Four new withanolides (2–5), together
with 4β,7β,20-trihydroxy-1-oxowitha-2,5,24-trienolide
(1), were isolated from the aerial parts of Eriolarynx
iochromoides. The antiproliferative activity of all compounds
purified from E. iochromoides together with four
withaphysalins and four physangulidines isolated previously from three Deprea species were evaluated against human solid tumor
cell lines. Four withanolides showed antiproliferative activity comparable
in potency to cisplatin. Selectivity toward cancer cells and interaction
with P-glycoprotein of the active withanolides were evaluated.
A set of new guaianolide derivatives (1–9) was obtained from ludartin, achalensolide, and 11,13‐dihydroachalensolide by application of catalytic nitrene transfer reactions. Intermolecular nitrene C(sp3)−H insertions led to the amination of C‐1, C‐2, and C‐10 positions, while alkene aziridination was also observed under these reaction conditions. The antiproliferative activity of natural compounds and their derivatives was evaluated against a panel of human solid tumor cell lines. The results show that an increase in the biological activity was observed following amination at the C‐2 position of Ludartin, thereby demonstrating the interest in late‐stage C−H amination to improve the bioactivity of natural products.
The Front Cover shows the Stevia plant (Stevia yaconensis var. subeglandulosa Hieron) from which Ludartin is isolated. Catalytic C(sp3)–H amination at the C‐2 position of Ludartin provides new analogs of guaianolides with improved antiproliferative properties. Dr. F. Zuloaga and Dr M. Belgrano from Instituto de Botánica Darwinion, San Isidro, Buenos Aires, are gratefully acknowledged for the picture. More information can be found in the Communication by S. J. Castro, V. E. Nicotra, P. Dauban et al.
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