the initial column fractionation work. One of them, identified as 12-deoxy-16-hydroxyphorbol 20-acetate 13-phenylacetate 16-propionate (<b>20</b>), has not been described before.
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