Schinortriterpenoids with Identical Configuration but Distinct ECD Spectra Generated by Nondegenerate Exciton Coupling

Ten schinortriterpenoids with biogenetically related lancischiartane scaffolds, including the first 3-norlancischiartane (<b>1</b>) with unusual configuration inversions occurring at C-1 and C-10, were isolated from <i>Schisandra lancifolia</i>. Unusual ECD curve patterns observed in <b>6</b>–<b>8</b> were confirmed to be caused by nondegenerate exciton coupling, suggesting that ECD spectrum empirical comparison should be used with caution in configuration determination. Additionally, structure revision of <b>2</b>, originally proposed as arisanlactone A, was completed using NMR computation and X-ray diffraction analysis

Isoscoparins R and S, two new <i>ent</i>-clerodane diterpenoids from <i>Isodon scoparius</i>

<p>Two new <i>ent</i>-clerodane diterpenoids, named isoscoparins R and S (<b>1</b> and <b>2</b>), were isolated from the aerial parts of <i>Isodon scoparius</i>. Their structures were characterized mainly by analyzing the NMR and HRESIMS data, and the relative configuration of compound <b>1</b> was determined by single-crystal X-ray diffraction. Compound <b>2</b> showed weak activity as an autophagic inhibitor.</p

7α,20-Epoxy-<i>ent</i>-kaurane Diterpenoids from the Aerial Parts of <i>Isodon pharicus</i>

A phytochemical investigation of an ethyl acetate extract of the aerial parts of <i>Isodon pharicus</i> led to the isolation of 21 new 7α,20-epoxy-<i>ent</i>-kaurane diterpenoids, pharicins C–W (<b>1</b>–<b>21</b>), and 29 known (<b>22</b>–<b>50</b>) analogues. The structural characterization of <b>1</b>–<b>21</b> and assignment of their relative configurations were accomplished by spectroscopic data interpretation, while the structures of <b>1</b> and <b>16</b> were confirmed by X-ray crystallography. The absolute stereostructure of <b>1</b> was confirmed by electronic circular dichroism data analysis. Twenty-five of the diterpenoids were screened for their cytotoxic activities against a panel of tumor cell lines, including HL-60, SMMC-7721, A-549, MCF-7, and SW-480. Compounds <b>11</b>, <b>16</b>, <b>38</b>, and <b>48</b> exhibited inhibitory activities against these tumor cell lines with IC₅₀ values ranging from 1.01 to 9.62 μM, while <b>2</b>, <b>15</b>, <b>29</b>, and <b>47</b> exhibited moderate cytotoxic potency